Next Article in Journal
Optimal Scheduling of Integrated Energy Systems with Combined Heat and Power Generation, Photovoltaic and Energy Storage Considering Battery Lifetime Loss
Next Article in Special Issue
Biogas Quality across Small-Scale Biogas Plants: A Case of Central Vietnam
Previous Article in Journal
A Thermal Probability Density–Based Method to Detect the Internal Defects of Power Cable Joints
Previous Article in Special Issue
Valorization of Waste Wood as a Solid Fuel by Torrefaction
Font Type:
Arial Georgia Verdana
Font Size:
Aa Aa Aa
Line Spacing:
Column Width:

Wastewater Treatment and Biogas Recovery Using Anaerobic Membrane Bioreactors (AnMBRs): Strategies and Achievements

Mohammed Ali Musa
Syazwani Idrus
Hasfalina Che Man
1 and
Nik Norsyahariati Nik Daud
Department of Civil Engineering, Faculty of Engineering, University Putra Malaysia, Serdang 43400, Selangor, Malaysia
Department of Civil and Water Resources Engineering, University of Maiduguri, P.M.B. 1069, Maiduguri 600230, Borno State, Nigeria
Author to whom correspondence should be addressed.
Energies 2018, 11(7), 1675;
Submission received: 17 May 2018 / Revised: 14 June 2018 / Accepted: 19 June 2018 / Published: 27 June 2018
(This article belongs to the Special Issue Biofuel and Bioenergy Technology)


Anaerobic digestion is one of the most essential treatment technologies applied to industrial and municipal wastewater treatment. Membrane-coupled anaerobic bioreactors have been used as one alternative to the conventional anaerobic digestion process. They are presumed to offer the advantage of completely reducing or minimizing the volume of sludge and increasing biogas production. However, researchers have consistently reported different kinds of fouling that resulted in the reduction of membrane life span. Depending on the strength of the effluent, factors such as high suspended and dissolved solids, fats, oil and grease, transmembrane pressure (TMP) and flux were reported as major contributors to the membrane fouling. Moreover, extracellular polymeric substances (EPSs) are an important biological substance that defines the properties of sludge flocs, including adhesion, hydrophobicity and settling and have been found to accelerate membrane fouling as well. Extensive studies of AnMBR have been done at laboratory while little is reported at the pilot scale. The significance of factors such as organic loading rates (OLRs), hydraulic retention time (HRT), pH and temperature on the operations of AnMBRs have been discussed. Microbial environmental conditions also played the most important role in the production of biogas and the chemical oxygen demand (COD) removal, but adverse effects of volatile fatty acids formation were reported as the main inhibitory effect. Generally, evaluating the potential parameters and most cost effective technology involved in the production of biogas and its inhibitory effects as well as the effluent quality after treatment is technically challenging, thus future research perspectives relating to food to microorganism F/M ratio interaction, sufficient biofilm within the reactor for microbial attachment was recommended. For the purpose of energy savings and meeting water quality discharge limit, the use of micro filtration was also proposed.

1. Introduction

Over the past century, there has been quite a number of studies on the most economic, efficient and environmental friendly wastewater treatment technologies. Conventional aerobic methods have existed for over a century now, but they have major drawbacks that include sludge production, high energy use for aeration, large operating space and a higher maintenance cost. Moreover, the systems are characterized by uncontrolled release of potential atmospheric greenhouse gases such as methane (CH4), carbon dioxide (CO2), and nitrogen oxide (N2O) that contribute immensely to deterioration of the environment [1], although in the aerobic process quality effluents are produced which comply with standards limits set by the different regulatory bodies, especially in developed countries. However, one obvious disadvantage is the lack of material and energy recovery [2,3]. Hence, interest continues to grow in finding the best alternative.
The advent of anaerobic digestion in the field of wastewater treatment marks the beginning of economic and efficient technology [4]. This is seen in the quality of the effluents discharged, material recovered and energy generated as well as the mode of sludge production, handling and processing [5]. One of the early constraints detected from the onset of this technology was the long hydraulic retention time coupled with the slow growing methanogenic bacteria [6]. However, towards attaining higher efficiency, research focus was moved towards coupling anaerobic bioreactors with membrane filtration units. These systems were seen to offer a more unique and prudent technique over conventional anaerobic method [7]. It simply combines the anaerobic process and membrane technology operating simultaneously. Table 1 presents a comparison of conventional anaerobic treatment and anaerobic membrane bioreactor (AnMBR).
The combination of anaerobic bioreactors with membranes is presumed to reduce the overall energy demand and to facilitate the retention of microorganisms so as to operate with high biomass concentration [9]. Depending on the intended use of the treated effluent, membranes such as microfiltration, ultrafiltration, nano-filtration and reverse osmosis are usually coupled to anaerobic reactors in both industrial and municipal wastewater treatment systems [10]. Buntner et al. [11] studied the combination of an upflow anaerobic sludge blanket (UASB) reactor with ultrafiltration membranes for dairy wastewater treatment at ambient temperature. The intent of this combination was to decrease the COD of the dairy wastewater whilst producing biogas rich in methane and diminish the overall sludge production as well as obtaining high quality effluent. About 150 L/kg COD of biogas was achieved out of which 73% was methane gas. The organic loading rate was up to 4.85 kg COD/m3·day and 95% COD removal was realized, reaching 99% during its stable operation period. However, this is lower compared to the work of Deowan et al. [12]. Both studies were reported at pilot scales, but one configured the membrane externally while the other was submerged within the bioreactor. The aim of this review paper is to gain insight knowledge on the strategies and achievements recorded in the recent past on the use of AnMBR technology, since the idea was presented as a possible solution or substitute that might overcome the disadvantages of conventional wastewater treatment in terms of space utilization, superior effluent quality, energy generation and the overall operation and maintenance cost.

2. Fundamentals of AnMBR

An anaerobic reactor coupled with a membrane was first commercialized by Dorr-Oliver in the early 1980s [13]. It was constructed to treat high strength wastewater (whey) and was named anaerobic membrane bioreactor system. Since then, research on the feasibility and treatment efficiencies of AnMBRs continue, most especially on the type of material and configurations for treating low, medium, and high strength wastewater [14,15,16,17]. The two forms of membrane configuration includes internal and external, as shown in Figure 1, but the external configuration is the most widely reported.

Membrane Configuration Performance

A pilot scale study of municipal wastewater treatment with an external membrane configuration was reported by Huang et al. [14]. The system achieved COD removal efficiency close to 90%, but a slow and linear increase in the filtration resistance was observed under critical flux conditions and subsequently resulted in fouling due to solid accumulation on the surface of the membrane. However, it was observed that gas sparging and additional shear were needed to control membrane fouling. According to Chu et al. [10], high shear stress may interfere with the biological activities during anaerobic digestion of biomass. Furthermore, studies of Zhao et al. [15] showed that the external membrane configuration system is easier to maintain and monitor. However, these require more energy with high hydraulic shear force which might also disrupt anaerobic bio-solids favoring substrates with smaller particle sizes and this in turn causes membrane fouling. In another development, thorough investigations of submersible membrane module coupled to anaerobic bioreactors were reported in [16,17,18,19] and it is believed to overcome the numerous drawbacks of conventional methods of wastewater treatment. However, it also appears that the technology is more suitable for low strength organic loads, especially municipal wastewater as examined in the previous research of [20,21,22].
Martinez-Sosa et al. [3] also examined a submerged anaerobic membrane bioreactor and found 97% COD removal. The final effluent COD was less than 20 mg/L at volumetric organic loading rate of 0.5 to 12.5 kg/m3·day. The system could be termed efficient even though, the temperature fluctuates between 12 °C and 26 °C. Likewise the membrane permeability was not outstanding due to intermittent suction mode and membrane flux that lead to frequent membrane cleaning. Furthermore, investigation of Deowan et al. [12] on a submerged anaerobic membrane bioreactor (SAMBR) treating textile wastewater revealed COD removal efficiency around 90% with negligible fluctuations in some phases. However, 60% color removal was reported in the first phase and subsequently dropped to between 20–50% after the system stabilized. This phenomenon was attributed to color adsorption on the surface of the membrane. In a similar configuration manner, the defects in COD removal were ascribed to the presence of high total nitrogen (TN) and total phosphorus (TP) [23]. In view of that, application of anoxic conditions or an aerobic process or a combination of the two could enhance removal of both TN and TP. Katayon et al. [24], experimented on the effect of vertical and horizontal membrane configurations, in which two procedures consisting of low and high mixed liquor suspended solids (MLSS) concentrations were considered. The results showed that horizontally placed membrane was able to removed 99.2% total solids and 99.73% turbidity at lower MLSS concentration at a mean flux value of 5.03 L/m2h. This is quite higher than those found in vertical modules with high MLSS concentrations and mean flux value of 2.27 L/m2h. Hence, for higher efficiency, maintaining high biomass concentration and sufficient microbial activity with minimal energy utilization would enhance the process of anaerobic membrane bioreactor operation processes.

3. Membrane Performance of Various Wastewater Treatments

3.1. Industrial Wastewater

Industrial regulatory issues towards meeting the stringent water quality discharge permissible limits motivate researchers to study more on finding lasting solutions to the problems associated with the effluent released to the environment. Most industrial wastewaters are regarded as high strength wastewater, because they contain large amounts of settleable, dissolved and suspended solids or other elements such as heavy metals in greater proportion [25,26]. However, the strength of the wastewater could differ from one industry to another owing to the different types of operations. Generally, industrial wastewater comes from streams such as production lines, cooling towers or boiler and cleaning processes that contain diverse substances. These may include organic and inorganic compounds, viruses, bacteria and toxic compounds. Therefore, applying less energy and achieving high COD removal with minimum sludge production is of utmost priority to the water and wastewater treatment industry. For instance, a pilot scale study of SAMBR treating high strength wastewater (raw tannery wastewater) achieved higher COD removal efficiency up to 90% at organic loading rate OLR of 6 g/L·day and biogas yield (0.160 L/g COD removed) [27]. The system performed efficiently, but was strongly characterized by a high hydraulic retention time (HRT) (40 h) and as such, high energy was expended, although the permeate flux remained at (6.8 LMH) which was well below the critical flux (17.5 LMH) as determine in the earlier work of Hu et al. [28]. Similarly, Fush et al. [29] reported treatment of three different high strength wastewater effluents (artificial wastewater, animal slaughterhouse, and sauerkraut brine) using continuous stirrer tank reactor CSTR coupled with membrane filtration units. The COD removal in all the reactors were > 90% at OLR of 20 g COD/L·day, 8 g COD/L·day and 6–8 g COD/L·day respectively. The methane yields were in the range of 0.17–0.30, 0.20–0.34, and 0.12–0.32 Ln/g·COD fed. On the other hand, Saddoud et al. [30] showed that an anaerobic cross-flow ultrafiltration membrane bioreactor exhibited high efficiency removal of suspended solid (SS), biochemical oxygen demand BOD5, COD and microorganisms. It reached >100%, 90%, 88%, and 100% respectively. Biogas production got to 30 liters per day with average of 0.27 L CH4/g·COD yield. Interestingly, this high yield of biogas was achieved at low organic loading rate (OLR) of 2 g COD/L·day.
Most recently, the filtration performance of an AnMBR treating high strength lipid-rich wastewater and corn-to-ethanol thin stillage was conducted by Dereli et al. [31]. The reactors delivered a high COD removal efficiency of up to 99% under stable operating conditions with an average OLR of 8.3, 7.8, and 6.1 kg COD/m3·day. However, the permeate quality turned out to be inferior in quality with increased in solid retention time (SRT). Table 2 present some examples of the biological and membrane performance of different AnMBR applications for treatment of industrial wastewater. Unfortunately, information regarding the membrane performance with respect to biogas production is quite limited in most of the studies.

3.2. Municipal Wastewater

Effluents characterized by low organic strength and high particulate organic matter are mostly reported as municipal wastewater [32]. The ability of AnMBRs in retaining biomass within the reactor has made it a subject of research for municipal wastewater treatment as a possible alternative to the conventional anaerobic treatment process. According to Ho et al. [33], Kocadagistan and Nazmi [34], bioreactors coupled with membranes used for the treatment of municipal wastewater (MWW) have shown excellent effluent quality that meets the stringent discharge standards in terms of COD, suspended solids and pathogen counts removals when compared to conventional anaerobic methods. Moreover, the use membrane bioreactor (MBR), for anaerobic treatment of municipal wastewater in high temperate climate is still a challenge. This is because, domestic wastewater is usually complex in nature and characterized by high fraction of particulate organic matter. It could be in the form of proteins, suspended solids of different origin, and fatty acids with large to moderate biodegradability portions [35]. Based on these characteristics, operation of MWW treatment reactor under psychrophilic temperature (<20 °C) might be some how difficult. Smith et al. [36] compared simulated and actual domestic wastewater (DWW) at the bench-scale using submerged flat-sheet microfiltration membranes. A psychrophilic temperature of 15 °C was set. An average removal efficiency of 92 ± 5% COD was achieved, which corresponds to an average permeate COD of 36 ± 21 mg/L in simulated DWW, while 69 ± 10% was realized during actual DWW treatment. However, it is obvious the membrane in this study utilizes a lot of energy with relatively high concentration of dissolved methane. Although previous references [37,38,39,40,41] have reported the performance of simulated and actual DWW treatments, only a few of them were performed at psychrophilic temperature (15 °C and below). Table 3 summarizes some studies on the use of AnMBRs for domestic wastewater treatment.
Another investigation of Smith et al. [52] showed a simulated domestic wastewater using AnMBR at psychrophilic temperatures of 15, 12, 9, 6, and 3 °C. Remarkably, a total reduction of COD > 95% was realized at a temperature of 6 °C. The success was attributed to viable microbial activity in the membrane biofilm but subsequently give rise to high dissolved methane oversaturation in permeate and consequently fell to 86% at 3 °C. However, decreasing temperature resulted in increased soluble COD in the bioreactor. Thus, this signifies a reduction in suspended biomass activity. Dolejs et al. [53] conducted a research on the effect of psychrophilic temperature shocks on a gas-lift anaerobic membrane bioreactor (Gl-AnMBR) used for treating synthetic domestic wastewater. The stability of the system was measured by transiting between mesophilic and psychrophilic stages having several psychrophilic shocks (12–48 h). The result showed an average COD removal of 94 ± 2% at mesophilic with an average methane yield of 0.19 L CH4/g COD removed (including psychrophilic shocks). More than 80% of the influent COD accumulated in the reactor under psychrophilic in comparison to 39% under mesophilic conditions.
A pilot scale study of anaerobic urban wastewater treatment in a submerged hollow fiber membrane bioreactor was reported by Gimenez et al. [20]. They assessed the effect of a number of operational variables on both biological and physical separation process performance. Mesophilic temperature of 33 °C, at 70 days SRT, and HRT ranging from 20 h down to 6 h. COD removal stood almost at 90%, with no trace of irrevocable fouling observed but yet the methane yield was very low and this was mainly attributed to influent COD/SO4–S ratio. The work of Gouveia et al. [54] on a pilot scale AnMBR coupled to an external ultrafiltration treating MWW also attained COD removal efficiency of 87 ± 1% with specific methane yield of 0.18 and 0.23 Nm3 CH4/kg COD removed at a lower temperature of 18 ± 2 °C. More recently, a toxicity reduction in wastewater (synthetic wastewater) aiming at reuse possibilities was performed at relatively psychrophilic temperature (25 °C) using submerged anaerobic membrane bioreactor with forward osmosis membrane (FO-AnMBR) [55]. The FO-AnMBR process exhibited >96% removal of organic carbon, nearly 100% of total phosphorus and 62% of ammonia-nitrogen respectively. This suggests better removal efficiency than the conventional AnMBR. The average COD removal was 96.7% corresponding to the influent COD concentration of 460 mg/L and a methane production of 0.21 L CH4/g COD. Thus, the system demonstrates high feasibility of energy recovery.

3.3. Synthetic Wastewater

Compounds such as starch, glucose, molasses, peptone, yeast, and cellulose are usually used as synthetic substrates to test new concept of AnMBR. The results of a number of studies are summarized in Table 4. The COD removal efficiencies of those investigations were generally ˃90%, with OLR less than 10 kg COD/m3·day. Effect of HRT and SRT on treatment performance of submerged AnMBR for synthetic low-strength wastewater reveals a total COD removal efficiencies higher than 97% at all the operating conditions with a maximum biogas production in terms of mixed liquor volatile suspended solid (MLVSS) removals (0.056 L CH4/g MLVSS) at infinite SRT [66]. Though increasing in OLR with short hydraulic time HRT and long SRT boosted the methanogenic environment, but membrane fouling was worsened due to a decrease in HRT which heightened the growth of biomass and accumulation of soluble microbial products (SMP). The experiment performed by Jeison et al. [67] on synthetic wastewater using submerged anaerobic membrane bioreactor showed a reversible cake layer formation on short term basis. Additionally, cake consolidation was detected during a long-term operation at a flux close to the critical point. Remarkably, increasing OLR from 50–60 g COD/L·day towards the end of the operation presented high COD removal efficiency greater than 90%.
Fallah et al. [68] reported a significant COD removal of (<99%). In their studies, they considered two hydraulic retention times (24 h and 18 h) using a MBR to remove styrene from a synthetic wastewater having a chemical oxygen demand and styrene concentration of 1500 mg/L and 50 mg/L. nonetheless, reduction in HRT to 18 h caused a release of extracellular polymeric substance (EPS) from the bacterial cells that led to the rise in soluble microbial product (SMP) and sludge deflocculation. Moreover, the dramatic rise in transmembrane pressure TMP which was operating fairly low and constant for a number of days give rise to severe membrane fouling. This trend was attributed to the rise in SMP concentrations and the decrease in mean floc size. Similar research was reported in Ho et al. [69]. The HRT were varied during treatment of synthetic municipal wastewater. The permeate quality was outstanding, irrespective of HRT differences with over 90% COD removal at HRT of 6 h. Methane produce was 0.21 to 0.22 CH4/g COD removed. Conversely, the fraction of methane recovered from the synthetic municipal wastewater declined from 48 to 35% with the reduction of HRT from 12 to 6 h. Subsequently, the result of the increased mixed-liquor soluble COD which was precluded and accumulated in the AnMBR drastically affects the performance.

4. Effect of Microbial Activity on Anaerobic Membrane Performance

During microbial activity, the concentration of volatile fatty acids (VFA) usually reflects the state of anaerobic digestion performance, specifically in the acetogenic and methanogenic phase. According to Wijekoon et al. [70], 85–96% of high strength molasses-based synthetic wastewater was removed as total chemical oxygen demand (COD) at optimum organic loading rate of 8 ± 0.3 kg COD/m3·day. Though it was at higher temperature, but biogas production of 15, 20 and 35 L/day at OLR 5.1 ± 0.1, 8.1 ± 0.3 and 12.0 ± 0.2 kg COD/m3·day respectively was achieved. It was seen from the results of the treatment, increasing loading rate amounts to increase in hydrolytic and methanogenic activities. However, it was also observed that the process performance reached its maximum level with continuing increase in loading rate which subsequently reduce the biological activities of the system.
In anaerobic digestion, rapid methane formation is mostly attributed to the presence of acetic acid and butyric acid. However, acetic acid contributes 70% of the total acidic portion. This might be due to the fact that, all the volatile acids are converted into acetate during metabolism. The presence of propionic acid tends to upset anaerobic digestion processes due to its toxicity among the VFAs, but this effect could be counteracted under thermophilic conditions. The experiments of Speece et al. [71] showed that propionic acid degradation rate to other intermediate was very poor, largely because of lower partial pressure (H2) demand, but it also supports process start up and stabilization under strict anaerobic conditions.
Moreover, methanogenic activity might be inhibited with propionic acid concentrations greater than 1–2 g/L. It could also withstand acetic and butyric acid concentrations up to 10 g/L. Ahmed et al. [72] have found that, microbial respiratory quinones are essential parts of the bacterial respiratory chain that perform a vital role in electron transfer during the period of microbial respiration. However, an investigation of Hiraishi et al. [73] demonstrated that alterations in microbial community structure in a mixed culture of microbes could effectively be quantified using quinone profiles.
Recent research on the effects of temperature and temperature shock on the performance and microbial community structure of a submerged anaerobic membrane bioreactor (SAnMBR) was demonstrated by Gao et al. [21]. The result obtained indicates that not only the diversity, but also the species richness of microbial populations are affected by temperature variation. It further proves that submerged AnMBR performance under temperature shock conditions have no effect on the COD removal ability of the reactor. The biogas production rates were 0.21 ± 0.03, 0.20 ± 0.03 and 0.21 ± 0.02 L/g COD removed. Moreover, no major change is observed in the production and composition of biogas. Nevertheless, temporary production of biogas occurred at temperature shock which affected the abundance and diversity of microbial populations.
According to Iranpour et al. [83], the similarities that exist among the microbial community working under variable temperatures may be connected to the development of thermomesophiles rather than thermophiles. During microbial activity in anaerobic digestion, the release of soluble organic compounds called SMP in normal biomass metabolism is of great interest, not only in terms of achieving discharge standard limits, but also in setting the lower limit for treatments [84]. The significance of SMP in all kinds of wastewater treatment is at the moment objectively well recognized, but complications still come about in trying to measure SMP and draw conclusions when they are present in effluents from plants treating highly complex feeds. However, researchers like Sciener et al. [85] and Chidoba et al. [86] have studied this and conclude that large portions of the soluble organic matter in the effluent from the biological treatment processes are actually SMP.
The work of Judd [87] and Li et al. [88] reveals that microbial activity decreases under prolonged SRT in AnMBR. This is because microbes take a long time to degrade the inorganic matter and require a high concentration of biomass to ensure all the organics are totally degraded. Still, the application of high SRT is advantageous, since it favors biomass growth which is responsible for biodegradability of organic pollutants. It also provides room for higher MLSS in AnMBR that establish starvation conditions to achieve good quality effluent and create a low F/M ratio [89,90].

5. Operational and Performance Parameters

5.1. Temperature

In anaerobic digestion (AD) processes, temperature is a major factor that plays an important role in the stabilization and performance of the whole system [91,92]. Under strict anaerobic conditions, some bacteria thrive well under psychrophilic (<25 °C), mesophilic (25–40 °C) and thermophilic (>45 °C) conditions [93]. According to El-Mashad et al. [92] and Duran et al. [94], thermophilic conditions offer more advantage in terms of specific growth and metabolic rates with comparatively less ammonia inhibition than mesophiles. However, it could also cause higher microbial death rates, poor supernatant quality and reduced process stability due to chronically high propionate concentrations than mesophilic bacteria. Studies on biogas production and wastewater treatment at varying temperature such as psychrophilic (0–20 °C), mesophilic (20–42 °C), and Thermophilic (42–75 °C) were well investigated in [10,12,14,94].
The diversity and activities of microbial communities coupled with thermodynamic equilibrium of the biochemical reactions are adversely affected by temperature [95]. It usually shifts the abundance and activities of specific microbial populations and determines the roles of specific taxa in the AD food chain. It all begins with substrate hydrolysis, followed by acidogenesis, then acetogenesis, and ends with methanogenesis [96]. Study on temperature adaptation was examined by Chidoba, 1985 [86]. It was initially set at mesophilic condition (37 °C) and gradually switched to thermophilic (55 °C). A drastic reduction in biogas production by 15% from the original state of mesophilic was observed. This was attributed to the change in temperature along with increase in VFA to 3000 mg/L. More detailed studies were reported by Song et al. [97] on thermophilic and mesophilic temperature co-phase anaerobic digestions. Their examination exclusively focused on the sewage sludge using the exchange process of digesting sludge between spatially separated mesophilic and thermophilic digesters and compared with single-stage mesophilic and thermophilic anaerobic digestions. It was confirmed that the system stability, effluent quality, specific methane production during single-stage operation was greater in mesophilic than thermophilic., but volatile solids (VS) reduction and total coliform destruction were much higher in single-stage thermophilic than mesophilic digestion.
In the past, study on the effect of temperature range between 40–64 °C using cow manure as the main substrate was well studied by Angelidaki, 1994 [98]. Two different ammonia concentrations (2.5 and 6.0 g N/L) were continuously fed to the lab-scale reactor. It was observed at some stage, precisely (HRT 15 days); the high temperature and ammonia loading resulted in poor process performance. Consequently, a significant change in the amount of biogas production and process stability was seen when the ammonia load was high and temperature reduces to below 55 °C.

5.2. pH

Volatile fatty acid (VFA) concentration usually determines the pH of the effluent, which is one of the influential factor in anaerobic digestion (AD) processes [99]. Different range of pH is required for bacterial growth in AD, comprehensively between 4.0 to 8.5 [100]. However, a pH level of 6.8 to 7.2 suitably favors methanogenic bacteria [101,102]. On the other hand, hydrolysis and acidogenesis thrive well in the pH range between 5.5 and 6.5 [103,104]. It was also shown that, excessively alkaline pH may result in microbial granules disintegration and subsequent failure [105]. The pH adjustment studies in [101] favorably increased methane yield. The maximum cumulative biogas production reached 16,607 mL at pH 7.0 (0.4535 L methane/g VS). However, the yield decreased to 6916 and 9739 mL at pH 6.0 and 8.0, equivalent to 0.1889 L methane/g VS and 0.2659 L methane/g VS, respectively.
Recent research on novel biogas-pH automation control strategy using a combined gas-liquor phase monitoring was developed by Yu et al. [106] using an AnMBR treating high starch wastewater COD (27.53 g/L). The biogas pH progressed with threshold between biogas production rate >98 NmL·h−1 preventing overload and pH > 7.4 preventing under load. The OLR and the effluent COD was doubled to 11.81 kg COD/m3·day and halved as 253.4 mg/L, respectively. In another development, a ternary contour was performed by Mao et al. [107] to picture the pH dissimilarities in ternary buffer system. The variation was controlled by a system composing of VFAs, ammonia and carbonate. However, the accurate simulation of pH variation in AnMBR during methanogenesis is extremely challenging due to enormous magnitude of electrolytes, and as such the ternary macro-quantity buffer salts were chosen for the visualization which denotes the critical pH buffer capacity to during methanogenic stage.
Kim et al. [104] demonstrated that one major problem faced with COD removal especially for starch wastewater is the provision of sufficient carbonate alkalinity. The effect of high pH shocks (pH 8.0, 9.1 and 10.0) on the performance of submerged AnMBR was well reported in [105]. It was found that; pH 8.0 had slight influence, while pH 9.1 and 10.0 shocks have put forth vigorous impact on biogas production, COD removal, and membrane filtration performance. In addition, colloids and solutes accumulation in the sludge suspension further accelerates deterioration of membrane performance. Interestingly, when neutral pH (7) was taken up again, it cost the reactor approximately 1, 6, and 30 days to recover from the previous shocks.
An experiment on the effect of mixed liquor (pH 5 and 9) in the removal of trace organics in both acidic and basic environment was also reported in [106]. A reduction in total organic carbon TOC and total nitrogen TN removal efficiencies was detected with ionisable trace organic contaminants. Hence, the removal efficiencies were extremely pH dependent. Conversely, the biological performance was favorable at near optimum pH (i.e., approximately pH 6–7) with respect to TOC and TN removal efficiencies. As result of the differences in attainment of optimum pH by acidogenic bacteria (5.5–6.5) and methanogens (6.5–8.2), several studies have been conducted on phase separation of acidogenesis and methanogenesis using AnMBRs. For example, Mao et al. [107] demonstrated a two-stage reactor configuration and optimizes each one phase as an entity. VFA accumulation was drastically reduced and the system stability improves to the extent of forbearing greater loading rate and toxicity. Therefore, maintenance and adherence to these features would positively escalate the chance of achieving a high methane yield.

5.3. Effect of OLR

The amount of volatile solids VS fed to a bioreactor at an interval of time under continuous operation is termed as the OLR. Under normal operating conditions, it is expected that an increase in organic loading rate would also increase the quantity of biogas. AnMBR processes have the advantage of tolerating changes in organic loading similar to tolerance to fluctuations in temperature. Organic loadings ranging from 0.5 to 12.5 kg/m3·day was applied to AnMBR for the treatment of domestic wastewater. The system achieved 97% (COD) removal with less than 20 mg/L effluent COD [108]. In a similar experiment by Vincent et al. [109], less than 50 mg/L soluble COD in the effluent was obtained at organic loading rate 0.25 kg/m3·day and 0.7 kg/m3·day using AnMBR. This is not the case in the work of Qiao et al. [110]. The system exhibited very poor effluent quality after a long HRT. Study of the performance of AnMBR by Yingyu et al. [111] showed that biogas yield rose linearly with increasing organic loading. A similar trend was observed by Wijekoon et al. [70] using a two-stage thermophilic AnMBR with continuous increasing loading rate from 5 to 12 kg COD/m3·day. Bornare et al. [112] achieved biogas production increased from 159 to 289 L/day, but they observed a decreased in yield from 0.48 to 0.42 L biogas/g CODremoved when OLR was increased from 0.62 to 1.32 kg COD/m3·day. However, Dereli et al. [113] indicated that OLR could not be an independent parameter and therefore should be assessed along with SRT.
High performance integrated anaerobic–aerobic fixed-film pilot-scale reactor with an arranged media for treating slaughter house wastewater showed a removal efficiency of 93% at OLR of 0.77 kg COD with methane yield of 0.38 m3 CH4/kg COD [114]. High mixing as a result of system integration causes low extension of the anaerobic process and consequently affects the methanogenic activities. A fact known to most researchers in the field of anaerobic digestion is that an increase in OLR could result in excessive VFA formation which may inhibit microbial activities and deteriorate the system. For example, the research of Saddoud et al. [115] confirms that accumulation of VFA was the main reason for methanogenic inhibition, thus, resulting in a decrease in methane yield at OLR of 16.3 kg COD/m3 in one-phase AnMBR. To counteract this effect, they proposed the use of a two-stage AnMBR coupled with an anaerobic filter as acidogenic reactor while a jet flow AnMBR was used as methanogenic reactor at high OLR and realized a substantial improvement in biogas production in the subsequent stage. Jeison et al. [116] presented removal efficiency below 50% using continuous stirrer tank reactor CSTR fed with acidified and partially acidified substrate. Even though the organic loading rates reached 10–17 kg COD/m3·day, the low removal efficiency might be connected to soluble microbial product level within the AnMBR and these could cause irreversible pore fouling in the membranes.

5.4. Effect of HRT and SRT

Operational parameters such as hydraulic retention time (HRT) and solid retention time (SRT) are two factors that play a vital role in the treatment performance of AnMBRs. A study by Mei et al. [61] demonstrated using submerged anaerobic membrane bioreactors (SAnMBRs). SRTs of 30, 60 and infinite and HRT of 12, 10 and 8 h were used. A total COD removal efficiency >97% was observed at all operating conditions. Biogas production rate reached 0.056 L CH4/g MLVSS day at an infinite SRT. However membrane fouling occurred as a result of shorter HRT and infinite SRT. It was also seen that, longer SRT was the main cause of higher SMP production. The presence of SMP subsequently introduces more nutrients onto the membrane surface that caused the blockage of the pores and enhanced biocake formation. Dong et al. [117] reported the influence of SRT and HRT on bioprocess performance of pilot and bench scale AnMBRs using municipal wastewater as substrate. The SRT and HRT applied were 40–10 day and 2.5 to 8.5 h. A good permeate quality with COD concentration (40 mg/L) and BOD5 (10 mg/L) was observed in all conditions. The range of values tested for SRT and HRT have not considerably interfered with COD and BOD5 removal efficiencies. Moreover prolonged SRTs caused a reduced sludge production and increase methane yield.
Similarly, in the research of Ozgun et al. [65], reduction in permeate COD concentrations from 16.5 to 5 mg/L resulted in an increased methane yield from 0.12 to 0.25 L CH4/g COD. The improvement in the quality of effluent and the methane was attributed to prolonged SRT from 30 days to infinite. Salazar et al. [39] and Hu et al. [28] revealed a permeate COD concentration increase from 10 to 50 mg/L with decreasing HRT. However, Liao et al. [35] strongly suggested that, lower HRTs give room for shorter contact time between microorganisms and substrate and therefore might pave way for a part of influent COD leaving the reactor without proper treatment. One very important aspect of AnMBRs is the enabling environment that allows SRT to be completely independent from HRT irrespective of the sludge properties. Conversely, experience and frequent practice shows that longer SRTs operation yield more quantities of biogas. This is because any reduction in the SRT may decrease the extent of reactions required for stable digestion. For instance Huang et al. [66] clearly reported a methane yield of (0.670 ± 0.203 L CH4/day), (0.906 ± 0.357 L CH4/day), (1.290 ± 0.267 L CH4/day) at longer SRT of 30, 60, and infinite days respectively. Therefore, it is apparent that, longer SRT in AnMBRs operations give room for minimal sludge production, and hence cuts disposal cost significantly. Based on the studies on the effects of HRT and SRT conducted so far, it could be seen that prolonging HRT may result in inadequate utilization of AnMBRs’ volume and its reduction may lead to rapid VFA accumulation which may hinder methanogenic activities. Prolonged SRT might also result to membrane fouling. It could also encourage the release of soluble microbial products (SMP) as well as rapid cake formation and excessive decline in flux.

6. Inhibitors

Inhibitory substances are the primary cause of disparity in anaerobic reactors. This might also lead to entire failure of the digestion processes when the concentration is beyond tolerable limits. Anaerobic digestion usually presents different variations in the level of inhibition and toxicity. Mechanisms such as synergism, acclimation, and complexity substrate could considerably upset the phenomenon of inhibition. Nevertheless, bioreactor failures are regularly reported as the result of high ammonia inhibition which directly affects the microbial activity [118].
Kayhanian et al. [119], reported ammonia as one of the inhibitory substances found in anaerobic digestion. It is mainly as a result of biological degradation of nitrogenous matter in the form of proteins and urea. Inorganic ammonia nitrogen like ammonium ion NH4+ and free ammonia (FA) are usually found in aqueous form. FA is considered as the primary cause of inhibition since it is freely membrane-permeable [120,121]. Calli et al. [122] reveal an apparent COD removal of 78–96% in a study of the effect of high free ammonia concentrations in synthetic wastewater using UASB reactor. The reactor was fed at OLR of 1.2 kg COD m3/day with total ammonia nitrogen concentration total ammonia nitrogen (TAN) increasing from 1000 to 6000 mg/L. However, Tchobanoglous et al. [123] showed that, the accumulation of propionic acid along with reduction in eubacterial suggest a sensitivity of propionate degrading acetogenic bacteria to free ammonia than methanogenic archaea. A theoretical stoichiometric relationship of estimating the quantity of ammonia that could be generated from organic substrate in anaerobic biodegradation is shown in Equation (1):
CaHbOcNd + ((4a − b − 2c + 3d)/4)H2O → ((4a + b − 2c − 3d)/8)CH4 + ((4a − b + 2c + 3d)/8)CO2 + dNH3
According to Kayhanian [124], methanogens are the most sensitive to ammonia inhibition among the four bacteria types that exist in anaerobic digestion processes. The effect might even cause the bacteria to cease to grow. Study on the effects of ammonia on propionate degradation and microbial community in bioreactors showed that, using propionate as a sole carbon source result to reactor failure after four hydraulic retention times [125]. A total ammonia nitrogen (TAN) concentration of 2.5 g NL−1 at OLR of 0.8 g propionic acid (HPr)/L·day were observed and 95% of the degraded HPr was converted to methane. On the average, the degradation rate of HPr is below 53%, likewise an average of 74% and 99% HPr degradation and methane recovery rates was also recorded during the last HRT. Thus, these behaviors demonstrate an alteration of the microbial community. Frequent maintenance, change in intracellular pH of methanogens and inhibition of a specific enzyme reactions are some of the numerous suggested pathways for overcoming ammonia inhibition. Thorough understanding of the ammonia toxicity occurrence which ammonia may affect methanogenic bacteria is not readily available but, is the few available studies with unadulterated cultures this was revealed to influence the treatment in two ways: (i) direct inhibition of methane- producing enzymes by ammonium ion and/or (ii) the hydrophobic nature of ammonia molecules which may diffuse passively into bacterial cells causing proton imbalance [126].
Another important anaerobic digestion inhibiting parameter is sulfate. Sulfate is a common constituent of many industrial wastewaters that is converted in to sulfide by the sulfate-reducing bacteria (SRB) [127]. Major SRB includes complete and incomplete oxidizers. Complete oxidizers convert acetate to CO2 and HCO3 completely. Compounds such as lactate are reduced to acetate and CO2 by incomplete oxidizers. Furthermore, primary and secondary inhibitions are the two stages that exist during sulfate reduction [128]. Methane production is suppressed by primary inhibitors as a result of competition for common organic and inorganic substrate by the SBR, but secondary inhibition is caused by various bacterial groups due to the toxicity of sulfide [129,130].

7. Membrane Fouling

Membrane fouling is the result of gradual accumulation of suspended solids (SS) and dissolved solids (DS) mostly in the form of fats, oil and grease onto the surface of the membrane [131]. Mechanisms that propel fouling occur via: (1) deposition of sludge flocs onto the surface, (2) adsorption of solutes within the membrane, (3) surface cake layer formation, and (4) the shear force that exists between membrane surface, soluble microbial products (SMPs) and extracellular polymeric substances (EPS) [132]. The surface blockage or clogging phenomenon is always attributed to the type of membrane itself, biomass and operating conditions. Fouling due to the membrane itself could be attributed to the nature of the material, configuration, hydrophobicity, porosity and pore size of the membrane [8]. Moreover, biomass characteristic such as MLSS, EPS or SMP, flock structure and dissolved matter contribute immensely to causing fouling [4]. Conditions at which membrane bioreactor operates might also increase fouling if not properly monitored. Other factors like cross flow velocity, HRT or SRT, aeration and transmembrane pressure could also contribute significantly to fouling [133].
Zhang et al. [134] further revealed that, the use of adsorbent/flocculants in (AnMBR) could rarely overcome the effect of fouling completely. However, their research revealed that, among the combination of eight additives (three powdered activated carbon PACs, two granular activated carbons, one cationic polymer, and two metal salts), 400 mg/L of PAC was able to reduce transmembrane pressure rise from 0.94 to 0.06 kPa/h. This outcome signified an outstanding fouling reduction technique. Still, the effect of increasing in OLR and reduction of HRT (24–18 h) is clearly confirmed as the main factor responsible for severe membrane fouling, but research by Jeison et al. [67] showed that, extracellular polymeric compounds (EPS) from microbial cells was responsible for the release of SMP and a drastic increase in TMP during the long term operation that led to the occurrence of fouling. Filtration performance of membrane bioreactors is largely dependent on the mixed liquor suspended solids. In the experiments performed by Meng et al. [135], filtration resistance including membrane resistance (12%), cake resistance (80%), blocking and irremovable fouling resistance (8%), depicts that the formation of cake layer is the main cause of membrane fouling. Lee et al. [136] pointed out that cake layers are not uniformly distributed on the entire surface of all of the membrane fibers. It could be wholly covered by a static sludge cake that could not be removed by the sheer force due to aeration, and partially by a thin sludge film that might frequently washed away due to aeration turbulence. A study of Jeison [67] concluded that cake layer formation could be removed despite longer operation period (>200 days). However, during these periods, cake consolidation was seen close to the critical flux. A normal backwashing cycle was unable to remove the consolidated cake and as such physical external treatment was applied. Similarly, Cho et al. [131] and Di-Bella et al. [137] showed that cake layer formations on AnMBRs coupled with external aeration zone could easily be removed. This study suggest that AnMBRs operating with aerobic zones external to the membrane module could achieve higher cake layer removal as compared to cake layer formed on membrane embedded within an anaerobic bioreactor.

8. Conclusions

They has been a quite significant development of technologies towards meeting the stringent environmental regulatory discharge requirements and biogas production. These can be seen in the manner, in which MBRs are configured, variations of operational parameters, and the different techniques adopted towards provision of the basic living conditions for microorganisms to strive. However, membrane lifespan is still the main concern of stakeholders in the water and wastewater treatment industries. The efficiency of physical, chemical and biological methods of reversing fouling on membrane surface is being exploited. Though physical and chemical methods have been sufficient, the disadvantages are huge. A lot of energy is consumed during aeration and considerable amount of chemicals are utilized which does not favor the players in this field with regards to cost and environmentally-wise. Research is still ongoing on the most economical biological methods of producing quality effluent and biogas production using AnMBRs, and future studies should take in to account the following factors:
  • Food to microorganism F/M ratio interaction and HRT of bioreactors operating at thermophilic, mesophilic or psychrophilic temperature. These will offer more information on biogas production and effluent quality.
  • Provision of lining or rough surfaces within the bioreactor (biofilm) would facilitate the retention of large microbial populations preventing them from exiting the reactor along with the effluent if shorter HRT is to be used.
  • If the purpose of the treatment is to meet discharge standard limits, and subsequently discharge the effluent to water bodies, then the use of microfiltration should be encouraged rather than ultrafiltration. This is because; smaller size membrane surface area would require more energy for water to pass through and as such applying ultrafiltration for such treatment would be costly.

Author Contributions

M.A.M. and S.I. conceived the concept for the review; M.A.M. and S.I. analyzed the existing literature; H.C.M. and N.N.N.D. wrote and edited the paper. All authors have read and approved this review.


The work required for the preparation and writing of this review was funded by Universiti Putra Malaysia (UPM) baseline funding GP-IPS/9633400 awarded to Mohammed Ali Musa.

Conflicts of Interest

The authors declare no conflicts of interest.


  1. Tock, J.Y.; Lai, C.L.; Lee, K.T.; Tan, K.T.; Bhatia, S. Banana Biomass as Potential Renewable Energy Resource: A Malaysian Case Study. Renew. Sustain. Energy Rev. 2010, 14, 798–805. [Google Scholar] [CrossRef]
  2. Verstraete, W.; van de Caveye, P.; Diamantis, V. Maximum use of resources present in domestic used water. Bioresour. Technol. 2009, 100, 5537–5545. [Google Scholar] [CrossRef] [PubMed]
  3. Martinez-Sosa, D.; Helmreich, B.; Netter, T.; Paris, S.; Bischof, F.; Horn, H. Anaerobic Submerged Membrane Bioreactor (AnSMBR) for Municipal Wastewater Treatment under Mesophilic and Psychrophilic Temperature Conditions. Bioresour. Technol. 2011, 102, 10377–10385. [Google Scholar] [CrossRef] [PubMed]
  4. Yoon, Y.; Kim, S.; Oh, S.; Kim, C. Potential of Anaerobic Digestion for Material Recovery and Energy Production in Waste Biomass from a Poultry Slaughterhouse. Waste Manag. 2014, 34, 204–209. [Google Scholar] [CrossRef] [PubMed]
  5. Kim, K.Y.; Yang, W.; Ye, Y.; LaBarge, N.; Logan, B.E. Performance of Anaerobic Fluidized Membrane Bioreactors Using Effluents of Microbial Fuel Cells Treating Domestic Wastewater. Bioresour. Technol. 2016, 208, 58–63. [Google Scholar] [CrossRef] [PubMed]
  6. Kanai, M.; Ferre, V.; Wakahara, S.; Yamamoto, T.; Moro, M. A Novel Combination of Methane Fermentation and MBR—Kubota Submerged Anaerobic Membrane Bioreactor Process. Desalination 2010, 250, 964–967. [Google Scholar] [CrossRef]
  7. Harb, M.; Hong, P. Anaerobic Membrane Bioreactor Effluent Reuse: A Review of Microbial Safety Concerns. Fermentation 2017, 3, 39. [Google Scholar] [CrossRef]
  8. Lin, H.; Peng, W.; Zhang, M.; Chen, J.; Hong, H.; Zhang, Y. A Review on Anaerobic Membrane Bioreactors. Applications, Membrane Fouling and Future Perspectives. Desalination 2013, 314, 169–188. [Google Scholar] [CrossRef]
  9. Padmasiri, S.I.; Zhang, J.; Fitch, M.; Norddahl, B.; Morgenroth, E.; Raskin, L. Methanogenic Population Dynamics and Performance of an Anaerobic Membrane Bioreactor (AnMBR) Treating Swine Manure under High Shear Conditions. Water Res. 2007, 41, 134–144. [Google Scholar] [CrossRef] [PubMed]
  10. Chu, L.B.; Yang, F.L.; Zhang, X.W. Anaerobic Treatment of Domestic Wastewater in a Membrane-Coupled Expended Granular Sludge Bed (EGSB) Reactor under Moderate to Low Temperature. Process Biochem. 2005, 40, 1063–1070. [Google Scholar] [CrossRef]
  11. Buntner, D.; Sanchez, A.; Garrido, J.M. Feasibility of Combined UASB and MBR System in Dairy Wastewater Treatment at Ambient Temperatures. Chem. Eng. J. 2013, 230, 475–481. [Google Scholar] [CrossRef]
  12. Deowan, S.A.; Galiano, F.; Hoinkis, J.; Figoli, A.; Drioli, E. Submerged Membrane Bioreactor (SMBR) for Treatment of Textile Dye Wastewatertowards Developing Novel MBR Process. APCBEE Procedia 2013, 5, 259–264. [Google Scholar] [CrossRef]
  13. Skouteris, G.; Hermosilla, D.; López, P.; Negro, C.; Blanco, Á. Anaerobic Membrane Bioreactors for Wastewater Treatment. A Review. Chem. Eng. 2012, 198–199, 138–148. [Google Scholar] [CrossRef]
  14. Huang, Z.; Ong, S.L.; Ng, H.Y. Feasibility of Submerged Anaerobic Membrane Bioreactor (SAMBR) for Treatment of Low-Strength Wastewater. Water Sci. Technol. 2008, 58, 1925–1931. [Google Scholar] [CrossRef] [PubMed]
  15. Zhao, L.; Liu, D.; Wang, X. Effect of Several Factors on Peracetic Acid Pretreatment of Sugarcane Bagasse for Enzymatic Hydrolysis. J. Chem. Technol. Biotechnol. 2007, 82, 115–121. [Google Scholar] [CrossRef]
  16. Van Zyl, P.J.; Wentzel, M.C.; Ekama, G.A.; Riedel, K.J. Design and Start-up of a High Rate Anaerobic Membrane Bioreactor for the Treatment of a Low pH, High Strength, Dissolved Organic Waste Water. Water Sci. Technol. 2008, 57, 291–295. [Google Scholar] [CrossRef] [PubMed]
  17. Akram, A.; Stuckey, D.C.; Kram, A.A.; Tuckey, D.C.S. Biomass Acclimatisation and Adaptation during Start-Up of a Submerged Anaerobic Membrane Bioreactor (SAMBR) Biomass Acclimatisation and Adaptation during Start-Up of a Submerged Anaerobic Membrane Bioreactor (Sambr). Environ. Technol. 2014, 29, 1053–1065. [Google Scholar] [CrossRef] [PubMed]
  18. Vyrides, I.; Stuckey, D.C. Saline Sewage Treatment Using a Submerged Anaerobic Membrane Reactor (SAMBR): Effects of Activated Carbon Addition and Biogas-Sparging Time. Water Res. 2009, 43, 933–942. [Google Scholar] [CrossRef] [PubMed]
  19. Lin, H.; Liao, B.; Chen, J.; Gao, W.; Wang, L.; Wang, F.; Lu, X. New Insights into Membrane Fouling in a Submerged Anaerobic Membrane Bioreactor Based on Characterization of Cake Sludge and Bulk Sludge. Bioresour. Technol. 2011, 102, 2373–2379. [Google Scholar] [CrossRef] [PubMed]
  20. Giménez, J.B.; Robles, A.; Carretero, L.; Durán, F.; Ruano, M.V.; Gatti, M.N.; Ribes, J.; Ferrer, J.; Seco, A. Experimental Study of the Anaerobic Urban Wastewater Treatment in a Submerged Hollow-Fibre Membrane Bioreactor at Pilot Scale. Bioresour. Technol. 2011, 102, 8799–8806. [Google Scholar] [CrossRef] [PubMed]
  21. Gao, W.J.; Leung, K.T.; Qin, W.S.; Liao, B.Q. Effects of temperature and temperature Shock on the Performance and Microbial Community Structure of a Submerged Anaerobic Membrane Bioreactor. Bioresour. Technol. 2011, 102, 8733–8740. [Google Scholar] [CrossRef] [PubMed]
  22. Zhang, X.; Wang, Z.; Wu, Z.; Wei, T.; Lu, F.; Tong, J.; Mai, S. Membrane Fouling in an Anaerobic Dynamic Membrane Bioreactor (AnDMBR) for Municipal Wastewater Treatment: Characteristics of Membrane Foulants and Bulk Sludge. Process Biochem. 2011, 46, 1538–1544. [Google Scholar] [CrossRef]
  23. Lin, H.; Chen, J.; Wang, F.; Ding, L.; Hong, H. Feasibility evaluation of submerged anaerobic membrane bioreactor for municipal secondary wastewater treatment. Desalination 2011, 280, 120–126. [Google Scholar] [CrossRef]
  24. Katayon, S.; Noor, M.J.M.M.; Ahmad, J.; Ghani, L.A.A.; Nagaoka, H.; Aya, H. Effects of Mixed Liquor Suspended Solid Concentrations on Membrane Bioreactor Efficiency for Treatment of Food Industry Wastewater. Desalination 2004, 167, 153–158. [Google Scholar] [CrossRef]
  25. Hogye, S.P. National Small Flows Clearinghouse at West Virginia University, Morgantown; National Environmental Services Center (NESC): Morgantown, WV, USA, 2003. [Google Scholar]
  26. Robinson, A.H. New Developments in the Application of Membrane Bioreactors (MBR) for Industrial Wastewater Treatment; Wehrle Environmental: Witney, UK, 2001. [Google Scholar]
  27. Umaiyakunjaram, R.; Shanmugam, P. Study on Submerged Anaerobic Membrane Bioreactor (SAMBR) Treating High Suspended Solids Raw Tannery Wastewater for Biogas Production. Bioresour. Technol. 2016, 216, 785–792. [Google Scholar] [CrossRef] [PubMed]
  28. Hu, A.Y.; Stuckey, D.C. Treatment of dilute wastewaters using a Novel Submerged Anaerobic Membrane Bioreactor. J. Environ. Eng. 2006, 132, 190–198. [Google Scholar] [CrossRef]
  29. Fuchs, W.; Binder, H.; Mavrias, G.; Braun, R. Anaerobic Treatment of Wastewater with High Organic Content Using a Stirred Tank Reactor Coupled with a Membrane Filtration Unit. Water Res. 2003, 37, 902–908. [Google Scholar] [CrossRef]
  30. Saddoud, A.; Ellouze, M.; Dhouib, A.; Sayadi, S. Anaerobic Membrane Bioreactor Treatment of Domestic Wastewater in Tunisia. Desalination 2007, 207, 205–215. [Google Scholar] [CrossRef]
  31. Dereli, R.K.; Heffernan, B.; Grelot, A.; van der Zee, F.P.; van Lier, J.B. Influence of High Lipid Containing Wastewater on Filtration Performance and Fouling in AnMBRs Operated at Different Solids Retention Times. Sep. Purif. Technol. 2015, 139, 43–52. [Google Scholar] [CrossRef]
  32. Van Lier, J.B. High-Rate Anaerobic Wastewater Treatment: Diversifying from End-of-the-Pipe Treatment to Resource-Oriented Conversion Techniques. Water Sci. Technol. 2008, 57, 1137–1148. [Google Scholar] [CrossRef] [PubMed]
  33. Ho, J.; Sung, S. Methanogenic Activities in Anaerobic Membrane Bioreactors (AnMBR) Treating Synthetic Municipal Wastewater. Bioresour. Technol. 2010, 101, 2191–2196. [Google Scholar] [CrossRef] [PubMed]
  34. Kocadagistan, E.; Topcu, N. Treatment Investigation of the Erzurum City Municipal Wastewaters with Anaerobic Membrane Bioreactors. Desalination 2007, 216, 367–376. [Google Scholar] [CrossRef]
  35. Liao, B.; Kraemer, J.T.; Bagley, D.M. Anaerobic Membrane Bioreactors. Applications and Research Directions Anaerobic Membrane Bioreactors. Applications and Research Directions. Crit. Rev. Environ. Sci. Technol. 2006, 36, 489–530. [Google Scholar] [CrossRef]
  36. Smith, A.L.; Skerlos, S.J.; Raskin, L. Psychrophilic Anaerobic Membrane Bioreactor Treatment of Domestic Wastewater. Water Res. 2013, 47, 1655–1665. [Google Scholar] [CrossRef] [PubMed]
  37. Lew, B.; Tarre, S.; Beliavski, M.; Dosoretz, C.; Green, M. Anaerobic Membrane Bioreactor (AnMBR) for Domestic Wastewater Treatment. Desalination 2009, 243, 251–257. [Google Scholar] [CrossRef]
  38. Martinez-Sosa, D.; Helmreich, B.; Horn, H. Anaerobic Submerged Membrane Bioreactor (AnSMBR) Treating Low-Strength Wastewater under Psychrophilic Temperature Conditions. Process Biochem. 2012, 47, 792–798. [Google Scholar] [CrossRef]
  39. Salazar-Peláez, M.L.; Morgan-Sagastume, J.M.; Noyola, A. Influence of Hydraulic Retention Time on Fouling in a UASB Coupled with an External Ultrafiltration Membrane Treating Synthetic Municipal Wastewater. Desalination 2011, 277, 164–170. [Google Scholar] [CrossRef]
  40. Gao, D.W.; Zhang, T.; Tang, C.Y.Y.; Wu, W.M.; Wong, C.Y.; Lee, Y.H.; Yeh, D.H.; Criddle, C.S. Membrane Fouling in an Anaerobic Membrane Bioreactor: Differences in Relative Abundance of Bacterial Species in the Membrane Foulant Layer and in Suspension. J. Membr. Sci. 2010, 364, 331–338. [Google Scholar] [CrossRef]
  41. Giménez, J.B.; Martí, N.; Ferrer, J.; Seco, A. Methane Recovery Efficiency in a Submerged Anaerobic Membrane Bioreactor (SAnMBR) Treating Sulphate-Rich Urban Wastewater: Evaluation of Methane Losses with the Effluent. Bioresour. Technol. 2012, 118, 67–72. [Google Scholar] [CrossRef] [PubMed]
  42. Svojitka, J.; Dvorak, L.; Studer, M.; Straub, J.O.; Fromelt, H.; Wintgens, T. Performance of an Anaerobic Membrane Bioreactor for Pharmaceutical Wastewater Treatment. Bioresour. Technol. 2017, 229, 180–189. [Google Scholar] [CrossRef] [PubMed]
  43. Kaya, Y.; Bacaksiz, A.M.; Bayrak, H.; Gnder, Z.B.; Vergili, I.; Hasar, H.; Yilmaz, G. Treatment of Chemical Synthesis-Based Pharmaceutical Wastewater in an Ozonation-Anaerobic Membrane Bioreactor (AnMBR) System. Chem. Eng. J. 2017, 322, 293–301. [Google Scholar] [CrossRef]
  44. Mei, X.; Wang, Z.; Miao, Y.; Wu, Z. A Pilot-Scale Anaerobic Membrane Bioreactor under Short Hydraulic Retention Time for Municipal Wastewater Treatment: Performance and Microbial Community Identification. J. Water Reuse Desalin. 2017. [Google Scholar] [CrossRef]
  45. Erkan, H.S.; Engin, G.O. The Investigation of Paper Mill Industry Wastewater Treatment and Activated Sludge Properties in a Submerged Membrane Bioreactor. Water Sci. Technol. 2017. [Google Scholar] [CrossRef] [PubMed]
  46. Hu, D.; Su, H.; Chen, Z.; Cui, Y.; Ran, C.; Xu, J.; Xiao, T.; Li, X.; Wang, H.; Tian, Y.; et al. Performance Evaluation and Microbial Community Dynamics in a Novel AnMBR for Treating Antibiotic Solvent Wastewater. Bioresour. Technol. 2017, 243, 218–227. [Google Scholar] [CrossRef] [PubMed]
  47. Hu, D.; Xiao, T.; Chen, Z.; Wang, H.; Xu, J.; Li, X.; Su, H.; Zhang, Y. Effect of the High Cross Flow Velocity on Performance of a Pilot-Scale Anaerobic Membrane Bioreactor for Treating Antibiotic Solvent Wastewater. Bioresour. Technol. 2017, 243, 47–56. [Google Scholar] [CrossRef] [PubMed]
  48. Hu, D.; Xu, J.; Chen, Z.; Wu, P.; Wang, Z.; Wang, P.; Xiao, T.; Su, H.; Li, X.; Wang, H.; et al. Performance of a Pilot Split-Type Anaerobic Membrane Bioreactor (AnMBR) Treating Antibiotics Solvent Wastewater at Low Temperatures. Chem. Eng. J. 2017, 325, 502–512. [Google Scholar] [CrossRef]
  49. Chen, H.; Chang, S.; Guo, Q.; Hong, Y.; Wu, P. Brewery Wastewater Treatment Using an Anaerobic Membrane Bioreactor. Biochem. Eng. J. 2016, 105, 321–331. [Google Scholar] [CrossRef]
  50. Xia, T.; Gao, X.; Wang, C.; Xu, X.; Zhu, L. An Enhanced Anaerobic Membrane Bioreactor Treating Bamboo Industry Wastewater by Bamboo Charcoal Addition: Performance and Microbial Community Analysis. Bioresour. Technol. 2016, 220, 26–33. [Google Scholar] [CrossRef] [PubMed]
  51. Ng, K.K.; Shi, X.; Ng, H.Y. Evaluation of System Performance and Microbial Communities of Abioaugmented Anaerobic Membrane Bioreactor Treating Pharmaceutical Wastewater. Water Res. 2015, 81, 311–324. [Google Scholar] [CrossRef] [PubMed]
  52. Smith, A.L.; Skerlos, S.J.; Raskin, L. Anaerobic Membrane Bioreactor Treatment of Domestic Wastewater at Psychrophilic Temperatures Ranging from 15 °C to 3 °C. Environ. Sci. Water Res. Technol. 2015, 1, 56–64. [Google Scholar] [CrossRef]
  53. Dolejs, P.; Ozcan, O.; Bair, R.; Ariunbaatar, J.; Bartacek, J.; Lens, P.N.L.; Yeh, D.H. Effect of Psychrophilic Temperature Shocks on a Gas-Lift Anaerobic Membrane Bioreactor (Gl-AnMBR) Treating Synthetic Domestic Wastewater. J. Water Process Eng. 2017, 16, 108–114. [Google Scholar] [CrossRef]
  54. Gouveia, J.; Plaza, F.; Garralon, G.; Fdz-polanco, F.; Peña, M. Long-Term Operation of a Pilot Scale Anaerobic Membrane Bioreactor (AnMBR) for the Treatment of Municipal Wastewater under Psychrophilic Conditions. Bioresour. Technol. 2015, 185, 225–233. [Google Scholar] [CrossRef] [PubMed]
  55. Chen, L.; Gu, Y.; Cao, C.; Zhang, J.; Ng, J.W.; Tang, C. Performance of a Submerged Anaerobic Membrane Bioreactor with Forward Osmosis Membrane for Low-Strength Wastewater Treatment. Water Res. 2014, 50, 114–123. [Google Scholar] [CrossRef] [PubMed]
  56. Wu, B.; Li, Y.; Lim, W.; Lee, S.L.; Guo, Q.; Fane, A.G.; Liu, Y. Single-Stage versus Two-Stage Anaerobic Fluidized Bed Bioreactors in Treating Municipal Wastewater: Performance, Foulant Characteristics, and Microbial Community. Chemosphere 2017, 171, 158–167. [Google Scholar] [CrossRef] [PubMed]
  57. Zhu, X.; Li, M.; Zheng, W.; Liu, R.; Chen, L. Performance and Microbial Community of a Membrane Bioreactor System-Treating Wastewater from Ethanol Fermentation of Food Waste. J. Environ. Sci. 2017, 53, 284–292. [Google Scholar] [CrossRef] [PubMed]
  58. Cerón-Vivas, A.; Noyola, A. Fouling Membrane in an Anaerobic Membrane Bioreactor Treating Municipal Wastewater. Water Pract. Technol. 2017, 12, 314–321. [Google Scholar] [CrossRef]
  59. Chen, C.; Guo, W.S.; Ngo, H.H.; Liu, Y.; Du, B.; Wei, Q.; Wei, D.; Nguyen, D.D.; Chang, W.S. Evaluation of a Sponge Assisted-Granular Anaerobic Membrane Bioreactor (SG-AnMBR) for Municipal Wastewater Treatment. Renew. Energy 2017, 111, 620–627. [Google Scholar] [CrossRef]
  60. Gurung, K.; Ncibi, M.C.; Sillanpää, M. Assessing Membrane Fouling and the Performance of Pilot-Scale Membrane Bioreactor (MBR) to Treat Real Municipal Wastewater during Winter Season in Nordic Regions. Sci. Total Environ. 2017, 579, 1289–1297. [Google Scholar] [CrossRef] [PubMed]
  61. Mei, X.; Quek, P.J.; Wang, Z.; Ng, H.Y. Alkali-Assisted Membrane Cleaning for Fouling Control of Anaerobic Ceramic Membrane Bioreactor. Bioresour. Technol. 2017, 240, 25–32. [Google Scholar] [CrossRef] [PubMed]
  62. Nie, Y.; Tian, X.; Zhou, Z.; Li, Y. Impact of Food to Microorganism Ratio and Alcohol Ethoxylate Dosage on Methane Production in Treatment of Low-Strength Wastewater by a Submerged Anaerobic Membrane Bioreactor. Front. Environ. Sci. Eng. 2017, 11, 6. [Google Scholar] [CrossRef]
  63. Mei, X.; Wang, Z.; Miao, Y.; Wu, Z. Recover Energy from Domestic Wastewater Using Anaerobic Membrane Bioreactor: Operating Parameters Optimization and Energy Balance Analysis. Energy 2016, 98, 146–154. [Google Scholar] [CrossRef]
  64. Ozgun, H.; Tao, Y.; Ersahin, M.E.; Zhou, Z.; Gimenez, J.B.; Spanjers, H.; van Lier, J.B. Impact of Temperature on Feed-Flow Characteristics and Filtration Performance of an Upflow Anaerobic Sludge Blanket Coupled Ultrafiltration Membrane Treating Municipal Wastewater. Water Res. 2015, 83, 71–83. [Google Scholar] [CrossRef] [PubMed]
  65. Ozgun, H.; Gimenez, J.B.; Ersahin, M.E.; Tao, Y.; Spanjers, H.; van Lier, J.B. Impact of Membrane Addition for Effluent Extraction on the Performance and Sludge Characteristics of Upflow Anaerobic Sludge Blanket Reactors Treating Municipal Wastewater. J. Membr. Sci. 2015, 479, 95–104. [Google Scholar] [CrossRef]
  66. Huang, Z.; Ong, S.L.; Ng, H.Y. Submerged Anaerobic Membrane Bioreactor for Low-Strength Wastewater Treatment: Effect of HRT and SRT on Treatment Performance and Membrane Fouling. Water Res. 2011, 45, 705–713. [Google Scholar] [CrossRef] [PubMed]
  67. Jeison, D.; van Lier, J.B. Cake Formation and Consolidation: Main Factors Governing the Applicable Flux in Anaerobic Submerged Membrane Bioreactors (AnSMBR) Treating Acidified Wastewaters. Sep. Purif. Technol. 2007, 56, 71–78. [Google Scholar] [CrossRef]
  68. Fallah, N.; Bonakdarpour, B.; Nasernejad, B.; Moghadam, M.R.A. Long-Term Operation of Submerged Membrane Bioreactor (MBR) for the Treatment of Synthetic Wastewater Containing Styrene as Volatile Organic Compound (VOC): Effect of Hydraulic Retention Time (HRT). J. Hazard. Mater. 2010, 178, 718–724. [Google Scholar] [CrossRef] [PubMed]
  69. Ho, J.; Sung, S. Anaerobic Membrane Bioreactor Treatment of Synthetic Municipal Wastewater at Ambient Anaerobic Membrane Bioreactor Treatment of Synthetic Municipal Wastewater at Ambient Temperature. Water Environ. Res. 2009, 81, 922–928. [Google Scholar] [CrossRef] [PubMed]
  70. Wijekoon, K.C.; Visvanathan, C.; Abeynayaka, A. Effect of Organic Loading Rate on VFA Production, Organic Matter Removal and Microbial Activity of a Two-Stage Thermophilic Anaerobic Membrane Bioreactor. Bioresour. Technol. 2011, 102, 5353–5360. [Google Scholar] [CrossRef] [PubMed]
  71. Speece, R.E.; Boonyakitsombut, S.; Kim, M.; Azbar, N.; Ursillo, P. Overview of Anaerobic Treatment: Thermophilic and Propionate Implications—Keynote Address, Association of Environmental Engineering and Science Professors, 78th Annual Water Environment Federation Technical Exposition and Conference, Washington, DC, USA, 27 October–2 November 2005. Water Environ. Res. 2006, 78, 460–473. [Google Scholar] [PubMed]
  72. Ahmed, Z.; Cho, J.; Lim, B.-R.; Song, K.-G.; Ahn, K.-H. Effects of Sludge Retention Time on Membrane Fouling and Microbial Community Structure in a Membrane Bioreactor. J. Membr. Sci. 2007, 287, 211–218. [Google Scholar] [CrossRef]
  73. Hiraishi, A.; Ueda, Y.; Ishihara, J. Quinone Profiling of Bacterial Removal Quinone Profiling of Bacterial Communities in Natural and Synthetic Sewage Activated Sludge for Enhanced Phosphate Removal. Appl. Environ. Microbiol. 1998, 64, 992–998. [Google Scholar] [PubMed]
  74. Nie, Y.; Chen, R.; Tian, X.; Li, Y.-Y. Impact of Water Characteristics on the Bioenergy Recovery from Sewage Treatment by Anaerobic Membrane Bioreactor via a Comprehensive Study on the Response of Microbial Community and Methanogenic Activity. Energy 2017, 139, 459–467. [Google Scholar] [CrossRef]
  75. Kunacheva, C.; Soh, Y.N.A.; Trzcinski, A.P.; Stuckey, D.C. Soluble Microbial Products (SMPs) in the Effluent from a Submerged Anaerobic Membrane Bioreactor (SAMBR) under Different HRTs and Transient Loading Conditions. Chem. Eng. J. 2017, 311, 72–81. [Google Scholar] [CrossRef]
  76. Zolfaghari, M.; Drogui, P.; Seyhi, B.; Brar, S.K.; Buelna, G.; Dubé, R.; Klai, N. Investigation on Removal Pathways of Di 2-Ethyl Hexyl Phthalate from Synthetic Municipal Wastewater Using a Submerged Membrane Bioreactor. J. Environ. Sci. 2015, 37, 37–50. [Google Scholar] [CrossRef] [PubMed]
  77. Zhang, H.; Jiang, W.; Cui, H. Performance of Anaerobic Forward Osmosis Membrane Bioreactor Coupled with Microbial Electrolysis Cell (AnOMEBR) for Energy Recovery and Membrane Fouling Alleviation. Chem. Eng. J. 2017, 321, 375–383. [Google Scholar] [CrossRef]
  78. Xiao, Y.; Yaohari, H.; de Araujo, C.; Sze, C.C.; Stuckey, D.C. Removal of Selected Pharmaceuticals in an Anaerobic Membrane Bioreactor (AnMBR) with/without Powdered Activated Carbon (PAC). Chem. Eng. J. 2017, 321, 335–345. [Google Scholar] [CrossRef]
  79. Li, Y.; Hu, Q.; Chen, C.H.; Wang, X.L.; Gao, D.W. Performance and Microbial Community Structure in an Integrated Anaerobic Fluidized-Bed Membrane Bioreactor Treating Synthetic Benzothiazole Contaminated Wastewater. Bioresour. Technol. 2017, 236, 1–10. [Google Scholar] [CrossRef] [PubMed]
  80. Watanabe, R.; Nie, Y.; Wakahara, S.; Komori, D.; Li, Y.Y. Investigation on the Response of Anaerobic Membrane Bioreactor to Temperature Decrease from 25 °C to 10 °C in Sewage Treatment. Bioresour. Technol. 2017, 243, 747–754. [Google Scholar] [CrossRef] [PubMed]
  81. Basset, N.; Santos, E.; Dosta, J.; Matalvarez, J. Start-up and Operation of an AnMBR for Winery Wastewater Treatment. Ecol. Eng. 2016, 86, 279–289. [Google Scholar] [CrossRef]
  82. Chen, C.; Guo, W.; Ngo, H.H.; Chang, S.W.; Nguyen, D.D.; Nguyen, P.D.; Bui, X.T.; Wu, Y. Impact of Reactor Configurations on the Performance of a Granular Anaerobic Membrane Bioreactor for Municipal Wastewater Treatment. Int. Biodeterior. Biodegrad. 2017, 121, 131–138. [Google Scholar] [CrossRef]
  83. Iranpour, R.; Cox, H.H.J.; Shao, Y.J.; Moghaddam, O.; Kearney, R.J.; Deshusses, M.A.; Stenstrom, M.K.; Ahring, B.K. Changing Mesophilic Wastewater Sludge Digestion into Thermophilic Operation at Terminal Island Treatment Plant. Water Environ. Res. 2002, 74, 494–507. [Google Scholar] [CrossRef] [PubMed]
  84. Barker, D.J.; Stuckey, D.C. A Review of Soluble Microbial Products (SMP) in Wastewater Treatment Systems. Water Res. 1999, 33, 3063–3082. [Google Scholar] [CrossRef]
  85. Sciener, P.; Nachaiyasit, S.; Stuckey, D.C. Production of Soluble Microbial Products (SMP) in an Anaerobic Baffled Reactor: Composition, Biodegradability and the Effect of Process Parameters. Environ. Technol. 1998, 4, 391–400. [Google Scholar] [CrossRef]
  86. Chudoba, J.A.N. Inhibitory effect of refractory organic compounds produced by activated sludge micro-organisms on microbial activity and flocculation. Water Res. 1985, 19, 197–200. [Google Scholar] [CrossRef]
  87. Judd, S. Principles and Applications of Membrane Bioreactors in Water and Wastewater Treatment; Butterworth-Heinemann: Oxford, UK, 2006. [Google Scholar]
  88. Li, H.; Yang, M.; Zhang, Y.; Yu, T.; Kamagata, Y. Nitrification Performance and Microbial Community Dynamics in a Submerged Membrane Bioreactor with Complete Sludge Retention. J. Biotechnol. 2006, 123, 60–70. [Google Scholar] [CrossRef] [PubMed]
  89. Van Den Broeck, R.; van Dierdonck, J.; Nijskens, P.; Dotremont, C.; Krzeminski, P. The Influence of Solids Retention Time on Activated Sludge Bioflocculation and Membrane Fouling in a Membrane Bioreactor (MBR). J. Membr. Sci. 2012, 401–402, 48–55. [Google Scholar] [CrossRef]
  90. De Vrieze, J.; Saunders, A.M.; He, Y.; Fang, J.; Nielsen, P.H.; Verstraete, W.; Boon, N. Ammonia and Temperature Determine Potential Clustering in the Anaerobic Digestion Microbiome. Water Res. 2015, 75, 312–323. [Google Scholar] [CrossRef] [PubMed]
  91. Pap, B.; Györkei, Á.; Boboescu, I.Z.; Nagy, I.K.; Bíró, T.; Kondorosi, É.; Maróti, G. Temperature-Dependent Transformation of Biogas-Producing Microbial Communities Points to the Increased Importance of Hydrogenotrophic Methanogenesis under Thermophilic Operation. Bioresour. Technol. 2015, 177, 375–380. [Google Scholar] [CrossRef] [PubMed]
  92. El-Mashad, H.M.; Zeeman, G.; van Loon, W.K.P.; Bot, G.P.A.; Lettinga, G. Effect of Temperature and Temperature Fluctuation on Thermophilic Anaerobic Digestion of Cattle Manure. Bioresour. Technol. 2004, 95, 191–201. [Google Scholar] [CrossRef] [PubMed]
  93. Van Lier, J.B. Thermophilic Anaerobic Wastewater Treatment; Temperature Aspects and Process Stability. Ph.D. Thesis, Wageningen University & Research, Wageningen, The Netherlands, 1995. [Google Scholar]
  94. Duran, M.; Speece, R.E. Temperature-Staged Anaerobic Processes. Environ. Technol. 1997, 18, 747–753. [Google Scholar] [CrossRef]
  95. Wilson, C.A.; Murthy, S.M.; Fang, Y.; Novak, J.T. The Effect of Temperature on the Performance and Stability of Thermophilic Anaerobic Digestion. Water Sci. Technol. 2008, 57, 297–304. [Google Scholar] [CrossRef] [PubMed]
  96. Lin, Q.; de Vrieze, J.; Li, J.; Li, X. Temperature Affects Microbial Abundance, Activity and Interactions in Anaerobic Digestion. Bioresour. Technol. 2016, 209, 228–236. [Google Scholar] [CrossRef] [PubMed]
  97. Song, Y.C.; Kwon, S.J.; Woo, J.H. Mesophilic and Thermophilic Temperature Co-Phase Anaerobic Digestion Compared with Single-Stage Mesophilic- and Thermophilic Digestion of Sewage Sludge. Water Res. 2004, 38, 1653–1662. [Google Scholar] [CrossRef] [PubMed]
  98. Angelidaki, I. Anaerobic thermophilic digestion of manure at different ammonialoads: Effect of temperature. Water Res. 1994, 28, 727–731. [Google Scholar] [CrossRef]
  99. Chandra, R.; Vijay, V.K.; Subbarao, P.M.V.; Khura, T.K. Production of Methane from Anaerobic Digestion of Jatropha and Pongamia Oil Cakes. Appl. Energy 2012, 93, 148–159. [Google Scholar] [CrossRef]
  100. Appels, L.; van Assche, A.; Willems, K.; Degrève, J.; van Impe, J.; Dewil, R. Peracetic Acid Oxidation as an Alternative Pre-Treatment for the Anaerobic Digestion of Waste Activated Sludge. Bioresour. Technol. 2011, 102, 4124–4130. [Google Scholar] [CrossRef] [PubMed]
  101. Zhou, J.; Zhang, R.; Liu, F.; Yong, X.; Wu, X.; Zheng, T.; Jiang, M.; Jia, H. Biogas Production and Microbial Community Shift through Neutral pH Control during the Anaerobic Digestion of Pig Manure. Bioresour. Technol. 2016, 217, 44–49. [Google Scholar] [CrossRef] [PubMed]
  102. Wang, S.; Nomura, N.; Nakajima, T.; Uchiyama, H. Case Study of the Relationship between Fungi and Bacteria Associated with High-Molecular-Weight Polycyclic Aromatic Hydrocarbon Degradation. J. Biosci. Bioeng. 2012, 113, 624–630. [Google Scholar] [CrossRef] [PubMed]
  103. Kim, J.; Park, C.; Kim, T.-H.; Lee, M.; Kim, S.; Kim, S.-W.; Lee, J. Effects of Various Pretreatments for Enhanced Anaerobic Digestion with Waste Activated Sludge. J. Biosci. Bioeng. 2003, 95, 271–275. [Google Scholar] [CrossRef]
  104. Kim, M.; Gomec, C.Y.; Ahn, Y.; Speece, R.E. Hydrolysis and Acidogenesis of Particulate Organic Material in Mesophilic and Thermophilic Anaerobic Digestion. Environ. Technol. 2003, 24, 1183–1190. [Google Scholar] [CrossRef] [PubMed]
  105. Sandberg, M.; Ahring, B.K. Anaerobic Treatment of Fish Meal Process Waste Water in a UASB Reactor at High pH. Appl. Microbiol. 1992, 36, 800–804. [Google Scholar] [CrossRef]
  106. Yu, D.; Liu, J.; Sui, Q.; Wei, Y. Biogas-pH Automation Control Strategy for Optimizing Organic Loading Rate of Anaerobic Membrane Bioreactor Treating High COD Wastewater. Bioresour. Technol. 2016, 203, 62–70. [Google Scholar] [CrossRef] [PubMed]
  107. Mao, C.; Feng, Y.; Wang, X.; Ren, G. Review on Research Achievements of Biogas from Anaerobic Digestion. Renew. Sustain. Energy Rev. 2015, 45, 540–555. [Google Scholar] [CrossRef]
  108. Wen, C.; Huang, X.; Qian, Y. Domestic Wastewater Treatment Using an Anaerobic Bioreactor Coupled with Membrane Filtration. Process Biochem. 1999, 35, 335–340. [Google Scholar] [CrossRef]
  109. Vincent, N.M.; Tong, J.; Yu, D.; Zhang, J.; Wei, Y. Membrane Fouling Characteristics of a Side-Stream Tubular Anaerobic Membrane Bioreactor (AnMBR) Treating Domestic Wastewater. Processes 2018, 6, 50. [Google Scholar] [CrossRef]
  110. Qiao, W.; Takayanagi, K.; Niu, Q.; Shofie, M.; Li, Y.Y. Long-Term Stability of Thermophilic Co-Digestion Submerged Anaerobic Membrane Reactor Encountering High Organic Loading Rate, Persistent Propionate and Detectable Hydrogen in Biogas. Bioresour. Technol. 2013, 149, 92–102. [Google Scholar] [CrossRef] [PubMed]
  111. An, Y.Y.; Yang, F.L.; Bucciali, B.; Wong, F.S. Municipal Wastewater Treatment Using a UASB Coupled with Cross-Flow Membrane Filtration. J. Environ. Eng. 2009, 135, 86–91. [Google Scholar] [CrossRef]
  112. Bornare, J.; Kalyyanraman, V.; Sonde, R.R. Application of Anaerobic Membrane Bioreactor (AnMBR) for Low-Strength Wastewater Treatment and Energy Generation. In Industrial Wastewater Treatment, Recycle and Reuse; Butterworth-Heinemann: Oxford, UK, 2014; pp. 399–434. [Google Scholar]
  113. Dereli, R.K.; Ersahin, M.E.; Ozgun, H.; Ozturk, I.; Jeison, D.; van der Zee, F.; van Lier, J.B. Potentials of Anaerobic Membrane Bioreactors to Overcome Treatment Limitations Induced by Industrial Wastewaters. Bioresour. Technol. 2012, 122, 160–170. [Google Scholar] [CrossRef] [PubMed]
  114. Del Pozo, R.; Diez, V. Integrated Anaerobic-Aerobic Fixed-Film Reactor for Slaughterhouse Wastewater Treatment. Water Res. 2005, 39, 1114–1122. [Google Scholar] [CrossRef] [PubMed]
  115. Saddoud, A.; Sayadi, S. Application of Acidogenic Fixed-Bed Reactor prior to Anaerobic Membrane Bioreactor for Sustainable Slaughterhouse Wastewater Treatment. J. Hazard. Mater. 2007, 149, 700–706. [Google Scholar] [CrossRef] [PubMed]
  116. Jeison, D.; Plugge, C.M.; Pereira, A.; van Lier, J.B. Effects of the Acidogenic Biomass on the Performance of an Anaerobic Membrane Bioreactor for Wastewater Treatment. Bioresour. Technol. 2009, 100, 1951–1956. [Google Scholar] [CrossRef] [PubMed]
  117. Dong, Q.; Parker, W.; Dagnew, M. Influence of SRT and HRT on Bioprocess Performance in Anaerobic Membrane Bioreactors Treating Municipal Wastewater. Water Environ. Res. 2016, 88, 158–167. [Google Scholar] [CrossRef] [PubMed]
  118. Hejnfelt, A.; Angelidaki, I. Anaerobic Digestion of Slaughterhouse by-Products. Biomass Bioenergy 2009, 33, 1046–1054. [Google Scholar] [CrossRef]
  119. Kayhanian, M. Ammonia Inhibition in High-Solids Biogasification: An Overview and Practical Solutions. Environ. Technol. 1999, 20, 355–365. [Google Scholar] [CrossRef]
  120. De Baere, L.A.; Devocht, M.; van Assche, P.; Verstraete, W. Influence of High NaCl and NH4Cl salt levels on methanogenic associations. Water Res. 1984, 18, 543–548. [Google Scholar] [CrossRef]
  121. Kroeker, E.J.; Shulte, D.D.; Sparling, A.B.; Lapp, H.M. Anaerobic Process Treatment Stability. J. WPCF 1979, 51, 718–727. [Google Scholar]
  122. Calli, B.; Mertoglu, B.; Inanc, B.; Yenigun, O. Effects of High Free Ammonia Concentrations on the Performances of Anaerobic Bioreactors. Process Biochem. 2005, 40, 1285–1292. [Google Scholar] [CrossRef]
  123. Tchobanoglous, G.; Theisen, H.; Vigil, S. Integrated Waste Management: Engineering Principles and Management Issues; McGraw-Hill: New York, NY, USA, 1993. [Google Scholar]
  124. Kayhanian, M. Performance of a High-Soilds Anaerobic Digestion Process under Various Ammonia Concentrations. J. Chem. Technol. Biotechnol. 1994, 59, 349–352. [Google Scholar] [CrossRef]
  125. Li, Y.; Zhang, Y.; Kong, X.; Li, L.; Yuan, Z.; Dong, R.; Sun, Y. Effects of Ammonia on Propionate Degradation and Microbial Community in Digesters Using Propionate as a Sole Carbon Source. J. Chem. Technol. Biotechnol. 2017. [Google Scholar] [CrossRef]
  126. Gallert, C.; Bauer, S.; Winter, J. Effect of Ammonia on the Anaerobic Degradation of Protein by a Mesophilic and Thermophilic Biowaste Population. Appl. Microbiol. Biotechnol. 1998, 50, 495–501. [Google Scholar] [CrossRef] [PubMed]
  127. Koster, I.W.; Rinzema, A.; de Vegt, A.L.; Lettinga, G. Sulfide Inhibition of the Methanogenic activity of granular sludge at various pH-levels. Water Res. 1986, 20, 1561–1567. [Google Scholar] [CrossRef]
  128. Harada, H.; Uemura, S.; Momonoi, K. Interaction Between Sulfate Reducing Bacteria and Methane Producing Bacteria In Uasb Reactors Fed With Low Strength Wastes Containing Different Levels of Sulfate. Water Res. 1994, 28, 355–367. [Google Scholar] [CrossRef]
  129. Stefanie, J.W.H.; Elferink, O.; Visser, A.; Pol, L.W.H.; Stams, A.J.M. Sulfate Reduction in Methanogenic Bioreactors. FEMS Microbiol. Rev. 1994, 15, 119–136. [Google Scholar] [CrossRef]
  130. Colleran, E.; Pender, S.; Philpott, U.; O’Flaherty, V.; Leahy, B. Full-Scale and Laboratory-Scale Anaerobic Treatment of Citric Acid Production Wastewater. Biodegradation 1998, 9, 233–245. [Google Scholar] [CrossRef] [PubMed]
  131. Cho, J.; Song, K.G.; Yun, H.; Ahn, K.H.; Kim, J.Y.; Chung, T.H. Quantitative Analysis of Biological Effect on Membrane Fouling in Submerged Membrane Bioreactor. Water Sci. Technol. 2005, 51, 9–18. [Google Scholar] [CrossRef] [PubMed]
  132. Colleran, E.; Finnegan, S.; Lens, P. Anaerobic Treatment of Sulfate-Containing Waste Streams. Antonie Van Leeuwenhoek Int. J. Gen. Mol. Microbiol. 1995, 67, 29–46. [Google Scholar] [CrossRef]
  133. Wang, Z.; Ma, J.; Tang, C.Y.; Kimura, K.; Wang, Q. Membrane Cleaning in Membrane Bioreactors: A Review. J. Membr. Sci. 2014, 468, 276–307. [Google Scholar] [CrossRef]
  134. Zhang, Q.; Singh, S.; Stuckey, D.C. Fouling Reduction Using Adsorbents/Flocculants in a Submerged Anaerobic Membrane Bioreactor. Bioresour. Technol. 2017, 239, 226–235. [Google Scholar] [CrossRef] [PubMed]
  135. Meng, F.; Chae, S.R.; Drews, A.; Kraume, M.; Shin, H.S.; Yang, F. Recent Advances in Membrane Bioreactors (MBRs): Membrane Fouling and Membrane Material. Water Res. 2009, 43, 1489–1512. [Google Scholar] [CrossRef] [PubMed]
  136. Lee, J.; Ahn, W.; Lee, C. Comparison of the Filtration Characteristics Between Attached and Suspended Growth Microorganisms in Submerged Membrane Bioreactor. Water Res. 2001, 35, 2435–2445. [Google Scholar] [CrossRef]
  137. Di Bella, G.; Durante, F.; Torregrossa, M.; Viviani, G.; Mercurio, P.; Cicala, A. The Role of Fouling Mechanisms in a Membrane Bioreactor. Water Sci. Technol. 2007, 55, 455–464. [Google Scholar] [CrossRef] [PubMed]
Figure 1. A schematic of AnMBR configurations—(a) Side or external membrane (b) submerged membrane.
Figure 1. A schematic of AnMBR configurations—(a) Side or external membrane (b) submerged membrane.
Energies 11 01675 g001
Table 1. Comparison of conventional anaerobic treatment and anaerobic membrane bioreactor (AnMBR) [8].
Table 1. Comparison of conventional anaerobic treatment and anaerobic membrane bioreactor (AnMBR) [8].
FeatureConventional Anaerobic TreatmentAnMBR
Discharge qualityModerate-PoorHigh
Sludge volumelowlow
substrate loading concentrationHighHigh
Removal efficiency (Effluent)HighHigh
Biomass retentionLowComplete
Alkalinity RequirementDepends on microbial activityDepends on microbial activity
Nutrient requirementLowLow
Startup period2–4 MonthsLess than 2 Weeks
Temperature requirementLow-ModerateLow-Moderate
Energy inputLowLow
Pre-treatment requirementNot necessaryMostly for high solid substrates
Biogas recoveryYesYes
Table 2. References on anaerobic membrane bioreactors (AnMBRs) for industrial wastewater.
Table 2. References on anaerobic membrane bioreactors (AnMBRs) for industrial wastewater.
Type of System/Module Configuration/Membrane ConfigurationMembrane Type/Material/CharacteristicWastewater TreatedOperating ConditionReactor Working Volume + ScaleInfluent COD mg/LEffluent COD Mg/LMaximum COD Removal (%)Biogas Production (L CH4/g COD removedReference
AnMBR/External cross flow membrane/Tubular-/ceramic (ZrO2–TiO2)/
Pore size = 0.2 μm
Area = 0.25 m2
Industrial wastewaterFlux = 8.4 L/m2·h,
HRT = 1.7–5, 3.5, 3–3.5,
SRT = 120–450 day,
Temp = 35–37 °C,
MLSS = OLR = 2.5 g, COD L/day
V = 50 L
S = P
4300830780.5 and 0.6[42]
SAMBR/Submerged/Flat sheet and hollow fiberMF (Polipropilen-PP)/Chlorinated polyethylene/
Pore size = 0.05 μm
Area = 0.66 m2
Synthetic industrial wastewaterFlux = 3–0.9 L/m2·h,
HRT = 390, 167, 168,
SRT = ∞, Temp = 35 °C,
MLSS = OLR = 0.3–0.54 g, COD/L·day
V = 4 L
S = L
Submerged anaerobic membrane bioreactor (SAnMBR)/Submerged/Hollow fiberMF/Curtain-type/
Pore size = 0.2 μm
Area 5.4 m2
Synthetic industrial wastewaterFlux = 6 L/m2·h,
HRT = 2.2 h, SRT = -, Temp = 35 °C,
MLSS =10.9 g/L,
OLR = 3.0 kg COD/m3·day
V = 25 L
S = P
223 ± 11150 ± 22870.12[44]
SAnMBR/Submerged/Hollow fiberMF/Curtain-type/
Pore size = 0.4 μm
Area = 0.040 m2
Paper mill wastewaterFlux = 7.2 L/m2·h,
HRT = 35 h, SRT = 40 day,
Temp = 21 °C,
MLSS = 12.90 g/L,
OLR = 7.0 kg COD/m3·day
V = 10 L
S = L
11,415 ± 15228.3 ± 598-[45]
fiber/Polyvinylidene fluoride (PVDF)
Pore size = -
Area = 20 m2
Synthetic anti-biotic solventFlux = 20 L/m2·h,
HRT = 48, 36, 24, and 18 h,
Temp = 35 ± 1 °C,
MLSS = 16.5–12.4 g/L,
OLR = 3.9–12.7 kg, COD/m3·day
V = 4.4 m3
S = P
93.6 and 98.794 and 130.7[46]
AnMBRUF/Hollow fiber/
Polyvinylidene fluoride (PVDF)
Pore size = -
Area = 20 m2
Synthetic anti-biotic solventFlux = 20 L/m2·h,
HRT = 48 h,
Temp = 37 °C,
MLSS = 52.2 g/L,
OLR = 3.79 kg , COD/m3·day
V = 4.4 m3
S = P
AnMBRUF/Hollow fiber/
Polyvinylidene fluoride (PVDF)
Pore size = -
Area = 20 m2
Synthetic anti-biotic solventFlux = 20 L/m2·h,
HRT = 48–24 h,
Temp = (35 ± 3 °C, 25 ± 3 °C, 15 ± 3 °C, 25 ± 3 °C),
MLSS = 16.5 g/L,
OLR = 10.0 kg, COD/m3·day
V = 4.4 m3
S = P
AnMBRUF/Hollow fiber/
Pore size = 0.04 μm
Area = 0.047 m2
Brewery wastewaterFlux = 8.64 ± 0.69, L/m2·h,
HRT = 44 h,
Temp = (35 °C),
MLSS = 2.8 g/L,
OLR = 3.5–11.5 g , COD/L·d
V = 15 L
S = L
19,100171990.53 ± 0.015[49]
AnMBR and B-AnMBRUF/Hollow fiber/
Polyvinylidene fluoride (PVDF)
Pore size = 0.02 μm
Area = 0.07 m
Bamboo wastewaterFlux = 33.4–16.2 L/m2·h,
HRT = 3 d,
Temp = 32 ± 2 °C,
MLSS = 16 g/L,
OLR = 6 kg , COD/m3·day
V = 15 L
S = L
17,160 ± 814278.9 ± 4.2 mg/L and
125.3 ± 3.2 mg/L
94.5 ± 2.9
and 89.1 ± 3.1
13.2 ± 1.2,
10.3 ± 0.8
C-AnMBR and B-AnMBRUF/Hollow fiber/
Polyvinylidene fluoride (PVDF)
Pore size = 0.04 μm
Area = 0.047 m2
Pharmaceutical wastewaterFlux = 6 L/m2·h,
HRT = 30.6 h,
Temp = 27 ± 1.0 °C,
MLSS = 9500–10,200 and 10,000 mg/L,
OLR = 13.0 ± 0.6 kg, COD/m3·day
V = 10 L
S = L
16,249 ± 7148723 ± 593 and 6432 ± 44546.1 ± 2.9 and 60.3 ± 2.824.5 ± 2.1
And 17.6 ± 1.5
AnMBR = anaerobic membrane bioreactor, COD = chemical oxygen demand, HRT = hydraulic retention time, MLSS = Mixed liquor suspended solids, OLR = organic loading rate, P = pilot scale, - = not reported.
Table 3. References on anaerobic membrane bioreactors (AnMBRs) for municipal wastewater treatment.
Table 3. References on anaerobic membrane bioreactors (AnMBRs) for municipal wastewater treatment.
Type of System/Module Configuration/Membrane ConfigurationMembrane Type/Material/CharacteristicWastewater TreatedOperating ConditionReactor Working Volume + ScaleInfluent COD mg/LEffluent COD mg/LMaximum COD Removal (%)Biogas Production (L CH4/g COD removed)Reference
AFMBR/Submerged/Hollow fiber-/Non-woven
Fibrous (chlorinated polyethylene)/
Pore size = 0.1 μm
Area 0.022 m2
Raw municipal wastewaterFlux = 30 L/m2·h, HRT = 4 h, SRT = ∞, Temp = 23 ± 1 °C, MLSS = -,
OLR = 3–6
V = 2.7 L
S = L
SAMBRs/Submerged/Hollow fiberMF/Polyvinylidene fluoride/
Pore size = 0.02 μm
Area = -
Municipal (wastewater from the ethanol fermentation of food waste)Flux = 9.72 L/m2·h,
HRT 110 h, SRT = -,
Temp = 23–25 °C,
MLSS = 8–12 g/L,
OLR =2.3–3.6 g/L·day
V = 0.628 L
S = L
15,000 ± 1000202 ± 2398.2-[57]
UASB/Submerged/TubularUF/Polyvinylidene fluoride/
Pore size = -
Area = 0.2375 m2
Raw municipal wastewaterFlux = 2.5 L/m2·h,
HRT = 8 h,
Temp = 18–21 °C,
MLSS = -, OLR = -
V = 0.7 m3
S = P
525 ± 174,
657 ± 235
222 ± 61,
130 ± 55
CG-AnMBR and SG-AnMBR/Submerged/Hollow fiber-/A polyvinylidence (PVDF)/
Pore size = 0.22 μm
Area = 0.06 m2
Synthetic domestic wastewaterFlux = 5.3 L/m2·h, HRT = 12 h, SRT = 25–30 day,
Temp = 20 °C,
MLSS = 20.50 ± 1.53 g/L,
OLR = -
V = 3 L
S = L
330–370-90156.3 ± 5.8[59]
MBR/Submerged/Flat sheetMF/-/
Pore size = 0.4 μm
Area = 16 m2
Real municipal wastewaterFlux = 7.8 L/m2·h
HRT = 35 h, SRT = 25–30 day
Temp = 6.5–21 °C/7.0–20 °C
MLSS = 5300–9800 mg/L
OLR = -
V = 3 m3
S = P
896 GC mL−118.7 ± 2.993-[60]
AnCMBRs/Submerged/Flat sheet-/Ceramic membrane/
Pore size = 80 nm
Area = 0.08 m2
Domestic wastewaterFlux = 8 L/m2·h, HRT = 5.8 h, SRT = 60 day,
Temp = 25 °C, MLSS = -,
OLR =10.0 kg COD/m3·day
V = 3.6 L
S = L
417 ± 61-87-[61]
SAnMBR/Submerged/Flat-sheet-/Polyethylene terephthalate/
Pore size = 0.2 μm
Area = 0.116 m2
Synthetic municipal wastewater (alcohol ethoxylates)Flux = -, HRT = 42–12 h
SRT = -, Temp = 25 ± 1 °C
MLSS = -, OLR = 3.0–6.0 kg COD/m3·day
V = 6 L
S = L
SAnMBR/Submerged/Flat-sheetUF/Polyvinylidene fluoride/
Pore size =0.2 μm
Area 0.735 m2
Domestic wastewaterFlux = 8.3–9.5 L/m2·h and 6.0–6.7 L/m2·h,
HRT = 5.8–4.8 and 8.0 –7.1 h, SRT = 50 day,
Temp = 35 °C and 25 °C,
MLSS = -, OLR = 0.43–0.90 kg COD/m3·day
V = 15 L
S = L
400-90276 ± 13[63]
AnMBR/External/TubularUF/Polyethersulfone/Pore size = 30 μm
Area 0.11 m2
Synthetic municipal wastewaterFlux 12.3 L/m2·h,
HRT = 6 h, SRT = 126 day,
Temp = 25 °C and 15 °C,
MLSS = -, OLR = 2 kg/m3·day
V = 7 L
S = L
530 ± 3042 and 5292 and 90-[64]
AnMBR/External/TubularUF/Polyethersulfone/Pore size = 30 μm
Area 0.0038 m2
Synthetic municipal wastewaterFlux 12.3 L/m2·h,
HRT = 6 h,
SRT = 126 day,
Temp = 25–15 °C,
MLSS = -,
OLR = 2 kg/m3·day
V = 7 L
S = L
530 ± 30149 ± 5.9 to 42 ± 4.4,92-[65]
AnMBR = anaerobic membrane bioreactor, COD = chemical oxygen demand, HRT = hydraulic retention time, MLSS = Mixed liquor suspended solids, OLR = organic loading rate, P = pilot scale, - = not reported.
Table 4. References on anaerobic membrane bioreactors for synthetic wastewater treatment.
Table 4. References on anaerobic membrane bioreactors for synthetic wastewater treatment.
Type of System/Module Configuration/Membrane ConfigurationMembrane Type/Material/CharacteristicWastewater TreatedOperating ConditionReactor Working Volume + ScaleInfluent COD mg/LEffluent COD mg/LMaximum COD Removal (%)Biogas Production (L CH4/g CODremoved)Reference
Flat sheet
fibrous (chlorinated polyethylene)/
Pore size = 0.2 μm
Area = 0.116 m2
Synthetic municipal wastewater (linear alkyl benzene sulfonate concentration in sewage)Flux = -, HRT = 24–12 h, SRT = Temp = 25 ± 1 °C
MLSS = -, OLR = 3–6 kg COD/m3·day
V = 6 L
S = L
Flat sheet
MF/Polymethyl methacrylate/
Pore size = 0.2 μm
Area = 0.116 m2
Synthetic sewageFlux = 15 L/m2·h,
HRT = 12, 8, 6, 4 and 2 h, SRT = 200 day,
Temp = 35 ± 1 °C,
MLSS = 6000 mg/L and 7000 mg/L,
OLR = -
V = 3 L
S = L
544 ± 2214 ± 2˃97252 ± 27,
236 ± 27,
249 ± 29,
264 ± 46,
134 ± 23
SMBR/-/-MF/Polymethyl methacrylate/
Pore size = 0.04 μm
Area = 0.047 m2
Synthetic wastewaterFlux = 10.64L/m2·h,
HRT = 8 h, SRT = 140 day, Temp = 18 ± 15 °C, MLSS = 6000 mg/L, OLR = 1.77 ± 0.03 g COD/L·day
V = 4 L
S = L
--91 and 98-[76]
AnOMBR/submerged/-Cathode/Stainless steel mesh/
Pore size = -
Area 1.5 m2
Synthetic wastewaterFlux = 3.532 LMH
HRT = -, SRT = -
Temp = 35 ± 1 °C
MLSS = 16.31 g/L
OLR = -
V = 6.8 L
S = P
SAMBRs/Submerged/Flat sheetMF/Non-woven
fibrous (chlorinated polyethylene)/
Pore size = 0.2 μm
Area = 0.116 m2
Synthetic sewageFlux = 5 L/m2·h,
HRT = 12–6 h,
SRT = ,Temp = 35 °C,
MLSS = -,OLR = 3–6 kg COD/m3·day
V = 3.2 L
S = L
-29 ± 893.2 ± 6.61.7 ± 0.3[78]
Integrated anaerobic fluidized bed membrane (IAFMBR)/-/--/Hollow fiber/
Pore size = 0.4 μm
Area = 0.21 m2
Synthetic benzothiazole wastewaterFlux = 11.3 L/m2·h,
HRT = 24 h, Temp = 35 °C, MLSS = -, OLR = -
V = 6.1 L
S = L
-230960.31 ± 0.02, 0.32 ± 0.03 and 0.31 ± 0.01[79]
SAMBRs/Submerged/Flat sheetMF/Chlorinated polyethylene/
Pore size = 0.2 μm
Area = 0.116 m2
Synthetic sewageFlux = -,
HRT = 48, 24, 12, 6 h,
Temp = 25, 15, 10 °C,
MLSS = -, OLR = -
V = 6 L
S = L
AnMBRs/External/--/Polyvinylidence (PVDF) hollow fiber/
Pore size = 0.22 μm
Area = 0.06 m2
Synthetic sewageFlux = 20.2 ± 8.5 L/m2·h, HRT = 3.5 ± 1.1, 2.2 ± 0.5, 2.3 ± 0.3 day, Temp = 35 °C,
MLSS = 4.78 ± 1.9 g L−1, OLR = 3.4 kg COD/m3·day
V = 3.5 L
S = L
6752 ± 6630.095 ± 0.15 0.14 ± 0.23 0.28 ± 0.3596.7 ± 2.70.50 ± 0.17[81]
EG-AnMBR and SG-AnMBR-/Polyvinylidence (PVDF) hollow fiber/
Pore size = 0.22 μm
Area = 0.06 m2
Synthetic sewageFlux = 7 L/m2·h,
HRT = 12 h, Temp = 20 °C, MLSS = 22.34 ± 0.41 g/L, OLR = 0.53–0.59 kg COD/m3
V = 4 L
S = L
AnMBR = anaerobic membrane bioreactor, COD = chemical oxygen demand, HRT = hydraulic retention time, MLSS = Mixed liquor suspended solids, OLR = organic loading rate, P = pilot scale, - = not reported.

Share and Cite

MDPI and ACS Style

Musa, M.A.; Idrus, S.; Che Man, H.; Nik Daud, N.N. Wastewater Treatment and Biogas Recovery Using Anaerobic Membrane Bioreactors (AnMBRs): Strategies and Achievements. Energies 2018, 11, 1675.

AMA Style

Musa MA, Idrus S, Che Man H, Nik Daud NN. Wastewater Treatment and Biogas Recovery Using Anaerobic Membrane Bioreactors (AnMBRs): Strategies and Achievements. Energies. 2018; 11(7):1675.

Chicago/Turabian Style

Musa, Mohammed Ali, Syazwani Idrus, Hasfalina Che Man, and Nik Norsyahariati Nik Daud. 2018. "Wastewater Treatment and Biogas Recovery Using Anaerobic Membrane Bioreactors (AnMBRs): Strategies and Achievements" Energies 11, no. 7: 1675.

Note that from the first issue of 2016, this journal uses article numbers instead of page numbers. See further details here.

Article Metrics

Back to TopTop