Search Results (48)

The recirculating aquaculture system (RAS) has been rapidly adopted worldwide in recent years due to its high productivity, good stability, and good environmental controllability (and therefore friendliness to environment and ecology). Nevertheless, the effluent from seawater RAS contains a high level of ammonia nitrogen which is toxic to fish, so it is necessary to overcome the salinity conditions to achieve rapid and efficient nitrification for recycling. The moving bed biofilm reactor (MBBR) has been widely applied often by using PE fillers for efficient wastewater treatment. However, the start-up of MBBR in seawater environments has remained a challenge due to salinity stress and harsh inoculation conditions. This study investigated a new PE-filler surface modification method towards the enhanced start-up of mariculture MBBR by combining liquid-phase oxidation and maifanstone powder. The aim was to obtain a higher porous surface and roughness and a strong adsorption and alkalinity adjustment for the MBBR PE filler. The hydrophilic properties, surface morphology, and chemical structure of a raw polyethylene filler (an unmodified PE filler), liquid-phase oxidation modified filler (LO-PE), and liquid-phase oxidation combined with a coating of a maifanstone-powder-surface-modified filler (LO-SCPE) were first investigated and compared. The results showed that the contact angle was reduced to 45.5° after the optimal liquid-phase oxidation modification for LO-PE, 49.8% lower than that before modification, while SEM showed increased roughness and surface area by modification. Moreover, EDS presented the relative content of carbon (22.75%) and oxygen (42.36%) on the LO-SCPE surface with an O/C ratio of 186.10%, which is 177.7% higher than that of the unmodified filler. The start-up experiment on MBBRs treating simulated marine RAS wastewater (HRT = 24 h) showed that the start-up period was shortened by 10 days for LO-SCPE compared to the PE reactor, with better ammonia nitrogen removal observed for LO-SCPE (95.8%) than the PE reactor (91.7%). Meanwhile, the bacterial community composition showed that the LO-SCPE reactor had a more diverse and abundant AOB and NOB. The Nitrospira has a more significant impact on nitrification because it would directly oxidize NH₄⁺-N to NO₃⁻-N (comammox pathway) as mediated by AOB and NOB. Further, the LO-SCPE reactor showed a higher NH₄⁺-N removal rate (>99%), less NO₂⁻-N accumulation, and a shorter adaption period than the PE reactor. Eventually, the NH₄⁺-N concentrations of the three reactors (R1, R2, and R3) reached <0.1 mg/L within 3 days, and their NH₄⁺-N removal efficiencies achieved 99.53%, 99.61%, and 99.69%, respectively, under ammonia shock load. Hence, the LO-SCPE media have a higher marine wastewater treatment efficiency. Full article

Furfural is a relevant industrial product, but its presence in water and soil generates contamination and health risks. Moving bed biofilm reactors (MBBRs) are an increasingly used alternative to eliminate contaminants with the advantage of occupying small spaces, despite their high dependence on support and the microorganisms involved in the process. This work proposes furfural elimination through a laboratory-scale MBBR using Bacillus licheniformis GTQ1, Microbacterium sp. GISTAQ2, and Brevundimonas sp. GISTAQ1 isolated from an industrial effluent and agroforestry waste (rice husks, pine sawdust, and quebracho chips) as supports. The biofilm development was tested with both axenic and mixed cultures, confirming high coverage by Scanning Electron Microscope (SEM) images, especially in triple-mixed cultures. Biodegradation tests were carried out in the MBBR with 15 g rice husks or quebracho chips as supports and a 4000 mg L⁻¹ initial furfural concentration for 72 h. The mixed culture achieved almost a 100% furfural removal in three days with a rate of 3.97% per hour with rice husks and 2.61% per hour with quebracho chips. This laboratory-scale MBBR development is a promising first step ready for a scale-up for its implementation in industries to significantly reduce the environmental impact of the discharge of this type of effluent. Full article

This study aimed to examine the impacts of hydraulic retention time (HRT) and organic loading rate (OLR) on the alginate-like exopolymers’ (ALEs) recovery potential from a biofilm-based process. A lab-scale moving bed biofilm reactor (MBBR) was operated under different HRT (12.0, 6.0, and 2.0 h) and OLR (1.0, 2.0, and 6.0 kg COD/m³/d) conditions. The results demonstrated that the reduction in HRT and increase in OLR had remarkable effects on enhancing ALE production and improving its properties, which resulted in the ALE yield increasing from 177.8 to 221.5 mg/g VSS, with the protein content rising from 399.3 to 494.3 mg/g ALE and the enhanced alginate purity by 39.8%, corresponding to the TOC concentration increasing from 108.3 to 157.0 mg/g ALE. Meanwhile, to illustrate different ALE recovery potentials, microbial community compositions of the MBBR at various operational conditions were also assessed. The results showed that a higher relative abundance of EPS producers (29.86%) was observed in the MBBR with an HRT of 2.0 h than that of 12.0 h and 6.0 h, revealing its higher ALE recovery potential. This study yields crucial results in terms of resource recovery for wastewater reclamation by providing an effective approach to directionally cultivating ALEs. Full article

The rapid development of the residential and industrial sectors produces a huge amount of treated domestic wastewater. The treated wastewater is discharged and could affect the environment in the long term. Improving the quality of treated domestic wastewater for water reclamation would benefit both sectors. This study aims to determine the efficiency of the biofilm-phytoremediation integration process in reclaiming domestic wastewater. A cuboid-shaped reactor was filled with 15 L of domestic wastewater, utilizing water hyacinth and a polyethylene carrier as supporting media for the process. The integrated reactor is tested in two phases: the initial adaptation of bacteria with domestic and synthetic wastewater (Phase I) and the integration process of biofilm-phytoremediation, based on the factors of NH₃-N concentration and hydraulic retention time (HRT), for 24 to 48 h (Phase II). In Phase II, pollutant removal was observed at varying NH₃-N concentrations: C1 (11–13 mg/L), C2 (9–11 mg/L), and C3 (3–5 mg/L). The study’s findings indicate a consistent performance in the first phase, with removal rates for COD and NH₃-N ranging between 86.7–100.0% and 79.0–99.6%, respectively. The reactor effectively removed pollutants at varying concentrations of NH₃-N, with average removal up to 100% (COD), 99% (NH₃-N), and 80% (PO₄³⁻). This integrated reactor shows the finest treated water quality outcomes for non-potable water recovery, as well as offers an alternative to resolve water scarcity for use in various sectors. Full article

Urbanization growth has intensified the challenge of managing and treating increasing amounts of municipal solid waste (MSW). Landfills are commonly utilized for MSW disposal because of their low construction and operation costs. However, this practice produces huge volumes of landfill leachate, a highly polluting liquid rich in ammoniacal nitrogen (NH₃-N), organic compounds, and various heavy metals, making it difficult to treat in conventional municipal wastewater treatment plants (WWTPs). In recent years, research has shown that microbial biofilms, developed on carriers of different materials and called “moving bed biofilm reactors” (MBBRs), may offer promising solutions for bioremediation. This study explored the biofilm development and the nitrification process of moving bed biofilms (MBBs) obtained from high ammonia-selected microbial communities. Using crystal violet staining and confocal laser-scanning microscopy, we followed the biofilm formation stages correlating nitrogen removal to metagenomic analyses. Our results indicate that MBBs unveiled a 10-fold more enhanced nitrification rate than the dispersed microbial community present in the native sludge of the Porto Sant’Elpidio (Italy) WWTP. Four bacterial families, Chitinophagaceae, Comamonadaceae, Sphingomonadaceae, and Nitrosomonadaceae, accumulate in structured biofilms and significantly contribute to the high ammonium removal rate of 80% in 24 h as estimated in leachate-containing wastewaters. Full article

Using wastewater in response to water-related challenges from climate variation has gained significance. Various sophisticated technologies have been developed to meet the demand for wastewater treatment and reuse. Graywater, an intrinsic component of wastewater, is acknowledged for its practical potential in the context of reuse. Decentralized wastewater treatment systems, exemplified by Moving Bed Biofilm Reactors (MBBRs), have emerged as efficient alternatives in urban settings. By comparing the physicochemical analyses conducted in the three treatment units and evaluating the treatment efficiency of each unit, we will first establish the validity of the MBBR system for treating and recycling graywater, achieving up to 98% elimination rates for BOD5. Subsequently, the possibility of optimizing the system will be explored by evaluating the different treatment stages of MBBR reactors. Full article

Rural and semi-urban areas in arid/semi-arid regions are facing severe water scarcity and a series of environmental challenges nowadays, specifically due to rapid urbanization and economic development, climate change, population growth, increasing water demand, influxes of refugees caused by war and regional political conflict, etc. To solve the emerging problems, the safe reuse of treated wastewater in agriculture can provide an additional water resource for countries with high water scarcity. The aim of this study was to investigate the treatment performance and effectiveness of small decentralized wastewater treatment (DWWT) technologies treating high-strength wastewater with concentrations far beyond the European Union testing ranges of parameters such as five-day biochemical oxygen demand (BOD₅ > 500 mg/L), chemical oxygen demand (COD > 1000 mg/L), or total suspended solids (TSS > 700 mg/L). Four (4) commercially available DWWT technologies with a design capacity of 4–8 PE (population equivalent) were selected and operated with various wastewater compositions in Leipzig, Germany. The technologies were (i) the moving bed biofilm reactor (MBBR), (ii) the sequencing batch reactor (SBR), (iii) the membrane bioreactor (MBR) and (iv) the aerated vertical-flow constructed wetland (AVFCW). This study results clearly demonstrated that the EU-certified small DWWT technologies are quite capable of treating high-strength wastewater and can provide high-quality treated water for safe reuse in rural communities of arid and semi-arid regions. During operation with high-strength wastewater with a mean inflow BOD₅, COD and TSS concentrations of 1532 ± 478, 2547 ± 830 and 546 ± 176 mg/L, a low mean BOD₅ (<10 mg/L), COD (<70 mg/L) and TSS (<15 mg/L) in the outflow of the four systems showed removal efficiency of BOD₅ (>99%), COD (>97%) and TSS (>97%), and met the maximum allowable limit value of water quality class A for reuse in agriculture according to Jordanian and Omani standard. The MBR showed almost a complete removal of Escherichia coli (E. coli) in a range of 6.1–6.9-log removal in the outflow during all three experimental phases and performed best for BOD₅, COD, TSS and pathogen removal when treating high-strength wastewater if properly maintained to prevent potential fouling and clogging of the membrane. Before the final permitting process, long-term monitoring under local temperature and climatic conditions as well as guidelines based on local needs (e.g., in Jordan, Oman, etc.) should be developed to guarantee a minimum level of performance standards of such small DWWT technologies and requirements for operation and maintenance (O&M). Full article

Moving bed biofilm reactors (MBBRs) are compact biofilm systems that provide a sustainable solution for biological nitrogen removal. A study was conducted on an innovative post-denitrification method as a polishing step to reduce low nitrate nitrogen concentrations (10 mg/L) to 2.1–4.9 mg/L. The objective was to minimize residual chemical oxygen demand (COD) in the effluent caused by the external carbon source required for this final treatment step. Therefore, four continuous flow reactors with varying synthetic loads and hydraulic retention times (HRTs), as well as two carrier sizes, were operated over 335 days. The results showed that an HRT of 2 h is necessary to successfully reduce the residual COD to 5–6 mg/L. Additionally, it was demonstrated that the protected volume of the biofilm carriers has a significant impact on MBBRs compared to the protected surface, which is commonly discussed in the literature. The available protected volume can limit biofilm growth, as demonstrated by measuring the total biofilm solids (TBS) and biofilm thickness on the carrier at varying COD eliminations. When providing sufficient protected volume for the biofilm through the filling ratio and carrier size, a COD elimination rate of 1.4 to 1.45 kg/(m³d) was achieved with a biofilm thickness of only 500 µm. Full article

This study extensively analyzed the bacterial information of biofilms and activated sludge in oxic reactors of full-scale moving bed biofilm reactor-integrated fixed-film activated sludge (MBBR-IFAS) systems. The bacterial communities of biofilms and activated sludge differed statistically (R = 0.624, p < 0.01). The denitrifying genera Ignavibacterium, Phaeodactylibacter, Terrimonas, and Arcobacter were more abundant in activated sludge (p < 0.05), while comammox Nitrospira was more abundant in biofilms (p < 0.05), with an average relative abundance of 8.13%. Nitrospira and Nitrosomonas had weak co-occurrence relationships with other genera in the MBBR-IFAS systems. Potential function analysis revealed no differences in pathways at levels 1 and 2 based on the Kyoto Encyclopedia of Genes and Genomes (KEGG) between biofilms and activated sludge. However, in terms of pathways at level 3, biofilms had more potential in 26 pathways, including various organic biodegradation and membrane and signal transportation pathways. In comparison, activated sludge had more potential in only five pathways, including glycan biosynthesis and metabolism. With respect to nitrogen metabolism, biofilms had greater potential for nitrification (ammonia oxidation) (M00528), and complete nitrification (comammox) (M00804) concretely accounted for methane/ammonia monooxygenase (K10944, K10945, and K10946) and hydroxylamine dehydrogenase (K10535). This study provides a theoretical basis for MBBR-IFAS systems from the perspective of microorganisms. Full article

Traditional aquaculture systems appear challenged by the high levels of total ammoniacal nitrogen (TAN) produced, which can harm aquatic life. As demand for global fish production continues to increase, farmers should adopt recirculating aquaculture systems (RAS) equipped with biofilters to improve the water quality of the culture. The biofilter plays a crucial role in ammonia removal. Therefore, a biofilter such as a moving bed biofilm reactor (MBBR) biofilter is usually used in the RAS to reduce ammonia. However, the disadvantage of biofilter operation is that it requires an automatic system with a water quality monitoring and control system to ensure optimal performance. Therefore, this study focuses on developing an Internet of Things (IoT) system to monitor and control water quality to achieve optimal biofilm performance in laboratory-scale MBBR. From 35 days into the experiment, water quality was maintained by an aerator’s on/off control to provide oxygen levels suitable for the aquatic environment while monitoring the pH, temperature, and total dissolved solids (TDS). When the amount of dissolved oxygen (DO) in the MBBR was optimal, the highest TAN removal efficiency was 50%, with the biofilm thickness reaching 119.88 μm. The forthcoming applications of the IoT water quality monitoring and control system in MBBR enable farmers to set up a system in RAS that can perform real-time measurements, alerts, and adjustments of critical water quality parameters such as TAN levels. Full article

A compatible microbial consortium with a high organic pollutant degradation ability, which includes a gram-positive Brevibacillus parabrevis B50 NCAIM B 001413 bacterial strain and a gram-negative Pseudoxanthomonas mexicana P32 NCAIM (P) B 001414 bacterial strain, was selected using high-throughput screening techniques. The compatible microbial consortium, encapsulated in alginate beds, was used to inoculate moving bed biofilm reactors from a small municipal wastewater treatment plant. The bioaugmentation performance of the inoculated consortium was evaluated by determining the water quality parameters before inoculation and one month after bioaugmentation treatment. The removal of organic matter was enhanced after treatment with the selected microbial consortium. Full article

Dhaka, the economic hub of Bangladesh, houses numerous healthcare facilities, resulting in increased medical waste generation. However, waste management systems in these facilities are often inadequate, posing a threat to public health and the environment. Wastewater characteristics vary regionally, making treatment strategies location-specific. This study characterizes medical waste streams in Dhaka, and suggests appropriate treatment strategies. Twenty samples from four major public hospitals were analyzed for various parameters, including dissolved oxygen (DO), pH, Total Dissolved Solids (TDS), Total Suspended Solids (TSS), color, Total Coliform counts, Chemical Oxygen Demand (COD), and Biochemical Oxygen Demand (BOD₅). Samples were categorized as acceptable, moderate, or highly polluted. Results were compared to the standard values provided by the department of Environment of Bangladesh to find that samples show moderate to high pollution levels in terms of TDS, TSS, color, and bacteria. Effective wastewater treatment strategies are needed to mitigate pollution and ensure health and safety. Treatment recommendations include the implementation of pre-treatment processes such as sedimentation and filtration to remove solids and aeration to increase dissolved oxygen levels. To reduce organic pollution, treatment methods including sequencing batch reactor (SBR), Moving Bed Biofilm Reactor (MBBR), and Membrane Bio Reactor (MBR) were recommended according to the applicability of the processes in respective hospitals. Advanced treatment methods such as activated carbon adsorption and ultraviolet disinfection processes were also suggested to address the specific issues like color and bacterial contamination. Full article

A combined anaerobic–anoxic–oxic moving bed biofilm reactor (A²O-MBBR) constructed wetlands process was used to treat low carbon-to-nitrogen (C/N) simulated sewage. The results showed that the removal rates of chemical oxygen demand (COD), ammonia nitrogen (NH₄⁺-N), total nitrogen (TN), and total phosphorus (TP) by this process were 94.06%, 94.40%, 67.11%, and 84.57%, respectively, and the concentrations of COD, NH₄⁺-N, TN, and TP in the effluent were lower than the Class I-A standard of GB18918-2002. In the anoxic zone, NH₄⁺-N had an inhibitory effect on phosphorus uptake via phosphorus-accumulating organisms (PAOs). The highest community diversity was observed in the anoxic zone sludge at 24 d. During the water-quality-shock loads stage, microbial community diversity decreased in a combined A²O-MBBR constructed wetlands reactor. At the phylum level, bacteria within the mature activated sludge were dominated by Proteobacteria, while Planctomycetes bacteria were the dominant species in the constructed wetlands. At the genus level, Tolumonas spp. were the dominant species in the 12 d and 24 d constructed wetlands and the anaerobic zone, with relative abundance percentages ranging from 20.24 to 33.91%. In the water-quality-shock loads stage, they were replaced by denitrifying bacteria such as Herbaspirillum spp. Unclassified_Burkholderiales was the dominant species in the constructed wetlands, with a relative abundance of 33.09%. Full article

Landfill leachate is a complex and highly polluted wastewater that poses significant environmental challenges worldwide. This study proposes an innovative approach to addressing this challenge by developing an integrated anaerobic–aerobic moving bed biofilm reactor (MBBR) and biochar adsorption method for the efficient removal of organic matter and nutrients from landfill leachate. The MBBR provides a suitable environment for the growth of microorganisms that can degrade organic matter and nutrients, while biochar adsorption removes any remaining pollutants that are not biodegradable. The performance of this integrated system was evaluated under different operating conditions, such as the hydraulic retention time and the organic loading rate, to optimize its efficiency and sustainability. The results showed that the integrated system achieved high removal efficiencies for chemical oxygen demand (COD), ammonium–nitrogen (NH₄-N), and total phosphorus (TP), with maximum removal rates of 98.5% (77% after the anaerobic–aerobic MBBR and 85.4% after biochar adsorption), 91.2% (87% after the anaerobic–aerobic MBBR and 95.9% after biochar adsorption), and 99.9% (92% after the anaerobic–aerobic MBBR and 91.7% after biochar adsorption), respectively. The proposed method offers a promising solution for the treatment of landfill leachate, which is a critical environmental issue worldwide. This study also highlights the importance of developing more effective and sustainable methods for treating landfill leachate, which can have significant impacts on public health and the environment. Full article

This study investigated the efficiency of two advanced oxidation processes (AOPs), ozonation (O₃), and electrochemical oxidation (EO), applied individually or in combination, in the removal of contaminants of emerging concern (CECs) contained in hospital wastewaters, focusing on pharmaceuticals. The optimisation of the single technologies was performed using synthetic wastewater composed of four refractory pharmaceuticals, (carbamazepine-CBZ, lorazepam-LZP, ketoprofen-KTP, 10,11-epoxicarbamazepine-E-CBZ), first alone and then in mixture, in an initial concentration of 1 mg L⁻¹ each. Once the best operational conditions for EO and O₃ were defined, their combination (both simultaneous and sequential) was evaluated for the mixture of the selected pharmaceuticals. The treatment solution that showed the best performance was the simultaneous combination of O₃ and EO. This treatment was validated using real hospital wastewater previously treated through a moving bed biofilm reactor (MBBR), evaluating its viability by testing the toxicity of the final effluent via Vibrio fischeri inhibition tests. The obtained results showed that the simultaneous combination of O₃ and EO as the polishing step after a biological treatment is a very promising solution for hospital wastewater treatment, allowing for obtaining a non-toxic effluent and full degradation of refractory compounds. The disinfection potential of the proposed AOP was also assessed by determining Escherichia coli inactivation potential. Full article