Search Results (102)

This study compared the effectiveness of the Sequencing Batch Biofilter Granular Reactor (SBBGR) plant with and without the integration of ozone (BIO-CHEM process) in the remediation of medium-aged landfill leachate. Special attention is given to the removal of per- and polyfluoroalkyl substances (PFAS) as a group of bioaccumulative and persistent pollutants. The findings highlight the high SBBGR performance under biological process only for key wastewater contaminants, with 82% for chemical oxygen demand (COD), 86% for total nitrogen, and 98% for ammonia. Moderate removal was observed for total (TSS) and volatile (VSS) suspended solids (41% and 44%, respectively), while phosphorus and colour removal remained limited. Remarkably, the SBBGR process achieved complete removal of long-chain PFAS, while its performance declined for shorter-chain PFAS. BIO-CHEM process significantly improved COD (87.7%), TSS (84.6%), VSS (86.7%), and colour (92–96%) removal. Conversely, ozonation led to an unexpected increase in the concentrations of several PFAS in the effluent, suggesting ozone-induced desorption from the biomass. SBBGR treatment was characterised by a low specific sludge production (SSP) value, i.e., 5–6 times less than that of conventional biological processes. SSP was further reduced during the application of the BIO-CHEM process. A key finding of this study is a critical challenge for PFAS removal in this combined treatment approach, different from other ozone-based methods. Full article

To address the slow growth rate of photosynthetic bacteria (PSB), this study introduces pantothenic acid as a biological enhancing factor. The effects of pantothenic acid on PSB proliferation and its effectiveness in treating high-concentration ammonia–nitrogen wastewater were systematically evaluated. Additionally, the effects of different culture conditions, including dark aeration, darkness, light exposure, and light aeration, on PSB growth were investigated. The results show that optimal PSB growth was achieved with 20 mg/L of pantothenic acid; however, higher concentrations of pantothenic acid inhibited bacterial growth. The addition of pantothenic acid also significantly enhanced the performance of PSB in treating high-concentration organic wastewater, increasing the removal rates of COD, ammonia nitrogen, total phosphorus, and total nitrogen to 43.0%, 94.0%, 49.7%, and 51.0%, respectively. Furthermore, a synergistic effect between dark aeration and light exposure was observed. When the time of light and dark aeration was set at 1:1, the highest PSB yield was recorded, and the removal efficiencies of COD, ammonia nitrogen, total nitrogen, and total phosphorus increased to 71.4%, 95.3%, 57.1%, and 74.7%, respectively. Through the introduction of pantothenic acid and optimization of culture mode, the rapid growth of PSB and highly efficient treatment of organic wastewater were achieved, providing a new approach for advanced wastewater treatment and resource utilization. Full article

There is a lack of research on screening new strains of high-efficiency ammonia nitrogen degrading bacteria and treating high-concentration ammonia nitrogen aquaculture wastewater using immobilized composite bacteria. In this study, two strains capable of degrading ammonia nitrogen and nitrite were isolated from surface water. The species of the strains were accurately identified using ITS sequencing technology. Scp1 was identified as Pseudomonas and Scr1 as Rhodococcus erythropolis. Both strains were preserved. When the initial concentration of ammonia nitrogen was 1.50 mg/L, the degradation efficiency of ammonia nitrogen after 4 days of inoculation with Scp1, Scr1, and a combination of Scp1 and Scr1 was 90%, 93.3%, and 99.99%, respectively. Similarly, when the initial concentration of nitrite was 0.25 mg/L, the degradation efficiency after 4 days of inoculation with Scp1, Scr1, and a combination of Scp1 and Scr1 was 60%, 82%, and 97.2%, respectively. In addition, when the initial concentration of COD was 20 mg/L, the degradation efficiency after 6 days of inoculation with Scp1, Scr1, and a combination of Scp1 and Scr1 was 59%, 59.4%, and 93.75%, respectively. The results demonstrated that the combined bacteria, Scp1 and Scr1, had a better degradation effect on ammonia nitrogen, nitrite, and COD. Furthermore, a degradation test was conducted in a Penaeus vannamei breeding base, which showed good degradation effects. These findings provide theoretical support for the treatment of high ammonia nitrogen wastewater in aquaculture and have important practical applications. Full article

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

This study examined total ammoniacal nitrogen (TAN) rejection by two reverse osmosis (RO) and two nanofiltration (NF) membranes as a function of pH for three ammonium salts to optimize conditions for a hybrid membrane system that can produce high-purity TAN streams suitable for reuse. The results showed that TAN rejection was significantly influenced by membrane type, feed pH, and the ammonium salt used. This study represents the first attempt to simulate real manure wastewater conditions typically found in pig manure. TAN rejection for (NH₄)₂SO₄ and NH₄HCO₃ reached up to 95% at pH values below 7, with the SW30 membrane showing the highest performance (99.5%), attributed to effective size exclusion and electrostatic repulsion of SO₄²⁻ and HCO₃⁻ ions. In contrast, lower rejection was observed for NH₄Cl, particularly with the MPF-34 membrane, due to its higher molecular weight cut-off (MWCO), which diminishes both exclusion mechanisms. TAN rejection decreased markedly with increasing pH across the BW30, NF90, and MPF-34 membranes as the proportion of uncharged NH₃ increased. The lowest rejection rates (<15%) were recorded at pH 11.5 for both NF membranes. These results reveal a notable shift in separation behavior, where NH₃ permeation under alkaline conditions becomes dominant over the commonly reported NH₄⁺ retention at low pH. This novel insight offers a new perspective for optimizing membrane-based ammonia recovery in systems simulating realistic manure wastewater conditions. TAN recovery was evaluated using a hybrid membrane system, where NF membranes operated at high pH promoted NH₃ permeation, and the SW30 membrane at pH 6.5 enabled TAN rejection as (NH₄)₂SO₄. This hybrid system insight offers a new perspective for optimizing membrane-based ammonia recovery in systems simulating realistic manure wastewater conditions. Based on NH₃ permeation and membrane characteristics, the NF90 membrane was operated at pH 9.5, achieving a TAN recovery of 48.3%, with a TAN concentration of 11.7 g/L, corresponding to 0.9% nitrogen. In contrast, the MPF-34 membrane was operated at pH 11.5. The NF90–SW30 system also achieved a TAN recovery of 48.3%, yielding 11.7 g/L of TAN with a nitrogen content of 1.22%. These nitrogen concentrations indicate that both retentate streams are suitable for use as liquid fertilizers in the form of (NH₄)₂SO₄. A preliminary economic assessment estimated the chemical consumption cost at 0.586 EUR/kg and 0.729 EUR/kg of (NH₄)₂SO₄ produced for the NF90–SW30 and MPF-34–SW30 systems, respectively. Full article

Microalgae–fungal pellets (MFPs) effectively degrade pollutants in high-density aquaculture wastewater; however, their structural instability limits their long-term applicability. This study evaluated the effects of three crosslinking agents, sodium alginate (SA), chitosan (CTS), and polyvinyl alcohol (PVA), on enhancing the stability of MFPs. The results demonstrated that the initial 20 g/L SA-crosslinked MFP sample (SMFP₀) exhibited significantly improved structural stability, maintaining superior mechanical hardness (57.05 g) after 9 days. Further analysis revealed that SMFP₀ exhibited a more negative absolute Zeta potential (−13.05 mV), increased fluorescence intensity (0.020) in its tightly bound extracellular polymeric substances (TB-EPSs), and significantly higher protein (PN, 64.22 mg/L) and polysaccharide (PS, 56.99 mg/L) concentrations compared with the control (p < 0.05). These findings suggest that SMFP₀ possesses physicochemical properties that are conducive to microalgae–fungal aggregation. A scanning electron microscopy (SEM) analysis confirmed that the SA gel network enhanced the system’s stability by strengthening the microalgae–fungal interfacial adhesion and maintaining a porous, light-permeable structure. In practical wastewater treatment, SMFP₀ achieved superior removal rates for COD (84.19%), ammonia nitrogen (95.29%), total nitrogen (89.50%), and total phosphorus (93.46%) compared with non-crosslinked MFPs (p < 0.05). After 9 days of continuous operation (SMFP₉), the pollutant removal efficiencies remained comparable to those observed in the initial stage of the non-crosslinked system, indicating improved structural durability for extended practical application. Full article

Landfill leachate, characterized by its high concentration of organic matter (high COD), elevated ammonia and nitrogen levels, high salinity, and toxicity, poses a significant challenge for environmental pollution control. In recent years, extensive research efforts have been dedicated to treating landfill leachate, resulting in the implementation of various engineering technologies. However, with the advancement of analytical techniques, an increasing number of emerging contaminants (ECs) have been detected in landfill leachate. These pollutants pose potential environmental and health risks, yet traditional wastewater treatment technologies struggle to effectively remove them, necessitating innovative upgrades to existing methods. This paper reviews the current research status of landfill leachate treatment technologies, compares the advantages and disadvantages of various techniques, and emphasizes the importance of technological innovation in treatment processes. Full article

Oxidation ditch and Anaerobic–Anoxic–Oxic (A²/O) processes have been applied in urban wastewater treatment plants for decades, but the differences between two processes in engineering applications are less studied. Based on the continuous monitoring of Ningyang’s sewage treatment plant (Shandong, China) for one year, this study systematically analyzed the removal efficiencies of nutrients in the oxidation ditch and the modified high-efficiency multi-cycle A²/O processes. The results showed that chemical oxygen demand (COD) and total phosphorus (TP) removal in the modified high-efficiency multi-cycle A²/O process of the Phase II project was better than that in the oxidation ditch process of the Phase I project, and the average concentration of COD and TP in the effluent was 49.9% and 51.7% lower than that in the oxidation ditch process, respectively. The removal rate of ammonia nitrogen (NH₄⁺-N) by the two processes was basically the same, while the total nitrogen (TN) effluent concentration of the oxidation ditch process was 31.4% lower than that in the high-efficiency multi-cycle A²/O process. In summary, the high-efficiency multi-cycle A²/O process had a better treatment performance regarding nutrient removal than the oxidation ditch process under the same conditions. Furthermore, the engineering and operational costs of the high-efficiency multi-cycle A²/O process were lower. Full article

Electro-chlorination (E-Cl) is an emerging and promising electrochemical advanced oxidation technology for wastewater treatment with the advantages of high efficiency, deep mineralization, a green process, and easy operation. It was found that the mechanism of pollutant removal by electro-chlorination mainly involves an indirect oxidation process, in which pollutant removal is mainly driven by the intermediate active species, especially RCS and chlorine radicals, with a strong oxidization ability produced at the anodes. In this work, we summarized the principles and pathways of the removal/degradation of pollutants (organic pollutants and ammonia nitrogen) by E-Cl and the major affecting factors including the applied current density, voltage, electrolyte concentration, initial pH value, etc. In the E-Cl system, the DSA and BDD electrodes were the most widely used electrode materials. The flow-through electrode reactor was considered to be the most promising reactor since it had a high porosity and large pore size, which could effectively improve the mass transfer efficiency and electron transfer efficiency of the reaction. Of the many detection methods for chlorine radicals and RCS, electron paramagnetic resonance (EPR) and spectrophotometry with N, N-diethyl-1,4-phenylenediamine sulfate (DPD) as the chromogenic agent were the two most widely used methods. Overall, the E-Cl process had excellent performance and prospects in treating salt-containing wastewater. Full article

Aquaculture wastewater is rich in nutrients such as nitrogen and phosphorus. If discharged directly without treatment, it can cause eutrophication of water bodies and the proliferation of algae. This study explores the treatment of aquaculture wastewater using cerium nitrate and hydrogen peroxide. To improve the treatment efficiency of ammonia and nitrite in aquaculture wastewater, a Box–Behnken design with three factors at three levels was used to optimize the process of treating aquaculture wastewater with cerium nitrate and hydrogen peroxide. The optimal process conditions for removing ammonia and nitrite were determined to be a Ce(NO₃)₃ dosage of 0.18 g/L, an H₂O₂ reaction concentration of 1.0%, and a reaction time of 30 min. Under the optimal reaction conditions, the degradation rate of ammonia and nitrite can reach 80% or more. Finally, high-throughput sequencing technology was used to explore the impact of cerium nitrate and hydrogen peroxide treatment on microbial community structure and metabolic pathways. The results showed that, at the phylum level, the dominant positions of Actinobacteriota, Proteobacteria, and Bacteroidota were maintained throughout the entire culture period. At the genus level, the relative abundance of the hgcI_clade genus under Actinobacteriota significantly increased, becoming the main dominant genus throughout the culture period. Under the condition of adding cerium nitrate and hydrogen peroxide, the metabolic functions of the microbial community were enhanced. The addition of cerium nitrate and hydrogen peroxide increased the abundance of key nitrogen metabolism genes such as amo, hao, and nap, thereby enhancing the potential nitrification/denitrification capabilities of microorganisms. The combination of cerium nitrate and hydrogen peroxide showed positive effects in the treatment of aquaculture wastewater, providing a new strategy for the green treatment of wastewater. Full article

The management of swine wastewater (SW) presents significant environmental challenges, requiring solutions that combine effective treatment with resource recovery. This study highlights the dual role of microalgae in wastewater remediation and bioenergy production. H. rubescens KNUA214 was cultivated in media containing varying concentrations of diluted swine wastewater (DSW; 0%, 25%, 50%, and 100%). Cultivating with Blue Green-11 (BG-11) medium + 50% DSW maximized biomass growth, the chlorophyll content, and carotenoid production. Nutrient removal efficiency in 100% DSW over 8 days demonstrated reductions of 59.3% in total nitrogen, 67.7% in ammonia nitrogen, and 40.7% in total phosphorus, confirming the species’ capacity for effective wastewater treatment. The carotenoid analysis using HPLC revealed that astaxanthin, lutein, canthaxanthin, and beta-carotene exhibited the highest levels in BG-11 + 50% DSW. Furthermore, the biomass analyses confirmed its potential for bioenergy applications, with high calorific values and significant polyunsaturated fatty acid concentrations, enhancing its utility for bioenergy and biolubricant production. These findings position H. rubescens KNUA214 as an effective resource for integrating SW management with the sustainable production of high-value biochemicals, offering environmental and economic benefits. Full article

Microalgae demonstrate significant efficacy in wastewater treatment. Anaerobic digestion effluent (ADE) is regarded as an underutilized resource, abundant in carbon, nitrogen, phosphorus, and other nutrients; however, the presence of inhibitory factors restricts microalgal growth, thereby preventing its direct treatment via microalgae. The purpose of this study was to dilute ADE using various dilution media and subsequently cultivate Chlorella sp. to identify optimal culture conditions that enhance microalgal biomass and water quality. The effects of various dilution conditions were assessed by evaluating the biomass, sedimentation properties, and nutrient removal efficiencies of microalgae. The results demonstrate that microalgal biomass increases as the dilution ratio increased. The microalgae biomass in the treatments diluted with simulated wastewater was significantly higher than that with deionized water, but their effluent quality failed to meet discharge standards. The treatment diluted with deionized water for 10 times exhibited abundant microbial biomass with strong antioxidant properties. The corresponding total phosphorus concentration in the effluent (6.96 mg/L) adhered to emission limits under the Livestock and Poultry Industry Pollutant Emission Standards (8 mg/L), while ammonia nitrogen concentration (90 mg/L) was near compliance (80 mg/L). The corresponding microbial biomass, with a sludge volume index (SVI₃₀) of 72.72 mL/g, can be recovered economically and efficiently by simple precipitation. Its high protein (52.07%) and carbohydrate (27.05%) content, coupled with low ash (10.75%), makes it a promising candidate for animal feed and fermentation. This study will aid in understanding microalgal growth in unsterilized ADE and establish a theoretical foundation for cost-effective ADE purification and microalgal biomass production. Full article

This study investigates the efficiency of a hybrid coagulation–flocculation process for the treatment of industrial wastewater from the steel industry. The novel method combines a natural coagulant, processed Rosehip Seed Powder (RSP), with a chemical coagulant, aluminum chloride (AlCl₃), across varying concentrations and pH levels. The study simulated the pH 8 conditions of iron and steel industrial wastewater and examined the removal of heavy metals, total suspended solids (TSS), chemical oxygen demand (COD), and ammonia–nitrogen (NH₃-N). At pH 8, the optimal coagulant dosage was determined to be 0.75:0.75 (g/g) of RSP/AlCl₃ powder, resulting in high removal efficiencies across several parameters: 88.29% for COD, 91.85% for color, 99% for TSS, 93.11% for NH₃-N, 94.3% for Mn, 98.5% for Fe, 96.7% for Zn, and 99.3% for Ni. The pH optimization demonstrated high removal efficiencies without pH adjudication. The removal of heavy metals at pH 8 demonstrated high efficiencies, with Mn, Fe, Zn, and Al achieving 99.00%, 90.6%, 95.73%, and 92.3%, respectively. These results suggest that no pH adjustment is required when using RSP/AlCl₃ for the treatment of iron and steel industry wastewater through the coagulation method. Full article

This study investigated the efficacy of membrane bioreactor (MBR) technology in treating saline industrial wastewater, focusing on the impact of the organic loading rate (OLR) and the food-to-microorganism (F/M) ratio on treatment performance. This research utilized saline industrial wastewater from Al-Hasa, which had salinity levels ranging from 5000 to 6900 mg/L. It explored treatment processes at varying Chemical Oxygen Demand (COD) concentrations of 800, 1400, and 2000 mg/L, corresponding to an OLR of 0.80 ± 0.05, 1.41 ± 0.07, and 1.98 ± 0.12 g COD/L, respectively. The average F/M ratios used were 0.20, 0.36, and 0.50 g COD/g MLSS·d, maintaining a constant Sludge Residence Time (SRT) of 12 days, a hydraulic retention time (HRT) of 24 h (hrs.), and a flux of 10 L/m²·h. The MBR system demonstrated high COD removal efficiencies, averaging 95.7 ± 1.6%, 95.5 ± 0.4%, and 96.1 ± 0.3%, alongside Biochemical Oxygen Demand (BOD) removal rates of 98.3 ± 0.2%, 99.8 ± 0.1%, and 98.5 ± 0.1%, respectively. However, an increased OLR led to elevated residual COD and BOD levels in the treated effluent, with COD concentrations reaching 34.2 ± 12.8, 63.3 ± 5.9, and 76.5 ± 5.4 mg/L, respectively. This study also reveals a significant decline in ammonia and Total Kjeldahl Nitrogen (TKN) removal efficiencies as OLR increases, dropping from 96.1 ± 0.5% to 80.2 ± 0.9% for ammonia and from 83.8 ± 3.4% to 65.8 ± 2.3% for TKN. Furthermore, higher OLRs significantly contribute to membrane fouling and elevate the transmembrane pressure (TMP), indicating a direct correlation between OLRs and operational challenges in MBR systems. The findings suggest that for optimal performance within the Saudi disposal limits for industrial wastewater, the MBR system should operate at an F/M ratio of ≤0.33 g COD/g of Mixed Liquor Suspended Solid (MLSS)·d. This study underscores the critical role of the OLR and F/M ratio in treating saline industrial wastewater using MBR technology, providing valuable insights for enhancing treatment efficiency and compliance with environmental standards. Full article

In this paper, a lab-scale reactor designed to simulate the operations of the North Water Saline Wastewater Treatment Plant (SWWTP) located in Delfzijl, The Netherlands, was constructed and assessed. Unlike conventional municipal wastewater treatment facilities, this industrial plant deals with wastewater containing stubborn chemicals that are difficult to break down, along with a high ratio of chemical oxygen demand (COD) to nitrogen and elevated sodium chloride levels. Furthermore, its treatment process diverges from standard industrial setups by employing an aerobic process preceding the anaerobic phase. The proposed lab-scale reactors were proven stable and effective in mimicking the conditions of the studied industrial SWWTP, particularly in the presence of abundant glycerol, a factor not explored in similar lab-scale models. Throughout the experiment, the removal of COD (specifically glycerol) and nitrogen were monitored, alongside changes in the microbial community within both reactors. The data enabled us to examine the proliferation of microbial populations within the sludge. The results indicated the complete removal of glycerol and ammonia from the system, with some residual nitrate detected in the effluent. The soluble COD decreased in the first reactor (R1) to approximately 50% of the influent and reduced further to less than 100 mg/L in the second reactor (R2), while nitrogen was majorly removed in the R1. By the experiment’s conclusion, Actinomycetales was identified as the dominant order in the anaerobic reactor (sometimes even exceeding 70% of the population), which is known for its utilization of glycerol as a carbon source and its tolerance to high salt concentrations in the influent. Conversely, the aerobic reactor was predominantly inhabited by the order Flavobacteriales, which correlates with ammonia concentration. Full article