Low-strength Domestic Wastewater Research Articles

Integration of bioflocculation with anaerobic digestion guided by physicochemical profiling enhances valorization potential of domestic wastewater.

Domestic wastewater is a dilute, variable, and complex carbon source for bioprocessing. Despite various treatment technologies, tailored bioprocessing and profiling studies are needed to fully explore its potential. Efficient integration of bioflocculation with anaerobic digestion (AD) is evaluated as a potential platform for small molecules and biogas recovery. Bioflocculation of low strength domestic wastewater (COD ∼ 0.1 g/L) using a bioflocculant resulted in clear water and flocculated sludge, having 30-90-fold increase in Chemical Oxygen Demand (COD). Alkali pretreatment of flocculated sludge (COD ∼ 10 g/L) significantly enhanced biogas production, resulting in a methane yield of 49 %. 1H NMR and GC-MS based profiling demonstrated the desirable impact of bioflocculation and alkali treatment on small molecule abundance. This study establishes an integrated approach that combines bioflocculation, alkali pretreatment, and AD, guided by small molecule profiling, as an effective process for valorizing domestic wastewater into biogas and recoverable organic molecules.

Toward Integrating EBPR and the Short-Cut Nitrogen Removal Process in a One-Stage System for Treating High-Strength Wastewater.

Enhanced biological phosphorus removal (EBPR) is an economical and sustainable process for phosphorus removal from wastewater. Despite the widespread application of EBPR for low-strength domestic wastewater treatment, limited investigations have been conducted to apply EBPR to the high-strength wastewaters, particularly, the integration of EBPR and the short-cut nitrogen removal process in the one-stage system remains challenging. Herein, we reported a novel proof-of-concept demonstration of integrating EBPR and nitritation (oxidation of ammonium to nitrite) in a one-stage sequencing batch reactor to achieve simultaneous high-strength phosphorus and short-cut nitrogen removal. Excellent EBPR performance of effluent 0.8 ± 1.0 mg P/L and >99% removal efficiency was achieved fed with synthetic high-strength phosphorus wastewater. Long-term sludge acclimation proved that the dominant polyphosphate accumulating organisms (PAOs), Candidatus Accumulibacter, could evolve to a specific subtype that can tolerate the nitrite inhibition as revealed by operational taxonomic unit (OTU)-based oligotyping analysis. The EBPR kinetic and stoichiometric evaluations combined with the amplicon sequencing proved that the Candidatus Competibacter, as the dominant glycogen accumulating organisms (GAOs), could well coexist with PAOs (15.3-24.9% and 14.2-33.1%, respectively) and did not deteriorate the EBPR performance. The nitrification activity assessment, amplicon sequencing, and functional-based gene marker quantification verified that the unexpected nitrite accumulation (10.7-21.0 mg N/L) in the high-strength EBPR system was likely caused by the nitritation process, in which the nitrite-oxidizing bacteria (NOB) were successfully out-selected (<0.1% relative abundance). We hypothesized that the introduction of the anaerobic phase with high VFA concentrations could be the potential selection force for achieving nitritation based on the literature review and our preliminary batch tests. This study sheds light on developing a new feasible technical route for integrating EBPR with short-cut nitrogen removal for efficient high-strength wastewater treatment.

Pilot-scale aerobic granular sludge reactors with granular activated carbon for effective nitrogen and phosphorus removal from domestic wastewater

Aerobic granular sludge (AGS) is a breakthrough biotechnology of 21st century and an innovative alternative to activated sludge for treating wastewater. Concerns on long-start up periods for development of AGS and stability of granules are impeding its widespread implementation for treating low-strength domestic wastewater especially in tropical climate conditions. Addition of nucleating agents have been shown to improve development of AGS while treating low-strength wastewaters. There are no previous studies on AGS development and biological nutrient removal (BNR) in the presence of nucleating agents during treatment of real domestic wastewater. This study investigated AGS formation and BNR pathways while treating real domestic wastewater in a 2 m3 pilot-scale granular sequencing batch reactor (gSBR) operated without and with granular activated carbon (GAC) particles. The gSBRs were operated under tropical climate (T ≈ 30 °C) for >4-years to evaluate the effect of GAC addition on granulation, granular stability and BNR at pilot-scale. Formation of granules was observed within 3 months. MLSS values of 4 and 8 g/L were recorded within 6 months in gSBRs without and with GAC particles, respectively. The granules had an average size of 1.2 mm and SVI5 of 22 mL/g. Ammonium was mainly removed through nitrate formation in the gSBR without GAC. But, ammonium was removed by short-cut nitrification via nitrite due to washout of nitrite oxidizing bacteria in the presence of GAC. Phosphorus removal was much higher in gSBR with GAC due to the establishment of enhanced biological phosphorus removal (EBPR) pathway. After 3 months, the phosphorus removal efficiencies were at 15 % and 75 %, respectively, without and with GAC particles. The addition of GAC led to moderation in bacterial community and enrichment of polyphosphate-accumulating organisms. This is the first ever report on pilot-scale demonstration of AGS technology in the Indian sub-continent and GAC addition on BNR pathways.

Organics and coliform removal from low strength domestic wastewater using integrated constructed wetland – microbial fuel cell reactor with bioelectricity generation

Wastewater treatment with energy recovery is a major concern in environmental engineering research nowadays. The current study focuses on the removal of organics and fecal coliforms which are primary source of pollution in domestic wastewater, using three identical reactors. One vertical planted constructed wetland (R1), one planted CW-MFC (R2), and one unplanted CW-MFC (R3). Bioenergy production in R2 and R3 was also monitored. In terms of COD removal, R2 reactor achieved 93.13 ± 4.83% efficiency, and R1 and R3 achieved 87.21 ± 4.56% and 86.31 ± 4.37% efficiencies, respectively. BOD removal efficiency in R1, R2, and R3 reactors were found to be similar around 91.79 ± 3.58% to 92.7 ± 3.3%. The total coliform removal was better in R1 (log 2.95) than in R2 (log 2.93). However, the fecal coliform removal in R2 was much higher (log 3.51) compared to R1 (log 2.94). Coliform and organic removal deteriorated during winter time, though electricity generation remained unaffected. The maximum open-circuit voltage in R2 was 886 mV and in the R3 was 487 mV during the complete study. Plants played a positive role in enhancing the electrical performance of R2 compared to unplanted R3 by increasing the redox potential. Presence of dissolved oxygen in the range of 1.97–2.1 mg/L was also detected near the rhizosphere of the planted reactors. Combined role of plants and electrodes was crucial for COD removal and anaerobic condition near anode with low ORP governed the pathogen removal from domestic wastewater.

Highly Enriched Anammox Bacteria with a Novel Granulation Model Regulated by Epistylis spp. in Domestic Wastewater Treatment.

Anammox granulation is an efficient solution proffered to enrich slow-growing anammox bacteria (AnAOB), but the lack of effective granulation strategies for low-strength domestic wastewater impedes its application. In this study, a novel granulation model regulated by Epistylis spp. for highly enriched AnAOB was revealed for the first time. Notably, anammox granulation was achieved within 65 d of domestic wastewater treatment. The stalks of Epistylis spp. were found to act as the skeleton of granules and provide attachment points for bacterial colonization, and the expanded biomass layer in turn provided more area for the unstalked free-swimming zooids. Additionally, Epistylis spp. exerted much less predation stress on AnAOB than on nitrifying bacteria, and AnAOB tended to grow in aggregates in the interior of granules, thus favoring the growth and retention of AnAOB. Ultimately, the relative abundance of AnAOB reached up to a maximum of 8.2% in granules (doubling time of 9.9 d) compared to 1.1% in flocs (doubling time of 23.1 d), representing the most substantial disparity between granules and flocs. Overall, our findings advance the current understanding of interactions involved in granulation between protozoa and microbial communities and offer new insight into the specific enrichment of AnAOB under the novel granulation model.

Aerobic granular sludge development using diatomite for low-strength wastewater treatment

This paper presents an assessment of the start-up performance of aerobic granular sludge (AGS) for the treatment of low-strength (chemical oxygen demand, COD < 200mg/L) domestic wastewater by the application of a diatomite carrier. The feasibility was evaluated in terms of the start-up period and stability of the aerobic granules as well as COD and phosphate removal efficiencies. A single pilot-scale sequencing batch reactor (SBR) was used and operated separately for the control granulation and granulation with diatomite. Complete granulation (granulation rate ≥ 90%) was achieved within 20days for the case of diatomite with an average influent COD concentration of 184mg/L. In comparison, control granulation required 85days to accomplish the same feat with a higher average influent COD concentration (253mg/L). The presence of diatomite solidifies the core of the granules and enhances physical stability. AGS with diatomite recorded the strength and sludge volume index of 18 IC and 53mL/g suspended solids (SS) which is superior to control AGS without diatomite (19.3 IC, 81mL/g SS). Quick start-up and achievement of stable granules lead to an efficient COD (89%) and phosphate removal (74%) in 50days of bioreactor operation. Interestingly, this study revealed that diatomite has some special mechanism in enhancing the removal of both COD and phosphate. Also, diatomite has a significant influence on microbial diversity. The result of this research implies that the advanced development of granular sludge by using diatomite can provide promising low-strength wastewater treatment.

Ammonia-Nitrogen Reduction in Low Strength Domestic Wastewater by Polyvinyl Alcohol (PVA) Gel Beads

This study aimed to evaluate the efficacy of polyvinyl alcohol (PVA) gel beads as an immobilized biofilm carrier to enhance the reduction rate of Ammonia-Nitrogen (NH3-N) and Chemical Oxygen Demand (COD) in domestic wastewater. Laboratory scale reactors were developed to assess the reduction levels of ammonia-nitrogen and COD with and without PVA gel beads using optimal and non-optimal treatment mode settings based on operation procedures from the sewage treatment plant in Taman Kajang Utama, Selangor. The treatment method used is an activated sludge sequencing batch reactor with a treatment cycle duration of 288 minutes. The findings showed the ammonia-nitrogen reduction by non-optimal treatment mode is more effective, with a reduced rate of 62.96% to 65.71% compared to optimal treatment mode with a reduced rate of 30.94% and treatment without PVA gel beads (optimal and non-optimal) with a reduced rate of 32.41% to 47.85%. The ammonia-nitrogen reduction rate using PVA gel beads for non-optimal treatment mode was significantly increased from 17.86% to 18.82% and complied with ammonia-nitrogen reduction parameter 10mg/L, Standard A of Environmental Quality (Sewage) Regulations 2009 (EQSR 2009). The rate of COD reduction using the non-optimal treatment mode was also more stable, with a reduced rate of 70.68%. It was also found that the COD reduction rate using PVA gel beads for the non-optimal mode was better than the optimal mode, which was 70.68% compared to 42.0%, and both treatment modes complied with COD reduction parameters 120mg/L, Standard A of EQSR 2009.

Nitrogen recovery from wastewater as nitrate by coupling mainstream ammonium separation with side stream cyclic up-concentration and targeted conversion

A sustainable strategy to recover nitrogen as nitrate by ammonium ion exchange and regeneration (AIR) from low-strength domestic wastewater was proposed to reduce nitrogenous pollutants discharge and alleviate nitrogen loss from atmosphere. In the AIR module, ammonium is rapidly swapped by ion exchangers from the wastewater, and then converted and concentrated as nitrate by cyclic regeneration and side stream nitrification. Nitrate is further concentrated by electrodialysis, and recovered as NaNO3. Then chemically enhanced primary treatment, AIR and membrane bioreactor were coupled to construct an efficient and compact Chemically enhanced primary treatment - Ammonium Ion exchange and Regeneration - Membrane bioreactors (CAIRM) process for nitrogen recovery and synchronous pollutants removal from domestic wastewater under stringent discharge standards. Pilot-scale CAIRM efficiently removed pollutants (nitrogen removal of 93.7%) and recovered 77.1% ammonium during long-term operation without damage to performance of ion exchangers. Compared with the anaerobic/anoxic/aerobic process, CAIRM process reduced land occupancy by 70.1%, decreased upfront investment and treatment cost by 29.3% and 40.7% after resource recovery, and cut greenhouse gas emission by 52.5%. Application of the proposed strategy is expected to save energy of nitrate production and convert global nitrogen circular pollution to circular economy.

High-speed treatment of low strength domestic wastewater for irrigation water production in pilot-scale classical, moving bed and fixed bed hybrid MBRs

To evaluate the treatability of domestic wastewater under conditions of low hydraulic retention time and high organic loadings, 3 pilot-scale automatically controlled membrane bioreactors (MBRs) as classical (C-MBR), moving bed (MB-MBR), and fixed bed (FB-MBR) were established and operated for a total of 268 days. Established pilot plants were compared in terms of treatment performance, membrane fouling, irrigation water criteria, and power consumption values. Results obtained have shown that all three systems were able to achieve more than 93% removal of chemical oxygen demand (COD) in an average hydraulic retention time (HRT) of 1 hour, and MB-MBR and FB-MBR were superior in terms of total nitrogen (TN) and total phosphorus (TP) removals. It has been determined that MB-MBR and FB-MBR are also advantageous in terms of power consumption. Especially it has been found that FB-MBR can produce better quality irrigation water with 40% lower power consumption than C-MBR under the same conditions. It was concluded that biofilm-supported hybrid systems could be a practical application in the fight against increasing water scarcity and global warming, both in obtaining clean water with less power consumption and in protecting human and environmental health.

Formation and stability of aerobic granular sludge in a sequential batch reactor for the simultaneous removal of organic matter and nutrients from low-strength domestic wastewater

Simultaneous removal of organic matter, nitrogen, and phosphorus, via simultaneous nitrification and denitrification (SND) and enhanced biological phosphorus removal processes, was evaluated in a pilot-scale sequential batch reactor. The focus was on granule's morphology, stability, microbiological composition, and reactor performance while treating diluted domestic wastewater with total chemical oxygen demand (CODt) of ≈ 200 mg.L-1. The applied organic loading rate was 0.9 ± 0.3 kg CODt.m−3.d−1 in the experiment. Aerobic granular sludge developed gradually. After 87-day operation, granules (diameter ≥ 0.2 mm) were ≥ 50 % of the biomass, and after 168 days, complete granulation was obtained (≥ 80 % of biomass). In the third period (days 168–247, complete granulation), mixed liquor biomass reached a volatile suspended solids (VSS) concentration of 1.2 ± 0.3 g VSS.L−1, with the granules remaining stable until the experimental end. In this period, low effluent concentrations of COD, nitrogen (NH4+-N, NO2−-N and NO3−-N) and phosphate (PO43—P) were obtained (mg.L−1): 36 ± 11; 4 ± 5; 3 ± 3, 4 ± 5; and 0.9 ± 0.4, respectively. COD, NH4+-N, and PO43−-P removal efficiencies (%) were 80 ± 11; 83 ± 20; and 55 ± 24, respectively. Heterotrophic nitrification and SND were observed, resulting in a process efficiency of 31 % even with dissolved oxygen applied to saturation. The phosphate removal was mainly attributed to denitrifying phosphorus accumulating organisms. Pseudomonas, the dominant genus found, acted in nitrogen and phosphorus removal. Pseudoxanthomonas also assisted in phosphorus removal. Bacterial communities in the flocs (≈ 20 % of biomass) during the last period were similar to those in the granules; therefore, they constituted the basis for granule formation, directly contributed to the simultaneous good removal of organic matter and nutrients.

How volumetric exchange ratio and carbon availability contribute to enhance granular sludge stability in a fill/draw mode SBR treating domestic wastewater?

This work evaluated the granulation process and the stability of aerobic granular sludge in a pilot-scale reactor (1 m³), during a long-term operation (> 650 days) treating real low-strength domestic wastewater. Two operational strategies, distinguished by volumetric exchange ratio (VER: 50 and 75 %), were tested enabling higher organic loading rates. Different topics involving wastewater biological treatment was evaluated from physical-chemical and kinetic parameters to molecular biology techniques. Since process variability can only be described in statistical terms, multivariate statistical process control was applied to verify and integrate the results found. Successful granulation in terms of settling properties (Sludge volumetric index - SVI30 < 70 mL gTSS L−1 and SVI30/SVI5 ∼ 0.70) and granules fraction (>80 %) were achieved when applying VER = 75 %. Multivariate analysis supported that an increment in VER from 50 to 75 % is an important strategy for AGS stability, especially during rainy periods where the carbon availability is lower (OLR < 0.4 kgSCOD m-3 d−1). Carbon compounds were mainly removed during anaerobic feeding phase, however, the presence of particulate matter led to hydrolysis in the aerated phase. Nitrification was observed in both strategies. Nitrospira spp. was predominant under lower VER, whereas Nitrosomonas spp. overcame increasing VER. Although partial denitrification and low phosphorus removal were achieved under both strategies, these factors could be target by controlling the excess of DO in aeration phase and improving the availability of readily organic substrate in feeding phase.

Evaluation of water lettuce, giant salvinia and water hyacinth systems in phytoremediation of domestic wastewater

AbstractThe objective of this research was to ascertain the best conditions for efficient applications of water lettuce, giant salvinia and water hyacinth in improving the quality of low strength domestic wastewater. Water quality assessment of the wastewater samples before (influent) and after treatment (effluent) with effect to retention times (6, 12 and 24 h) was analysed. The outcome of the study at 6 h retention showed that water lettuce (6.8–7.0 pH, 50.5% colour, 46.7% biochemical oxygen demand (BOD) and 37.8% chemical oxygen demand (COD)), giant salvinia (6.9–7.1 pH, 40.5% colour, 60% BOD and 43.2% COD) and water hyacinth (6.7–6.9 pH, 45.5% colour, 53% BOD and 35.1% COD) reduction values were achieved. At 12 h retention, water lettuce (6.6–7.0 pH, 57.2% colour, 77.1% BOD and 74.6% COD), giant salvinia (6.4–6.8 pH, 81.1% colour, 66.7% BOD and 72.2% COD) and water hyacinth (6.4–6.7 pH, 61.9% colour, 70% BOD and 61.1% COD) reduction values were achieved. Similarly, for 24 h retention, water lettuce (6.6–7.0 pH, 76.7% colour, 53.2% BOD and 70.3% COD), giant salvinia (6.6–7.0 pH, 91.4% colour, 74.7% BOD and 81.0% COD) and water hyacinth (6.4–6.9 pH, 74% colour, 58% BOD and 67.2% COD) reduction values were achieved. These findings indicated that the retention times of 12 and 24 h provided suitable conditions to break down the organic contaminants present in the shallow ponds.

Anammox reactor treating low strength domestic wastewater: a review

Anaerobic ammonia oxidation (anammox) is a promising biological wastewater treatment process. It has been widely implemented in many industries due to lower oxygen consumptions besides being an environmental friendly method for wastewater treatment. However, there are several challenges in the process for potential application such as low anammox bacterial abundance and slow growth rate that lower the efficiency of the reaction. Therefore, several factors are being considered during operation of the anammox process. There are various anammox bacteria, which may be enriched using special techniques. Lower nitrogen content of influent brings great challenges for anammox performance due to inhibition caused by ammonium-oxidizing bacteria (AOB) and nitrite oxidizing bacteria (NOB) in nitrification process. This review highlighted the anammox process in various industry as well their anammox bacteria morphology, mechanism and strategies to enrich the bacteria. Coupled anammox process with low strength domestic wastewater requires more research to enable potential application in wastewater treatment.

Effects of pharmaceutical load on the effluent quality using sequencing batch reactor

The effect of pharmaceutical load on the performance of laboratory scale sequencing batch reactor (SBR) in terms of effluent quality and sludge settling ability was studied. The SBR was operated using low-strength domestic wastewater and spiked with a unique combination of drugs namely atenolol, gliclazide and prazosin after 21 days of reactor operation. Atenolol and gliclazide were spiked at concentration of 1000 µg/l while 100 µg/l for prazosin. Several parameters were observed which includes concentration of COD, ammonia, MLSS and SVI30. The effluent quality and sludge settling ability before and after drugs introduction were compared. The average COD removal efficiency before and after the introduction of pharmaceutical was 85% and 74%, respectively. The average ammonia removals were 84% and 62% before and after addition of pharmaceutical respectively. MLSS and SVI30 values was successfully maintained within desired value at the end of experiment indicating good sludge accumulation and sludge settling ability.

Use of a low-cost and energy-efficient device for treating low-strength wastewater at low temperatures focusing on nitrogen removal and microbial community

Treating wastewater at low temperatures has always been challenging. In this study, an anoxic filter (ANF)/multi-stage waterwheel driving rotating biological contactors (ms-wdRBCs) device was investigated as a potential solution for treatment of low-strength domestic wastewater at low temperatures (6–18 °C). Parameters, including the recirculation ratio (RR) and hydraulic retention time (HRT), were regulated to identify the optimum operating conditions. Using the optimum parameters of 200% RR, 10.67 h HRTANF, and 1.33 h HRTwdRBC, 75.37% ± 4.43% COD, 44.81% ± 3.67% TN, 75.05% ±1.86% NH4+-N, and 35.46% ± 4.87% TP were removed. The microbial communities in eight different sections of the device were investigated through the 16s rRNA analysis. The microbial results helped to explain the device performance. Denitrification-related bacteria were present in great abundance in both the ANF and the ms-wdRBCs. Anammox-related bacteria were also in significant abundance in ANF and some parts of ms-wdRBCs, which suggested a potential solution for improving the device performance by expanding the role of these anammox bacteria. Considering both the pollutant removal efficiency and investment costs, this device is acceptable as part of a low-strength domestic wastewater treatment solution at low temperatures.

Performance of Aerobic Granular Sludge for Domestic Wastewater Treatment

Aerobic granular sludge can be used to treat various types of wastewater, such as industrial, municipal and domestic wastewater. This study investigated the treatment of low-strength domestic wastewater while simultaneously developed aerobic granular sludge in a sequencing batch reactor (SBR). Activated sludge was used as the seeding for granulation. The results indicated good COD and ammoniacal nitrogen removal at 72% and 73%, respectively. Aerobic granular sludge was successfully developed with low sludge volume index (SVI30) of 29 mL/g, which demonstrated an excellent settling property of aerobic granular sludge. Biomass concentration increased significantly compared to the seed sludge, indicating high biomass density in the SBR system. Settling velocity of aerobic granular sludge was significantly higher compared to the conventional activated sludge. This study showed the feasibility of aerobic granular sludge to be developed using low-strength domestic wastewater. Moreover, this study demonstrated the long-term application of aerobic granular sludge in domestic wastewater treatment.

Kinetic of on Nutrient Removal in Low-Strength Domestic Wastewater under Continuous Operation of Pilot Scale of Hybrid Reed Bed System (SF-VF-HF)

Kinetic of on Nutrient Removal in Low-Strength Domestic Wastewater under Continuous Operation of Pilot Scale of Hybrid Reed Bed System (SF-VF-HF)

Domestic wastewater treatment and energy harvesting by serpentine up-flow MFCs equipped with PVDF-based activated carbon air-cathodes and a low voltage booster

Microbial fuel cells (MFCs) exhibit high capital cost and low energy output, which are major issues of the expected practical application of MFCs in wastewater treatment. Here, we have developed serpentine up-flow MFCs equipped with polyvinylidene fluoride (PVDF)-based activated carbon (AC) air-cathode (MFC-PVDF/AC) and continuously operated for more than 6 months with real domestic wastewater as a substrate. The MFC-PVDF/ACs achieved average total COD removal rates (5.11 ± 0.94 kg tCOD/m3/d) and power densities (3.96 ± 3.01 W/m3) without major water leakage, which were even higher than those of MFCs equipped with Pt-based air-cathode (MFC-Pts). The MFC-PVDF/ACs also achieved high and stable suspended solid (SS) removal efficiency (>90%) at 1.5-h HRT without any clogging event during the entire operation period. Since the PVDF-based AC air-cathode is less expensive, more durable, and easy to manufacture, expensive Pt cathodes are not necessary for MFCs treating low strength domestic wastewater. Furthermore, we have developed a low voltage booster (LVB) to increase low output voltage of MFC-PVDF/ACs (i.e., <0.4 V). Connecting a single LVB with a single MFC-PVDF/AC increased the voltage from <0.4 V to 4.35–5.2 V without the voltage reversal, which was enough to turn on three LED bulbs for >12 days. Taken together, the MFC-PVDF/AC with a LVB circuit exhibits excellent and stable performance of domestic wastewater treatment and usable power generation, suggesting that it could be used as a cost- and energy-saving primary wastewater treatment system.

Effects of Hydraulic Retention Time (HRT) on the Performance of a Pilot-Scale Trickling Filter System Treating Low-Strength Domestic Wastewater

Effects of Hydraulic Retention Time (HRT) on the Performance of a Pilot-Scale Trickling Filter System Treating Low-Strength Domestic Wastewater

Inhibition effect of magnetic field on nitrous oxide emission from sequencing batch reactor treating domestic wastewater at low temperature

This study aims to investigate the effect of a magnetic field on nitrous oxide (N2O) emission from a sequencing batch reactor treating low-strength domestic wastewater at low temperature (10°C). After running for 124 days in parallel, results indicated that the conversion rate of N2O for a magnetic field-sequencing batch reactor (MF-SBR) decreased by 34.3% compared to that of a conventional SBR (C-SBR). Meanwhile, the removal efficiencies for total nitrogen (TN) and ammonia nitrogen (NH4-N) of the MF-SBR were 22.4% and 39.5% higher than those of the C-SBR. High-throughput sequencing revealed that the abundances of AOB (Nitrosomonas), NOB (Nitrospira) and denitrifiers (Zoogloea), which could reduce N2O to N2, were promoted significantly in the MF-SBR. Enzyme activities (Nir) and gene abundances (nosZ nirS and nirK) for denitrification in the MF-SBR were also notably higher compared to C-SBR. Our study shows that application of a magnetic field is a useful approach for inhibiting the generation of N2O and promoting the nitrogen removal efficiency by affecting the microbial characteristics of sludge in an SBR treating domestic wastewater at low temperature.