Digestion Of Wastewater Research Articles

Effect of time and temperature of pretreatment and anaerobic co-digestion of rice straw and swine wastewater by domesticated paddy soil microbes

Rice straw and swine wastewater are abundant, easy to obtain, and inexpensive biomass materials. Anaerobic digestion of rice straw and swine wastewater effectively regulates the carbon-to-nitrogen ratio and also improves methane production efficiency. The dense lignocellulosic structure, unsuitable carbon-to-nitrogen ratio, and light texture of rice straw hinder its application in anaerobic digestion. Effective pretreatment technologies can improve degradation efficiency and methane production. Our study is the first to apply domesticated paddy soil microbes to enhance the efficiency of hydrolytic acidification of rice straw and swine wastewater at varying temperatures and times. The results show that the highest total organic carbon (1757.2 mg/L), soluble chemical oxygen demand (5341.7 mg/L), and organic acid concentration (4134.6 mg/L) appeared in the hydrolysate after five days of hydrolytic acidification at 37 °C. Moreover, the use of hydrolysate produced 13% more gas and reduced the anaerobic digestion period by ten days compared to the untreated control. This suggests that using domesticated paddy soil microbes as a pretreatment might be a sustainable and cost-effective strategy for improving the degradation efficacy and methane production from lignocellulosic materials.

Enhanced anaerobic digestion of post-hydrothermal liquefaction wastewater: Bio-methane production, carbon distribution and microbial metabolism.

Hydrothermal liquefaction (HTL) is a cost-effective and environment-friendly technology for using biomass to produce bio-crude oil. The critical challenge of HTL is its complicated aqueous product containing high concentrations of organics and diverse toxicants. This paper reports the continuous anaerobic digestion of raw and zeolite-adsorbed Chlorella HTL wastewater using up-flow anaerobic sludge bed reactors. The bio-methane production capacity, total carbon distribution and microbial response were investigated. The anaerobic process was severely suppressed when more than 20% raw wastewater was fed; while it showed essentially improved performance till 60% pre-treated wastewater was added. Produced methane contained 17.3% of the total carbon in feedstock, which was comparable with the value (16.7%) when 25% of raw wastewater was added. The metagenomic analysis revealed distinct microbial community structures in different stages and feedstock shifts. The abundance of functional genes was consistent with anaerobic digester performance.

Effects of functional modules and bacterial clusters response on transmission performance of antibiotic resistance genes under antibiotic stress during anaerobic digestion of livestock wastewater

The formation and transmission of antibiotic resistance genes (ARGs) have attracted increasing attention. It is unclear whether the internal mechanisms by which antibiotics affect horizontal gene transfer (HGT) of ARGs during anaerobic digestion (AD) were influenced by dose and type. We investigated the effects of two major antibiotics (oxytetracycline, OTC, and sulfamethoxazole, SMX) on ARGs during AD according to antibiotic concentration in livestock wastewater influent. The low-dose antibiotic (0.5 mg/L) increased ROS and SOS responses, promoting the formation of ARGs. Meanwhile, low-dose antibiotics could also promote the spread of ARGs by promoting pili, communication responses, and the type IV secretion system (T4SS). However, different types and doses of antibiotics would lead to changes in the above functional modules and then affect the enrichment of ARGs. With the increasing dose of SMX, the advantages of pili and communication responses would gradually change. In the OTC system, low-dose has the strongest promoting ability in both pili and communication responses. Similarly, an increase in the dose of SMX would change T4SS from facilitation to inhibition, while OTC completely inhibits T4SS. Microbial and network analysis also revealed that low-dose antibiotics were more favorable for the growth of host bacteria.

Assessment of Magnetic Nanomaterials for Municipality Wastewater Treatment Using Biochemical Methane Potential (BMP) Tests.

Wastewater as a substrate potential for producing renewable energy in the form of biogas is gaining global attention. Herein, nanomaterials can be utilised as a nutrient source for microorganisms for anaerobic digestion activity. Therefore, this study explored the impact of seven different magnetic nanomaterials (MNMs) on the anaerobic digestion of wastewater via biochemical methane potential (BMP) tests for biogas production. The BMP assay was carried out with eight bioreactors, where each was charged with 50% wastewater and 30% activated sludge, leaving a headspace of 20%. Aside the control bioreactor, the other seven (7) bioreactors were dosed with 1.5 g of MNMs. This was operated under anaerobic conditions at a mesophilic temperature of 35 °C for 31 days. At the degree of 80% degradation of contaminants, the results that showed bioreactors charged with 1.5 g MNMs of TiO2 photocatalyst composites were more effective than those constituting metallic composites, whereas the control achieved 65% degradation. Additionally, the bioreactor with magnetite (Fe3O4) produced the highest cumulative biogas of 1172 mL/day. Kinetically, the modified Gompertz model favoured the cumulative biogas data obtained with a significant regression coefficient (R2) close to one.

ANAEROBIC BIOLOGICAL WASTEWATER TREATMENT OF SUGAR PRODUCTION

Water usage of sugar beet factories is characterized by a high level of consumption and a large volume of generated wastewater with a high concentration of mineral and organic pollution. Artificial biological purification facilities are mainly used for purification of sugar production effluents. While a scheme with two-stage aeration tanks is the most widespread in our country,anaerobic-aerobic regimens are frequently used abroad. It is more cost-effective, since the oxidation of large amounts of organic substances exclusively under aerobic conditions is associated with high energy consumption. The use of anaerobic digestion at the first stage allows reducing the concentration of organic substances in effluents by 60-90%, while the post-purification of remaining contaminants is carried out in stage-two aeration tanks with lower energy consumption. To assess the appropriateness of using a digester in the system of purification facilities of a particular enterprise, it is necessary to have information on the effectiveness of digestion and the optimal purification regime of the wastewater of that particular enterprise. This work studies the process of anaerobic digestion of wastewater at one of the beet sugar factories in Ukraine. The experiments were carried out in a bioreactor with an upward flow of activated sludge. The method of mathematical planning of an experiment was used in order to shorten the duration of the research. As a result, data was obtained regarding the influence of determining factors (flow rate, pH, temperature) on biogas yield and substrate fermentation depth. Received data proves the effectiveness and prospects of using anaerobic digestion in the first stage of biological fermentation of wastewater at a sugar beet production.

Exploring CO2 Bio-Mitigation via a Biophotocatalytic/Biomagnetic System for Wastewater Treatment and Biogas Production

Carbon dioxide (CO2) emissions from fossil fuels have led industries to seek cheaper carbon abatement technologies to mitigate environmental pollution. Herein, the effect of a magnetic photocatalyst (Fe-TiO2) on biogas production in anaerobic digestion (AD) of wastewater was investigated with three bioreactors coupled with UV-light (18 W). Three experimental setups defined as the control (AD system with no Fe-TiO2), biophotoreactor (BP), and biophotomagnetic (BPM) systems were operated at a mesophilic temperature (35 ± 5 °C) for a hydraulic retention time (HRT) of 30 days. The control system (ADs) had no Fe-TiO2 additives. The BPMs with 2 g Fe-TiO2 were exposed to a magnetic field, whereas the BPs were not. The removal rate of the chemical oxygen demand (COD), volatile solids (VS), and total solids (TS), together with biogas production and composition were monitored for each reactor. The degree of degradation of 75% COD was observed for the BPMs at a pH of 6.5 followed by the BPs (65% COD) and the ADs (45% COD). The results showed that the rate of degradation of COD had a direct correlation with the cumulative biogas production of the BPMs (1330 mL/d) > BPs (1125 mL/d) > AD (625 mL/d). This finding supports the use of biophotomagnetic systems (BPMs) in wastewater treatment for resource recovery and CO2 reduction (0.64 kg CO2/L) as an eco-friendly technology.

Preparation and testing of low-cost bioadsorbents for improving the anaerobic digestion of post-hydrothermal liquefaction wastewater (PHWW)

There are currently several promising technologies for the removal of toxic compounds from wastewater; most of them are expensive or require sophisticated equipment. Thus, this study proposes that peanut shells be used as low-cost bioadsorbents for the removal of organic matter (COD) and ammoniacal nitrogen (NH4+-N) from Spirulina hydrothermal liquefaction wastewater (PHWW). Additionally, anaerobic digestion (AD) was used as a biological treatment for pretreated PHWW (by adsorption) to promote additional organic matter removal while recovering energy in the form of methane. In this way, native (PB) and modified (APB) forms of peanut shell bioadsorbents were investigated. APB was activated using NaOH and HCl. For comparison, granular activated carbon (GAC) was chosen as the standard. The adsorbate-PHWW was obtained by using 20% solids (w/v) in the hydrothermal liquefaction (HTL) of Spirulina at 260 °C for 60 min. Response surface methodology (RSM) was used to explore and optimize the effect of various adsorption parameters, such as temperature, pH, and adsorbent dosage. Biochemical potential (BMP) tests were conducted under mesophilic conditions. In adsorption assays, PB was found to be more efficient at removing NH4+-N, while APB and GAC achieve higher COD removal percentages. In comparison to untreated PHWW, bioadsorption promoted higher efficiency phenol removal and COD conversion to methane during BMP tests. The anaerobic processes that followed APB and PB adsorption significantly removed more COD than the process fed with GAC-pretreated PHWW. These results established the feasibility of using peanut shells as bioadsorbents in the pretreatment of PHWW, which resulted in an increase in biogas/methane yield.

Energy, exergy, economic, and environment (4E) assessment of trans-critical organic Rankine cycle for combined heating and power in wastewater treatment plant

In order to realize energy utilization of the biogas produced by anaerobic digestion of wastewater and sludge, this paper proposes an organic Rankine cycle (ORC) based cogeneration system for wastewater treatment plants (WWTPs). However, due to the seasonal changes in human eating habits, there are significant changes in organic matter content in wastewater and sludge, biogas production and exhaust gas discharged from the internal combustion engine all change consequently. The rated value of the exhaust gas was firstly ascertained. In addition, the thermodynamic model of the trans-critical organic Rankine cycle (TCORC) was constructed based on the first and second laws of thermodynamics. Finally, the economic and environmental benefits of the TCORC system were also analyzed. Results show that the annual weighted average value of the exhaust gas is used as the selection rule to ascertain the rated value of exhaust gas. There exists supercritical temperature and pressure to maximize the power output, thermal and exergetic efficiencies. Moreover, the choice of the working fluid has a greater impact on the performance of the TCORC system, and the higher the critical state point, the easier it is to obtain better performance. For various working fluids in the trans-critical cycle, the optimal operating point are taken at supercritical pressure and temperature slightly above the critical parameters. For n-Decane, the maximum annual fossil fuel savings and the annual reduction of CO2 are 0.36 × 106 L and 1.15 × 106 kg, respectively, when supercritical pressure and temperature are 4.21 MPa and 352 °C, respectively. The TCORC enhances the overall performance of the WWTPs, which should be employed in engineering applications.

Process characteristics and energy self-sufficient operation of a low-fouling anaerobic dynamic membrane bioreactor for up-concentrated municipal wastewater treatment

Up-concentration of municipal wastewater using physico-chemical methods can effectively enrich organic matter, facilitating subsequent anaerobic digestion of up-concentrated wastewater for enhanced methanogenesis at reduced energy consumption. An anaerobic dynamic membrane bioreactor (AnDMBR) assisted with biogas-sparging was developed to treat up-concentrated municipal wastewater, focusing on the effects of operating temperature and hydraulic retention time (HRT) as well as COD mass balance and energy balance. The COD removal stabilized at about 98 % over the experimental period, while gaseous and dissolved methane contributed 43–49 % and 2–3 % to the influent COD reducing greenhouse gas emissions. The formed dynamic membrane exists mainly as a heterogeneous cake layer with a uneven distribution feature, ensuring the stable effluent quality. Without adopting any physico-chemical cleaning, the transmembrane pressure (TMP) maintained at a low range (2.7 to 14.67 kPa) with the average TMP increasing rate of 0.089 kPa/d showing a long-term low-fouling operation. Increasing the concentration ratio, the methane production rate decreased from 0.18 to 0.15 L CH4/gCOD likely due to the accumulation of particulate organics. Microbial community analysis indicated the predominant methanogenic pathway shifted from hydrogenotrophic to acetoclastic methanogenesis in response to the temperature change. Net energy balance (0.003–0.600 kWh/m3) can be achieved only under room temperature (25 °C) rather than mesophilic conditions (36 °C).

Investigating microbial dynamics and potential advantages of anaerobic co-digestion of cheese whey and poultry slaughterhouse wastewaters

Resource recovery and prevention of environmental pollution are key goals for sustainable development. It is widely reported that agro-industrial activities are responsible for the discharge of billions of liters of wastewater to the environment. Anaerobic digestion of these energy rich agro-industrial wastewaters can simultaneously mitigate environmental pollution and recover embedded energy as methane gas. In this study, an assessment of mono- and co-digestion of cheese whey wastewater (CWW) and poultry slaughterhouse wastewater (PSW) was conducted in 2.25-L lab-scale anaerobic digesters. Treatment combinations evaluated included CWW (R1), PSW (R2), 75:25 CWW:PSW (R3), 25:75 CWW:PSW (R4), and 50:50 CWW:PSW (R5). The digestion efficiencies of the mixed wastewaters were compared to the weighted efficiencies of the corresponding combined mono-digested samples. R4, with a mixture of 25% CWW and 75% PSW, achieved the greatest treatment efficiency. This corresponded with an average biodegradability of 84%, which was greater than for R1 and R2 at 68.5 and 71.9%, respectively. Similarly, R4 produced the highest average cumulative methane value compared to R1 and R2 at 1.22× and 1.39× for similar COD loading, respectively. The modified Gompertz model provided the best fit for the obtained methane production data, with lag time decreasing over progressive treatment cycles. PCoA and heatmap analysis of relative microbial abundances indicated a divergence of microbial communities based on feed type over the treatment cycles. Microbial community analysis showed that genus Petrimonas attained the highest relative abundance (RA) at up to 38.9% in the first two cycles, then subsequently decreased to near 0% for all reactors. Syntrophomonas was highly abundant in PSW reactors, reaching up to 36% RA. Acinetobacter was present mostly in CWW reactors with a RA reaching 56.5%. The methanogenic community was dominated by Methanothrix (84.3–99.9% of archaea). The presence of phosphate and Acinetobacter in CWW feed appeared to reduce the treatment efficiency of associated reactors. Despite Acinetobacter being strictly aerobic, previous and current results indicate its survival under anaerobic conditions, with the storage of phosphate likely playing a key role in its ability to scavenge acetate during the digestion process.

Characterization of trace metal impact on organic acid metabolism and functional microbial community in treating dairy processing wastewater with thermophilic anaerobic membrane bioreactor

The anaerobic digestion (AD) of dairy processing wastewater (DPW) to produce bioenergy is considered promising but also associated with the possibility of an unbalanced organic matter and trace metal (TM) content. In this study, the TM content and its impact on AD were determined in an anaerobic membrane bioreactor operated to treat DPW. The results indicated that a deficiency in TMs resulted in the slow deterioration of the process, reducing biogas production, disrupting the buffer system, and the massive accumulation of organic acid. The deficiency of Co/Ni was significant, while iron fluctuated due to microbial and chemical effects. Syntrophic propionate oxidizing bacteria and methanogen were the main groups suppressed under the TM deficient environment, resulting in AD failure. No inhibitory effect on the lactic acid metabolism was observed. Hence, supplying theoretical TM dosage to DPW was necessary to realize the efficient and stable AD process and robust microbial community.

Activated Carbon Facilitates Anaerobic Digestion of Furfural Wastewater: Effect of Direct Interspecies Electron Transfer

Anaerobic digestion of furfural wastewater suffers from toxicity to microbes, which reduces its performance. The toxic effects may be eliminated by a sustainable way of conductive material supplementation. In this study, the effect on anaerobic digestion of furfural (0.5–4 g/L) was investigated by adding 0–40 g/L granular activated carbon (GAC) in batch tests. The innovation of this current study is to explore the potential direct interspecies electron transfer (DIET) for the first time in furfural degradation as the sole substrate in anaerobic digestion. The results demonstrated that when furfural was the sole substrate, in the presence of GAC, the peak methane production rate was increased by 46.0%, while the specific methane yield was improved by 24.7%, compared with the control. Additionally, the electroactive Geobacter sulfurreducens abundance in biofilms attached to the surface of GAC was 19.0 folds higher than that in the control. The abundances of the related genes of methane metabolism and furfural degradation in biofilms were 1.1 and 5.8 folds higher than the control by metagenomic analysis, respectively. These lines of evidence suggested that the pathway of furfural metabolism to methane among Moorella species, G. sulfurreducens, and Methanothrix species based on DIET was likely established.

Assessment of Physicochemical Parameters and Heavy Metals in Sagamu Abattoir Waste Water Ogun State, Nigeria

Abattoir wastewater is a great threat to environmental safety. This study was aimed at assessing the physiochemical constituents using standard methods and some heavy metals using Agilent Microwave Atomic Emission Spectrometer (MP-AES) 4200 model after sample digestion of wastewater from three (3) major abattoirs in Sagamu, Ogun State, Nigeria. The sample was digested using a mixture of nitric acid, hydrochloric acid and hydrogen peroxide. The digested samples were then analyzed for heavy metals. Data from the physicochemical characterization show that pH, TS, TDS, TSS and COD ranged from; (5.8 – 6.2), (11500 – 27733.33), (5500 – 9066.67), (6000 – 18666.67), and (1507.67 – 3671) respectively. The assessed heavy metals are in the range (mg/L): Zn (0.132-0.337), Cu (0.091 – 0.516), Mn (0.410 – 0.994), Fe (5.294 – 15.44), V (0.132 – 0.32), Cd (0.036 – 0.119), Ni (0.029 – 0.17), Pb (0.136 – 0.234), Cr (0.299 – 1.277), and Co (0.015 – 0.079). Zn, Cu and Fe are essential metals within tolerable limits except Mn that exceeded the limits of World Health Organization (0.04 mg/L) but below Federal Ministry of Environment (5 mg/L) while Ni, Pb and Chromium are above permissible limits in all samples. The pretreatment of the wastewater before discharging into environment is highly recommended and more research should be done on remediation to reduce the abattoir wastewater heavy metals concentration and the effect it is having on the ecosystem and the environment at large.

Composition Characterization and Transformation Mechanism of Dissolved Organic Matters in a Full-Scale Membrane Bioreactor Treating Co-Digestion Wastewater of Food Waste and Sewage Sludge

The membrane bioreactor (MBR) serves as the most widely used technology in anaerobic digestion wastewater treatment, but the composition and transformation of the dissolved organic matters (DOMs) are vague. This study focused on the composition characterization and transformation mechanism of DOMs in real co-digestion wastewater of food waste and sewage sludge from a full-scale MBR via molecular weight cut-off, 3D-EEM, FT-IR, and SPME-GC/MS. The results indicated that the co-digestion wastewater mainly comprised organics with molecular weight (MW) lower than 1 kDa and dominated by tryptophane-protein-like substances. The hydrolytic/acidogenic process improved the biodegradability with the conversion of high-MW organics into low-MW organics, while the two-stage A/O process possessed the highest contribution to the organic removal with the consumption of most DOMs. However, the deficient removal of refractory organics (MW < 5 kDa) in the ultrafiltration unit led to the residual DOMs in the effluent. The potential functional bacteria in the biological processes have also been identified and were principally affiliated with Proteobacteria and Firmicutes. These findings could help to advance the understanding of the co-digestion wastewater and provide fundamental information for the optimization and development of MBR in anaerobic digestion wastewater treatment.

Enhancing anaerobic digestion of sulphate wastewater by adding nano-zero valent iron

ABSTRACT In this paper, the effects of nano-zero valent iron (nZVI) on anaerobic digestion of sulphate wastewater with different /COD ratios, including the COD removal rate, methane yield, intermediate products and the change of microbial community structure, were investigated. The results showed that nZVI could effectively enhance the treatment efficiency and methane yield. Compared with the control group without nZVI, the methane yield increased from 348.6833 to 1007.05 mL CH4/gCODremoval with 4 g nZVI loading at /COD = 0.1. nZVI could make electron flow from sulphate reduction to methane production, which increased methane yield even at high sulphate concentration. The microbial community analysis showed that adding nZVI could increase the abundance of acetoclastic methanogens, which accelerated hydrolysis acidification.

Anaerobic Digestion of Hydrothermal Liquefaction Wastewater and Biochar from Spent Coffee Grounds

Anaerobic Digestion of Hydrothermal Liquefaction Wastewater and Biochar from Spent Coffee Grounds

Biogas production from winery wastewater: Effect of the substrate-inoculum ratio on fly ash addition and iron availability

The effect of substrate-inoculum ratio and fly ash (FA) concentration on the anaerobic digestion of winery wastewater was studied. Two substrate-inoculum ratios (0.50 and 1 g soluble COD/g VSS) and five fly ash concentrations (25, 50, 75, 100 and 150 mg/L) were tested under mesophilic conditions. The results showed that 0.50 g soluble COD/g VSS was the best substrate-inoculum ratio. Regarding the FA, 100 mg/L improved the specific methane production by 79% compared to the control assay. In comparison, 150 mg/L produced an inhibition of methane production, with a 55% decrease in specific methane production with respect to the control assay. According to the bioavailability study, FA had a similar effect to a system with Fe-EDTA on anaerobic digestion, which could indicate that the Fe present in FA was present in the solution and bioavailable to microorganisms. Therefore, a possible mechanism for the action of FA on anaerobic digestion was proposed. Finally, the kinetic analysis showed that FA improved the maximum specific methane production rate and decreased the lag phase.

Enhanced anaerobic digestion of dairy wastewater in a granular activated carbon amended sequential batch reactor.

This study investigated the potential of granular activated carbon (GAC) supplementation to enhance anaerobic degradation of dairy wastewater. Two sequential batch reactors (SBRs; 0.8 L working volume), one control and another amended with GAC, were operated at 37°C and 1.5–1.6 m/h upflow velocity for a total of 120 days (four cycles of 30 days each). The methane production at the end of each cycle run increased by about 68%, 503%, 110%, and 125% in the GAC‐amended SBR, compared with the Control SBR. Lipid degradation was faster in the presence of GAC. Conversely, the organic compounds, especially lipids, accumulated in the absence of the conductive material. In addition, a reduction in lag phase duration by 46%–100% was observed at all four cycles in the GAC‐amended SBR. The peak methane yield rate was at least 2 folds higher with GAC addition in all cycles. RNA‐based bacterial analysis revealed enrichment of Synergistes (0.8% to 29.2%) and Geobacter (0.4% to 11.3%) in the GAC‐amended SBR. Methanolinea (85.8%) was the dominant archaea in the biofilm grown on GAC, followed by Methanosaeta (11.3%), at RNA level. Overall, this study revealed that GAC supplementation in anaerobic digesters treating dairy wastewater can promote stable and efficient methane production, accelerate lipid degradation and might promote the activity of electroactive microorganisms.

Enhanced organic degradation and biogas production of domestic wastewater at psychrophilic temperature through submerged granular anaerobic membrane bioreactor for energy-positive treatment

This study deals with the conversion of organic matter into methane at ambient temperature, during anaerobic digestion of domestic wastewater combined with a submerged ultrafiltration membrane with no gas-sparging. A one-stage submerged granular anaerobic membrane bioreactor (G-AnMBR) and a control anaerobic digester (UASB type) were operated during four months, after 500 days of biomass acclimatization to psychrophilic and low loading rate conditions. Membrane barrier led to the retention of biomass, suspended solids and dissolved and colloidal organic matter which greatly enhanced total COD (tCOD) removal (92.3%) and COD to methane conversion (84.7% of tCOD converted into dissolved and gaseous CH4). G-AnMBR overcame the usual long start-up period and led to a higher sludge heterogeneity, without altering the granular biomass activity. The feasibility of the G-AnMBR without gas-sparging was also assessed and the net positive energy balance was estimated around + 0.58 kWh.m−3.

Enhancing ammonium rejection in forward osmosis for wastewater treatment by minimizing cation exchange

Ammonium permeation to draw solution (DS) is very common in forward osmosis (FO) treatment due to the negative charge nature of the membrane, which restricts the application of FO for wastewater treatment particularly with a purpose of ammonium recovery and water reuse. Membrane modification by reducing the negative charge of membrane surface could improve ammonium rejection. This study investigated ammonium rejection in the FO process by selecting DSs with different physicochemical properties. Results show an increased ammonium rejection rate with divalent cation-based DS (i.e. Mg2+) due to larger hydrated cation radius compared with monovalent cations such as Na+ under the same osmotic pressure. Non-ionic DSs such as glucose, glycine and ethanol are able to minimize ion exchange across the membrane, leading to a 98.5–100% ammonium rejection. This indicates that cation exchange is the critical factor for ammonium permeation. Real wastewater treatment such as municipal wastewater and sludge digestate liquor by FO with NaCl and glucose as DS, respectively, further confirms that minimizing cation exchange by selecting appropriate DS could significantly improve ammonium rejection, which is not negatively affected by the more complex nature of real wastewater. This study developed an alternative method by selecting appropriate DS to increase ammonium rejection. Furthermore, it shed light on the mechanism of enhanced ammonium rejection with different types of DSs, which could provide general guidance on the selection of DS from the perspective of wastewater treatment with ammonium considered.