Sulfur Removal Efficiency Research Articles

Managing sulfate ions produced by sulfate radical-advanced oxidation process using sulfate-reducing bacteria for the subsequent biological treatment

Persulfate and sulfate radicals with strong standard oxidation potentials and relatively low cost be used in advanced oxidation processes. The object of this study was to evaluate the performance of a sulfate radical-based advanced oxidation process with surfactant-modified zeolite for treatment of the composting leachate followed by the effect of Surfactant-modified zeolite for the removal of sulfate from leachate in an ASBR biological process. The BOD/COD ratio under the optimal condition of oxidation process was 0.7712. The most contributed factor in this process was temperature. Analysis showed that persulfate causes an increase in sulfate ions during the oxidation process. Surfactant-modified zeolite had a significant effect on decrease of the final sulfate ions concentration produced by persulfate. Therefore, the combination of advanced oxidation process and surfactant-modified zeolite with biological sulfate reduction processes for simultaneous removal of COD and sulfate ions could be recommended. The effect of COD/sulfate ratio on the activity of sulfate-reducing bacteria in the ASBR reactor was discussed. The study showed that applying the process can clearly improve the removal efficiencies of COD and sulfate from the leachate. The optimum condition for ASBR reactor operation was obtained in COD/sulfate ratio of 1.34. These process provides significant efficiencies of 93% and 74% for sulfate ion and COD removal, respectively. On the other hands, the TOC removal efficiency increased from 61% to 76% in row leachate samples without biological treatment by addition of SMZ to SR-AOP.

STATISTICAL OPTIMIZATION OF ETTRINGITE PRECIPITATION IN LANDFILL LEACHATE

In the present study, experiments were conducted to optimize sulfate removal efficiency with ettringite precipitation from landfill leachate using Response Surface Methodology (RSM) and Central Composite Design (CCD). The statistical analysis of the results showed that the operating parameters such as molar rates of Ca/SO4 and Al/SO4, and pH had a significant effect on sulfate removal efficiency. Aluminum hydroxide and calcium hydroxide were used for external sources of aluminum and calcium. The goodness of the model was checked by different criteria including the coefficient of determination (R2 = 0.94), p value (<0.0001), adequate precision (14.78), and coefficient of variance (7.30). The RSM results indicated that the fitted model could be appropriate to predict sulfate removal efficiency. A 55.7% maximum sulfate removal efficiency was obtained at pH 11.95 for 2.29 Ca/SO4 and 0.74 Al/SO4 molar ratios. Sulfate inhibition effects on treatment methods such as the anaerobic process decreased with increasing COD/SO4 ratio from 14:1 to 25:1 by ettringite precipitation.

Effect of Pd- precursor and support acid properties on the Pd electronic state and the hydrodesulfurization activity of Pd-zeolite catalysts

We studied on the function of Pd species located in mesopores and inside zeolite channels (micropores) of the montmorillonite-modified zeolite catalyst for the hydrodesulfurization of diesel fraction with 350 ppm of sulfur as DBT, 4-MDBT, and 4,6-DMDBT. It was shown that the ex-dihydrogentetrachloropalladate impregnated catalyst as well as the ex-tetraamminepalladium(II) chloride ion-exchanged catalyst have high efficiency of sulfur removal from the diesel fuel in temperature range 280–300 оC.The sulfur tolerance of catalyst depended on the method of Pd adding. The catalyst prepared by ion-exchange with tetraamminepalladium chloride solution exhibited the highest sulfur tolerance. According to FTIR of adsorbed CO, this catalyst contains a small Pd metal atoms or cluster in electron-deficient state inside zeolite channels. They probably ensure sulfur tolerance due to hydrogen spillover.The montmorillonite addivite significantly modifies performance of the Pd-Zeolite catalyst in hydrotreating of diesel fraction. It leads to a decrease of cracking function, while those of hydrogenolysis of sulfurorganic molecules and hydrogenation of aromatic molecules are strengthened in comparison with the unmodified catalyst. This effect is explained by the change of acidic properties of the catalyst, limitations of diffusion of various molecules into the zeolite channels, and diffusion of Pd from the zeolite channels.

Treatment of acidic sulfate-containing wastewater using revolving algae biofilm reactors: Sulfur removal performance and microbial community characterization

Industries such as mining operations are facing challenges of treating sulfur-containing wastewater such as acid mine drainage (AMD) generated in their plant. The aim of this work is to evaluate the use of a revolving algal biofilm (RAB) reactor to treat AMD with low pH (3.5–4) and high sulfate content (1–4 g/L). The RAB reactors resulted in sulfate removal efficiency up to 46% and removal rate up to 0.56 g/L-day, much higher than those obtained in suspension algal culture. The high-throughput sequencing revealed that the RAB reactor contained diverse cyanobacteria, green algae, diatoms, and acid reducing bacteria that contribute the sulfate removal through various mechanisms. The RAB reactors also showed a superior performance of COD, ammonia and phosphorus removal. Collectively, the study demonstrated that RAB-based process is an effective method to remove sulfate in wastewater with small footprint and can be potentially installed in municipal or industrial wastewater treatment facilities.

Avaliação da remoção adsortiva do tiofeno de uma gasolina modelo utilizando ZSM-35 impregnada com molibdênio

A busca por processos alternativos para a remoção de compostos enxofre nos combustíveis é uma constante, visto que a legislação ambiental em todo o mundo está cada vez mais rigorosa quanto às reduções das frações desses compostos nos combustíveis. Este estudo avaliou a capacidade adsortiva da zeólita ZSM-35 pura e impregnada com molibdênio a 2,5% e 5% na remoção do tiofeno, composto organossulfurado, de uma gasolina modelo. Os materiais foram preparados via impregnação úmida e caracterizados por DRX, MEV, análise térmica (TG/DTG). A cinética de adsorção foi realizada nas temperaturas de 303 K e 313 K, em um sistema em batelada sob uma agitação de 140 rpm por 12 horas. A cinética de adsorção foi avaliada pelos modelos cinéticos de peseudoprimeira ordem, pseudossegunda ordem, difusão intrapartícula e Elovich. Os resultados revelaram que o aumento da temperatura e a concentração do molibdênio na estrutura da zeólita tem influência no rendimento da remoção de enxofre da gasolina.

Sonoreactor optimization for ultrasound assisted oxidative desulfurization of liquid hydrocarbon

ABSTRACTIn this study, the geometrical parameters of sonoreactor like the probe, reactor diameters, probe immersion depth and amplitude are assessed. The reaction time and H2O2 concentration effect on the sulfur removal efficiency are studied. The results indicate that, first, an increase in probe diameter decreases the efficiency of the process and further increase up to 40 mm diameter increases desulfurization efficiency up to 98.25%. An increase in probe immersion depth, increases desulfurization efficiency. Reactor diameter of 7.4 cm among other diameters (6.1, 6.5, 8 cm and 8.6 cm) achieved higher desulfurization efficiency.

Mitigation and treatment of pollutants from railway and highway runoff by pocket wetland system; A case study

This study performed in Sapanca Lake catchment area, used as a drinking water resource. Two highways located at northern and southern shores, and a railway at its south are significant sources of pollution. As a possible solution for protecting water quality a pocket wetland constructed and operated. Performances statistically interpreted by Spearman's Correlation test and univariate analysis of variance on collected data. The mean removal efficiencies obtaited were 52% (TSS), 4% (Nitrate), 26% (TN), −5% (TOC), 63% (TP), 4.5% (Chloride), 3% (Sulfate), 33% (Cr), 39% (Co), −19.5% (Ni), 7% (Cu), 55% (Zn), 36% (As), 38% (Cd) and 18% (Pb). TSS removal was in positive significant medium correlation with Co, Cu, Zn, and Pb removal respectively (p < 0.05). Other statistically significant positive high correlations calculated between removal efficiency of Nitrate–TN, Chloride–Sulfate, Cr–Co–Cu–As–Cd. According to ANOVA and Kruskal-Wallis test results, removal efficiencies of TSS and TOC partially affected by different temperature (p < 0.1 for TSS and p < 0.05 for TOC) and pH ranges (p < 0.1 for both removal efficiencies), TP removal efficiency significantly affected by different pH ranges (p < 0.001), and Chloride and Sulfate removal efficiencies were significantly (p < 0.001) affected by different temperature ranges. Regardless of geographical location and climatic factors, pocket wetland systems can be relied upon for minimizing heavy metals such as Cr, Co, Zn, As, Cd and Pb and critical pollutants such as TP and TSS caused by highway runoff.

Sulfur removal from model fuel by Zn impregnated retorted shale and with assistance of design of experiments.

There is global concern about acid rain and other pollution which is caused by the consumption of oil. By decreasing sulfur content in the oil, we can reduce unwanted emissions and acid rain. Shale was usedwhich is a solid waste generated in the pyrolysis of shale, impregnated with Zn as an adsorbent which removes sulfur present in fuels from the hexane/toluene model solution. An influence of the agitation time (60-180min), temperature (25-35°C), adsorbent mass (0.1-0.25g), and initial sulfur concentration (100-250ppm) factorial 24 with three central points totaling 19 experiments was applied to investigate the effect of the variables on the efficiency of sulfur removal in fuels. The values of the parameters tested for maximum sulfur removal were obtained as follows: contact time = 180min, temperature = 35°C, adsorbent mass = 0.25g, and initial sulfur concentration = 100ppm. The mathematical model proposed with R2 99.97% satisfied the experimental data. This may provide a theoretical basis for new research and alternative uses for tailings of schist industrialization in order to evaluate its potential.

Diesel desulfurization using a ultrasound-assisted oxidative process

ABSTRACTIn this study, the removal of sulfur compounds from diesel samples using ultrasound-assisted oxidative desulfurization (UAODS) process in presence of different types of oxidizing agents was studied. Experiments were performed to assess the effects of influential parameters on the performance of UAODS process including ultrasonic irradiation time, oxidant type, mass ratio of oxidant to diesel fuel (oxidant: diesel), and finally acetic acid as an oxidative promoter. The efficiency of sulfur compounds removal from the diesel fuel dramatically improved using appropriate oxidative process with the assistance of ultrasound irradiation. H2O2 was found to be the most promising oxidant component whose concentration in the media directly affected total sulfur removal and thiol group conversion efficiencies. Using 4 wt% of H2O2 followed by 15 min of ultrasonic irradiation leaded to sulfur removal efficiency of 76% and thiol group conversion of 79% at ambient temperature and atmospheric pressure. Using acid acetic as the promoter of H2O2 also leaded to further sulfur compounds removal.

Design and experimental study on desulphurization process of ship exhaust

This desulfurization process involves removing sulfur oxides with seawater or alkaline aqueous solutions and then treating the effluent by aeration and pH adjustment before discharging it into the ocean. In the desulfurization system, the spray tower is the key equipment and the venturi tubes are the pretreatment device. The two stages of plates are designed to fully absorb sulfur oxides in exhaust gases. The spiral nozzles atomize and evenly spray the desulfurizers into the tower. This study experimentally investigated the effectiveness of this desulfurization process and the factors influencing it under laboratory conditions, with a diesel engine exhaust used to represent ship exhaust. The experimental results show that this process can effectively absorb the SO2 in the exhaust. When the exhaust flow rate was 25 m3/h and the desulfurizer flow rate was 4 L/min, the sulfur removal efficiency (SRE) reached 99.7%. The flow rate, alkalinity, and temperature of seawater were found to have significant effects on the SRE. Adjusting seawater flow rate (SWR) and alkalinity within certain ranges can substantially improve the SRE.

Anaerobic digestion of sulphate-rich post-tanning wastewater at different COD/sulphate and F/M ratios.

Anaerobic digestion of post-tanning wastewater was performed in batch anaerobic digester to evaluate the effect of COD/sulphate ratio [0.62, 0.69, and 1.20 (w/w) %] and F/M ratio [0.2, 0.3, 0.5, 0.7, 0.9, 1.1, 1.3, and 1.5 (w/w) %)] on the removal efficiency of COD. The F/M ratio of 0.3 was found to be the optimum ratio for the removal of COD by 53, 57, and 65%, respectively at COD/sulphate ratio of 0.62, 0.69, and 1.20. The maximum sulphate removal was observed at F/M ratio of 0.2 and the removal efficiency was 48, 50, and 58% at COD/sulphate ratio of 0.62, 0.69, and 1.20, respectively. The removal efficiency of COD and sulphate was increased with increase in COD/sulphate ratio from 0.62 to 1.20 and decreased with increase in F/M ratio from 0.2 to 1.5 in anaerobic digestion of post-tanning wastewater. The maximum concentration of sulphide formation was 784mg/L at COD/sulphate ratio of 0.62 in anaerobic digestion process and the process was inhibited at this sulphide concentration. The microbial activity in the sludge was evaluated through live and dead cell assay using fluorescent microscopy. The maximum amount of dead microbes was observed in the anaerobic digester, which was operated at COD/sulphate ratio of 0.62 than other studied ratio.

Central composite design for optimization and formulation of desulphurization of iron ore concentrate using atmospheric leaching process

Owing to the negative effects of sulphur in iron ore on steelmaking process and environment, a tank leaching process was performed in atmospheric conditions to remove the sulphur from the iron ore concentrate and simultaneously to transform sulphide minerals into useful by-products. To achieve desirable sulphur removal rate and efficiency, central composite design was adopted as a response surface methodology for the optimization and evaluation of the process. A full-quadratic polynomial equation between the sulphur removal and the studied parameters was established to assess the behaviour of sulphur removal as a function of the factors and to predict the results in various conditions. The optimum conditions were obtained based on the variance tests and response surface plots, from which the optimized ranges for each factor resulting in the best response (corresponding to the highest percentage of desulphurization) could be then achieved. The results show that most desirable conditions are atmospheric leaching in 1.39 mol/dm3 nitric acid and 0.88 mol/dm3 sulphuric acid for 47 h. The designed process under the optimized desulphurization conditions was applied to a real iron ore concentrate. More than 75% of the total sulphur was removed via the leaching process. In addition to the desulphurization, the conversion of sulphide-bearing minerals into useful by-products, extraction of valuable metals, and executing the process under atmospheric conditions are the other advantages of the proposed method.

Research of a hydrodynamic purifying device of exhaust and effluent gases from toxic components under dynamic conditions of their emissions into the atmosphere

The article describes the air purifying device of the “OTPO-9” type, which implements the technology of hydrodynamic purification with a foam method where foam was produced by bubbling. The article considers it as the most environmentally efficient and energy-saving device, based on the results of implementation of the methodology of technology selection for purifying exhaust and effluent gases from toxic components of industrial, public and domestic power units up to 1000 kW developed by the authors. The full-scale laboratory studies of the semi-industrial model of the developed device were carried out by the authors. These studies allowed us to define the nitrogen oxide and sulfur removal efficiency depending on the electric voltage, the shape of the device’s side wall in layout, the submersion of inlet and outlet pipe side holes, the ratio of the anode total area to the cathode one. Moreover, the authors have revealed the device scope of application and its advantages. The article states that the proposed device provides environmental safety of the implementation process in comparison with the use of chemical alkaline solutions, which are dangerous for human health and environment.

SIMULTANEOUS TREATMENT OF SULFATE WASTEWATER AND DOMESTIC SEWAGE WITH MICRO-AERATION

High sulfide inhibited the activities of sulfate-reducing bacteria (SRB) and methane-producing bacteria (MPB). In addition, a large number of domestic sewages should be treated in China. Thus, it is the first time that domestic sewage was collected to dilute high-sulfate wastewater in this study to achieve simultaneous treatment of sulfate wastewater and domestic sewage in the anaerobic baffled reactor (ABR). The results showed that there were obvious separation of sulfate reduction phase and methane production phase in the ABR, and large sulfate were reduced in the front compartments. Micro-aeration (oxygen demand of 0.4-0.6 mg/L) could significantly decrease sulfide concentration from 45 mg/L to 5 mg/L. Furthermore, micro-aeration between sulfate-reducing and methane-producing phases could significantly promote the synergistic removal of organics by SRB and MPB, while COD removal efficiency increased from 80% to 95%, and sulfate removal efficiency increased from 80% to 90%. And the highest elemental sulfur recovery rate was 0.27 kg/(m3.d). Finally, the ABR that operated with C/S of 2, HRT of 12 h and COD load of 4 kg/ (m3.d), micro-aeration (DO of 0.4-0.6 mg/L) at the end of sulfate reduction phase (the compartment 5) has proved to be efficient in simultaneous sulfate wastewater and domestic sewage treatment and is suitable for elemental sulfur recovery.

Effect of sulfate on hydrogen production from the organic fraction of municipal solid waste using co-culture of E. coli and Enterobacter aerogenes

In the present study, the effect of sulfate on the hydrogen production from the organic fraction of municipal solid (OFMSW) waste using co-culture of Enterobacter aerogenes and E. coli has been studied under varying pH conditions. The presence of sulfate in the feedstock declines hydrogen production efficiency. To evaluate the effect of sulfate on hydrogen production from OFMSW, COD/sulfate ratio of 17.5, 15.0, 12.5, 10.0, 7.5, 5.0 and 2.5 were applied at different pH conditions (i.e. pH 5.5, 6.0 and 6.5). The hydrogen production continuously declined with the decreasing COD/sulfate ratio and increase in pH. The cumulative hydrogen production decreased from 220.8 ± 10.5 mL in control to a minimum of 98.3 ± 10.5 mL, 74.4 ± 10.4 mL, and 44.6 ± 2.6 mL at pH 5.5, 6.0 and 6.5 respectively. The major content of gaseous composition included hydrogen and CO2 at higher COD/sulfate ratio and low pH, while H2S formation started with the decrease in COD/sulfate ratio and increase in the pH. Similarly, sulfate removal efficiency was found to be influenced by COD/sulfate ratio and pH condition. Soluble metabolite analysis revealed that total volatile fatty acid concentration was not affected by sulfate addition. Thus, Sulfate removal is essential prior to fermentation in order to improve hydrogen yield.

Removal of high concentration of sulfate from pigment industry effluent by chemical precipitation using barium chloride: RSM and ANN modeling approach

Sulfate ions pose a major threat and challenge in the treatment of industrial effluents. The sample of wastewater obtained from a pigment industry contained large quantities of sulfate in the form of sodium sulfate which resulted in high TDS. As the removal of sulfate from pigment industry effluent was not reported previously, this work was focused on removing the sulfate ions from the effluent by chemical precipitation using barium chloride. The efficiency of sulfate removal was nearly 100% at an excess dosage of barium chloride, which precipitates the dissolved sulfate ions in the form of barium sulfate. Optimization of the parameters was done using Response Surface Methodology (RSM). This work is the first attempt for modeling the removal of sulfate from pigment industry effluent using RSM and Artificial Neural Network (ANN). Prediction by both the models was evaluated and both of them exhibited good performance (R2 value > 0.99). It was observed that the prediction by RSM (R2 value 0.9986) was closer to the experimental results than ANN prediction (R2 value 0.9955). The influence on the pH and conductivity of the solution by dosage of precipitant was also studied. The formation of barium sulfate was confirmed by characterization of the precipitate. Therefore, the sulfate removed from the effluent was converted into a commercially valuable precipitate.

Effects of nitrate and sulfate on the performance and bacterial community structure of membrane-less single-chamber air-cathode microbial fuel cells

ABSTRACTMembrane-less, single-chamber, air-cathode, microbial fuel cells (ML-SC MFCs) have attracted attention as being suitable for wastewater treatment. In this study, the effects of nitrate and sulfate on the performance of ML-SC MFCs and their bacterial structures were evaluated. The maximum power density increased after nitrate addition from 8.6 mW·m−2 to 14.0 mW·m−2, while it decreased after sulfate addition from 11.5 mW·m−2 to 7.7 mW·m−2. The chemical oxygen demand removal efficiencies remained at more than 90% regardless of the nitrate or sulfate additions. The nitrate was removed completely (93.0%) in the ML-SC MFC, while the sulfate removal efficiency was relatively low (17.6%). Clostridium (23.1%), Petrimonas (20.0%), and unclassified Rhodocyclaceae (6.2%) were dominant on the anode before the addition of nitrate or sulfate. After the addition of nitrate, Clostridium was still the most dominant on the anode (23.6%), but Petrimonas significantly decreased (6.0%) and unclassified Rhodocyclaceae increased (17.1%). After the addition of sulfate, the amount of Clostridium almost doubled in the composition on the anode (43.2%), while Petrimonas decreased (5.5%). The bacterial community on the cathode was similar to that on the anode after the addition of nitrate. However, Desulfovibrio was remarkably dominant on the cathode (32.9%) after the addition of sulfate. These results promote a deeper understanding of the effects of nitrate or sulfate on the ML-SC MFCs' performance and their bacterial community.

Acidic polymeric ionic liquids based reduced graphene oxide: An efficient and rewriteable catalyst for oxidative desulfurization

A new type of graphene-based catalyst with rewriteable function was designed and synthesized based on poly(1-vinyl-3-ethylimidazolium bromide) modified and reduced graphene oxide (denoted as poly[ViEtIm]Br-rGO). The modified polymeric ionic liquid poly[ViEtIm]Br not only acted as interlink between the polar catalytic anion and the non-polar graphene substrate, but also endowed the favorable dispersibility of poly[ViEtIm]Br-rGO in ionic liquid, leading to the adequate exposure of immobilized catalytic sites during the process of desulfurization. Moreover, due to the reversible anion-exchange property of the modified poly[ViEtIm]Br, various anions of Brønsted acids or heteropolyacids could be sequentially ‘written in’ or ‘erased’ on the nanosheets of rGO for desulfurization, thus establishing a green model for screening suitable catalysts based only on the limits of the same carrier. Such a rewriteable cycle was confirmed and monitored by characterization of TEM, FTIR spectroscopy and X-ray photoelectron spectroscopy (XPS). Based on this catalyst screening process of a rewriteable cycle, poly[ViEtIm][PW12O40]-rGO, a heteropolyanoin modified rGO, was selected as the optimized catalyst. Benefiting from the synergistic effects between rGO and acidic anions, together with the large surface area and open two-dimensional structure of rGO, poly[ViEtIm][PW12O40]-rGO was found to exhibit an excellent catalytic performance toward various sulfur-containing compounds. Furthermore, the outstanding reusability of poly[ViEtIm][PW12O40]-rGO was also displayed owing to its structural stability. It was found that the sulfur removal efficiency of DBT could still reach 98.0% after the catalyst poly[ViEtIm][PW12O40]-rGO had even been recycled eight times.

Biological Hydrogen Sulfide and Sulfate Removal from Rubber Smoked Sheet Wastewater for Enhanced Biogas Production

The sulfate-rich wastewater from rubber smoked sheet industry could generate hydrogen sulfide (H2S) under anaerobic condition, which created bad smell to the community and might cause toxicity and damage to the environment. The H2S can be removed from the biogas by sulfur-oxidizing bacteria (SOB) with the ability to converted H2S to sulfate. Sulfate-reducing bacteria (SRB) could remove sulfate in wastewater before anaerobic treatment for biogas production. The microbial sludge from wastewater and anaerobic digestion system was collected and test for sulfate and H2S removal efficiency. Anaerobic microbial sludge has a high ability to produced methane from gelatin with a specific methane production rate of 92.4 ml CH4 gVSS-1 day-1. Anaerobic microbial sludge has lower methane production when gelatin and sulfate used as a substrate with a specific methane production rate of 81.4 ml CH4 gVSS-1 day-1. The biomethane potential, hydrogen sulfide removal and sulfate removal in anaerobic digestion system by addition of enriched cultures of SOB and SRB were investigated. The methane yield of SRB consortium was 60.1 ml CH4/gCOD with 20% sulfate reduction from wastewater and no sulfide reduction. The methane yield of SOB consortium was 41.9 ml CH4/gCOD with no sulfate and sulfide reduction from wastewater. The addition of SRB consortium could increase methane production by reducing sulfate concentration in wastewater consequently to a reduced concentration of H2S in biogas.

Performance evaluation and microbial community analysis of the function and fate of ammonia in a sulfate-reducing EGSB reactor.

Ammonia is widely distributed in sulfate-reducing bioreactor dealing with sulfate wastewater, which shows potential effect on the metabolic pathway of sulfate and ammonia. This study investigates the sulfate-reducing efficiency and microbial community composition in the sulfate-reducing EGSB reactor with the increasing ammonia loading. Results indicated that, compared with low ammonia loading (166-666mg/L), the sulfate and organic matter removal efficiencies were improved gradually with the appropriate ammonia loading (1000-2000mg/L), which increased from 63.58±3.81 to 71.08±1.36% and from 66.24±1.32 to 81.88±1.83%, respectively. Meanwhile, with the appropriate ratio of ammonia and sulfate (1.5-3.0) and hydraulic retention time (21h), the sulfate-reducing anaerobic ammonia oxidation (SRAO) process was occurred efficiently, inducing the accumulation of S0 (270mg/L) and the simultaneous ammonia removal (70.83%) in EGSB reactor. Moreover, the key sulfate-reducing bacteria (SRB) (Desulfovibrio) and denitrification bacteria (Pseudomonas and Alcaligenes) were responsible for the sulfate and nitrogen removal in these phases, which accounted for 3.66-5.54 and 3.85-9.13%, respectively. However, as the ammonia loading higher than 3000mg/L (phases 9 and 10), the sulfate-reducing efficiency was decreased to only 28.3±1.26% with the ammonia removal rate of 18.4±3.37% in the EGSB reactor. Meanwhile, the predominant SRB in phases 9 and 10 were Desulfomicrobium (1.22-1.99%) and Desulfocurvus (4.0-5.46%), and the denitrification bacteria accounted for only 0.88% (phase 10), indicating the low nitrogen removal rate.