Biodegradation of 2-methylisoborneol by bacteria enriched from biological activated carbon

One of the most common taste and odour compounds (TOCs) in drinking water is 2-methylisoborneol (2-MIB) which cannot be readily removed by conventional water treatments. Four bacterial strains for degrading 2-MIB were isolated from the surface of a biological activated carbon filter, and were characterized as Micrococcus spp., Flavobacterium spp., Brevibacterium spp. and Pseudomonas spp. based on 16S rRNA analysis. The removal efficiencies of 2-MIB with initial concentrations of 515 ng·L^-1 were 98.4%, 96.3%, 95.0%, and 92.8% for Micrococcus spp., Flavobacterium spp., Brevibacterium spp. and Pseudomonas spp., respectively. These removal efficiencies were slightly higher than those with initial concentration at 4.2 mg·L^-1 (86.1%, 84.4%, 86.7% and 86.0%, respectively). The kinetic model showed that biodegradation of 2-MIB at an initial dose of 4.2 mg·L^-1 was a pseudo-first-order reaction, with rate constants of 0.287, 0.277, 0.281, and 0.294 d^-1, respectively. These degraders decomposed 2-MIB to form 2-methylenebornane and 2-methyl-2-bornane as the products.     

Optimization of thermophilic anaerobic-aerobic treatment system for Palm Oil Mill Effluent (POME)

Optimization of an integrated anaerobic-aerobic bioreactor (IAAB) treatment system for the reduction of organic matter (Chemical Oxygen Demand (COD), Biochemical Oxygen Demand (BOD) and Total Suspended Solids (TSS) concentrations) in Palm Oil Mill Effluent (POME) to legal standards with high methane yield was performed for the first time under thermophilic condition (50°C–55°C) by using response surface methodology (RSM). The experiments were conducted based on a central composite rotatable design (CCRD) with three independent operating variables, organic loading rates in anaerobic compartment (OLR_an) and mixed liquor volatile suspended solids (MLVSS) concentration in anaerobic (MLVSS_an) and aerobic compartments (MLVSS_a). The optimum conditions for the POME treatment were determined as OLR_an of 15.6 g COD·L^-1·d^-1, MLVSS_an of 43100 mg·L^-1, and MLVSS_a of 18600 mg·L^-1, where high aerobic COD, BOD and TSS removal efficiencies of 96.3%, 97.9%, and 98.5% were achieved with treated BOD of 56 mg·L^-1 and TSS of 28 mg·L^-1 meeting the discharge standard. This optimization study successfully achieved a reduction of 42% in the BOD concentrations of the final treated effluent at a 48% higher OLR_an as compared to the previous works. Besides, thermophilic IAAB system scores better feasibility and higher effectiveness as compared to the optimized mesophilic system. This is due to its higher ability to handle high OLR with higher overall treatment efficiencies (more than 99.6%), methane yield (0.31 L CH₄·g^-1 COD_removed) and purity of methane (67.5%). Hence, these advantages ascertain the applicability of thermophilic IAAB in the POME treatment or even in other high-strength wastewaters treatment.     

Gold modified microelectrode for direct tetracycline detection

The residues of tetracycline antibiotics in water have attracted many concerns due to their harmful impact to human health. This paper reports an electrochemical sensor for the determination of tetracycline (TC) by the microelectrode, which was fabricated by electrodeposited gold colloids on tungsten tip. Cyclic voltammerty was used to study the electrochemical behavior of TC on the microelectrode. Well anodic wave was obtained at about 1.5 V in acidic solutions. Electrochemical determination of tetracycline was investigated using microelectrode by cyclic voltammetry. Under optimized conditions, the calibration curves for TC were obtained. The oxidation peak currents were linearly related to TC concentrations in the range of 1–10 mg·L^-1 and 10–100 mg·L^-1, respectively. The detection limit was 0.09 mg·L^-1 (S/N = 3).     

Degradation of bisphenol A by microorganisms immobilized on polyvinyl alcohol microspheres

In this study, microorganisms （named B111） were immobilized on polyvinyl alcohol microspheres prepared by the inverse suspension crosslinked method. The biodegradation of bisphenol A （BPA） and 4-hydro- xybenzaldehyde, a degradation product of BPA, by free and immobilized B lll was investigated. The BPA degradation studies were carried out at initial BPA concentrations ranging from 25 to 150 mg·L^-1. The affinity constant Ks and maximum degradation rate Rmax were 98.3 mg·L^-1 and 19.7mg·mg^-1VSS·d^-1 for free B111, as well as 87.2mg·L^-1 and 21.1mg·mg^-1VSS·d^-1 for immobilized B 111, respectively. 16S rDNA gene sequence analyses confirmed that the dominant genera were Pseudomonas and Brevundimonas for BPA biodegradation in microorganisms B 111.     

Upgrade of three municipal wastewater treatment lagoons using a high surface area media

Lagoon-based municipal wastewater treatment plants (WWTPs) are facing difficulties meeting the needs of rapid population growth as well as the more stringent requirements of discharge permits. Three municipal WWTPs were modified using a high surface area media with upgraded fine-bubble aeration systems. Performance data collected showed very promising results in terms of five-day biochemical oxygen demand (BOD₅), ammonia (NH₃) and total suspended solids (TSS) removal. Two-year average ammonia effluents were 4.1 mg·L^-1 for Columbia WWTP, 4 mg·L^-1 for Larchmont WWTP and 2.1 mg·L^-1 for Laurelville WWTP, respectively. Two- year average BOD₅ effluents were 6.8, 4.9 and 2.7 mg·L^-1, and TSS effluents were 15.0, 9.6 and 7.5 mg·L^-1. The systems also showed low fecal coliform (FC) levels in their effluents.     

Selective recovery of Cu2+ and Ni2+ from wastewater using bioelectrochemical system

As the bioelectrochemical system, the microbial fuel cell (MFC) and the microbial electrolysis cell (MEC) were developed to selectively recover Cu²⁺ and Ni²⁺ ions from wastewater. The wastewater was treated in the cathode chambers of the system, in which Cu²⁺ and Ni²⁺ ions were removed by using the MFC and the MEC, respectively. At an initial Cu²⁺ concentration of 500 mg·L^-1, removal efficiencies of Cu²⁺ increased from 97.0%±1.8% to 99.0%±0.3% with the initial Ni²⁺ concentrations from 250 to 1000 mg·L^-1, and maximum power densities increased from 3.1±0.5 to 5.4±0.6 W·m^-3. The Ni²⁺ removal mass in the MEC increased from 6.8±0.2 to 20.5±1.5 mg with the increase of Ni²⁺ concentrations. At an initial Ni²⁺ concentration of 500 mg·L^-1, Cu²⁺ removal efficiencies decreased from 99.1%±0.3% to 74.2%±3.8% with the initial Cu²⁺ concentrations from 250 to 1000 mg·L^-1, and maximum power densities increased from 3.0±0.1 to 6.3±1.2 W·m^-3. Subsequently, the Ni²⁺ removal efficiencies decreased from 96.9%±3.1% to 73.3%±5.4%. The results clearly demonstrated the feasibility of selective recovery of Cu²⁺ and Ni²⁺ from the wastewater using the bioelectrochemical system.     

Micro-analysis of nitrogen transport and conversion inside activated sludge flocs using microelectrodes

To investigate the nitrogen transport and conversion inside activated sludge flocs, micro-profiles of O₂, NH₄⁺, NO₂^–, NO₃^–, and pH were measured under different operating conditions. The flocs were obtained from a laboratory-scale sequencing batch reactor. Nitrification, as observed from interfacial ammonium and nitrate fluxes, was higher at pH 8.5, than at pH 6.5 and 7.5. At pH 8.5, heterotrophic bacteria used less oxygen than nitrifying bacteria, whereas at lower pH heterotrophic activity dominated. When the ratio of C to N was decreased from 20 to 10, the ammonium uptake increased. When dissolved oxygen (DO) concentration in the bulk liquid was decreased from 4 to 2 mg·L^-1, nitrification decreased, and only 25% of the DO influx into the flocs was used for nitrification. This study indicated that nitrifying bacteria became more competitive at a higher DO concentration, a higher pH value (approximately 8.5) and a lower C/N.     

低碳氮比废水好氧颗粒污泥系统稳定性及微生物种群多样性研究

低碳氮比(C/N)废水处理是含氮废水处理中的难题之一.本实验在C/N为4:1和2:1(COD和NH₄⁺-N浓度分别为400 mg·L^-1和100 mg·L^-1,400 mg·L^-1和200 mg·L^-1)条件下,考察好氧颗粒污泥系统对低碳氮比废水的处理效果、长期运行稳定性,研究C/N对好氧颗粒微生物结构变化的影响.研究结果表明,在C/N为4:1的废水中接种活性污泥培养好氧颗粒污泥,形成的颗粒沉降性能良好,MLSS为4.94 g·L^-1,SVI30为40 mL·g^-1,COD去除率90%以上,氨氮去除率接近100%.降低碳氮比,即C/N为2:1后,好氧颗粒的物理及硝化性能无明显变化,MLSS为11.38 g·L^-1,SVI₃₀/SVI₅维持在1左右,COD去除率大于85%,氨氮去除率98%.碳氮比降低使颗粒微生物多样性减少,其中陶厄氏菌受影响较小,而硝化功能菌出现更替:噬氢菌、食酸菌、里德拜特氏菌消失,鞘氨醇单胞菌、束缚杆菌等成为优势菌种.实验表明,该低碳氮比条件下好氧颗粒污泥系统能够稳定运行,且具有优良的处理性能.     

Kinetics of oxidation of dimethyl trisulfide by potassium permanganate in drinking water

Metabolites of algae such as geosmin, 2-methylisoborneol etc. are reported to induce pungent odors into drinking water and attract additional scientific attention. Recently, in China, taste and odor outbreaks in drinking water supply have become increasingly common. In source water affected by eutrophication, dimethyl trisulfide, speculated to be produced by decayed algae, was found to be the source of taste and odor issues and can be removed effectively by usual oxidation agents. In this experimental study, batch scale tests were carried out focusing on the removal of dimethyl trisulfide. Reaction kinetics of dimethyl trisulfide oxidized by potassium permanganate in water had been studied; influence factors such as pH, organic substrate, other existed taste, and odor contaminant in equivalent concentration were also discussed. Results showed that dimethyl trisulfide can be removed by potassium permanganate efficiently; the ratio can reach more than 70% with oxidant dosage of 4 mg·L^-1 and contact time prolonged to 120 min. The dimethyl trisulfide decomposition followed a second-order kinetics pattern with a rate constant k = 0.00213 L·(min·mg)^-1. Typically, the degradation rate of dimethyl trisulfide was increased with the increasing KMnO₄ dosage, but dramatically dropped with the increasing levels of humic acid (1.8–4.5 mg·L^-1) and other odor-causing compounds (e.g. β-cyclocitral, 0–1886.0 μg·L^-1). Solution pH (5.2–9.0) and initial dimethyl trisulfide concentration did not significantly affected the degradation. This study demonstrates that KMnO₄ oxidation is an effective option to remove dimethyl trisulfide from water.     

Technical feasibility study of an onshore ballast water treatment system

To fulfill the requirements of Guidelines for approval of ballast water management system (G8), a set of onshore ballast water treatment equipment utilizing micro-pore ceramic filtration (MPCF) and UV radiation (MPCF&UV) system was designed and set up with a maximum flow rate of 80 m³·h^-1. Technical feasibilities of MPCF&UV system were evaluated in three areas: removal efficiencies of indicator organism and oceanic bacteria, perdurability of a ceramic filter, and application on native seawater. The results showed that no indicator organism (Dunaliella) or oceanic bacteria was detected after treatment of 20 L MPCF and UV radiation at 1.3× 10⁴ μW·s·cm^-2. A 20 L ceramic filter can run continuously for 5.3 h at the flow rate of 15 m³·h^-1 before its pressure drop up to 0.195 MPa. The removal percentage of total plankton amounts were 91.9% at a flow rate of 70 m³·h^-1 by 80 L MPCF and UV radiation at 1.3× 10⁴ μW·s·cm^-2.     

A new procedure combining GC-MS with accelerated solvent extraction for the analysis of phthalic acid esters in contaminated soils

An optimized procedure based on gas chromatography-mass spectrometry (GC-MS) combined with accelerated solvent extraction (ASE) is developed for the analysis of six phthalic acid esters (PAEs), which are priority soil pollutants nominated by United States Environmental Protection Agency (USEPA). Quantification of PAEs in soil employs ultrasonic extraction (UE) (USEPA 3550) and ASE (USEPA 3545), followed by clean up procedures involving three different chromatography columns and two combined elution methods. GC-MS conditions under selected ion monitoring (SIM) mode are described and quality assurance and quality control (QA/QC) criteria with high accuracy and sensitivity for target analytes were achieved. Method reliability is assured with the use of an isotopically labeled PAE, di-n-butyl phthalate-d4 (DnBP-D4), as a surrogate, and benzyl benzoate (BB) as an internal standard, and with the analysis of certified reference materials (CRM). QA/QC for the developed procedure was tested in four PAE-spiked soils and one PAE-contaminated soil. The four spiked soils were originated from typical Chinese agricultural fields and the contaminated soil was obtained from an electronic waste dismantling area. Instrument detection limits (IDLs) for the six PAEs ranged 0.10–0.31 μg·L^-1 and method detection limits (MDLs) of the four spiked soils varied from a range of 20–70 μg·kg^-1 to a range of 90– 290 μg·kg^-1. Linearity of response between 20 μg·L^-1 and 2 mg·L^-1 was also established and the correlation coefficients (R) were all>0.998. Spiked soil matrix showed relative recovery rates between 75 and 120% for the six target compounds and about 93% for the surrogate substance. The developed procedure is anticipated to be highly applicable for field surveys of soil PAE pollution in China.     

Ozone kinetics of dimethyl sulfide in the presence of water vapor

The outdoor smog chamber was used to thorough investigate the rate constants of gas-phase reaction between dimethyl sulfide （DMS） and ozone （O3） under conditions of relative humidity 55.0%-67.8% at （296±2）K for the first time. The rate constants were measured, at a total pressure of 1 atm, to be （10.4±0.2） × 10^-19 cm^3·molecule^-1·s^-1 at relative humidity of 67.5%±0.3% at 298K, （10.1±0.1） × 10^-19cm^3·molecule^-1·s^-1 at relative humidity of 66.5%±0.5% at 296K, （7.75±0.39） × 10^-19cm^3·molecule^-1·s^-1 at relative humidity of 64.8%± 0.1% at 294K and （3.42±0.21） × 10^-19cm^3·molecu- le^-1·s^-1at relative humidity of 55.8%±0.8% at 295K. Base on these results, it is possible to see the reaction of O3/ DMS in the presence of water vapor as an important sink for DMS in the earth atmosphere.     

Validation of polymer-based nano-iron oxide in further phosphorus removal from bioeffluent: laboratory and scaledup study

The efficient removal of phosphorous from water is an important but challenging task. In this study, we validated the applicability of a new commercially available nanocomposite adsorbent, i.e., a polymer-based hydrated ferric oxide nanocomposite (HFO-201), for the further removal of phosphorous from the bioeffluent discharged from a municipal wastewater treatment plant, and the operating parameters such as the flow rate, temperature and composition of the regenerants were optimized. Laboratory-scale results indicate that phosphorous in real bioeffluent can be effectively removed from 0.92 mg·L^-1 to<0.5 mg·L^-1 (or even<0.1 mg·L^-1 as desired) by the new adsorbent at a flow rate of 50 bed volume (BV) per hour and treatable volume of 3500–4000 BV per run. Phosphorous removal is independent of the ambient temperature in the range of 15°C–40°C. Moreover, the exhausted HFO-201 can be regenerated by a 2% NaOH+ 5% NaCl binary solution for repeated use without significant capacity loss. A scaled-up study further indicated that even though the initial total phosphorus (TP) was as high as 2 mg·L^-1, it could be reduced to<0.5 mg·L^-1, with a working capacity of 4.4–4.8 g·L^-1 HFO-201. In general, HFO-201 adsorption is a choice method for the efficient removal of phosphate from biotreated waste effluent.     

In vitro agonistic and antagonistic endocrine disrupting effects of organic extracts from waste water of different treatment processes

Effluents from wastewater treatment plant （WWTP） have been reported to have a broad spectrum of endocrine disrupting compounds （EDCs）. The majority of studies have focused on the occurrence of estrogenic activity, while ignoring nuclear hormone receptors （NRs） pathways. In the present study, a battery of in vitro yeast bioassays and a cell bioassay, including antagonistic and agonistic effects on estrogen receptor （ER）, androgen receptor （AR）, progesterone receptor （PR）, estrogen- related receptor （ERR） and aryl hydrocarbon receptor （AHR）, were conducted to evaluate the removal efficien- cies of EDCs by different treatment processes of a WWTP located in Beijing. Estrogenic, anti-estrogenic, anti- androgenic, anti-progesteronic, anti-ERR and the activa- tion of AHR activities were detected in samples from all treatment processes and the receiving water. The concen- tration of estrogenic contaminants with estradiol （E2） equivalent concentrations ranged from 0.82 x 10-9 to 3.54 x 10 9g Ee_EQ.L-1. The concentration of anti-estrogenic contaminants with 4-hydroxytamoxifen （4-OHT） equiva- lent concentrations ranged from 1.24 × 10-6 to 2.36 x 10-6 g 4-OHT-EQ.L-1. The concentration of anti-androgenic contaminants ranged from 2.21 x 10-s to 3.52 × 10-6g flutamide-EQ. L-1. The concentration of anti-progesteronic contaminants ranged from 3.15 x 10^-5 to 2.71 x 10^-4g RU486-EQ. L-1. The concentration of anti-ERR contami- nants ranged from 7.09 x 10-5 to 6.50 x 104 g 4-OHT-EQ × L^-10. The concentration of AHR activators ranged from 1.7 × 10-10 to 3.4 × 10^-10g TCDD-EQ-L-1. These processes including secondary clarifier, coagulation, as well as coal and sand filtration could eliminated 67.2% of estrogenic contaminants, 47.0% of anti-estrogenic contaminants, 98.3% of anti-androgenic contaminants, 88.4% of anti- progesteronic contaminants, 65.4% of anti-ERR contami- nants and 46.9% of AHR activators. WWTP effluents contain multiple receptor disruptors may have very complex adverse effects on exposed organisms.     

Effects of humic acid on residual Al control in drinking water treatment plants with orthophosphate addition

This study aimed to investigate the effects of humic acid (HA) on residual Al control in drinking water facilities that used orthophosphate addition. The results showed that adding orthophosphate was an effective method for residual Al control for the raw water without HA. When orthophosphate was added at 1.0 min before the addition of poly aluminum chloride (PACl), the concentrations of soluble aluminum (Sol-Al) and total aluminum (Tot-Al) residue were 0.08 and 0.086 mg·L^-1, respectively; both were reduced by 46% compared with the control experiment. The presence of HA would notably increase the residual Al concentration. For the raw water with 5 mg·L^-1 of HA, the concentrations of Sol-Al and Tot-Al increased from 0.136 and 0.174 mg·L^-1 to 0.172 and 0.272 mg·L^-1, respectively. For water with a HA concentration above 5 mg·L^-1, orthophosphate was ineffective in the control of residual Al, though there were still parts of orthophosphate were removed in coagulation. The amounts of Al removal were positively correlated with the solids freshly formed in coagulation. Similar to the raw water without HA, the best Al control was obtained with orthophosphate salt added at 1.0 min before PACl. HA concentrations in the raw water, solution pH, and the orthophosphate dosage suitable for residual Al control by orthophosphate precipitation were also investigated.     

Preparation of hapten-specific monoclonal antibody for cadmium and its ELISA application to aqueous samples

High-affinity and specific monoclonal antibodies against cadmium-ethylene diamine tetraacetic acid (EDTA) complex have been produced using the hybridoma technique. A hapten was synthesized and characterized by Fourier Transform Infrared Spectroscopy (FT-IR) and UV-Vis. Competitive enzyme-linked immunosorbent assay (ELISA) for quantitative detection of cadmium in aqueous sample was developed. The monoclonal antibody with high level of binding affinity for Cd-IEDTA-BSA and high specificity for soluble Cd-EDTA complex showed less than 0.99% cross-reactivity with other 11 metals. The limit of detection was 0.10 μg·L^-1, and the effective linear range was 10^-1–10³ μg·L^-1. The intra- and inter-assay coefficient variations were 1.5%–6.3% and 3.2%–7.4%, respectively. The spike recovery in different water samples were between 98.5% and 110.3%. The detection limit of this assay was well below the allowable concentration of cadmium (3 μg·L^-1), and the working range was wider than that of other methods which showed the range of 2.19–86.38 and 0–10³ μg·L^-1. The competitive ELISA established in this paper was sensitive and accurate in the screening of cadmium in aqueous samples. The results will lay a solid foundation for construction of an immunoassay kit for cadmium.     

Rapid method for on-site determination of phenolic contaminants in water using a disposable biosensor

A disposable biosensor was fabricated using single-walled carbon nanotubes, gold nanoparticles and tyrosinase (SWCNTs-AuNPs-Tyr) modified screen-printed electrodes. The prepared biosensor was applied to the rapid determination of phenolic contaminants within 15 minutes. The SWCNTs-AuNPs-Tyr bionanocomposite sensing layer was characterized with scanning electron microscopy, electrochemical impedance spectroscopy and cyclic voltammetry methods. The characterization results revealed that SWCNTs could lead to a high loading of tyrosinase (Tyr) with the large surface area and the porous morphology, while AuNPs could retain the bioactivity of Tyr and enhance the sensitivity. The detection conditions, including working potential, pH of supporting electrolyte and the amount of Tyr were optimumed. As an example, the biosensor for catechol determination displayed a linear range of 8.0 × 10^-8 to 2.0 × 10^-5 mol·L^-1 with a detection limit of 4.5 × 10^-8 mol·L^-1 (S/N = 3). This method has a rapid response time within 10 s, and shows excellent repeatability and stability. Moreover, the resulting biosensor could be disposable, low-cost, reliable and easy to carry. This kind of new Tyr biosensor provides great potential for rapid, on-site and cost-effective analysis of phenolic contaminants in environmental water samples.     

Enhanced dewatering characteristics of waste activated sludge with Fenton pretreatment: effectiveness and statistical optimization

In this work, the enhanced dewaterabing characteristics of waste activated sludge using Fenton pretreatment was investigated in terms of effectiveness and statistical optimization. Response surface method （RSM） and central composite design （CCD） were applied to evaluate and optimize the effectiveness of important operational parameters, i.e., H202 concentrations, Fe2＋ concentrations and initial pH values. A significant quadratic polynomial model was obtained （R2= 0.9189） with capillary suction time （CST） reduction efficiency as the response. Numerical optimization based on desirability function was carried out. The optimum values for H202, Fe2, and initial pH were found to be 178 mg-g-1 VSS （volatile suspended solids）, 211mg.gI VSS and 3.8, respectively, at which CST reduction efficiency of 98.25% could be achieved. This complied well with those predicted by the established polynomial model. The results indicate that Fenton pretreatment is an effective technique for advanced waste activated sludge dewatering. The enhancement of sludge dewaterability by Fenton＇s reagent lies in the migration of sludge bound water due to the disintegration of sludge flocs and microbial cells lysis.     

高效液相色谱-串联质谱法同时检测水体中26种药物及个人护理品

通过优化固相萃取条件和高效液相色谱-串联质谱参数,建立了可以同时检测地表水和地下水中26种典型药物及个人护理品(pharmaceuticals and personal care products,PPCPs),包括磺胺类、大环内酯类、喹诺酮类、酰胺醇类、精神类、消炎止痛类以及个人护理品的检测方法.通过将水样pH值调节至7,利用HLB固相萃取柱对水样中PPCPs进行富集,以甲醇和含0.005%甲酸的水溶液作为正离子模式流动相,甲醇和含0.5 mmol·L^-1乙酸铵的水溶液作为负离子模式流动相进行梯度洗脱,采用多反应监测的质谱扫描模式(MRM)分析测定.26种PPCPs的检出限为0.007—1.78 ng·L^-1,定量限为0.02—5.68 ng·L^-1,回收率为52.28%—115.24%.利用该方法检测北京潮白河地表水和地下水中PPCPs的浓度,结果表明,地表水中PPCPs的含量普遍高于地下水,磺胺甲恶唑、舒必利、咖啡因、卡马西平和布洛芬在地表水和地下水中的含量相对较高,检测浓度分别高达147.83、52.48、78.35、166.58、30.63 ng·L^-1.     

Performance of an ANAMMOX reactor treating wastewater generated by antibiotic and starch production processes

A pilot-scale anaerobic ammonia oxidation (ANAMMOX) reactor was used to treat mixed wastewater resulting from a chlortetracycline and starch production process. The results, collected over the course of 272 days, show that the ratio of influent ammonium to nitrite, pH, and temperature can all affect the efficiency of nitrogen removal. The ratio of influent ammonium to nitrite was maintained at about 1:1 at a concentration below 200 mg·L^-1 for both influent ammonium and nitrite. The total nitrogen (TN) loading rate was 0.15–0.30 kgN·m^-3·d^-1, pH remained at 7.8–8.5, and temperature was recorded at 33±1°C. The rate of removal of ammonia, nitrite, and TN were over 90%, 90%, and 80%, and the effluent ammonium, nitrite and TN concentrations were below 50, 30, and 100 mg·L^-1.