Wastewater Nitrogen Removal Research Articles

Innovative biological nitrogen removal in domestic wastewater with a membrane biofilm reactor (MBfR) using methane as the electron donor

Innovative biological nitrogen removal in domestic wastewater with a membrane biofilm reactor (MBfR) using methane as the electron donor

Correlating microbial community structure with operational conditions in biological aerated filter reactor for efficient nitrogen removal of municipal wastewater

In this study, the combination of strengthen circulation anaerobic (SCA) and biological aerated filter (BAF) reactor was employed to treat municipal wastewater. Different reflux percentages or gas/water ratios were selected for evaluating the removal performance of contaminants in SCA-BAF system and sequential nitrification and denitrification process in BAF reactor. In general, reflux percentage (200%) and gas/water ratio (3:1) were a relatively suitable operational condition for BAF reactor. The COD, NH3-N, TN concentrations of effluents collected from BAF reactor varied in the ranges of 18–80, 0.2–7.2, 9.1–33.0 mg L−1, respectively. A higher NO3-N concentration in effluents of BAF reactor resulted from the lack of organic carbon resource in wastewater. High throughput sequencing analysis indicated that different nitrification and denitrification bacteria thrived in the BAF reactor. The DO, NO2-N and NO3-N concentrations showed a strong correlation with Nitrospira and Nitrosomonas in bacterial samples outlet (c and e) under gas/water ratio of 3:1.

Anammox bacteria with attached-growth media for nitrogen removal in wastewater

In side-by-side tests with high nitrogen wastewaters (483–1096 mg N/L), it was shown that an attached-growth media system more effectively removed nitrogen than did a suspended-growth system. The attached-growth system better handled the high nitrogen loading concentrations as calculated by the specific annamox activities (SAA) of the two systems. Moreover, the attached-growth medium was able to retain the anammox culture within the system. Based on these results, attached-growth was chosen for additional investigation of the effect of acetate in short- and long-term studies. In a short-term experiment, acetate concentrations of 0.25 and 0.5 mM did not affect the anammox bacteria activity. However, in a long-term experiment, the addition of acetate at 0.25 mM decreased the ammonium oxidation rate. The results from this study suggest that attached-growth systems show more promise for use in the field than suspended-growth systems.

Design and Synthesis of a Novel Silicate Material from Red Mud for Simultaneous Removal of Nitrogen and Phosphorus in Wastewater

This study reports on a material (CSH@SiO2@MgO) that is formed by calcium silicate hydrate (CSH) and silicon dioxide (SiO2), and then coated with magnesium oxide (MgO) on the surface. CSH@SiO2@MgO can simultaneously remove ammonia nitrogen (NH4+) and phosphate (PO43–) in water. The raw material SiO2 is extracted from the red mud by acid leaching. A simple preparation method is employed to synthesize CSH@SiO2@MgO composite material by using CSH@SiO2 with core-layer structure doped with MgO. The removal process of NH4+ and PO43– is as follows: First, the struvite precipitation method was used to remove NH4+ and a part of PO43–, and then the CSH@SiO2 was used to remove the residual part of PO43– through chemical precipitation reaction. The CSH@SiO2@MgO automatically regulated pH in water, and the removal rate of NH4+ and PO43– could reach 83.88% and 93.87%. Also, the CSH@SiO2@MgO was recycled five times, and the removal rate of NH4+ and PO43– was maintained at about 73.51% and 80.86%. It was characterized by...

Short-Term and Long-Term Effects of Tourmaline on Activated Sludge Viability and Performance

The study aimed to explore the short-term and long-term effects of tourmaline on activated sludge viability and biological nutrient removal performance. The experimental results indicated that ultrafine tourmaline particles (1 g/L) promoted sludge viability, the reaction rates, and relative enzyme activities in wastewater nitrogen removal. The difference between short-term and long-term effects of tourmaline was not significant. Although the NH4 +-N removal rate and NO3 −-N formation rate in the presence of 1 g/L ultrafine tourmaline particles were increased to 13.8 and 6.8 mg/L•h, which were higher than those in the control (11.0 and 6.0 mg/L•h), short-term and long-term exposure to 1 g/L ultrafine tourmaline particles did not change the effluent concentrations of ammonia nitrogen, nitrite, and nitrate because the relative substrate concentrations were low in the influent. Denaturing gradient gel electrophoresis (DGGE) analysis results indicated that the microorganism community structures including the whole bacteria community, ammonia-oxidizing bacteria community, or the whole fungi community were not changed after the long-term exposure to 1 g/L ultrafine tourmaline particles, and Shannon diversity indices (H′) assays revealed that the diversities of community structures were not changed after the exposure to 1 g/L ultrafine tourmaline particles.

Comparison of N2O Emissions and Gene Abundances between Wastewater Nitrogen Removal Systems.

Biological nitrogen removal (BNR) systems are increasingly used in the United States in both centralized wastewater treatment plants (WWTPs) and decentralized advanced onsite wastewater treatment systems (OWTS) to reduce N discharged in wastewater effluent. However, the potential for BNR systems to be sources of nitrous oxide (NO), a potent greenhouse gas, needs to be evaluated to assess their environmental impact. We quantified and compared NO emissions from BNR systems at a WWTP (Field's Point, Providence, RI) and three types of advanced OWTS (Orenco Advantex AX 20, SeptiTech Series D, and Bio-Microbics MicroFAST) in nine Rhode Island residences ( = 3 per type) using cavity ring-down spectroscopy. We also used quantitative polymerase chain reaction to determine the abundance of genes from nitrifying () and denitrifying () microorganisms that may be producing NO in these systems. Nitrous oxide fluxes ranged from -4 × 10 to 3 × 10 µmol NO m s and in general followed the order: centralized WWTP > Advantex > SeptiTech > FAST. In contrast, when NO emissions were normalized by population served and area of treatment tanks, all systems had overlapping ranges. In general, the emissions of NO accounted for a small fraction (<1%) of N removed. There was no significant relationship between the abundance of or genes and NO emissions. This preliminary analysis highlights the need to evaluate NO emissions from wastewater systems as a wider range of technologies are adopted. A better understanding of the mechanisms of NO emissions will also allow us to better manage systems to minimize emissions.

Enhanced nitrogen and phosphorus removal from municipal wastewater in an anaerobic-aerobic-anoxic sequencing batch reactor with sludge fermentation products as carbon source

An anaerobic-aerobic-anoxic sequencing batch reactor (AOA-SBR) using sludge fermentation products as carbon source was developed to enhance nitrogen and phosphorus removal in municipal wastewater with low C/N ratio (<4) and reduce sludge production. The AOA-SBR achieved simultaneous partial nitrification and denitrification (SND), aerobic phosphorus uptake and anoxic denitrification through the real-time control and the addition of sludge fermentation products. The average removal efficiencies of total nitrogen (TN), phosphorus (PO43−-P) and chemical oxygen demand (COD) after 145-day operation were 88.8%, 99.3% and 81.2%, respectively. Nitrite accumulation ratio (NAR) reached 99.1% and sludge reduction rate reached 44.1–52.1%. Specifically, 34.4% of the TN removal was carried out by SND and 57.5% by denitrification. Illumina MiSeq sequencing indicated that ammonium-oxidizing bacteria (Nitrosomonas) were enriched and nitrite-oxidizing bacteria (Nitrospira) did not exist in AOA-SBR. The system demonstrated potential to solve the dual problem of insufficient carbon source and sludge reduction.

Nitrogen removal and microbial diversity of activated sludge entrapped in modified poly(vinyl alcohol)–sodium alginate gel

We investigated nitrogen removal from secondary effluent via microbial entrapment with poly (vinyl alcohol)–sodium alginate gel modified with alumina nanoparticles. Fourier transform infrared spectroscopy (FT–IR) and Raman spectroscopy revealed changes in functional groups on the embedding beads with the modification and the Brunauer–Emmett–Teller (BET) demonstrated that the mechanical strength of beads improved. Batch experiments were conducted to investigate nitrogen removal in synthetic wastewater with initial total nitrogen concentrations of 10–45 mg L−1. The maximum ammonia removal loads ranged from 9.63 to 59.58 mg L−1 h−1. Scanning electron microscope (SEM) observations showed that the beads were highly porous and conducive for microorganism adhesion. Microbial diversity analysis (High throughput sequencing) demonstrated that the microbial community structure inside the beads changed significantly after acclimation to the reactor environment and the reaction process. Alcaligenaceae_uncultured and Comamonadaceae_unclassified, which can conduct both heterotrophic nitrification and aerobic denitrification, were identified. They may facilitate pathways for non-traditional biological denitrification inside embedding beads.

Isolation of a Novel Heterotrophic Nitrification–Aerobic Denitrification Bacterium Serratia marcescens CL1502 from Deep-Sea Sediment

Abstract A novel bacterium capable of simultaneous heterotrophic nitrification and aerobic denitrification was isolated from deep-sea sediment of the North Atlantic and identified as Serratia marcescens CL1502. The aim of this study was to study the ability, influence factors, and application in application to tannery wastewater nitrogen removal by S. marcescens CL1502. Results showed that S. marcescens CL1502 had good ability to remove NH4+-N, NO3−-N, and NO2−-N. High average NH4+-N, NO3−-N, and NO2−-N removal rates of 4.57 mg/(L·h), 4.60 mg/(L·h), and 4.42 mg/(L·h) were observed. The optimum carbon source for heterotrophic NH4+-N removal by S. marcescens CL1502 was glucose. Higher C/N ratios were favorable to heterotrophic NH4+-N removal. S. marcescens CL1502 had a good tolerance to salinity (1–5%) and Cr(III). In addition, application of strain CL1502 in actual tannery industry wastewater resulted in chemical oxygen demand (COD), NH4+-N, and TN removal efficiencies of 63.1%, 76.7%, and 72.9%. This is t...

Energy-positive nitrogen removal of pharmaceutical wastewater by coupling heterotrophic nitrification and electrotrophic denitrification

An attempt was made to cohesively assess the aerobic nitrification treatment (ANT) and bioelectrochemical denitrification treatment (DNT) of real-field pharmaceutical wastewater. The ANT resulted in the removal of 73% ammonium and 78.5% organic carbon content. Subsequently, the outlet of ANT reactor was fed to DNT reactor and the relative influence of external circuitry was investigated. The DNT reactor operated with closed circuit mode (CCM) resulted in ~83% of nitrates and % ~61% of organic content removal even at low C/N ratio of 2.18. The other pollutant concentrations viz., phosphates, sulfates and total dissolved salts were also significantly removed by both ANT and DNT processes. In this study, a sequential integration of both ANT and DNT processes exhibited high potential for self-sustained energy-positive nutrient removal.

Nitrogen Removal Performance and Microbial Community Analysis of Activated Sludge Immobilization

Immobilization of activated sludge was used to further remove nitrogen from secondary effluent. Intermittent sequencing batch reactor experiments were conducted to measure nitrogen removal in synthetic wastewater with initial total nitrogen concentrations (TN) of 10-45 mg·L-1 and C/N ratio of 1.78-10, and microbial community characteristic of embedding beads was investigated. When the packing ratio of embedding beads was 10%, and the temperature of wastewater, dissolved oxygen (DO), initial concentration of chemical oxygen demand (COD) were maintained at 10-15℃, 2-4 mg·L-1, and 80-100 mg·L-1, respectively, the results showed that the maximum total nitrogen removal loads ranged from 7.78 to 23.18 mg·(L·h)-1during the stable phase. SEM observations showed that the embedding beads were highly porous and microorganisms adhered to the interior and external surface of embedding beads, demonstrating that embedding beads acted as an ideal support material. Based on high-throughput sequencing analysis, the structure of microbial communities in the beads'interior and exterior changed significantly compared with embedding activated sludge. The advantage of denitrifying bacteria in embedding beads was obvious and the microbial diversity was good. Some microorganisms which can conduct both heterotrophic nitrification and aerobic denitrification, were identified. These processes may facilitate pathways for untraditional biological denitrification in the beads'interior.

Impacts of ammonia on zinc oxide nanoparticle toxicity to Nitrosomonas europaea

A Although the toxicity effects of engineering nanoparticles (NPs) in biological wastewater nitrogen removal (BNR) system have been extensively attracted, the impacts of co-existing contaminants from wastewater on NP toxicity have been less addressed. In this study, the effects of ammonia on ZnO NP toxicity to typical ammonia oxidizing bacteria-Nitrosomonas europaea were investigated, as indicated by the cell density, membrane integrity, ammonia oxidation rate, and AMO activity. After 6-h’s exposure to 10 mg/L ZnO NPs, the cell density, membrane integrity, ammonia oxidation rate, and AMO activity was dramatically suppressed despite of the increasing ammonia loading. Ammonia at varying concentrations did not obviously affect ZnO NPs toxicity to cell density. The presence of ammonia at 100 or 200 mg/L significantly alleviated the antibacterial effects of ZnO NPs on cells. The reduction of the concentration of released Zn2+ might be responsible for the compromised ZnO NPs toxicity. However, the presence of extremely dosed ammonia at 200 mg/L imposed restrictions on further alleviation of ZnO NPs toxicities probably due to the production of free ammonia and acclamation of nitrite. All these findings would provide new insights for risk assessment of the combined effects of NPs with other co-existing contaminants in the BNR system.

Optimized biological nitrogen removal of high-strength ammonium wastewater by activated sludge modeling

Abstract Wastewater containing high ammonium concentrations is produced from various industrial activities. In this study, the author used a complex activated sludge model, improved by utilizing BioWin© (EnviroSim, Hamilton, Canada) simulation software, to gain understanding of the problem of instability in biological nitrogen removal (BNR). Specifically, the study focused on BNR in an industrial wastewater treatment plant that receives high-strength ammonium wastewater. Using the data obtained from a nine-day sampling campaign and routinely measured data, the model was successfully calibrated and validated, with modifications to the sensitive stoichiometric and kinetic parameters. Subsequently, the calibrated model was employed to study various operating conditions in order to optimize the BNR. These operating conditions include alkalinity addition, sludge retention time, and the COD/N ratio. The addition of a stripping step and modifications to the configuration of the aerators are suggested by the author to increase the COD/N ratio and therefore enhance denitrification. It was found that the calibrated model could successfully represent and optimize the treatment of the high-strength ammonium wastewater.

Energy-positive wastewater treatment and desalination in an integrated microbial desalination cell (MDC)-microbial electrolysis cell (MEC)

Abstract Simultaneous removal of nitrogen in municipal wastewater, metal in industrial wastewater and saline in seawater was achieved in an integrated microbial desalination cell-microbial electrolysis cell (MDC-MEC) system. Batch tests showed that more than 95.1% of nitrogen was oxidized by nitrification in the cathode of MDC and reduced by heterotrophic denitrification in the anode of MDC within 48 h, leading to the total nitrogen removal rate of 4.07 mg L −1 h −1 . Combining of nitrogen removal and desalination in MDC effectively solved the problem of pH fluctuation in anode and cathode, and led to 63.7% of desalination. Power generation of MDC (293.7 mW m −2 ) was 2.9 times higher than the one without salt solution. The electric power of MDC was harvested by a capacitor circuit to supply metal reduction in a MEC, and 99.5% of lead (II) was removed within 48 h. A kinetic MDC model was developed to elucidate the correlation of voltage output and desalination efficiency. Ratio of wastewater and sea water was calculated for MDC optimal operation. Energy balance of nutrient removal, metal removal and desalination in the MDC-MEC system was positive (0.0267 kW h m −3 ), demonstrating the promise of utilizing low power output of MDCs.

Regulation of membrane fixation and energy production/conversion for adaptation and recovery of ZnO nanoparticle impacted Nitrosomonas europaea.

The ZnO nanoparticle (NP) effects on typical ammonia-oxidizing bacteria, Nitrosomonas europaea in a chemostat bioreactor, and the cells' toxicity adaptation and recovery potentials were explored. Hardly any inhibition was observed when the NP concentration was high up to 10mg/L. The cells exposed to 50mg/L ZnO NPs displayed time-dependent impairment and recovery potentials in terms of cell density, membrane integrity, nitrite production rate, and ammonia monooxygenase activity. The 6-h NP stress impaired cells were nearly completely restored during a 12-h recovery incubation, while the longer exposure time would cause irretrievable cell damage. Microarray analysis further indicated the transcriptional adaptation of N. europaea to NP stress. The regulations of genes encoding for membrane permeability or osmoprotectant, membrane integrity preservation, and inorganic ion transport during NP exposure and cell recovery revealed the importance of membrane fixation and the associated metabolisms for cells' self-protection and the following recovery from NP stress. The oxidative phosphorylation, carbon assimilation, and tricarboxylic acid (TCA) cycling pathways involved in the cells' antitoxicity activities and would promote the energy production/conversion efficiency for cell recovery. The heavy metal resistance, histidine metabolism, toxin-antitoxin defense, glycolysis, and sulfate reduction pathways were also suggested to participate in the cell detoxication and recovery processes. All these findings provided valuable insights into the mechanisms of cell-mediated ZnO NP cytotoxicity and their potential impacts on wastewater nitrogen removal system.

Optimization of a baffled-reactor microbial fuel cell using autotrophic denitrifying bio-cathode for removing nitrogen and recovering electrical energy

Microbial fuel cells (MFCs) gained emerging attention as an eco-friendly pathway for recovering electrical energy and treating wastewater. The electrochemical catalysis of cathodic reactions was one of the important issues for practical application of MFC technology. Here, it was disclosed the performance of a stake up-flow baffled-reactor MFC in which autotrophic denitrifying microorganisms catalyzed the cathodic reactions, reducing nitrate to nitrogen gas. The maximum power produced in this bio-electrochemical system (BES) was 15±0.4Wm−3 NCV (net cathode volume) at an optimum cathodic nitrate loading rate (CNLR) of 150g NO3−−N m−3 NCV d−1 using acetate as electron donor. A maximum of 76.5±0.5Am−3 NCV current and 97.7±1.8% cathodic coulombic efficiency obtained at this CNLR. Autotrophic denitrification achieved on this bio-cathode was 148.3±1.4gNm−3 NCV d−1 utilizing biological anode. The efficiency of autotrophic denitrification and current generation of this BES was inhibited by the accumulation of denitrifying by-product, nitrite (NO2−), at concentrations beyond 3.59±0.8mgNO2−−N L−1 in the cathodic stream. The results demonstrated that this bio-cathode based baffled-reactor MFC had a good potential to eliminate abiotic cathodes and thus, made the system more economical and sustainable alternative for wastewater treatment, nitrogen removal and energy generation.

吸附–过滤法预处理奶牛养殖废水的试验研究

分别用玉米秸秆滤料和玉米秸秆–沸石双层滤料对奶牛养殖废水进行吸附–过滤预处理，研究了玉米秸秆滤料和玉米秸秆–沸石双层滤料在不同滤速下对奶牛养殖废水中氨氮、磷及CODcr的去除效果。结果表明玉米秸秆–沸石双层滤料对氨氮、磷及CODcr的去除效果明显优于玉米秸秆滤料。以玉米秸秆–沸石双层滤料为过滤介质，滤速为4 m/h时，氨氮、磷及CODcr的去除率最大，分别为70.85%、46.11%和51.60%。 The adsorption-filtration pretreatment of dairy farming wastewater was carried out by using corn stalk filter and corn stalk-zeolite filter. The effects of corn stalk filter and corn stalk-zeolite filter on the removal of ammonia nitrogen, phosphorus and CODcr in dairy farming wastewater were studied under different filtration rates. The results showed that the removal efficiency of ammonia nitrogen, phosphorus and CODcr by corn stalk-zeolite filter was better than that of corn stalk. The removal rate of ammonia nitrogen, phosphorus and CODcr was the highest when the filtration rate was 4 m/h, which was 70.85%, 46.10% and 49.2%, respectively, with corn stalk-zeolite filter as filter medium.

Effect of Hydraulic Retention Time on Biological Nitrogen Removal in Land-based Fish Farm Wastewater

Effect of Hydraulic Retention Time on Biological Nitrogen Removal in Land-based Fish Farm Wastewater

Electrochemical Treatment of Recirculating Aquaculture Wastewater Using a Ti/RuO2-IrO2 Anode for Synergetic Total Ammonia Nitrogen and Nitrite Removal and Disinfection

Wastewater treatment and biosecurity are essential for intensive recirculating aquaculture system (RAS) production. In this study, the viability of the electrochemical process using a Ti/RuO2-IrO2 anode for synergetic total ammonia nitrogen (TAN) and nitrite removal and disinfection of semi-commercial RAS wastewater was evaluated. During the electrochemical oxidation process, the effects of the applied current density, sodium chloride concentration, and initial pH on the removal of TAN and nitrite were investigated. Experiment results indicated that under the conditions of 1.7 g L-1 sodium chloride concentration and 60 min electrolysis time, TAN removal efficiencies reached 78% at a current density of 60 mA cm-2, while nitrite removal efficiencies reached more than 95% at a current density of 30 mA cm-2. TAN removal due to an indirect oxidation mechanism followed second-order kinetics, while nitrite removal was described by pseudo-first-order kinetics in low-salt water (1.7 g L-1). The kinetics for electro-oxidation of TAN and nitrite affected by the current density were expressed as kTAN = 1.0 x 10-5 J-0.0002 and kNO2- = 1.9 x 10-3 J-0.0041, respectively. For disinfection, the active chlorine in situ generated by electrochemical treatment caused and inactivation. The results showed that the two objective pathogens can be sterilized rapidly, which indicated that no extra treatment for disinfection was needed. Finally, a comparison was made of the energy consumption in this study with those in the literature. This study showed that the Ti/RuO2-IrO2 anodic oxidation process has a potential for sustainable RAS wastewater treatment.

Improving municipal wastewater nitrogen and phosphorous removal by feeding sludge fermentation products to sequencing batch reactor (SBR)

This study presents a novel strategy to improve the removal efficiency of nitrogen and phosphorus from municipal wastewater by feeding sequencing batch reactor (SBR) with sludge alkaline fermentation products as carbon sources. The performances of two SBRs treating municipal wastewater (one was fed with sludge fermentation products; F-SBR, and the other without sludge fermentation products; B-SBR) were compared. The removal efficiencies of total nitrogen (TN) and phosphorus (PO43−-P) were found to be 82.9% and 96.0% in F-SBR, while the corresponding values in B-SBR were 55.9% (TN) and −6.1% (PO43−-P). Illumina MiSeq sequencing indicated that ammonium-oxidizing bacteria (Nitrosomonadaceae and Nitrosomonas) and denitrifying polyphosphate accumulating organisms (Dechloromonas) were enriched in F-SBR, which resulted in NO2−-N accumulation and denitrifying phosphorus removal via nitrite (DPRN). Moreover, feeding of sludge fermentation products reduced 862.1mg VSS/d of sludge in the F-SBR system (volume: 10L).