Effluent Ammonia Nitrogen Concentration Research Articles

Nitrogen removal performance and bacterial flora analysis of a partial nitrification-anaerobic ammonium oxidation-denitrification system treating rare earth element tailings wastewater

In this study, the start of partial nitrification (activated sludge)-anaerobic ammonia oxidation (immobilized fillers)-denitrification (immobilized fillers) and stable nitrogen removal in the treatment of rare earth element tailings wastewater were explored. The results showed that, at 25–30 °C, partial nitrification could be rapidly established by controlling the combination of average free ammonia concentration (25.4–60.2 mg/L) and dissolved oxygen concentration (0.5 mg/L). Adopting the stepwise substrate (three stages) and shortening hydraulic retention time (HRT) methods, the total nitrogen removal rate of anaerobic ammonia oxidation (anammox) immobilized fillers reached up to 0.99 kg N•(m3•d)−1. Adopting the C/N ratio of 4.5:1 and shorter HRT methods, the total nitrogen removal rate of denitrification immobilized fillers reached up to 1.07 kg N•(m3•d)−1. The activities of the anammox and denitrification immobilized fillers were increased by 8.39 and 4.46 times, respectively. At steady state operation, the average effluent ammonia nitrogen concentration was 3.01 mg/L, with an average effluent total nitrogen concentration of 5.11 mg/L, which met the requirements of the "Emission Standard for Pollutants from Rare Earth Industry" GB 26451–2011. High-throughput sequencing technology showed that the relative abundance ratios of Nitrosomonas and Nitrospira changed from 0.36:1–108.05:1. The dominant bacterial genera of the anammox immobilized fillers was Candidatus Kuenenia, and that of denitrification immobilized fillers were Pseudomonas and Thauera. This process provides a new technical approach for rare earth element tailings wastewater treatment, with high significance in engineering.

Removal of ammonia nitrogen from residual ammonium leaching solution by heterotrophic nitrification-aerobic denitrification process

ABSTRACT The aftermath of mining weathered crust elution-deposited rare earth ore produces a large amount of residual ammonium leaching solution, which causes ammonia and nitrogen pollution to the mine site. Recently, denitrification by heterotrophic nitrification-aerobic denitrification (HN-AD) bacteria has attracted much attention. However, limited studies exist regarding the denitrification process of HN-AD bacteria. In this study, we combined four strains of HN-AD bacteria, Pseudomonas fulva K3, Pseudomonas mosselii K17, Klebsiella oxytoca A12, and Enterobacter hormaechei A16, obtained from rare earth element leaching sites, to select the best microbial consortium for ammonia nitrogen removal. We designed an ammonia removal process applicable to HN-AD bacteria to directly remove ammonia nitrogen from acidic leaching solutions. The experimental results demonstrated that the most efficient microbial consortium for ammonia nitrogen removal to be K3 + K17 + A16, with a removal efficiency of 89.68% for 8 h. In this process, considering the influencing factors of the ammonia removal process, the larger the influent flow rate and influent ammonia nitrogen concentration, the greater the ammonia nitrogen accumulation and pH decrease in the reactor. In consecutive multi-batch experiments, the ammonia removal process was used to remove ammonia nitrogen, at concentrations of 100–600 mg/L, from the simulated leaching solution at pH 4–7, whereby the effluent ammonia nitrogen concentration was lower than 15 mg/L. The results demonstrate that the ammonia removal process is highly feasible and stable. These findings will provide new ideas for the application of HN-AD bacteria and new methods for the removal of ammonia nitrogen from acidic leaching solutions.

Process research of one‐stage partial nitrification‐anammox (S‐PN/A) technology in toilet water treatment and related kinetic simulation

AbstractBACKGROUNDToilet water is a typical wastewater that is abundant and has a low organic carbon‐to‐nitrogen ratio; therefore, it is necessary to explore an economical and efficient treatment option. Partial nitrification‐anammox (PN/A) technology is characterized by low aeration energy consumption and a high nitrogen removal rate. As a process technology that has emerged in recent years, PN/A technology involves operating conditions that require further study.RESULTSIn this work, two one‐stage partial nitrification‐anammox (S‐PN/A) reactors were operated to achieve nitrogen removal from toilet water. The total nitrogen removal rate of the two reactors reached 85%. The hydraulic nitrogen load of the first reactor was only 0.03 kg N m–3·d–1, while the hydraulic nitrogen load of the second reactor reached 0.09 kg N m–3·d–1. Nitrosomonas and Candidatus Kuenenia in the reactor were the main functional bacteria for partial nitrification and anammox. Kinetic simulations were performed using AQUASIM 2.0 software. The results showed that, in the partial nitrification system, the higher the (sludge retention time) SRT , the lower the effluent ammonia nitrogen concentration; the optimal operating condition's sludge retention time (SRT) was 10 days and dissolved oxygen (DO) was 0.2 mg L–1. The higher the SRT in the anammox system, the lower the concentration of ammonia and nitrite nitrogen in the effluent; in addition, the SRT should be greater than 60 days to ensure that as much nitrogen was removed as possible.CONCLUSIONIn summary, the research results confirm that it is feasible to use PN/A technology to remove nitrogen from toilet water. © 2021 Society of Chemical Industry (SCI).

Modeling and multi-objective optimization for ANAMMOX process under COD disturbance using hybrid intelligent algorithm.

Anaerobic ammonium oxidation (ANAMMOX) has been regarded as an efficient process to treat nitrogen-containing wastewater. However, the treatment process is not fully understood in terms of reaction mechanisms, process simulation, and control. In this paper, a multi-objective control strategy mixed soft-sensing model (MCSSM) is developed to systematically design the operating variations for multi-objective control by integrating the developed model, a least square support vector machine optimized with principal component analysis (PCA-LSSVM) and non-dominated sorting genetic algorithm-II (NSGA-II). The results revealed that the PCA-LSSVM model is a feasible and efficient tool for predicting the effluent ammonia nitrogen concentration ([Formula: see text]) and the total nitrogen removal concentration (CTN, rem) with determination coefficients (R2) were 0.997 for [Formula: see text] and 0.989 for CTN, rem, and gives us the reasonable solutions in influent by using NSGA-II. To achieve a better removal effect, the influent pH should be kept between 7.50 and 7.52, the COD/TN ratio is suggested to maintain at 0.15 and the NH4+-N/NO2--N ratio is suggested to maintain at 0.61. The developed MCSSM approach and its general modeling framework have a high potential of applicability and guidance to bioprocess in wastewater treatment, and numerical models can be structured for predicting and optimization and experiments can be conducted for data acquisition and model establishment.

Unraveling the Long-Term Effects of Cr(VI) on the Performance and Microbial Community of Nitrifying Activated Sludge System

The long-term effects of different influent Cr(VI) concentrations (0–0.5 mg L−1) on the nitrification activities and microbial community structures of nitrifying activated sludge system were investigated in this study. Results showed that the performance of ammonia oxidation was significantly inhibited, and the effluent concentration of ammonia nitrogen (NH4+-N) increased markedly when the influent Cr(VI) loading was equal or greater than 0.2 mg L−1. The specific oxygen utilization rate (SOUR), specific ammonium oxidation rate (SAOR), and specific nitrite oxidation rate (SNOR) of the system decreased from 53.24, 6.31, and 7.33 mg N g−1 VSS h−1 to 18.17, 1.68, and 2.88 mg N g−1 VSS h−1, respectively, with an increase of Cr(VI) concentration from 0 to 0.5 mg L−1. The protein/polysaccharide (PN/PS) ratio increased with the increasing Cr(VI) concentration, indicating that excessive PN secreted by microorganisms was conducive to resisting the toxicity of Cr(VI). High-throughput sequencing revealed that the relative abundance of ammonia-oxidizing bacteria (Nitrospira) and nitrite-oxidizing bacteria (Nitrosomonas and Nitrosospira) all decreased with the increasing Cr(VI) concentration, and ammonia-oxidizing bacteria were more sensitive to heavy metal toxicity than nitrite-oxidizing bacteria. The activities of nitrifying activated sludge system could not be completely recovered after a 30-d recovery process.

Biomass granulation in an upflow anaerobic sludge blanket reactor treating 500 m3/day low-strength sewage and post treatment in high-rate algal pond.

A pilot-scale upflow anaerobic sludge blanket-moving bed biofilm (UASB-MBB) reactor followed by a high-rate algal pond (HRAP) was designed and operated to remove organic matter, nutrients and pathogens from sewage and to facilitate reuse. For an influent chemical oxygen demand (COD) concentration of 233 ± 20 mg/L, final effluent COD was 50 ± 6 mg/L. Successful biomass granulation was observed in the sludge bed of the upflow anaerobic sludge blanket (UASB) reactor after 5 months of operation. Ammonia removal in HRAP was 85.1 ± 2.4% with average influent and effluent ammonia nitrogen concentrations of 20 ± 3 mg/L and 3 ± 1 mg/L, respectively. Phosphate removal after treatment in the HRAP was 91 ± 1%. There was a 2-3 log scale pathogen removal after treatment in HRAP with most probable number (MPN) of the final effluent being 600-800 per 100 mL, which is within acceptable standards for surface irrigation. The blackwater after treatment in UASB-MBBR-HRAP is being reused for gardening and landscaping. This proper hydro-dynamically designed UASB reactor demonstrated successful granulation and moving bed media improved sludge retention in UASB reactor. This combination of UASB-MBB reactor followed by HRAP demonstrated successful sewage treatment for a year covering all seasons.

Modeling Spatially Variant Processes in Plug-Flow-Like Activated Sludge Reactors

AbstractThe nonideal segregated flow (SF) model was adapted for modeling single-sludge carbonaceous biochemical oxygen demand (cBOD) reduction and nitrification within a plug-flow-like bioreactor. Principles associated with the CMFRs (complete-mix flow reactors) in series (also called continuous-flow stirred tank reactors, CFSTRs, in series, or simply tanks in series, TiS) and plug-flow with dispersion (PFD) models were combined with the SF model to develop a powerful modeling approach with the capability to predict reactant and product concentrations and process rates as a function of position along the reactor flow path. The single CMFR, plug-flow (PF), TiS, and SF models were then used to simulate the steady-state performance of a hypothetical activated sludge bioreactor to compare capabilities to predict spatial process variation. All simulations were forced to a common target effluent ammonia-nitrogen concentration, yielding unique sets of predicted performance parameters from each of the models. Pre...

Studies on the Performance of Biofilm-MBR

MBR technology for sewage treatment has the advantages of high volumetric load, good treatment performance and so on. But the MBR technology also has the shortage of membrane fouling. So this study selected the control method of fixing combination packing added in the MBR reactor, so as to reduce the membrane pollution, at the same time in the reactor to create the environment of coexistence of anaerobic and aerobic for biological denitrification. Through the research of the pollutants removal efficiency and the membrane pollution, it was founded that this method can remove 85-95% of COD and ammonia nitrogen. Effluent COD concentration generally is about 25mg/L, and the minimum of it is less than 10 mg/L. Effluent ammonia nitrogen is generally less than 10 mg/L. The minimum effluent concentration of ammonia nitrogen was less than 1 mg/L. The removal rate of total phosphorus was between 30-45%.

Impact of sorption functional media (SFM) from zeolite tailings on the removal of ammonia nitrogen in a biological aerated filter

Haydite and sorption functional media (SFM), made of clinoptilolite tailings, were used as filter media for biological aerated filter (BAF) to treat synthetic wastewater in parallel. The aim of this work was to evaluate impact of SFM on the removal of ammonia nitrogen in a biological aerated filter reactor under ammonium nitrogen shock loads. It could be demonstrated that: (1) the BAF with SFM presented higher ammonia nitrogen removal efficiency than that with haydite; (2) during the phase of higher influent concentrations SFMs were collecting ammonia nitrogen and can buffer ammonia nitrogen loads and dampen the effluent concentration of ammonia nitrogen; (3) when the influent concentration decreases ammonia nitrogen will desorb from the SFM and can be utilized by the nitrifying bacteria growing on the SFM. Therefore, with the SFM application existing BAF unites can be upgraded and the stability of the operation process of BAF can be improved significantly.

三相流動反応槽による養殖場排水の処理特性

The objectives of this research were to evaluate the optimum treatment conditions of the three phase fluidized bed with draft tube for the aquaculture wastewater treatment, and thereby reduce the volume of treatment process. Three phase fluidized bed process with draft tube had more effective than traditional methods for reducing ammonia in the culture system, which can results in the reduction of the water treatment tank volume. When Oreochromis niloticus was reared, the unit production of pollutants were 0.07g NH4+-N · kg fish-1 · d-1 and 0.06g PO43--P · kg fish-1 · d-1, and sludge production rate was 0.39g SS · kg fish-1 · d-1. The maximum removal rates of COD and ammonia were 1,200 mg · l-1 · d-1 and 488 mg · l-1 · d-1, respectively. Ammonia removal rates were more than 90% during HRT of 1hours. In the three phase fluidized bed, the volume of water treatment tank could be calculated from an empirical equation by using the relationship between the influent COD to NH4+-N ratio (C/N), media concentration (Cm, g · l-1), influent ammonia nitrogen concentration (N1, mg · l-1), effluent ammonia nitrogen concentration (Ne, mg · l-1), and influent flowrate (Q, m3 · hr-1). The empirical equation from was obtained from this study.V=1011.7507 C/N-1.2330 Cm-6.5715 Ni1.5091 Ne-1.8489 Q

Seasonal effectiveness of a constructed wetland for processing milkhouse wastewater

Constructed wetlands are gainign increased attention for treatment of nonpoint source pollution. Although constructed wetlands have been used for wastewater treatment in warm climates, their performance in cold climates has been questioned. A surface-flow wetland, designed to treat 2.65 m3d−1 of milkhouse wastewater, was constructed on the University of Connecticut’s Storrs campus in 1994. The purpose of the project was to determine the efficiency of the system to reduce nutrients, five-day biochemical oxygen demand (BOD5), bacteria, and total suspended solids and to reduce fecal coliform bacteria. During the first ten months of operation, outflow volume was 90% of inflow. Although the wetland was designed to process a BOD5 loading rate of 1500 mg/L, the average actual loading rate was 3000 mg/L. The overall percent mass retention of total suspended solids was 45% and for nutrients was 28%, 27%, 47%, and 6%, for total phosphorus, total Kjeldahl-N, nitrate-N, and ammonia-N, respectively. The percent reduction of fecal coliform and BOD5 was 31% and 28% respectively. Mass retention was significantly greater (p < 0.05) during the growing season than during plant senescence for total suspended solids, total phosphorus, total Kjeldahl, ammonia, and nitrate/nitrite nitrogen. Effluent ammonia nitrogen concentrations often exceeded influent values during the winter. Preliminary indications are that the treatment of the wastewater does not meet design standards, especially in the winter, probably due to overloading of BOD5.

The computation of the growth of a gaseous discharge in space-charge distored fields

Haydite and sorption functional media (SFM), made of clinoptilolite tailings, were used as filter media for biological aerated filter (BAF) to treat synthetic wastewater in parallel. The aim of this work was to evaluate impact of SFM on the removal of ammonia nitrogen in a biological aerated filter reactor under ammonium nitrogen shock loads. It could be demonstrated that: (1) the BAF with SFM presented higher ammonia nitrogen removal efficiency than that with haydite; (2) during the phase of higher influent concentrations SFMs were collecting ammonia nitrogen and can buffer ammonia nitrogen loads and dampen the effluent concentration of ammonia nitrogen; (3) when the influent concentration decreases ammonia nitrogen will desorb from the SFM and can be utilized by the nitrifying bacteria growing on the SFM. Therefore, with the SFM application existing BAF unites can be upgraded and the stability of the operation process of BAF can be improved significantly.