Wastewater Nitrogen Removal Research Articles

NaCS–PDMDAAC immobilized autotrophic cultivation of Chlorella sp. for wastewater nitrogen and phosphate removal

The unicellular green microalgae, Chlorella sp., entrapped in sodium cellulose sulphate/poly-dimethyl-diallyl-ammonium chloride (NaCS–PDMDAAC) to create microalgae capsules were used to remove total nitrogen (T-N) and phosphate (PO43−-P) from artificial wastewater. Batch and semi-continuous cultivations with capsules recycling were carried out in shake flasks within an illuminated incubator. Experimental results showed that the NaCS–PDMDAAC capsules have desirable biophysical properties such as good mechanical stability, biocompatibility with the microalgae cells resulting in biomass enrichment within the capsules, and high substrate concentration tolerance. NaCS–PDMDAAC Chlorella sp. capsules displayed a considerable high T-N and PO43−-P removal rate of 12.56 and 10.24mg/g biomass per day respectively. The developed immobilized microalgae system has the potential for continuous wastewater treatment operation with reduced downstream operation cost due to the large size of the capsules being 5–6mm.

Research on Influence Factors of Bamboo Charcoal Adsorb Ammonia Nitrogen in Wastewater

The influences of adsorption temperature, adsorption time, dosing quantity, adsorption environment pH value, initial concentration and bamboo charcoal type on adsorption of bamboo charcoal adsorb ammonia nitrogen in wastewater are studied. The result shows that the maximum adsorption values are 1.1715 mg/g and 0.9115 mg/g respectively at 25°C and 40°C. Bamboo charcoal can easily absorb ammonia nitrogen at low temperature condition. 180 min is a suitable adsorption time. Increasing bamboo charcoal dosing quantity is helpful to improve efficiencies of ammonia nitrogen removal in wastewater, but the adsorption capacity is declining as bamboo charcoal dosing quantity increasing. Solution pH value has a great impact on the adsorbed amount, the adsorbed effect in alkaline solution is much better than in acid one’s. The adsorption ability of the moderate temperature bamboo charcoal is higher than the high temperature one’s.

Research Progress on the Anammox Technology

With the continuing phenomenon of eutrophication, the pollution of nitrogen has caused wide concern. Lack of organic carbon sources is always considered to be a key problem for nitrogen removal efficiency and cost when conventional biological nitrogen removal process was used to the treatment of ammonium-rich wastewater, but the anaerobic ammonium oxidation（ANAMMOX）can solve this problem .Anammox has so many advantages that it has good prospects in the biological nitrogen removal in wastewater. Anammox bacteria grows slowly, has a long generation time, and is susceptible to the environmental conditions. DO, Temperature, pH and organic can impact the process of anammox, so it is necessary to take careful methods to cultivate Anammox biomass. Depending on the purpose of improve water quality, appropriate treatment reactors and seed sludge should be selected to start ANAMMON process. The discovery of anaerobic ammonia oxidation, the reaction mechanism, influence application, the enrichment of anammox bacteria, physiological and biochemical characteristics of anammox bacteria, the start of anaerobic ammonia oxidation are reviewed in this paper.

Long-Term Effects of Titanium Dioxide Nanoparticles on Nitrogen and Phosphorus Removal from Wastewater and Bacterial Community Shift in Activated Sludge

The expanding use of titanium dioxide nanoparticles (TiO(2) NPs) in a wide range of fields raises concerns about their potential environmental impacts. However, investigations of the potential effects of TiO(2) NPs on biological nitrogen and phosphorus removal and bacterial community in activated sludge are sparse. This study evaluated the influences of TiO(2) NPs on biological nutrient removal in the anaerobic-low dissolved oxygen (0.15-0.50 mg/L) sequencing batch reactor. It was found that 1 and 50 mg/L TiO(2) NPs had no acute effects on wastewater nitrogen and phosphorus removal after short-term exposure (1 day). However, 50 mg/L TiO(2) NPs (higher than its environmentally relevant concentration) was observed to significantly decrease total nitrogen (TN) removal efficiency from 80.3% to 24.4% after long-term exposure (70 days), whereas biological phosphorus removal was unaffected. Denaturing gradient gel electrophoresis profiles showed that 50 mg/L TiO(2) NPs obviously reduced the diversity of microbial community in activated sludge, and fluorescence in situ hybridization analysis indicated that the abundance of nitrifying bacteria, especially ammonia-oxidizing bacteria, was highly decreased after long-term exposure to 50 mg/L TiO(2) NPs, which was the main reason for the serious deterioration of ammonia oxidation. Further study revealed that 50 mg/L TiO(2) NPs inhibited the activities of ammonia monooxygenase and nitrite oxidoreductase after long-term exposure, but had no significant impacts on the activities of exopolyphosphatase and polyphosphate kinase, and the transformations of intracellular polyhydroxyalkanoates and glycogen, which were consistent with the observed influences of TiO(2) NPs on biological nitrogen and phosphorus removal.

Research of Treating High Ammonia-N Wastewater by CASS Process

High ammonia-N wastewater is leading to serious environment consequence. Adopting CASS process (Cyclic Activated Sludge System) to treat high ammonia-N wastewater is a good select, which is proved to be a flexible, convenient and efficient treatment. Kinds of factors which effected the nitrogen removal of high ammonia-N wastewater were studied and the optimum working condition of treating high ammonia-N wastewater by CASS process was discussed.

Effects of ZnO Nanoparticles on Wastewater Biological Nitrogen and Phosphorus Removal

With the increasing utilization of nanomaterials, zinc oxide nanoparticles (ZnO NPs) have been reported to induce adverse effects on human health and aquatic organisms. However, the potential impacts of ZnO NPs on wastewater nitrogen and phosphorus removal with an activated sludge process are unknown. In this paper, short-term exposure experiments were conducted to determine whether ZnO NPs caused adverse impacts on biological nitrogen and phosphorus removal in the unacclimated anaerobic-low dissolved oxygen sequencing batch reactor. Compared with the absence of ZnO NPs, the presence of 10 and 50 mg/L of ZnO NPs decreased total nitrogen removal efficiencies from 81.5% to 75.6% and 70.8%, respectively. The corresponding effluent phosphorus concentrations increased from nondetectable to 10.3 and 16.5 mg/L, respectively, which were higher than the influent phosphorus (9.8 mg/L), suggesting that higher concentration of ZnO NPs induced the loss of normal phosphorus removal. It was found that the inhibition of nitrogen and phosphorus removal induced by higher concentrations of ZnO NPs was due to the release of zinc ions from ZnO NPs dissolution and increase of reactive oxygen species (ROS) production, which caused inhibitory effect on polyphosphate-accumulating organisms and decreased nitrate reductase, exopolyphosphatase, and polyphosphate kinase activities.

Kinetics of Ammonium, Nitrate and Phosphate Uptake by Candidate Plants Used in Constructed Wetlands

Abstract The constructed/artificial wetland system is a new sewage technique with low cost and less energy consumption for removal of nitrogen and phosphorus in wastewater, and the wetland plants have the important functions in the system. In wastewater purification, plants can absorb and utilize the nutrients (nitrogen and phosphorus) directly, and enhance nutrient transformation processes such as nitrification, denitrification, adsorption and desorption. In this study, a series of experiments for investigating the kinetics of ammonium, nitrate and phosphate uptake by 8 candidate wetland plants, such as Carex taliensis Franch, Dracaena sanderiana Virens, Impatiens balsamina, rush (Juncus effusus L.), mulberry (Morus indica L.), wetland rice (Oriza Sativa L.), Salvia plebeia R. Br., and Sesbania cannabina Poir, were carried out under controlled conditions (temperature 25-28, illumination 3000Lux, relative°C humidity 60-70%). The results indicated that the kinetic characteristics of ammonium, nitrate and phosphate uptake by the selected plants could be well illustrated with the Michaelis-Menten equation, and the kinetic parameters (maximum rate and Km value of absorption) could also be calculated using the regression equations. The orders of maximum uptake rate were as follows: Morus indica L. > Carex taliensis Franch > Oriza Sativa L. > Impatiens balsamina > Juncus effusus L. > Sesbania cannabina Poir > Salvia plebeia R. Br. > Dracaena sanderiana for ammonium; Carex taliensis Franch > Oriza Sativa L. > Sesbania cannabina Poir > Juncus effusus L. > Impatiens balsamina > Morus indica L. > Salvia plebeia R. Br. > Dracaena sanderiana for nitrate; Oriza Sativa L. > Juncus effusus L. > Salvia plebeia R. Br. > Dracaena sanderiana > Impatiens balsamina > Morus indica L. Sesbania cannabina Poir > Carex taliensis Franch for phosphate. Sesbania cannabina Poir., Dracaena sanderiana Virens and Salvia plebeia R. Br. had the smallest Km value for ammonium uptake, and Impatiens balsamina, Dracaena sanderiana Virens and Salvia plebeia R. Br. had the smallest Km value for nitrate uptake, Sesbania cannabina Poir., mulberry and Dracaena sanderiana Virens had the smallest Km value for phosphate uptake. According to the kinetic characteristics of N and P uptake, we suggested that plant species with higher maximum uptake rates could be used in the first section for cleaning up wastewater with high nutrient concentrations, and plant species with lower Km values could be used in subsequent sections for cleaning up wastewater with lower nutrient concentrations.

Analysis of Organic Nitrogen Removal in Municipal Wastewater by Reverse Osmosis

Analysis of Organic Nitrogen Removal in Municipal Wastewater by Reverse Osmosis

Performance of Nitrogen and Phosphorus Removal of Municipal Wastewater in Sequencing Batch Biofilm Reactor

Performance of Nitrogen and Phosphorus Removal of Municipal Wastewater in Sequencing Batch Biofilm Reactor

Analysis of Organic Nitrogen Removal in Municipal Wastewater by Reverse Osmosis

The results of a pilot study that was conducted to determine the total nitrogen removal by the reverse osmosis process are presented. The organic nitrogen removal rates are compared with removals observed from three full-scale reverse osmosis facilities and four pilot studies. The results of this analysis suggest that organic nitrogen removal is variable and that reverse osmosis may not consistently produce total nitrogen levels less than 1.0 mg/L without additional treatment. Three hypotheses to explain the variability in organic nitrogen removal in the different data sets are presented.

Nitrifying bacterial growth inhibition in the presence of algae and cyanobacteria

Nitrifying bacteria, cyanobacteria, and algae are important microorganisms in open pond wastewater treatment systems. Nitrification involving the sequential oxidation of ammonia to nitrite and nitrate, mainly due to autotrophic nitrifying bacteria, is essential to biological nitrogen removal in wastewater and global nitrogen cycling. A continuous flow autotrophic bioreactor was initially designed for nitrifying bacterial growth only. In the presence of cyanobacteria and algae, we monitored both the microbial activity by measuring specific oxygen production rate (SOPR) for microalgae and cyanobacteria and specific oxygen uptake rate (SOUR) for nitrifying bacteria. The growth of cyanobacteria and algae inhibited the maximum nitrification rate by a factor of 4 although the ammonium nitrogen fed to the reactor was almost completely removed. Terminal restriction fragment length polymorphism (T-RFLP) analysis indicated that the community structures of nitrifying bacteria remained unchanged, containing the dominant Nitrosospira, Nitrospira, and Nitrobacter species. PCR amplification coupled with cloning and sequencing analysis resulted in identifying Chlorella emersonii and an uncultured cyanobacterium as the dominant species in the autotrophic bioreactor. Notwithstanding their fast growth rate and their toxicity to nitrifiers, microalgae and cyanobacteria were more easily lost in effluent than nitrifying bacteria because of their poor settling characteristics. The microorganisms were able to grow together in the bioreactor with constant individual biomass fractions because of the uncoupled solids retention times for algae/cyanobacteria and nitrifiers. The results indicate that compared to conventional wastewater treatment systems, longer solids retention times (e.g., by a factor of 4) should be considered in phototrophic bioreactors for complete nitrification and nitrogen removal.

Monitoring the removal of nitrogen by applying a nitrification–denitrification process in a Sequencing Batch Reactor (SBR)

In this study the evaluation of nitrogen removal in wastewater from a meat products processing company was performed, using a Sequencing Batch Reactor (SBR) at pilot scale. The phases of the SBR operation were: filling, reaction (aeration and intermittent anoxia), sedimentation and discharge. In each of these phases analyses of ammonium (NH(4)(+)), nitrite (NO(2)(-)), nitrate (NO(3)(-)), pH and dissolved oxygen (DO) were carried out to monitor the process of nitrification-denitrification. The results showed that stage IV had the best performance (2.49 g COD(F)/Ld and 1.02 g NH(4)(+)-N/Ld) with a NH(4)(+)-N removal of 71%. The transformation of much of the NH(4)(+)-N to gaseous nitrogen was confirmed, with the concentration of NO(2)(-)-N and NO(3)(-)-N increasing during the reaction phase but decreasing in the effluent due to its transformation to gaseous nitrogen.

Full-scale experiences of nitrogen removal of fish-processing wastewater with flotation and anoxic-aerobic activated sludge system

This article presents full scale experience of one of the largest fish-processing factories in Europe with a production capacity of about 50,000 tons herring per year and a maximum daily wastewater discharge of 1,500 m(3). The wastewater treatment plant is the only direct discharger in the fish-processing industry in Germany. Thus, very low effluent values have to be keep in, especially the nitrogen reduction has to be operated during the whole year even when the temperature is low. The central point of the multi-stage WWTP (about 90,000 PE) is the biological nutrient removal (BNR) with pre-denitrification. The wastewater pre-treatment with sieves (0.8 mm) and a two staged flotation reduces the nitrogen load - mainly the particle bounded fraction - but the optimal nutrient ratios for biological treatment need to be observed. The activated sludge system has maximum OLR of 0.12 g COD/(g MLSS d) and NLR of 0.015 g TN/(g MLSS d) but a "Stand-By"-Operation with periods without wastewater influent is unavoidable. Discontinuous operating is one problem. The dependence on temperature as one of the main influences of nitrification-activity is the second point. The article gives an overview about the start-up and the optimisation of the process.

Microbiological Mechanism of Nitrogen Loss in Aerobic or Oxygen-limited Wastewater Treatment System*

In recent years,the phenomenon of total nitrogen loss which is found in single aerobic or oxygen-limited wastewater treatment systems has attracted researchers’concern.Microbiological theory and related studies of nitrogen loss were reviewed in this paper.It involves the different groups of bacteria alone or in cooperation,including nitrogen removal by autotrophic nitrifying bacteria and aerobic denitrifying bacteria,the inter-synthesis between nitrifying bacteria and aerobic denitrifying bacteria;and the cooperation of nitrifying bacteria and anaerobic ammonia oxidation(Anammox)bacteria.The new biological nitrogen removal mechanisms,which have incomparable advantages to the traditional nitrification-denitrification nitrogen removal technique,have important significance to enhance nitrogen removal in wastewater treatment.Fig 8,Ref 53

Removal of nitrogen in wastewater by polyvinyl alcohol (PVA)-immobilization of effective microorganisms

To remove nitrogen and carbon simultaneously from municipal wastewater, a mixture of effective microor- ganisms (EM) was immobilized in polyvinyl alcohol (PVA) hydrogel beads. The modified PVA beads with calcium alginate show characteristic pores and mechanical stability and flexibility. The EM-immobilized PVA system was estab- lished in a 3 L sequential batch reactor (SBR) with a synthetic wastewater and operated at an HRT of 12 h with COD loading rate of 0.5-2.4 g COD/L·d. In this system, intermittent aeration is more efficient than continuous aeration, and removal rates of COD and total nitrogen (T-N) were increased as the feed COD/N ratio was increased from 1.9 to 5.6. At an optimal condition, 73% of total nitrogen and 93% of COD were stably removed at a COD loading rate lower than 2.4 g COD/L·d and at 3 : 1 ratio of aerobic time to anoxic time.

Ammoniacal nitrogen removal in wastewater using nitrifying and denitrifying bacteria in a SBR system

Ammoniacal nitrogen removal in wastewater using nitrifying and denitrifying bacteria in a SBR system

Rural wastewater irrigation and nitrogen removal by the paddy wetland system in the Tai Lake region of China

Rural wastewater irrigation and nitrogen removal by the paddy wetland system in the Tai Lake region of China

Impact of COD/N ratio on nitrous oxide emission from microcosm wetlands and their performance in removing nitrogen from wastewater

Constructed wetlands (CWs) are considered to be important sources of nitrous oxide (N 2O). In order to investigate the effect of influent COD/N ratio on N 2O emission and control excess emission from nitrogen removal, free water surface microcosm wetlands were used and fed with different influent. In addition, the transformation of nitrogen was examined for better understanding of the mechanism of N 2O production under different operating COD/N ratios. It was found that N 2O emission and the performance of microcosm wetlands were significantly affected by COD/N ratio of wastewater influent. Strong relationships exist between N 2O production rate and nitrite ( r = 0.421, p < 0.01). During denitrification process, DO concentration crucially influences N 2O production rate. An optimal influent COD/N ratio was obtained by adjusting external carbon sources for most effective N 2O emission control and best performance of the CWs in nitrogen removal from wastewater. It is concluded that under the operating condition of COD/N ratio = 5, total N 2O emission is minimum and the microcosm wetland is most effective in wastewater nitrogen removal.

Removal of ammonia nitrogen in wastewater by microwave radiation: A pilot-scale study

A large removal of ammonia nitrogen in wastewater has been achieved by microwave (MW) radiation in our previous bench-scale study. This study developed a continuous pilot-scale MW system to remove ammonia nitrogen in real wastewater. A typical high concentration of ammonia nitrogen contaminated wastewater, the coke-plant wastewater from a Coke company, was treated. The output power of the microwave reactor was 4.8 kW and the handling capacity of the reactor was about 5 m 3 per day. The ammonia removal efficiencies under four operating conditions, including ambient temperature, wastewater flow rate, aeration conditions and initial concentration were evaluated in the pilot-scale experiments. The ammonia removal could reach about 80% for the real coke-plant wastewater with ammonia nitrogen concentrations of 2400–11000 mg/L. The running cost of the MW technique was a little lower than the conventional steam-stripping method. The continuous microwave system showed the potential as an effective method for ammonia nitrogen removal in coke-plant water treatment. It is proposed that this process is suitable for the treatment of toxic wastewater containing high concentrations of ammonia nitrogen.

Biological Nitrogen and COD Removal of Nutrient-Rich Wastewater Using Aerobic and Anaerobic Reactors

A preliminary study on nitrogen and organic removal efficiency of a lab-scale system using aerobic and an-aerobic reactors was performed. A simulated wastewater containing elevated levels of nitrogen was used. This paper aims to compare the efficiency of aerobic and anaerobic reactors in achieving nitrogen and chemical oxygen demand (COD) removal of nutrient-rich wastewater. It also presents the start-up experi-mentation conducted on simulated wastewater using two different reactors configured as aerobic and anaero-bic. Start-up experiments were carried out using a 5-liter acrylic aerobic reactor and a 4-liter flask anaerobic reactor containing activated sludge taken from De La Salle University (DLSU) wastewater treatment plant as a source of inoculum. Simulated wastewater was continuously fed to the two reactors and the time course of biomass growth was monitored by measuring the biomass concentration represented by mixed liquor volatile solids (MLVS). The time course of organic pollutant reduction by measuring the chemical oxygen demand (COD) was conducted until steady state condition was reached. On the other hand, COD and nitrogen tests such as Ammonia nitrogen (NH3-N), Nitrite nitrogen (NO2--N), Nitrate nitrogen (NO3--N) were also per-formed using 5 batch aerobic reactors containing different concentrations of wastewater and a single batch anaerobic reactor to see the effect of different feed concentrations in the removal of nitrogen. Preliminary results showed that 98% reduction in COD was obtained in aerobic reactor, as supported by increasing con-centration of MLVS, with a hydraulic retention time (HRT) of 5 hours after 11 days while 34% reduction in COD was obtained in anaerobic reactor with the same HRT after 14 days.