Heterotrophic Nitrification Bacterium Research Articles

Performance of rice husk biocarrier on ammonia nitrogen removal in the MBBR treating aquaculture wastewater using biological attached growth process: Performance and kinetic study

This study investigates the feasibility of using rice husk (RH) as a cost-effective and environmentally friendly bio-carrier for immobilizing isolated microorganisms to treat synthetic recirculating aquaculture system (RAS) ‎wastewater. Two moving bed biofilm reactors (MBBR) inoculated with indigenous microorganisms were operated simultaneously for 391 days under various ‎cycle times and compared. The RH and Kaldnes-3 (K3) bio-carriers were placed in reactors R1 and R2, respectively.‎ The results indicated that at constant influent TAN, with increases in cycle ‎time from 6 to 24 h, TAN and COD ‎removal ‎efficiencies ‎increased in both bioreactors; but at an optimum cycle time of 6 h, the TAN and COD removal efficiencies were‎ ‎82 ± 1.5% ‎ ‎and‎ 77.9 ± 1.7%‎‎ for the R1 and, 89.9 ± 3.3%‎ ‎and ‎84 ± 1.2% ‎for the R2, respectively. Also, at a constant cycle time, ‎the performance of R2 was better ‎compared to R1 filled with RH. Microbial identification confirmed the presence of four dominant genera, including Arthrobacter, Bacillus, ‎Rhodococcus, and ‎Staphylococcus, which were heterotrophic nitrification bacteria (HNB). The TAN removal kinetics were investigated using a Modified Stover-Kincannon (MSK) model. In reactors R1 and R2, the biokinetic constants were determined to be Umax: 0.116 and 0.149 g/Lday, and KB: 0.158 and 0.182 g/Lday, respectively. The correlation coefficients (R2) of the MBBRs were higher than 0.97, indicating that the model adequately described the experimental data.

Enhanced treatment of low C/N ratio rural sewage by a modified multi-stage tidal flow constructed wetland at low temperature: Quantitative contributions of key functional genera

Rural sewage treatment was traditionally faced contradiction between low-treatment rates and the need for low-cost development. To address this challenge, we explored the coupling of effluent circulation and step-feeding strategies in a multi-stage tidal flow constructed wetland (TFCW) to achieve stable nitrogen (N) removal performance under conditions of low carbon-to-nitrogen (C/N) ratios and low temperatures. The modified multi-stage TFCW demonstrated the ability to significantly reduce the concentrations of effluent NH4+-N and NO3−-N by 33.9 % and 54.8 % respectively, resulting in values of 7.47 mg/L and 3.93 mg/L. Additionally, it achieved an average TN removal efficiency of 69.2 %. The improved N removal performance of rural sewage by the modified multi-stage TFCW at low temperatures was primarily attributed to autotrophic nitrification, heterotrophic nitrification, and autotrophic denitrification. Among the identified functional genera, Nitrosomonas and Nitrosospira played key roles as autotrophic nitrification bacteria (ANB), contributing to 28.2 % of NH4+-N removal. The key heterotrophic nitrification bacteria (HNB) Acidovorax and Rudaea were mainly responsible for 71.3 % of NH4+-N removal via the two-step ammonia assimilation through the organic nitrogen pathway. Furthermore, Rhodanobacter and Acinetobacter emerged as key autotrophic denitrification bacteria (ADNB), accounting for 79.9 % of NO3−-N conversion and removal. In summary, this study provides valuable theoretical insights and supports ongoing efforts in biological regulation to address the challenges associated with rural sewage treatment.

Comparison of Swine Wastewater Treatment by Microalgae and Heterotrophic Nitrifiers: Focusing on Nitrogen Removal Mechanism Revealed by Microbiological Correlation Analysis

Swine wastewater (SW) poses a great threat to the environment due to its high-nutrient profiles if not properly managed. Advanced biological treatment method is an efficient method to treat SW by screening potent microalgae or bacterial strains. In this study, activated sludge, three locally isolated heterotrophic nitrification bacteria and one microalgal strain (Chlorella) were used as inoculums in treating a local SW. Their treatment efficiencies were compared, while the nitrogen removal mechanisms and microbiome profile were explored in detail. It was found that certain heterotrophic nitrification strains had a slight advantage in removing chemical oxygen demand and phosphorus from SW, with the highest removal efficiencies of 83.9% and 76.2%, respectively. The removal efficiencies of ammonia nitrogen and total nitrogen in wastewater by microalgae reached 80.9% and 66.0% respectively, which were far higher than all the heterotrophic nitrification strains. Biological assimilation was the main pathway of nitrogen conversion by microalgae and heterotrophic nitrifying bacteria; especially microalgae showed excellent biological assimilation performance. Correlation analysis showed that Comamonas was highly positively correlated with nitrogen assimilation, while Acidovorax was closely correlated with simultaneous nitrification and denitrification. This study gives a comparison of microalgae and heterotrophic nitrifying bacteria on the nitrogen transfer and transformation pathways.

Changes in BNR Microbial Community in Response to Different Selection Pressure

This study investigated structural changes in microbial community of biological nutrient removal (BNR) in response to changes in substrate composition (ammonium and phosphate), redox condition, and morphological characteristics (flocs to granules), with a focus on nitrification and phosphate removal. Analyzing treatment performance and 16S rRNA phylogenetic gene sequencing data suggested that heterotrophic nitrification (HN) and autotrophic nitrification (AN) potentially happened in aerobic organic-rich (HN_AS) and aerobic organic-deficient (AN_AS) activated sludge batch reactors, respectively. However, phosphate release and uptake were not observed under alternating anaerobic/aerobic regime. Phosphate release could not be induced even when anaerobic phase was extended, although Accumulibacter existed in the inoculum (5.1% of total bacteria). Some potential HN (e.g., Thauera, Acinetobacter, Flavobacterium), AN (e.g., Nitrosomonas (3.2%) and Nitrospira), and unconventional phosphate-accumulating organisms (PAOs) were identified. Putative HN bacteria (i.e., Thauera (29–36%) and Flavobacterium (18–25%)) were enriched in aerobic granular sludge (AGS) regardless of the granular reactor operation mode. Enrichment of HN organisms in the AGS was suspected to be mainly due to granulation, possibly due to the floc-forming ability of HN species. Thus, HN is likely to play a role in nitrogen removal in AGS reactors. This study is supposed to serve as a starting point for the investigation of the microbial communities of AS- and AGS-based BNR processes. It is recommended that the identified roles for the isolated bacteria are further investigated in future works.

Efficient hydroxylamine removal through heterotrophic nitrification by novel bacterium Glutamicibacter arilaitensis EM-H8

Hydroxylamine, an intermediate product in the nitrification process, is widely found in nature. However, hydroxylamine accumulation can decrease the biological nitrogen removal efficiency by reducing the activities, inhibiting the reproductions, and even causing the death of microorganisms. In this study, a novel heterotrophic nitrification bacterium was separated from biogas digester and identified as Glutamicibacter arilaitensis EM-H8. Strain EM-H8 exhibited efficient hydroxylamine removal (93.75%). The optimal conditions for hydroxylamine removal were as follows: Carbon source, glucose; C/N ratio, 25; temperature, 20 °C; inoculum size, 0.53 × 108 CFU; and shaking speed, 150 rpm. The nitrogen balance results using strain EM-H8 showed that about 26.86% of the initial nitrogen was removed as nitrogenous gas, while 4.6% was converted into biomass under aerobic conditions, confirming that strain EM-H8 possessed the capacity for heterotrophic nitrification. Furthermore, the successful expression of hydroxylamine oxidase (0.065 U/mg protein) showed that strain EM-H8 had the ability to transform hydroxylamine from wastewater.

Characterization of a new heterotrophic nitrification bacterium Pseudomonas sp. strain JQ170 and functional identification of nap gene in nitrite production

Heterotrophic nitrification bacteria play a critical role in nitrogen cycling and pollution removal. However, the underlying nitrification mechanisms are diverse and have rarely been investigated at the genetic level. In this study, the new heterotrophic nitrifier Pseudomonas sp. strain JQ170 was isolated. Strain JQ170 can utilize ammonia (NH4+-N), nitrite (NO2−-N), or nitrate (NO3−-N) as sole nitrogen sources, preferring NH4+-N. A ratio of 96.4% of 1.0 mM NH4+-N was removed in 24 h. The optimum pH, temperature, and carbon source for NH4+-N removal were pH 7.0, 30 °C, and citrate, at a C/N ratio of 9–18, respectively. During the NH4+-N removal process, only NO2−-N but neither hydroxylamine, NO3−-N, nor gaseous nitrogen were detected. A random transposon insertion mutagenesis library of strain JQ170 was constructed. Two NO2−-N-production deficient mutants were screened and transposon insertion sites were located in nap genes (which encode periplasmic NO3−-N reductase Nap). Further gene knockout and complementation of the napA gene confirmed nap as essential for NO2−-N production. The following nitrification processes in strain JQ170 is proposed: NH4+-N to NO3−-N in the cytoplasm; then NO3−-N to NO2−-N in the periplasmic space by Nap; finally, NO2−-N secreted out of cells. Overall, this paper provides new insight towards understanding heterotrophic nitrification at the genetic level.

Performance of single-stage partial nitritation and anammox reactor treating low-phenol/ammonia ratio wastewater and analysis of microbial community structure.

Phenol and ammonia are common pollutants in many industrial wastewaters. The partial nitritation and anammox process is a very promisingtechnology for treating phenol-ammonia wastewater. This study was the first time to rapidly achieve the start-up and operation of the single-stage partial nitritation /anammox reactor treating phenol-ammonia wastewater. The optimized ratio of phenol and nitrogen (phenol/NH4 + -N=0.3) was set to start-up the reactor. After 60days of operation, the total nitrogen and COD removal efficiencies were around 73.0% and 79.5%, respectively. The activity of ammonium-oxidizing bacteria was291.1±3.0mg NH4 + -Ng-1 MLVSSd-1 and the specific anammox activity was 20.9±1.0mg NH4 + -Ng-1 MLVSSd-1 . The results indicated that the anammox bacteria had adapted to phenol condition and remained stable activity after the 60days' operation in the reactor. The sequence analysis of 16SrRNA showed that the microbial community structure evolved to a balanced distribution that the removals of phenol and ammonia could be achieved simultaneously. PRACTITIONER POINTS: Phenol/N ratio of 0.3 was set to start up the single-stage partial nitritation/anammox reactor. The single-stage partial nitritation /anammox reactor was rapidly started up when treating the phenol-ammonia wastewater. Total nitrogen removal rate and COD removal efficiencies could achieve to 73.0% and 79.5%, respectively. Microbial community structure evolved to stable distribution of which AOB, anammox bacteria, denitrification bacteria and heterotrophic nitrification bacteria coexisted.

Isolation and characterization of heterotrophic nitrifying bacteria and the removal of pollutants in black and malodorous water bodies

Aiming at the problem of high concentration of COD and NH3-N in black and odorous water bodies, heterotrophic nitrifying bacteria which can remove ammonia nitrogen and organic pollutants were screened out in the laboratory simultaneously. A heterotrophic nitrifying functional group was constructed by using the strategy of bacterial source reorganization ecologically, and the removal effect of heterotrophic nitrifying functional bacteria on organic pollutants and ammonia nitrogen in water was studied. The results showed that the removal rate of ammonia nitrogen in the water was more than 52%, and the removal rate of COD was 57%∼86%. The effect of heterotrophic nitrifying functional bacteria group 1 on the removal of COD and ammonia in water was better, and the removal rate was 76.5% and 54.8%, respectively. The optimum inoculation test showed that the optimum inoculation amount of the heterotrophic nitrification bacteria group 1 was 10 ppm.

Carbon and nitrogen metabolic pathways and interaction of cold-resistant heterotrophic nitrifying bacteria under aerobic and anaerobic conditions

In this study, both the carbon and nitrogen metabolisms of two heterotrophic nitrification bacteria were investigated under aerobic and anaerobic conditions at 2 °C. Similar catabolism and anabolism trends were observed for the two bacteria in stable experimental systems under aerobic and anaerobic conditions. Based on the nitrogen and carbon balance analysis and adenosine triphosphate (ATP) calculation, we proposed the following metabolic pathways: i) aerobic: except for microbial assimilation, the carbon and nitrogen sources were removed through respiration and nitrification, which provided energy for cell synthesis; and ii) anaerobic: the nitrification process almost stopped and most of the carbon sources decomposed into inorganic carbon, which dissolved in the medium. Based on our proposed metabolic pathways, we speculated that the nitrifying process almost stopped under anaerobic conditions and the nitrification bacteria would degrade more carbon contaminants to produce energy and maintain the cell growth. Furthermore, these bacteria may decompose the non-readily biodegradable carbon through anaerobic degradation. To verify these hypotheses, experiments with two types of synthetic wastewater were conducted: i) synthetic wastewater rich in carbon and poor in nitrogen, and higher carbon removal efficiencies of strain J and strain P (∼25%) were obtained under anaerobic conditions compared with aerobic conditions (∼19%); and ii) synthetic wastewater with recalcitrant carbon sources, and carbon removal efficiencies under anaerobic conditions were higher than those under aerobic conditions. The results of the synthetic wastewater experiments were consistent with the hypotheses and thus validated the metabolic pathways proposed for carbon and nitrogen.

Isolation and denitrification characteristics of a psychrotrophic and heterotrophic nitrification bacterium

利用异养硝化培养基，冬季从南四湖人工湿地底泥中分离筛选到一株具有较高脱氮性能的菌株Z01.经形态特征、生理生化特性以及16S rDNA序列分析，初步鉴定该菌株为假单胞菌属（Pseudomonas sp.），命名为Pseudomonas sp.Z01.实验探究得到菌株Z01的最佳初始投菌量为7%，最适温度、pH和盐度分别为15℃、6.0~8.0和0.3%，最佳碳源为葡萄糖.在最适生长条件下，通过氨氮去除试验发现该菌株对模拟污水中氨氮的去除率有一定提高，是异养硝化培养基中氨氮去除效率的1.1倍.此外，该菌株对模拟废水中总氮和COD也具有较好的去除效果.研究表明，菌株Z01在冬季污水处理中硝化脱氮具有良好的应用前景和很大的发展空间.;A heterotrophic nitrifying bacteria strain Z01 was isolated from the sediment of Lake Nansi constructed wetland in winter, and it was studied for its capacity of nitrification and nitrogen removal. Methods of morphological, physiological and biochemical were used to identify strain Z01 as well as 16S rDNA analysis. It is affiliated to be Pseudomonas sp., which named Pseudomonas sp. Z01. These data showed that the optimum dosage, temperature, pH and salinity of microbial strains Z01 were 7%, 15℃, 6.0-8.0 and 0.3%, as sucrose as optimum carbon. Under the optimum removal efficiency of ammonia nitrogen from simulated wastewater by strain 10 was 1.1 times higher than that of heterotrophic nitrification medium. Moreover, it was better on the removal performance of the total nitrogen and COD in the simulated wastewater. Therefore, strain Z01 has a good application prospect and great development space in nitrification denitrification of sewage treatment in winter.

Isolation and Nitrogen Removal Characteristics of an Aerobic Heterotrophic Nitrifying-Denitrifying Bacterium, Klebsiella sp. TN-10.

Nitrogen removal by microorganisms has attracted increasing attention in wastewater treatment. In the present study, a heterotrophic nitrification bacterium was isolated from tannery wastewater and identified as Klebsiella sp. TN-10 based on phenotypic and phylogenetic characteristics. The optimal conditions for cell growth and nitrogen removal were investigated, and the results showed that the greatest ammonium removal rate and maximum biomass were achieved by using sodium pyruvate (7g/L) as carbon source, C/N 12, pH7, and temperature 30°C. Under optimal conditions, the removal rate of ammonia nitrogen reached 96%. Besides, the growth characteristic and the ability of utilizing nitrate and nitrite were investigated. The results demonstrated that strain TN-10 exhibited excellent characteristics to remove both nitrate and nitrite, with the removal rate of 95.44% and 99.87%, respectively. In addition, the nitrite reductase (NiR) and nitrate reductase (NR) involved in denitrification were both active, with the activities of 0.0815 and 0.0283U/mg proteins, respectively. Furthermore, the aggregation ability, auto-aggregation kinetics, and the relationship between zeta potentials and flocculating efficiency were determined. These results indicated that the strain Klebsiella sp. TN-10, with efficient heterotrophic nitrification-aerobic denitrification ability, has potential application in wastewater treatment.

The nitrogen removal of autotrophic and heterotrophic bacteria in aerobic granular reactors with different feast/famine ratio

Aerobic granular sludge was cultivated in three column reactors, which had been operated for 120 days under different feast/famine ratio (1:7, 1:11, 1:15). The composition of total bacteria was analyzed by testing oxygen uptake rates of mixed liquor samples taken from the reactors and calculating according to activated sludge model. The results revealed that long famine phase favored the growth of heterotrophic bacteria. The heterotrophic bacteria accounts for 49.80, 53.37, 91.39% of total bacteria respectively in R1, R2 and R3. The heterotrophic nitrification was also observed in all the reactors, which accounts for 58.62, 58.33, 61.54% of total nitrification respectively in R1, R2 and R3. A novel nitrogen-removal pathway involving simultaneous nitrification-denitrification by heterotrophic nitrification bacteria was proposed. The results revealed that microbial system consisted of heterotrophic ammonia oxidizing bacteria showed stronger capacity of simultaneous nitrification-denitrification.

Consortium of heterotrophic nitrification bacteria Bacillus sp. and its application on urea fertilizer industrial wastewater treatment

Aims: Industrial wastewater can be processed by physical, chemical and biological treatment. Most biological treatment have no negative impact on environment and can minimize more cost. The aim of this study was to reduce ammonia in urea fertilizer industrial wastewater by Bacillus bacterial consortium. This strategy tried to develop biological processing of ammonia in wastewater with nitrification process. Methodology and results: Bacterial consortium consisted of three isolates: isolate W1.6 identified as Bacillus sp. A16ZZ, isolate W2.5 identified as Bacillus sp. BNPK-13, and isolate S2.6 identified as B. cereus strain CP1. Consortium culture was made based on shortest generation time on each isolate in order to be in exponential phase when it was used. Bacterial consortium was able to decrease ammonia concentration in wastewater seven days after incubation. Conclusion, significance and impact of study: Consortium of heterotrophic nitrification works optimally with concentration of 350 mg/L ammonia and decrease 96.28%. This consortium has potency to be developed as alternative biological agent in reducing ammonia compounds in high-concentrated urea fertilizer industrial wastewater.

Simultaneous removal of organic carbon and nitrogen pollutants in the Yangtze estuarine sediment: The role of heterotrophic nitrifiers

The Yangtze Estuary is one of the most eutrophic coastal areas in the world. The engagement of heterotrophic nitrification bacteria in the simultaneous removal of organic carbon and ammonium in the Yangtze estuarine sediment was investigated. The specific nitrification rate in the selective autotrophic nitrification inhibition treatment was about 25% of that in the control without autotrophic nitrification inhibition, suggesting that heterotrophic nitrification, in addition to autotrophic nitrification, was an important nitrification process in the sediment. The increase of heterotrophic nitrification can offset the decrease in autotrophic nitrification, which subsequently leads to the high tolerance of nitrification to the organic carbon. The number of heterotrophic nitrification bacteria was 7.1 × 107 MPN g−1 in sediment collected from Site 1 while that of autotrophic nitrification bacteria was 4.2 × 108 MPN g−1. The isolation of heterotrophic nitrification bacteria provides direct evidence of the engagement of heterotrophs in the nitrification of the Yangtze estuarine sediment. The results show that nitrification is catalyzed by both the autotrophs and the heterotrophs, indicating functional redundancy of nitrification in sediment. Since organic carbon usually coexists with ammonium, these findings indicate an alternative bioprocess for the simultaneous removal of organic carbon and ammonium in Yangtze estuarine sediment.