Nitrogen Removal Bacteria Research Articles

Effect of COD/N ratio on nitrogen removal in a membrane-aerated biofilm reactor

Efficient nitrogen removal for low COD/N wastewater is very important and membrane-aerated biofilm reactor (MABR) might be a solution. This study presented the performance of nitrogen removal in a MABR for wastewater with COD/N ratio from 10 to 3. The results indicated that the nitrogen removal in MABR was affected by the wastewater COD/N ratio but maintained high when the COD/N was 5 or higher. When the influent COD/N was 5, the COD, ammonium and total nitrogen removal efficiency reached 83.7%, 93.1% and 84.6% respectively. Meanwhile, the oxygen uptake rate of ammonia-oxidizing bacteria, nitrite-oxidizing bacteria and heterotrophic bacteria were 35.7, 46.7 and 25.7 mgO2/(gMLVSS·h), respectively. MABR had the advantage of high nitrogen removal efficiency at low wastewater COD/N than other bioreactors. Furthermore, PCR-DGGE was used to analyze the changes of amount and diversity of nitrogen removal bacteria with different COD/N ratios. Multiple bacteria related to biofilm formation, nitrification, denitrification and anaerobic ammonium oxidation processes were identified, and changed along with the change of COD/N ratio. The bacterial amount and density both declined significantly when the influent COD/N ratio was reduced to 3.

Using electric field to enhance the activity of anammox bacteria.

Electric field was applied to enhance the activity of anaerobic ammonium oxidation (anammox) bacteria for nitrogen removal in this study. The effect of different distributive modes with the total electric field time of 6 h/24 h (R2) and 18 h/24 h (R3) at 2 V/cm was determined through long-term tests. With the continuous application time increasing from 3 to 9 h in R3 (1 to 3 h in R2), the total nitrogen removal rate (NRR) showed an acceleration trend. When the electric field was applied continuously for 9 h (R3, mode 3, application-rest time: 9 h-3 h), the NRR dramatically increased 38.7 % over that of control on day 160. Besides, it was demonstrated that the increase of crude enzyme activities and the cell quantities were the main reasons for the enhancement of nitrogen removal performance of the anammox process. Additionally, transmission electron microscope observation proved the morphological change of anammox biomass under electric field application.

Biological characteristics of a denitrifying phosphorus-accumulating bacterium

To isolate highly efficient denitrifying phosphorus-accumulating bacteria (DPAB) for synchronous nitrogen and phosphorus removal, it is necessary to understand their biological characteristics. Using denitrification screening, polyphosphate (poly-P) and poly-β-hydroxybutyrate (PHB) granule staining, nitrate reduction, nitrate reduction producing N2, and phosphorus uptake tests, a strain of efficient DPAB was isolated. This strain was identified as Thauera by 16S rDNA sequencing and physiological–biochemical analyses, and named N11. The growth of the strain N11 was obviously affected by nitrogen source, carbon source, temperature, and pH (p<0.05 or p<0.01). LB was considered the suited nutrient removal medium and the optimum pH and temperature were 8 and 35°C, respectively. Under the optimal culture conditions for 32h, the bacteria could consistently keep active, OD600 maintained at approximately 1.8, and the count was 1.826×1013–3.218×1013cfu/mL. With anaerobic–aerobic training in synthetic wastewater, the polyhydroxyalkanoate (PHA) content in cells increased from 22.8mg/L to 150.6mg/L (under anaerobic conditions, 12h), and then gradually decreased to 20.4mg/L (under aerobic conditions, 24h). The phosphate (PO43−–P) concentration in culture supernatants increased from 4mg/L to 20.8mg/L (under anaerobic conditions, 12h), and then gradually decreased to 3.08mg/L (under aerobic conditions, 24h), and the phosphorus removal rate was 80.38%. The nitrate–nitrogen (NO3−–N) concentration decreased from 75.45mg/L to 7.12mg/L. Nitrite–nitrogen (NO2−–N) was at a low concentration (≤1.29mg/L). The denitrification rate was 89.96%. This study describes a novel strain of DPAB and the optimal conditions for nitrogen and phosphorus removal by this strain.

Bioaugmentation treatment of municipal wastewater with heterotrophic-aerobic nitrogen removal bacteria in a pilot-scale SBR

PCN bacteria capable of heterotrophic-aerobic nitrogen removal was successfully applied for bioaugmented treatment of municipal wastewater in a pilot-scale SBR. At an appropriate COD/N ratio of 8, the bioaugmentation system exhibited stable and excellent carbon and nutrients removal, the averaged effluent concentrations of COD, NH4+-N, TN and TP were 20.6, 0.69, 14.1 and 0.40mg/L, respectively, which could meet the first class requirement of the National Municipal Wastewater Discharge Standards of China (COD<50mg/L, TN<15mg/L, TP<0.5mg/L). Clone library and real-time PCR analysis revealed that the introduced bacteria greatly improved the structure of original microbial community and facilitated their aerobic nutrients removal capacities. The proposed emerging technology was shown to be an alternative technology to establish new wastewater treatment systems and upgrade or retrofit conventional systems from secondary-level to tertiary-level.

Succession of bacterial community in anaerobic–anoxic–aerobic (A2O) bioreactor using sludge fermentation liquid as carbon source

To analyze the effect of sludge fermentation liquid on succession of bacterial community as carbon source, a three-month-long experiment was conducted in anaerobic–anoxic–aerobic process at room temperature. Experimental results showed that the removal efficiencies of total nitrogen and total phosphorus were improved to 84.7 and 94.3% from 64.5 and 54.2% at flow ratio of fermentation liquid and municipal wastewater, 1:35. Meanwhile, the principal component analysis demonstrated that significant shifts of bacterial community were observed with fermentation liquid addition. In particular, fermentation liquid appeared to be selective for the phosphorus-removal bacteria Gammaproteobacteria, denitrifying bacteria Comamonas sp., nitrogen-removal bacteria Betaproteobacteria, and denitrifying phosphate accumulating organisms Sphingobacterium, indicating simultaneous nitrification and denitrification, and denitrifying dephosphatation might be present after fermentation liquid addition.

The Research of Fluorescence &lt;i&gt;In Situ&lt;/i&gt; Hybridization Approach Applied in Denitrification Bacteria in Metal Membrane Bioreactor

To research the composition and proportion of the denitrying bacterium in denitrification tank and increase the nitrogen removals rate. With the purpose of explore the curve between the amount of different denitrying bacterium and the quality of water treating, then find out the optimum of the species of nitrogen removal bacteria and the amount of the specific type of microorganism in the denitrification tank of metal membrane bioreactor at the optimized conditions of the water treating effects. The fluorescence in situ hybridization (FISH) approach is applied in this research, to set a preliminary study on the space-time character of denitrification bacteria population structure in denitrifical tank.

Enrichment of Anaerobic Ammonium Oxidation (Anammox) Bacteria for Biological Nitrogen Removal of Wastewater

Anaerobic ammonium oxidation (anammox) bacteria enrichment was explored for the potential application of ammonium rich wastewater removal. Samples of sludge from mature and young landfill leachate treatment plants were screened and used as inocula for anammox enrichment cultures. Enrichments were monitored for N-NH3, N-NO2- and N-NO3- to detect anammox potential activity. Six of the twelve enrichment cultures showed anammox activity after more than five months of enrichment period. All enrichment cultures that gave positive results were obtained from bottom part of sequencing batch reactor (SBR) lagoon indicating localization of anammox bacteria in anaerobic condition. Polymerase Chain Reaction (PCR) with specific primers targeting anammox and planctomycete were able to amplify the 16S rRNA sequence for anammox bacteria under PCR optimum condition. However, only three of six positive samples were successfully sequenced. DNA sequence analysis using NCBI (BLAST) and RDP showed that the anammox bacterial sequences of the investigated samples were identified as Candidatus Kuenenia stuttgartiensis with similarity of 100% (NCBI) and 99.3% (RDP).

Using graphene oxide to enhance the activity of anammox bacteria for nitrogen removal

Graphene oxide (GO) was applied in this study to enhance the activity of anaerobic ammonium oxidation (anammox) bacteria for nitrogen removal. A GO dose-dependent effect on anammox bacteria was observed through batch tests. The results showed that the activity increased as the GO dose was varied within 0.05–0.1gL−1. A maximum 10.26% increase of anaerobic ammonium oxidizing activity was achieved at 0.1gL−1 GO. Analysis of extracellular polymeric substances (EPS) indicated that the highest carbohydrate, protein, and total EPS contents (42.5, 125.7, and 168.2mg (g volatile suspended solids)−1, respectively) were obtained with 0.1gL−1 GO. Appropriate GO dose stimulated EPS production to promote the activity of anammox bacteria. Transmission electron microscopy showed the large surface area of GO benefited cell attachment. These findings proved that the application of GO was an effective approach to enhancing the activity of anammox bacteria.

Heterotrophic Nitrogen Removal Bacteria in Piggery Wastes in the Mekong Delta, Vietnam

A total of 2318 heterotrophic nitrogen removal (HNR) bacteria isolated from piggery wastes (after biogas container) were classified in four kinds of heterotrophic ammonia-oxidizing bacteria (569 isolates), nitrite-oxidizing bacteria (580 isolates), nitrate-oxidizing bacteria (600 isolates) and heterotrophic nitrifying and denitrifying bacteria (569 isolates). The virtually complete 16S rRNA gene was PCR amplified and sequenced. The sequences from the selected HNR bacteria showed high degrees of similarity to those of the GenBank references strains (between 97% and 99.8%). Phylogenetic trees based on the 16S rDNA sequences displayed high consistency, with nodes supported by high bootstrap (500) values. These presumptive HNR isolates were divided four groups that included members of genera Arthrobacter, Corynebacterium, Rhodococcus (high G+C content gram-positive bacteria), Staphylococcus, Bacillus (low G+C content gram-positive bacteria) and Klebsiella (gram-negative bacteria). Based on Pi value (nucleotide diversity), heterotrophic ammonium-oxidizing bac-teria group had highest values and heterotrophic nitrifying-denitrifying bacteria group had the lowest values and Theta values (per sequence) from S of SNP for DNA polymorphism showed that heterotrophic nitrate-oxidizing bacteria group had the highest theta values in comparison of three groups. The present study, the HNR bacteria from piggery wastes, showed a very diverse community of HNR bacteria with a relatively high number of species involved in solid-wastewater samples and many isolates have nitrogen utilization ability at high concentration (800 – 1200 mM) and high G+C gram-positive bacteria strain occupied higher than low G+C gram-positive bacteria strain.

Heterotrophic Nitrogen Removal Bacteria in Sedimentary and Water of Striped Catfish Ponds In The Mekong Delta, Vietnam

A total of 1682 heterotrophic nitrogen removal (HNR) bacteria isolated from sedimentary and water of striped catfish ponds were classified in four kinds of heterotrophic ammonia-oxidizing bacteria (402 isolates), nitrite-oxidizing bacteria (438 isolates), nitrate-oxidizing bacteria (444 isolates) and heterotrophic nitrifying and denitrifying bacteria (398 isolates). The virtually complete 16S rRNA gene was PCR amplified and sequenced. The sequences from the selected HNR bacteria showed high degrees of similarity to those of the GenBank references strains (between 97% and 99.8%). Phylogenetic trees based on the 16S rDNA sequences displayed high consistency, with nodes supported by high bootstrap (500) values. These presumptive HNR isolates were divided four groups that included members of genera Arthrobacter, Corynebacterium, Rhodococcus (high G+C content gram-positive bacteria), Bacillus (low G+C content gram-positive bacteria) and Pseudomonas (gram-negative bacteria). Based on Pi value (nucleotide diversity), heterotrophic ammonium-oxidizing bacteria group had highest values and heterotrophic nitrifying-denitrifying bacteria group had the lowest values and Theta values (per sequence) from S of SNP for DNA polymorphism showed that heterotrophic nitrate-oxidizing bacteria group had the highest theta values in comparison of three groups. The present study, the HNR bacteria from sedimentary and water of striped catfish ponds, showed a very diverse community of HNR bacteria with a relatively high number of species involved in sedimentary and water samples and many isolates have nitrogen utilization ability at high concentration (800 – 1200 mM) and high G+C gram-positive bacteria strain occupied higher than low G+C gram-positive bacteria strain.

Evaluation of water quality and nitrogen removal bacteria community in Fuhe River

Abstract The ecosystem of Fuhe River, which is the main inflow tributary of Baiyangdian Lake, is crucial to the ecological health and environmental safety of the lake. Understanding the variation of Fuhe River ecosystem and taking measures to reduce its pollutants can help relieve the eutrophication of Baiyangdian Lake. To investigate this, we monitored water quality and levels of nitrogen removal bacteria along the Fuhe River using comprehensive pollution indices and denaturing gradient gel electrophoresis (DGGE). Samples were collected in the low-flow, high-flow and mean-water periods of 2009 and 2010. The dissolved oxygen (DO) values were, on an average, lower than 4 mg/L suggesting that the river was in low oxygen conditions, mainly conducting anaerobic reactions. The chemical oxygen demand (CODCr) values decreased gradually along the river, with the highest value of 128.65 mg/L at the first sampling site. The concentrations of total nitrogen (TN) and total phosphorus (TP) increased to 56.21 mg/L and 4.96 mg/L respectively, with concentrations at the inlet of the wetland significantly higher than those in the lake. The comprehensive pollution indexes reached the highest in the low-flow period in 2009 and in 2010, up to 78.81 and 77.10, respectively. Overall, the high comprehensive pollution indices for TN and TP indicated that the Fuhe River was polluted by N and P nutrients. There were abundant denitrifying bacteria and anaerobic ammonium oxidation bacteria at the terrestrial-aquatic interface of the upstream region of the river according to the Shannon-Weiner index.

Estimation of nitrogen removal bacteria diversity in a full-scale pseudo- and pilot-scale biobead BNR process for treating sewage

Estimation of nitrogen removal bacteria diversity in a full-scale pseudo- and pilot-scale biobead BNR process for treating sewage