Denitrifying Phosphorus Removing Bacteria Research Articles

Changes of nitrogen and phosphorus removal pattern caused by alternating aerobic/anoxia from the perspective of microbial characteristics.

The purpose of this study was to compare the impact of different numbers of alternating aerobic/anoxic (A/O) cycles on pollutant removal. Three sequential batch reactors (SBRs) with varying numbers of alternating A/O cycles were established. Under the tertiary anoxic operating conditions, the removal efficiencies of chemical oxygen demand (COD), ammonia nitrogen (NH4+-N), total nitrogen (TN), and total phosphorus (TP) were 88.73%, 89.56%, 72.15%, and 77.61%, respectively. Besides, alternating A/O affected the dominant microbial community relative abundance (Proteobacteria and Bacteroidetes) and increased microbial richness and diversity. It also increased the relative abundance of aerobic denitrifying, heterotrophic nitrifying, and denitrifying phosphorus removal bacteria to change N and P removal patterns. Furthermore, the abundance of carbohydrate metabolism and amino acid metabolism was improved by alternating A/O to improve organic matter and TN removal.

The treatment effect and denitrification mechanism of low-temperature and low-carbon source municipal wastewater treated by micro pressure swirl reactor

To solve the practical problem of the difficulty of denitrification of urban sewage caused by low-temperature and low-carbon sources, the micro-pressure swirl reactor (MPSR) was used to carry out a simulation study of low-carbon source sewage treatment when the influent temperatures were 15, 12, and 10 °C. The results showed that the MPSR process had the best sewage treatment effect at 12 °C, and the average removal rates of COD, NH4+-N, TN, and TP were 85.93 %, 99.17 %, 76.4 %, 94.78 %. Through the study of the denitrification process, it was found that the main composition of TN in the effluent was changed from NO3−-N to NO2−-N at 12 °C, and the MPSR system achieved short-cut nitrification. The DO duration results suggested that a larger low DO range and a longer low DO duration promoted the formation of short-cut nitrification at 12 °C. When the temperature further dropped to 10 °C, the short-cut nitrification of the system was inhibited by the increase of DO. The Niabella was a genus of bacteria involved in nitrification in MPSR system, and its large number ensured the low-temperature nitrification effect of MPSR. The existence of denitrifying phosphorus removal bacteria (Dechloromonas and Rhodoferax) ensured the removal effect of nitrogen and phosphorus in the system. Based on metabolic pathway analysis, it was confirmed that the MPSR system achieved short-cut nitrification under low-temperature and low-carbon sources, which the carbon source consumption was saved and the denitrification effect was improved.

Study on the effectiveness of an independent biological phosphorus removal system based on immobilized biological fillers nitrogen removal system in municipal wastewater

This study focused on the problem that simultaneous nitrogen and phosphorus removal cannot be achieved in current urban sewage treatment systems. To address this, a pilot system was developed to first use immobilized biologically active fillers to remove nitrogen, and then use activated sludge to independently remove phosphorus. The goal was to maximize the effectiveness of biological phosphorus removal. This study mainly aimed at analyzing the post-independent phosphorus removal characteristics and mechanisms; the composition of the phosphorus removing bacteria; and the contribution rate of the system. The effluent PO43--P of the system remained stable at 0.15–0.2 mgL−1, with the phosphorus removal anaerobic tank maintaining a "micro-release" state. When the hydraulic retention time (HRT) of the aerobic phosphorus removal tank was reduced to 1 h, the contribution rate of the aerobic phosphorus removal bacteria decreased from 28.42% to 16.68%; the contribution rate of the denitrifying phosphorus removal bacteria increased from 72.58% to 83.32%; and the abundance of the dominant bacteria Dechloromonas and Thaurea significantly increased. The phosphorus removal system provides a new approach for deep phosphorus removal in main municipal wastewater systems.

Start-up and Optimization of Denitrifying Phosphorus Removal in ABR-MBR Coupling Process

The feasibility of the denitrifying phosphorus removal process in the ABR-MBR system with no sludge reflux and high concentration of seeding activated sludge (25 g ·L-1, in MLSS) in the ABR was investigated. The characteristics of the microbial community in the denitrifying phosphorus removal compartment were also evaluated. The denitrifying phosphorus removal function was achieved by gradually increasing the reflux ratio (R) from 0% to 200%. During the stable operation, the average removal rates of COD, PO43--P, and TN in the system were 88.28%, 54.45%, and 61.93%, respectively. When the influent loading rate, NOx--N reflux ratio, and hydraulic retention time (HRT) of ABR and MBR were 0.8 kg ·(m3 ·d)-1, 150%, and 9 h and 3.3 h, respectively, the average VFA concentration of 80.58 mg ·L-1, ρ(NO2--N)/ρ(NO3--N) reflux ratio of 1.68, and PO43--P and TN removal rates of 64.94% and 62.95% were obtained. The short-cut nitrification denitrifying phosphorus removal was achieved in the ABR-MBR system. Batch tests showed that denitrifying phosphorus removal bacteria (DPAOs) were the main functional bacteria in the ABR, with anaerobic phosphorus release and anoxic phosphorus uptake of 3.73 mg ·L-1 and 10.22 mg ·L-1, respectively. High throughput sequencing results showed that Proteobacteria and Bacteroidetes were the dominant phyla in the phosphorus removal compartment, accounting for 23.49%-53.66% and 16.55%-21.78% of the total phyla, respectively. Thauera, Thiothrix, Pseudomonas, norank_ f_Rhodocyclaceae, and unclassification_ f_Rhodocyclaceae in Proteobacteria, and Sphingobacteriales in Bacteroidetes were the potential denitrifying phosphorus removal microorganisms.

The start-up of denitrifying phosphorus removal system by using nitrite as electron acceptor

The inoculation of short-cut denitrifying polyphosphate-accumulating organisms (DPAOs) mainly included two-phase inoculation and three-phase inoculation. The short-cut denitrifying phosphorus removal bacteria were quickly inoculated by sequencing batch reactor (SBR) to treatment domestic wastewater. The results showed that the average effluent concentration of TP was 0.85 mg/L after 132 cycles by 44 days in two-phase inoculation. The removal rates of NO2--N, TP and COD were 94.73%, 95.47% and 89.96% after 126 cycles by 42 days in three-phase inoculation, and the effluent concentrations were separately 1.31 mg/L, 0.45 mg/L and 17.07 mg/L, which reached the first A class requirement of Urban sewage treatment plant pollutant discharge standard. It was indicated that the efficiency of three-phase inoculation was higher. Anoxic phosphorus uptake was influenced seriously by anaerobic residual carbon, and it was the difference of the two inoculations.

Role of influent split ratio in a two-line BNR process performing denitrifying phosphorus removal

Denitrifying phosphorus removal is very effective in retarding competition between denitrifying bacteria and phosphorus removing organisms for limited carbon in influent, and can enhance performances of biological nutrient removal processes (BNR) treating low strength wastewater. The aim of this study is to demonstrate the effects of influent split ratios on enrichment of denitrifying phosphorus removing bacteria (DPB) in a two-line BNR process. Performances of the process under different influent split ratios were investigated; profiles of intracellular compounds were characterized; mass flow were also described. The results showed that influent split ratio had no obvious effects on COD and total phosphorus distribution in bulk water when influent COD concentration was in the range of 172.0–183.3mg/L, but affected intracellular content in activated sludge significantly. Better performances for ammonia removal were observed under influent split ratios (AN/AO, ratio of influent flow rates between the anaerobic–anoxic–anoxic line and the anaerobic–aerobic–aerobic line) of 10:10, 12:8 and 8:12 than under 15:5. An optimized balance between anoxic and aerobic phosphorus removal could be reached by adjusting the influent split ratio. Total nitrogen removal rate was improved by 16% through increasing the influent AN/AO split ratio from 8:12 to 12:8. This study also helped to understand role of split ratio in balancing pollutants removal within BNR processes.

Enhancing denitrification phosphorus removal with a novel nutrient removal process: Role of configuration

Role of configurations on enriching denitrifying phosphorus removing bacteria (DPB) by biological nutrient removal processes was discussed. Effects of configurations on enhancement of denitrifying phosphorus removal in a novel nutrient removal process, the STB (six-tank-bioreactor) process were investigated. Profiles of model intracellular compounds i.e. glycogen and PHA (poly-hydroxyalknoates) under different configurations were characterized in order to reveal the biochemical pathway that DPBs might follow in the STB process. Mass flow characteristics of main pollutants under different configurations were also illustrated. Results showed that a higher anoxic to total volume ratio and the multi-barrier bioreactor strategy were crucial factors to enhance denitrifying phosphorus removal in the STB process. Both of the configurations performed well with average removal efficiencies of 74%, 98%, 51% and 85% under configuration I, and 74%, 99%, 72% and 70% under configuration II for COD, NH3–N, TN and TP respectively. A higher denitrifying phosphorus removal efficiency was achieved under configuration II than configuration I due to a bigger anoxic to total volume ratio.

Effects of Primary Settling Tank on Denitrifying Phosphorus Removal in a Full-Scale AAO Process

Effects of primary settling tank (PST) on phosphorus removal and the ratio of denitrifying phosphorus removing bacteria (DPB) to phosphorus accumulating organisms (PAOs) in a full-scale anaerobic/anoxic/aerobic (AAO) process were investigated by field survey and batch test. The AAO process without PST showed higher phosphorus removal efficiency than that with PST. In the anoxic tank, the phenomenon of anoxic phosphorus uptake and anaerobic phosphorus release were observed in the AAO process without and with PST, respectively. The DBP/PAOs ratio was 46% and 39% in the AAO process with and without PST, respectively. The AAO process with PST yielded higher microbial activities than that without PST.

Research of the Application of Denitrifying Phosphate Removal Bacteria in the A<sup>2</sup>/O Process

As a new type and high efficiency and low energy consumption one in biological denitrification and phosphorus removal technology, denitrifying phosphorus removal has become a hot topic in the research field of the water treatment technology. In this technology, denitrifying phosphate removal bacteria (DPBs) plays an important role. In each process stage of an A2/O process, denitrifying phosphorus removal bacteria (DPBs) plays different function. Combining with theory of the A2/O process, the function and main influence factors of denitrifying phosphorus removal bacteria (DPBs) are studied, and the prospect about DPBs is proposed.

Identification and Metabolic Mechanism of Non-fermentative Short-cut Denitrifying Phosphorus-removing Bacteria

To investigate the characteristics and metabolic mechanism of short-cut denitrifying phosphorus-removing bacteria (SDPB) that are capable of enhanced biological phosphorus removal (EBPR) using nitrite as an electron acceptor, an aerobic/anoxic sequencing batch reactor was operated under three phases. An SDPB-strain YC was screened after the sludge enrichment and was identified by morphological, physiological, biochemical properties and 16S rDNA gene sequence analysis. Denitrifying phosphorus-removing experiments were conducted to study anaerobic and anoxic metabolic mechanisms by analyzing the changes of chemical oxygen demand (COD), phosphate, nitrite, poly-β-hydroxybutyrate (PHB), and glycogen. The results show that strain YC is a non-fermentative SDPB similar to Paracoccus denitrificans. As a kind of non-fermentative bacteria, the energy of strain YC was mainly generated from phosphorus release (96.2%) under anaerobic conditions with 0.32 mg P per mg synthesized PHB. Under anoxic conditions, strain YC accumulated 0.45 mg P per mg degraded PHB, which produced most of energy for phosphate accumulation (91.3%) and a little for glycogen synthesis (8.7%). This metabolic mechanism of strain YC is different from that of traditional phosphorus-accumulating organisms (PAOs). It is also found that PHB, a kind of intracellular polymer, plays a very important role in denitrifying and accumulating phosphorus by supplying sufficient energy for phosphorous accumulation and carbon sources for denitrification. Therefore, monitoring ΔP/ΔPHB and Δ-NO−2-N/ΔPHB is more necessary than monitoring ΔP/ΔCOD, ΔNO−2-N/ΔCOD, or ΔP/ΔNO−2-N.

Study on Environment Materials with Separation and Identification of Denitrifying Phosphorus-Removing Bacteria

Environment material was a kind of material that considering the environment and ecology protection. Microbe as the key material of sewage treatment system played an important role in environmental protection. The paper researched that a strain of denitrifying phosphorus-removing bacteria could be isolated and screened from dephosphorization system by the conventional microbial breeding technology. The strain was preliminarily appraised itself belong to Pseudomonas sp., ultimately named as PX3.

Start-Up and Cultivation of A2N Denitrifying Phosphorus and Nitrogen Removal System

A2N is two-sludge system, by using the method that first bringing up the cultivation of denitrifying phosphorus removing bacteria (DPB) and nitrification biofilm separately then connecting them, which can start up A2N system successfully. Nitrification biofilm was cultivated in a sequencing batch reactor (SBR). After 30 days, NH4+-N effluent concentration steadily stayed below 0.5mg·L-1.In another SBR, the activated sludge for the enrichment of DPB is from the anaerobic tank, which was firstly operated under anaerobic/aerobic (A/O) condition. After 20 days, PAOs was successfully enriched. Then, the activated sludge was conducted under anaerobic/anoxic/aerobic (A/A/O) condition, maintaining the anaerobic time, gradually increased anoxic time and induced aerobic time. After 30 days DPB was successfully enriched, two phases totally take 50 days. The removal efficiency of total nitrogen and phosphorus are above 85 % and 95 %, so that A2N system was started up successfully.

Preliminary Discussion on the Activity of Denitrifying Phosphorus-Removing Bacteria in Sequencing Batch Reactors by Quinone Profile Analysis

Based on DPBs (Denitrifying Phosphorus-removing Bacteria) obtained from a lab-scale SBR, a quinone profile system had been established to analyze quinones in sludge samples. There existed a positive correlation between the contents of UQ-8 extracted from the sludge samples and the denitrifying and phosphorus removal efficiency of the treating system. With quinone profiles taken as a new important index, it was evidently feasible to determine the removal effect.

Using Sludge Fermentation Liquid To Improve Wastewater Short-Cut Nitrification-Denitrification and Denitrifying Phosphorus Removal via Nitrite

Wastewater biological nutrient removal (BNR) by short-cut nitrification-denitrification (SCND) and denitrifying phosphorus removal via nitrite (DPRN) has several advantages, such as organic carbon source saving. In this paper, a new method, i.e., by using waste activated sludge alkaline fermentation liquid as BNR carbon source, for simultaneously improving SCND and DPRN was reported. First, the performance of SCND and DPRN with sludge fermentation liquid as carbon source was compared with acetic acid, which was commonly used in literatures. Sludge fermentation liquid showed much higher nitrite accumulation during aerobic nitrification than acetic acid (81.8% versus 40.9%), and the former had significant anoxic denitrification and phosphorus uptake. The soluble phosphorus and total nitrogen removal efficiencies with sludge fermentation liquid were much higher than with acetic acid (97.6% against 73.4% and 98.7% versus 79.2%). Then the mechanisms for sludge fermentation liquid showed higher SCND and DPRN than acetic acid were investigated from the aspects of wastewater composition, microorganisms assayed by 16S rRNA gene clone library, and fluorescence in situ hybridization. More NO(2)(-)-N accumulated by the use of sludge fermentation liquid was attributed to be more humic acids in the influent, which inhibited nitrite oxidizing bacteria (NOB) more serious than ammonia oxidizing bacteria (AOB), and more AOB but less NOB were observed in the BNR system. The reasons for sludge fermentation liquid BNR system exhibiting greater short-cut denitrifying phosphorus removal were that there were less glycogen accumulating organisms and more phosphorus accumulating organisms and anoxic denitrifying phosphorus removal bacteria with higher nitrite reductase activity.

Kinetics Analysis of Anaerobic/Anoxic SBR Denitrifying Phosphorus Removal System

Kinetic equations of soluble components are analyzed in an anaerobic/ anoxic sequencing batch reactor (A/A SBR) enriched with denitrifying phosphorus removing bacteria (DPB) sludge. Mathematical model is established for denitrifying phosphorus removal process. The model is based on the simplification of the metabolic model for biological phosphorus removal by DPB. A proper set of kinetic parameters was calculated from the data obtained in the batch tests. The model was subsequently applied for the simulation of cycle behavior of soluble components in the A/A SBR. The results of the simulation indicated that the model can predict the concentration of each component for denitrifying phosphorus removal successfully.

Effect of different types of electron acceptors on the anoxic phosphorus uptake activity of denitrifying phosphorus removing bacteria

The effect of different types of electron acceptors (O 2, NO 3 - and NO 2 - ) on anoxic phosphorus uptake was investigated to obtain a better understanding of the metabolic behavior of denitrifying phosphorus removing bacteria (DPB). Two sets of sequencing batch reactor (SBR) were used to enrich phosphorus accumulation organisms (PAOs) by alternative anaerobic and aerobic operations (oxygen was used as the electron acceptor), batch experiments under two different electron acceptor conditions, nitrate and nitrite, were performed by using activated sludge generated from the above-operated SBR reactors. Anoxic phosphorus uptake achieved successful both by using nitrate or nitrite as the electron acceptor. However, the relative small amount of anoxic phosphorus was taken up by microorganisms with nitrite used as the electron acceptor in comparison with nitrate. The optimal stoichiometric loading amount of electron acceptors of nitrate and nitrite to phosphorus (N/P ratio) were 0.89 and 0.60, respectively. If the initial concentration of electron acceptors was controlled below the optimal ratio, the amount of phosphorus taken up increased with the concentration, otherwise it would decrease. It was also found that DPB lost the ability of phosphorus release and uptake rapidly under continuous anaerobic–anoxic operation condition.

Anoxic phosphorus removal in a pilot scale anaerobic-anoxic oxidation ditch process

The anaerobic-anoxic oxidation ditch (A2/O OD) process is popularly used to eliminate nutrients from domestic wastewater. In order to identify the existence of denitrifying phosphorus removing bacteria (DPB), evaluate the contribution of DPB to biological nutrient removal, and enhance the denitrifying phosphorus removal in the A2/O OD process, a pilot-scale A2/O OD plant (375 L) was conducted. At the same time batch tests using sequence batch reactors (12 L and 4 L) were operated to reveal the significance of anoxic phosphorus removal. The results indicated that: The average removal efficiency of COD, NH4+, PO43−, and TN were 88.2%, 92.6%, 87.8%, and 73.1%, respectively, when the steady state of the pilotscale A2/O OD plant was reached during 31–73 d, demonstrating a good denitrifying phosphorus removal performance. Phosphorus uptake took place in the anoxic zone by poly-phosphorus accumulating organisms NO2− could be used as electron receptors in denitrifying phosphorus removal, and the phosphorus uptake rate with NO2− as the electron receptor was higher than that with NO3− when the initial concentration of either NO2− or NO3− was 40 mg/L.

An efficient DPB utilization process: The modified A 2N process

The modified A 2N process was proposed on basis of the A 2N process. There are two waste sludge lines in the modified A 2N process: an AN (anaerobic-anoxic) waste sludge line and an AO (anaerobic–aerobic) waste sludge line. Denitrifying phosphorus removing bacteria (DPB) and common phosphorus accumulation organisms (PAOs) coexisted in the modified A 2N process but was relatively separated. Two streams of mixed liquor suspended solid (MLSS) were out of the anaerobic tank with one entering the anoxic tank, where DPB was the dominant microorganism, and the other the nitrification tank, where the aerobic PAOs dominated. The effects of pH and DO on process performance were investigated. Results showed that DPB might be more pH tolerable than aerobic PAOs while DPB and aerobic PAOs shared similar responses to DO. Parameters optimization was conducted and the following optimized parameters obtained: DO in nitrification tank was 2–3 mg L −1; nominal HRT for each unit (anaerobic, anoxic and aerobic units) was 3 h; SRT was 15 d. When the influent nutrient mass ratio (C/N/P) was 26.6/7.67/1 to 26.6/3/1, the average effluent COD, TN, and TP concentrations of the optimized process were 45, 10.5 and 0.7 mg L −1, respectively, with average removal efficiency 89%, 95.3% and 76.7% for COD, TN and TP.

Influence of carbon source and temperature on the denitrifying phosphorus removal process

To supply the valuable operating parameters for the popular usage of the new denitrifying phosphors removal process, it is essential to study the dominant biochemical reactions and the characteristics of denitrifying phosphorus removing bacteria (DPB). Thus, parallel batch experiments using DPB sludge were carried out to assess the effect of substrates (sewage, HAc, and endogenous carbon source) on denitrifying dephosphorus removal efficiency in this study. The results showed that the initial specific phosphorus release rate increased with the high concentration of the short-chain volatile fatty acids ratio in the influent, and sufficient phosphorus was released by DPB. This improved the subsequent denitrification and phosphorus uptake efficiency. The specific endogenous denitrification mainly relies on the internal carbon source (PHB) stored by poly-P bacteria. Denitrifying phosphorus removing bacteria were very hungry when the internal PHB was consumed. Consequently, the specific endogenous denitrification rate was low and the phosphorus uptake did not happen. On the other hand, in the experiment, the denitrifying phosphorus removal performance under two temperature conditions (8–10°C and 25–26°C) was also investigated and analyzed. It was found that the lower temperature decreased the specific phosphorus release and uptake rate, but did not inhibit the denitrifying phosphorus removal completely. Therefore, the negative influence of the low temperature on the overall phosphorus removal was not significant.

Effects of nitrite on phosphate uptake in anaerobic-oxic process

Abstract:Intermediate products of biological nitrogen removal process, nitrate and nitrite, could be used as electron acceptors for phosphorus removal. This study investigated the effects of nitrite on phosphorus uptake in anaerobic/oxic (A/O) biological phosphorus removal process. The results indicated that in addition to oxygen and nitrate (DPB(Na), Denitrifying Phosphorus removal Bacteria with nitrate as electron acceptor), to some extent, nitrite can also serve as electron acceptor to achieve the nitrite denitrifying phosphorus removal (DPB(Ni)). The quantity and rate of phosphorus uptake of DPBNi, however, were evidently lower than that of DPBN,. The nitrite existed in anoxic reactor made no difference to the quantity and rate of denitrifying phosphorus removal. But it would reduce the consumption of nitrate. Moreover, the data showed that the aerobic phosphate uptake of DPBNi was lower than that of anaerobic phosphorus-released sludge in traditional A/O process. However, there was no much difference between these two kinds of sludge in terms of the total phosphorus uptake quantity and the effluent quality.