Temporal Dynamics and Performance Association of the Tetrasphaera-Enriched Microbiome for Enhanced Biological Phosphorus Removal

Tetrasphaera have been recently identified based on the 16S ribosomal RNA(rRNA)gene as among the most abundant polyphosphate-accumulating organisms(PAOs)in global full-scale wastewater treatment plants(WWTPs)with enhanced biological phosphorus removal(EBPR).However,it is unclear how Tetrasphaera PAOs are selectively enriched in the context of the EBPR microbiome.In this study,an EBPR microbiome enriched with Tetrasphaera(accounting for 40%of 16S sequences on day 113)was built using a top-down design approach featuring multicarbon sources and a low dosage of allylthiourea.The microbiome showed enhanced nutrient removal(phosphorus removal~85%and nitrogen removal~80%)and increased phosphorus recovery(up to 23.2 times)compared with the seeding activated sludge from a local full-scale WWTP.The supply of 1 mg·L^(-1)allylthiourea promoted the coselection of Tetrasphaera PAOs and Microlunatus PAOs and sharply reduced the relative abundance of both ammonia oxidizer Nitrosomonas and putative competitors Brevundimonas and Paracoccus,facilitating the establishment of the EBPR microbiome.Based on 16S rRNA gene analysis,a putative novel PAO species,EBPR-ASV0001,was identified with Tetrasphaera japonica as its closest relative.This study provides new knowledge on the establishment of a Tetrasphaera-enriched microbiome facilitated by allylthiourea,which can be further exploited to guide future process upgrading and optimization to achieve and/or enhance simultaneous biological phosphorus and nitrogen removal from high-strength wastewater.

Nitrogen and phosphorus removal in pilot-scale anaerobic-anoxic oxidation ditch system

To achieve high efficiency of nitrogen and phosphorus removal and to investigate the rule of simultaneous nitrification and denitrification phosphorus removal （SNDPR）, a whole course of SNDPR damage and recovery was studied in a pilot-scale, anaerobicanoxic oxidation ditch （OD）, where the volumes of anaerobic zone, anoxic zone, and ditches zone of the OD system were 7, 21, and 280 L, respectively. The reactor was fed with municipal wastewater with a flow rate of 336 L/d. The concept of simultaneous nitrification and denitrification （SND） rate （rSND） was put forward to quantify SND. The results indicate that： （1） high nitrogen and phosphorus removal efficiencies were achieved during the stable SND phase, total nitrogen （TN） and total phosphate （TP） removal rates were 80% and 85%, respectively; （2） when the system was aerated excessively, the stability of SND was damaged, and rSND dropped from 80% to 20% or less; （3） the natural logarithm of the ratio of NOx to NH4^＋ in the effluent had a linear correlation to oxidation-reduction potential （ORP）; （4） when NO3^- was less than 6 mg/L, high phosphorus removal efficiency could be achieved; （5） denitrifying phosphorus removal （DNPR） could take place in the anaerobic-anoxic OD system. The major innovation was that the SND rate was devised and quantified.

Removal of nitrogen and phosphorus in a combined A^2/O-BAF system with a short aerobic SRT

A bench-scale anaerobic/anoxic/aerobic process-biological aerated filter （A^2/O-BAF） combined system was carded out to treat wastewater with lower C/N and C/P ratios. The A^2/O process was operated in a short aerobic sludge retention time （SRT） for organic pollutants and phosphorus removal, and denitrification. The subsequent BAF process was mainly used for nitrification. The BAF effluent was partially returned to anoxic zone of the A^2/O process to provide electron acceptors for denitrification and anoxic P uptake. This unique system formed an environment for reproducing the denitdfying phosphate-accumulating organisms （DPAOs）. The ratio of DPAOs to phosphorus accumulating organisms （PAOs） could be maintained at 28% by optimizing the organic loads in the anaerobic zone and the nitrate loads into the anoxic zone in the A^2/O process. The aerobic phosphorus over-uptake and discharge of excess activated sludge was the main mechanism of phosphorus removal in the combined system. The aerobic SRT of the A^2/O process should meet the demands for the development of aerobic PAOs and the restraint on the nitrifiers growth, and the contact time in the aerobic zone of the A^2/O process should be longer than 30 min, which ensured efficient phosphorus removal in the combined system. The adequate BAF effluent return rates should be controlled with 1--4 mg/L nitrate nitrogen in the anoxic zone effluent of A^2/O process to achieve the optimal nitrogen and phosphorus removal efficiencies.

Enhanced Biological Phosphorus Removal with Pseudomonas putida GM6 from Activated Sludge

The enhanced biological phosphorus removal （EBPR） method is widely adopted for phosphorus removal from wastewater, yet little is known about its microbiological and molecular mechanisms. Therefore, it is difficult to predict and control the deterioration of the EBPR process in a large-scale municipal sewage treatment plant. This study used a novel strain isolated in the laboratory, Pseudomonas putida GM6, which had a high phosphate accumulating ability and could recover rapidly from the deteriorated system and enhance the capability of phosphorus removal in activated sludge. Strain GM6 marked with gfp gene, which was called GMTR, was delivered into a bench-scale sequencing batch reactor （SBR） of low efficiency, to investigate the colonization of GMTR and removal of phosphorus. After 21 days, the proportion of GMTR in the total bacteria of the sludge reached 9.2%, whereas the phosphorus removal rate was 96%, with an effluent concentration of about 0.2 mg L^-1. In the reactor with the addition of GMTR, phosphorus was removed quickly, in 1 h under anaerobic conditions, and in 2 h under aerobic conditions. These evidences were characteristic of EBPR processes. Field testing was conducted at a hospital sewage treatment facility with low phosphorus removal capability. Twentyone days after Pseudomonas putida GM6 was added, effluent phosphorus concentration remained around 0.3 mg L^-1, corresponding to a removal rate of 96.8%. It was therefore demonstrated that Pseudomonas putida GM6 could be used for a quick startup and enhancement of wastewater biological phosphorus removal, which provided a scientific basis for potential large-scale engineering application.

Effects of COD to Phosphorus Ratios on the Metabolism of PAOs in Enhanced Biological Phosphorus Removal with Different Carbon Sources

To elucidate the phosphorus removal and metabolism under various COD / P ratio,a sludge highly enriched in PAOs was used to investigate the impacts of COD / P in batch tests under different carbon supply conditions. Acetate,propionate and a mixture of acetate and propionate at a ratio of 3 ∶ 1( COD basis) was used as carbon sources with the COD / P of 20,15,10 and 5. 0 g COD /gP,respectively. The minimum COD / P ratios for complete P removal were found to be 8. 24 g COD /gP for acetate,11. 40 g COD /gP for propionate and9. 10 g COD /gP for the 3 ∶ 1 mixture of acetate and propionate. Converted to a mass basis,all three cases had a very similar ratio of 7. 7 g VFA /gP,which represented a useful guide for operation of EBPR plants to identify possible shortages in VFAs. The trend in PHV accumulation during the anaerobic period along with the decrease of COD / P ratios suggested that,PAOs may use the TCA pathway for anaerobic VFA uptake to maintain the required NADH production with reduced glycogen degradation. During the aerobic phase,the glycogen pool was reduced but remained enough compared to the requirement for anaerobic VFA uptake,and the synthesis and degradation of glycogen was not the inhibition factor of PAOs.

Enhanced Biological Phosphorus Removal in SBR Using Glucose as a Single Organic Substrate

Enhanced biological phosphorus removal(EBPR) was investigated in an anaerobic/aerobic sequencing batch reactor(SBR) supplied with glucose as a single organic substrate.The results illustrated that EBPR process could also occur successfully with glucose other than short chain fatty acids(SCFAs).High phosphorus release and poly-hydroxyalkanoate(PHA) accumulation in the anaerobic phase was found vital for the removal of phosphorus during the aerobic phase.The measurement of intracellular reserves revealed that glycogen had a higher chance to replace the energy role of poly-P under anaerobic conditions.Moreover,glycogen was also utilized as the carbon source for PHA synthesis,as well as a reducing power as reported earlier.The accumulated PHA in this system was mainly in the form of poly-hydroxyvalerate(PHV) instead of poly-hydroxybutyrate(PHB),and was inferred to be caused by the excess reducing power contained in glucose.Lactate as a fermentation product was also found released into the bulk solution.Applying fundamental biochemistry knowledge to the experimental results,a conceptual biochemical model was developed to explain the metabolism of the glucose-induced EBPR.

Enhanced Nutrient Removal with Upflow Biological Aerated Filter for Reclaimed Water

A two-stage upflow biological aerated filter was designed as an advanced treatment process to optimize the operating parameters and study the correlative factors influencing the efficiency of nitrification, denitrification and phosphorus removal. The experimental results showed that the final effluent of the two-stage upflow biofilter process operated in series could meet the stringent limits of the reclaimed water for the total nitrogen of 2 mg/L, and total phosphorus of 0.3 mg/L. The high treatment efficiency allowed the reactor operating at very high hydraulic loadings and reaching nearly complete nitrification and denitrifieation.

Characteristics of intracellular polyphosphate granules and phosphorus-absorption of a marine polyphosphateaccumulating bacterium, Halomonas sp. YSR-3

Halomonas sp.YSR-3 was isolated from the Yellow Sea and identified as a polyphosphate-accumulating bacterium and the characteristics of its intracellular polyphosphate(polyP)granules and phosphorus absorption were studied.Most YSR-3 cells stored one or two polyP granules in regular appearance and high-density.The diameter of the granules was about 400 nm measuring by a transmission electron microscope(TEM).After stained with 4,6-diamidino-2-phenylindole(DAPI)and visualized by a fluorescence microscope,the cells turned blue and the granules were bright yellow.The composition of granules includes P(major ingredient),Mg,S,K,and Ca as detected by an energy dispersive X-ray spectrometer(EDS).When inorganic phosphorus(po34-)and ferric ion(Fe3+)were added into media,the biomass increased and the cells formed intracellular polyP granules owing to the phosphorus assimilation from media.The YSR-3 obtained higher biomass by adding 0.02 g/L FePO4 than 0.005 g/L and 0.01 g/L FePO4;however,the phosphorus absorption was higher with 0.01 g/L FePO4 than 0.005 g/L and 0.02 g/L FePO4.The optical density at wavelength 480 nm(OD480nm)was 0.79 and 100%cells could form intracellular polyP granules.These results show that strain YSR-3 is able to acquire higher biomass and absorb more inorganic phosphorus when 0.01 g/L FePO4 is added.The characteristics of absorbing and storing phosphorus as intracellular inorganic polyP granules have a potential for application in high-efficiency phosphorus removal in wastewater treatment.

Advanced nitrogen and phosphorus removal in A^(2)O-BAF system treating low carbon-to-nitrogen ratio domestic wastewater

A laboratory-scale anaerobic-anoxic-aerobic process(A^(2)O)with a small aerobic zone and a bigger anoxic zone and biologic aerated filter(A^(2)O-BAF)system was operated to treat low carbon-to-nitrogen ratio domestic wastewater.The A^(2)O process was employed mainly for organic matter and phosphorus removal,and for denitrification.The BAF was only used for nitrification which coupled with a settling tank Compared with a conventional A^(2)O process,the suspended activated sludge in this A^(2)OBAF process contained small quantities of nitrifier,but nitrification overwhelmingly conducted in BAF.So the system successfully avoided the contradiction in sludge retention time(SRT)between nitrifying bacteria and phosphorus accumulating organisms(PAOs).Denitrifying phosphorus accumulating organisms(DPAOs)played an important role in removing up to 91%of phosphorus along with nitrogen,which indicated that the suspended activated sludge process presented a good denitrifying phosphorus removal performance.The average removal efficiency of chemical oxygen demand(COD),total nitrogen(TN),total phosphorus(TP),and NH_(4)^(+)-N were 85.56%,92.07%,81.24%and 98.7%respectively.The effluent quality consistently satisfied the national first level A effluent discharge standard of China.The average sludge volume index(SVI)was 85.4 mL·g^(-1)additionally,the volume ratio of anaerobic,anoxic and aerobic zone in A^(2)O process was also investigated,and the results demonstrated that the optimum value was 1:6:2.

Effects of different external carbon sources and electron acceptors on interactions between denitrification and phosphorus removal in biological nutrient removal processes

The effects of two different external carbon sources （acetate and ethanol） and electron acceptors （dissolved oxygen, nitrate, and nitrite） were investigated under aerobic and anoxic conditions with non-acclimated process bi- omass from a full-scale biological nutrient removal-activated sludge system. When acetate was added as an external carbon source, phosphate release was observed even in the presence of electron acceptors. The release rates were 1.7, 7.8, and 3.5 mg P/（g MLVSS.h） （MLVSS： mixed liquor volatile suspended solids）, respectively, for dissolved oxygen, nitrate, and nitrite. In the case of ethanol, no phosphate release was observed in the presence of electron acceptors. Results of the experiments with nitrite showed that approximately 25 mg NO2-N/L of nitrite inhibited anoxic phosphorus uptake regardless of the concentration of the tested external carbon sources. Furthermore, higher deni- trification rates were obtained with acetate （1.4 and 0.8 mg N/（g MLVSS.h）） compared to ethanol （1.1 and 0.7 mg N/ （g MLVSS.h）） for both anoxic electron acceptors （nitrate and nitrite）.

Research on polyhydroxyalkanoates and glycogen transformations: Key aspects to biologic nitrogen and phosphorus removal in low dissolved oxygen systems

In this paper,a study was conducted on the effect of polyhydroxyalkanoates(PHA)and glycogen transformations on biologic nitrogen and phosphorus removal in low dissolved oxygen(DO)systems.Two laboratory-scale sequencing batch reactors(SBR1 and SBR2)were operating with anaerobic/aerobic(low DO,0.15-0.45 mg·L^(-1))configurations,which cultured a propionic to acetic acid ratio(molar carbon ratio)of 1.0 and 2.0,respectively.Fewer poly-3-hydroxybutyrate(PHB),total PHA,and glycogen transformations were observed with the increase of propionic/acetic acid,along with more poly-3-hydroxyvalerate(PHV)and poly-3-hydroxy-2-methyvalerate(PH2MV)shifts.The total nitrogen(TN)removal efficiency was 68%and 82%in SBR1 and SBR2,respectively.In the two SBRs,the soluble ortho-phosphate(SOP)removal efficiency was 94%and 99%,and the average sludge polyphosphate(poly-P)content(g·g-MLVSS^(-1))was 8.3%and 10.2%,respectively.Thus,the propionic to acetic acid ratio of the influent greatly influenced the PHA form and quantity,glycogen transformation,and poly-P contained in activated sludge and further determined TN and SOP removal efficiency.Moreover,significant correlations between the SOP removal rate and the(PHV+PH2MV)/PHA ratio were observed(R^(2)>0.99).Accordingly,PHA and glycogen transformations should be taken into account as key components for optimizing anaerobic/aerobic(low DO)biologic nitrogen and phosphorus removal systems.

Influence of Azo Dye on Metabolism of Phosphorus Accumulating Organisms Linked to Transformation of Intracellular Storage Products

In this study, the influence of azo dye of methyl red (MR) on COD, dye and phosphorus removal and the transformation of polyhydroxyalkanoate (PHA) and glycogen of phosphate accumulating organisms in enhanced biological phosphorus removal (EBPR) system were investigated. The results indicated COD and dye removal efficiencies were decreased from 97.9% to 72.8% and 99.7% to 82.0%, respectively, when MR concentration was increased from 0 to 40 mg/L. Low MR concentration (5 mg/L) had no influence on P removal and transformation of PHA and glycogen. However, P removal, PHA production and consumption, and glycogen replenishment were seriously inhibited at high MR concentration, while glycogen hydrolysis was simulated at MR concentration of 20 and 40 mg/L. The transformations of PHA and glycogen at aerobic condition were more sensitive to those at anaerobic condition at high MR concentration. These results demonstrated dye and its intermediate products would inhibit the metabolism of polyphosphate accumulating organisms, which should be taken into account in future work.

生物增效低曝气BC-BAF处理低碳高氨氮废水的性能研究

为改善传统曝气生物滤池(BAF)对低碳高氨氮比猪场沼液脱氮除磷效果差的困境,采用生物炭(Biochar,BC)为BAF载体填料,接种课题组前期驯化好的脱氮除磷功能菌泥,低曝气条件下构建生物增效BC-BAF工艺。研究该工艺对猪场沼液脱氮除磷的效能,并基于高通量测序技术分析启动前后微生物种群的组成变化,最后结合启动后污泥样品的能谱分析(EDS),探讨其强化脱氮除磷机理。结果表明,启动成功后的生物增效BC-BAF工艺对低碳高氨氮猪场沼液的NH4+-N、TN和TP的平均去除率分别达到了65.27%、60.31%和63.20%;与脱氮除磷功能相关的优势菌属Nitrosomonas(2.12%),Candidatus_Brocadia(3.24%),Acinetobacter(3.88%),Micropruina(24.72%),norank_o_RBG-13-54-9(11.71%),JGI_0001001-H03(1.77%)和unclassified_f_Burkholderiaceae(1.11%)在反应体系中实现了很好的富集。微曝气生物增效BC-BAF工艺处理猪场沼液反应体系中存在短程硝化、厌氧氨氧化以及反硝化脱氮等多种途径,而对于总磷的去除主要以生物除磷和吸附沉淀的联合方式进行。

Cassava stillage and its anaerobic fermentation liquid as external carbon sources in biological nutrient removal

The aim of this study was to investigate the effects of one kind of food industry effluent, cassava stillage and its anaerobic fermentation liquid, on biological nutrient removal （BNR） from municipal wastewater in anaerobic- anoxic-aerobic sequencing batch reactors （SBRs）. Experiments were carried out with cassava stillage supernatant and its anaerobic fermentation liquid, and one pure compound （sodium acetate） served as an external carbon source. Cyclic studies indicated that the cassava by-products not only affected the transformation of nitrogen, phosphorus, poly-13-hydroxyalkanoates （PHAs）, and glycogen in the BNR process, but also resulted in higher removal efficiencies for phosphorus and nitrogen compared with sodium acetate. Furthermore, assays for phosphorus accumulating or- ganisms （PAOs） and denitrifying phosphorus accumulating organisms （DPAOs） demonstrated that the proportion of DPAOs to PAOs reached 62.6% （Day 86） and 61.8% （Day 65） when using cassava stillage and its anaerobic fer- mentation liquid, respectively, as the external carbon source. In addition, the nitrate utilization rates （NURs） of the cassava by-products were in the range of 5.49-5.99 g N/（kg MLVSS.h） （MLVSS is mixed liquor volatile suspended solids） and 6.63-6.81 g N/（kg MLVSS.h）, respectively. The improvement in BNR performance and the reduction in the amount of cassava stillage to be treated in-situ make cassava stillage and its anaerobic fermentation liquid attractive alternatives to sodium acetate as external carbon sources for BNR processes.

基于污水厂运行数据的低温生物脱氮强化研究

基于太湖流域8家城镇污水处理厂的实际运行数据,结合动力学分析,探讨了低温生物脱氮的强化措施。动力学分析表明:温度对硝化、反硝化效果的影响较大,温度每降低1℃,硝化菌比增长速率和反硝化速率分别降低10%和9%。当污水厂的污泥负荷≤0.12 kgBOD5/(kgMLSS.d)、泥龄≥12 d时,出水NH3-N全面达标(GB 18918—2002一级B)。当BOD5/TN≤3时,对TN的去除效果与碳氮比呈显著正相关;而当BOD5/TN>3时,碳氮比对TN的去除效果影响较小,但此时对TN的去除效果与对NH3-N的去除效果呈显著正相关;约有50%的污水厂因原水碳源不足影响反硝化效果。最后提出了太湖流域城镇污水厂实现低温脱氮的优选参数及强化运行管理的措施。

复合式膜生物反应器强化脱氮除磷的实验研究

在传统好氧膜生物反应器(MBR)的基础上,结合厌氧/缺氧/好氧(A2/O)工艺开发了复合式A2/O膜生物反应器,并对其处理小区生活污水中的氮、磷等污染物的特性进行了研究。实验表明:在各自合适的条件下复合式A2/O膜生物反应器可保证化学需氧量(COD)的平均去除率达到90.17%,NH4+-N的去除率可达到92.32%,总氮(TN)平均去除率可达到72%,而总磷(TP)的平均去除率达到71.23%。

新型GS-MBR工艺生物强化除磷试验研究

采用新型GS-MBR对校园污水生物强化除磷效果进行了试验研究。小试装置采用全泥龄操作，正常运行92d。SBR运行条件为厌氧5h，好氧5h，沉淀1h，出水与进水合计1h，进水COD、NH4^＋—N、TP和TN分别为202-550mg/L、7．66～16．46mg／L、1．25～3．28mg／L和10．56-38．26mg／L，去除效率平均分别为95，2％、95％、96．4％和50．5％。进水COD／TP=148，出水磷浓度仅为70μg/L。分析表明：进水COD／TP是本装置生物强化除磷的关键因素，在进水COD／TP较高的条件下，无需排泥也能达到强化除磷的目的。此外，膜污染以无机盐为主，酸洗效果优于碱洗。

集约化猪场废水强化生化处理工艺试验研究

该文采用新型厌氧反应器技术和强化生物脱氮及硝化技术处理猪场废水。试验结果表明:新型厌氧反应器容积CODCr负荷可达8kg/(m3.d)以上,稳定运行CODCr平均去除率为75%;生物脱氮及硝化采用一体式A/O反应器,缺氧段水力停留时间为1h,好氧段水力停留时间为3d,氨氮浓度可控制在10mg/L以下。总出水CODCr平均550mg/L,BOD5平均53.0mg/L,NH3-N平均8.8mg/L,总CODCr去除率87%,总BOD5去除率96%,NH3-N总去除率在98%以上;采用原水碳源优化分配强化生物脱氮,TN去除率为77.11%左右。总出水BOD5/CODCr约0.10,出水CODCr中难生物降解成分占绝大多数,需经过后续物化处理才能达到广东省水污染物控制标准(DB44/26-2001)。

化学除磷药剂对EBPR系统处理效能的影响

为研究化学除磷药剂的种类及投加浓度对强化生物除磷系统(EBPR)处理效率的影响,采用以厌氧/好氧方式运行的SBR反应器,以人工配制废水为进水,通过长期试验,分别考察了FeCl_3和AlCl_3两种除磷药剂的投加对系统出水水质的影响。结果表明:随着化学除磷药剂投加浓度的增加,出水COD浓度逐渐降低,而氨氮去除率未随化学除磷药剂投加量的增加而产生明显的变化;低浓度(Fe^(3+)和Al^(3+)的投加浓度分别不大于8 mg/L和6 mg/L)化学除磷药剂将提高微生物活性,高浓度(Fe^(3+)和Al^(3+)的投加浓度分别为24 mg/L和18 mg/L时)产生抑制效果。长期试验中,当Fe^(3+)、Al^(3+)投加量分别为8 mg/L和6mg/L时,即Fe^(3+)、Al^(3+)投加量分别为8.6、7.0 mg/(g VSS)时,系统厌氧释磷量及好氧吸磷量均达到较大值,系统除磷效果最好,此时磷酸盐去除率分别为96.5%和89.5%。

SBR脱氮系统污泥对磷的去除研究

为了研究缺氧(75 min)-好氧(294 min)交替运行的SBR系统中除磷的原因,采用静态实验,对比了不同碳源、水质及运行环境下对磷的去除情况。实验结果表明,该SBR脱氮系统中的好氧段磷的减少是生物去除的结果。当供给碳源为丙酸-乙酸混合物(摩尔比为2∶1)、葡萄糖、淀粉或蛋白胨时,污泥都可将磷去除,去除效率依次降低;COD/NO3--N为8.77∶1(400 mg/L∶45.6 mg/L)时除磷效果明显好于5.41∶1(400 mg/L∶73.9 mg/L)和3.57∶1(400 mg/L∶112 mg/L);进水磷浓度为8 mg/L时,COD由50 mg/L增加到400 mg/L,污泥对磷的去除效果基本一样;完全的缺氧或完全的好氧环境下,污泥对磷的去除能力逐渐丧失。