The long-term effect of initial pH control on the enrichment culture of phosphorus- and glycogen-accumulating organisms with a mixture of propionic and acetic acids as carbon sources

In most studies on phosphorus- and glycogen-accumulating organisms (PAO and GAO), pH was controlled constantly throughout the entire anaerobic and aerobic periods, and acetic acid was used as the carbon source. In this paper, the effect of long-term initial pH values on PAO and GAO was investigated with mixed propionic and acetic acids as carbon sources. It was observed that with pH increasing from 6.4 to 8.0, the anaerobic propionic acid uptake rate by PAO linearly increased but that by GAO proportionally decreased. At pH 6.70 and pH 7.51, PAO and GAO exhibited the same acetic and propionic acid uptake rates, respectively. The acetic acid uptake rate by PAO was greater than that by GAO at pH > 6.70, and the propionic acid uptake rate by PAO was higher than that by GAO at pH > 7.51, which indicated that PAO would take predominance over GAO at pH > 7.51. Poly-3-hydroxybutyrate, poly-3-hydroxyvalerate and poly-3-hydroxy-2-methylvalerate shared 7%, 62% and 31%, respectively in the PAO system, and 11%, 44% and 45% respectively in the GAO system, and these fractions were observed independent of pH either in the PAO or in the GAO system. In the PAO system, with the increase of pH, the phosphorus removal efficiency was improved greatly, and a phosphorus removal efficiency of 100% was achieved at 8.0. Further investigation showed that the higher phosphorus removal efficiency at higher pH was mainly caused by a biological effect instead of chemical one.     

The long-term effect of initial pH control on the enrichment culture of phosphorus- and glycogen-accumulating organisms with a mixture of propionic and acetic acids as carbon sources

In most studies on phosphorus- and glycogen-accumulating organisms (PAO and GAO), pH was controlled constantly throughout the entire anaerobic and aerobic periods, and acetic acid was used as the carbon source. In this paper, the effect of long-term initial pH values on PAO and GAO was investigated with mixed propionic and acetic acids as carbon sources. It was observed that with pH increasing from 6.4 to 8.0, the anaerobic propionic acid uptake rate by PAO linearly increased but that by GAO proportionally decreased. At pH 6.70 and pH 7.51, PAO and GAO exhibited the same acetic and propionic acid uptake rates, respectively. The acetic acid uptake rate by PAO was greater than that by GAO at pH > 6.70, and the propionic acid uptake rate by PAO was higher than that by GAO at pH > 7.51, which indicated that PAO would take predominance over GAO at pH > 7.51. Poly-3-hydroxybutyrate, poly-3-hydroxyvalerate and poly-3-hydroxy-2-methylvalerate shared 7%, 62% and 31%, respectively in the PAO system, and 11%, 44% and 45% respectively in the GAO system, and these fractions were observed independent of pH either in the PAO or in the GAO system. In the PAO system, with the increase of pH, the phosphorus removal efficiency was improved greatly, and a phosphorus removal efficiency of 100% was achieved at 8.0. Further investigation showed that the higher phosphorus removal efficiency at higher pH was mainly caused by a biological effect instead of chemical one.     

3种短链脂肪酸对活性污泥储存PHA的影响

采用经乙酸钠驯化培养具有一定聚羟基烷酸酯(PHA)储存能力的活性污泥,考察乙酸、丙酸和丁酸3种短链脂肪酸,以及乙酸、丁酸分别与丙酸按1∶1、1∶2、2∶1比例组合成的6种混合酸作为碳源时对活性污泥中PHA的储存和转化的影响。实验结果表明,在3种短链脂肪酸中,以丁酸为碳源得到活性污泥PHA储存量最高,为40.53 mg/g;在混合酸中,乙酸与丙酸按1∶2组合时,系统PHA储存量最高,为773.4 mg/g。混合酸相对于单一的脂肪酸碳源更有利于活性污泥储存PHA。在混合酸总量一定的条件下,随着丙酸比例的增加,乙酸与丙酸混合比丁酸与丙酸混合更有利于微生物的PHA储存。     

The contribution of selected organic substrates to the anaerobic cometabolism of sulfamethazine

Biodegradation of organic micropollutants is likely to occur due to cometabolism by particular microbial groups. In an effort to identify the stages of anaerobic digestion potentially involved in the biodegradation of the veterinary antimicrobial sulfamethazine (SMZ), the influence of selected carbon sources (sucrose, glucose, fructose, ethanol, meat extract, cellulose, soluble starch, soy oil, acetic acid, propionic acid and butyric acid) on SMZ removal by anaerobic sludge was evaluated in short-term batch experiments. Adsorption to the granular sludge constituted a significant removal mechanism, accounting for 39% of SMZ removal in control experiments. The presence of glucose, fructose, sucrose and meat extract exerted an inducing effect on SMZ degradation, resulting in removal efficiencies of 54, 53, 58 and 61%, respectively, indicating the occurrence of cometabolism. Time courses of sucrose and meat extract degradation revealed markedly distinct organic acid profiles but resulted in similar SMZ removals. Temporal profiles of acetic and propionic acid degradation were not associated with SMZ removal, as changes in SMZ concentration were observed even after the organic acids had been completely removed. The experimental results suggest that SMZ cometabolism is not associated to sucrose hydrolysis, acetoclastic methanogenesis and acetogenesis from propionic acid.     

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。     

厌氧接触式反应器预处理高浓度丙烯酸废水

采用厌氧接触式反应器,对自配丙烯酸(AA)废水进行预处理.反应器经污泥驯化稳定运行后,在HRT为12h,进水丙烯酸浓度为1000～3 000 mg/L,丙烯酸容积负荷为2～6 kg AA/(m3·d),污泥负荷为0.67～2.00kg AA/(kg VSS·d)的条件下,丙烯酸去除率达95%以上,出水丙烯酸浓度低于16...     

食品废弃物厌氧消化产乙酸的研究

通过实验,研究了pH、总固体浓度(TS)、碳氮比(C/N)对食品废弃物厌氧消化产乙酸的影响,详细考察了挥发性脂肪酸(VFA)的组成和浓度及乙酸浓度随时间的变化规律.结果表明,pH为6.5、TS为7%(质量分数)、C/N为16:1时,总VFA的最大质量浓度为31.56 g/L,乙酸的最大质量浓度为19.46 g/L.     

酸-碱处理对剩余污泥水解酸化的影响

剩余污泥中富含有机质和营养元素可回收利用物质,污泥水解酸化液中的有机酸在去除或回收利用氨和磷后可作为进水化学需氧量(COD)不足的污水处理厂的补充碳源。通过控制pH,对比分析了不同处理方式(单独碱处理、酸-碱处理和碱-酸处理)对污泥水解酸化的影响。结果表明,单独碱处理的溶解性化学需氧量(SCOD)溶出量比酸碱联合处理要大16%左右,预处理第8天,达到5 406.1 mg/L。采用先酸(pH 4.0,4 d)后碱(pH 10.0,4 d)预处理,乙酸产量达到74.4 mg COD/g VSS,占总SCFAs的60.5%,产量及其占总短链脂肪酸(SCFAs)百分比含量均高于其他预处理方式。且酸-碱处理方式下NO4+-N和PO34--P溶出要优于其他处理方式。而单独碱处理方式下污泥减量效果最好,VSS去除率为36.6%。     

A practical method for quantification of phosphorus- and glycogen-accumulating organism populations in activated sludge systems.

Enhanced biological phosphorus removal (EBPR) from wastewater relies on the enrichment of activated sludge with phosphorus-accumulating organisms (PAOs). The presence and proliferation of glycogen-accumulating organisms (GAOs), which compete for substrate with PAOs, may be detrimental for EBPR systems, leading to deterioration and, in extreme cases, failure of the process. Therefore, from both process evaluation and modeling perspectives, the estimation of PAO and GAO populations in activated sludge systems is a relevant issue. A simple method for the quantification of PAO and GAO population fractions in activated sludge systems is presented in this paper. To develop such a method, the activity observed in anaerobic batch tests executed with different PAO/GAO ratios, by mixing highly enriched PAO and GAO cultures, was studied. Strong correlations between PAO/GAO population ratios and biomass activity were observed (R2 > 0.97). This served as a basis for the proposal of a simple and practical method to quantify the PAO and GAO populations in activated sludge systems, based on commonly measured and reliable analytical parameters (i.e., mixed liquor suspended solids, acetate, and orthophosphate) without requiring molecular techniques. This method relies on the estimation of the total active biomass population under anaerobic conditions (PAO plus GAO populations), by measuring the maximum acetate uptake rate in the presence of excess acetate. Later, the PAO and GAO populations present in the activated sludge system can be estimated, by taking into account the PAO/GAO ratio calculated on the basis of the anaerobic phosphorus release-to-acetate consumed ratio. The proposed method was evaluated using activated sludge from municipal wastewater treatment plants. The results from the quantification performed following the proposed method were compared with direct population estimations carried out with fluorescence in situ hybridization analysis (determining Candidatus Accumulibacter Phosphatis as PAO and Candidatus Competibacter Phosphatis as GAO). The method showed to be potentially suitable to estimate the PAO and GAO populations regarding the total PAO-GAO biomass. It could be used, not only to evaluate the performance of EBPR systems, but also in the calibration of potential activated sludge mathematical models, regarding the PAO-GAO coexistence.     

Temperature influence on biological phosphorus removal induced by aerobic/extended-idle regime

Previous researches have demonstrated that biological phosphorus removal (BPR) from wastewater could be driven by the aerobic/extended-idle (A/EI) regime. This study further investigated temperature effects on phosphorus removal performance in six A/EI sequencing batch reactors (SBRs) operated at temperatures ranging from 5 to 30 °C. The results showed that phosphorus removal efficiency increased with temperature increasing from 5 to 20 °C but slightly decreased when temperature continually increased to 30 °C. The highest phosphorus removal rate of 97.1 % was obtained at 20 °C. The biomass cultured at 20 °C contained more polyphosphate accumulating organisms (PAO) and less glycogen accumulating organisms (GAO) than that cultured at any other temperatures investigated. The mechanism studies revealed that temperature affected the transformations of glycogen and polyhydroxyalkanoates, and the activities of exopolyphosphatase and polyphosphate kinase activities. In addition, phosphorus removal performances of the A/EI and traditional anaerobic/oxic (A/O) SBRs were compared at 5 and 20 °C, respectively. The results showed the A/EI regime drove better phosphorus removal than the A/O regime at both 5 and 20 °C, and more PAO and less GAO abundances in the biomass might be the principal reason for the higher BPR in the A/EI SBRs as compared with the A/O SBRs.     

Micro-electrolysis/retinervus luffae-based simultaneous autotrophic and heterotrophic denitrification for low C/N wastewater treatment

Nitrogen bioremediation in organic insufficient wastewater generally requires an extra carbon source. In this study, nitrate-contaminated wastewater was treated effectively through simultaneous autotrophic and heterotrophic denitrification based on micro-electrolysis carriers (MECs) and retinervus luffae fructus (RLF), respectively. The average nitrate and total nitrogen removal rates reached 96.3 and 94.0% in the MECs/RLF-based autotrophic and heterotrophic denitrification (MRAHD) system without ammonia and nitrite accumulation. The performance of MRAHD was better than that of MEC-based autotrophic denitrification for the wastewater treatment with low carbon nitrogen (COD/N) ratio. Real-time quantitative polymerase chain reaction (qPCR) revealed that the relative abundance of nirS-type denitrifiers attached to MECs (4.9%) and RLF (5.0%) was similar. Illumina sequencing suggested that the dominant genera were Thiobacillus (7.0%) and Denitratisoma (5.7%), which attached to MECs and RLF, respectively. Sulfuritalea was discovered as the dominant genus in the middle of the reactor. The synergistic interaction between autotrophic and heterotrophic denitrifiers played a vital role in the mixotrophic substrate environment.     

超声破解污泥上清液对A~2O工艺脱氮除磷和微生物群落结构的影响

为了提高传统污水处理工艺的脱氮除磷效率、实现污泥资源化,本实验通过超声破解污泥获取碳源,采用耗氧呼吸速率分析上清液作为碳源的可行性,并将上清液回用于生活污水,考察其对A2O工艺长期运行的脱氮除磷效果和微生物群落结构的影响。结果表明,上清液中可降解有机物达到76.2%,具有作为内碳源的潜能;上清液和生活污水按1∶15投入A2O反应器后,氮、磷的去除率分别从63.2%和53.4%提高到了82.1%和94.7%;上清液明显改变了微生物群落结构,使除磷菌Actinobacteia和反硝化聚磷菌Sphingobacterium富集。     

Decolorizing of lignin wastewater using the photochemical UV/TiO2 process

Studies on applying the photochemical UV/TiO2 oxidation process to treat the lignin-containing wastewater for dissolved organic carbon (DOC), color and reducing A254 (the absorption at the wavelength of 254 nm) have been carried out. The data obtained in this study demonstrate that the UV/TiO2 process is effective in oxidizing the lignin thus reducing the color and DOC of the wastewater treated. The combined UV/TiO2 treatment can achieve better removal of DOC and color than the UV treatment alone. Color removal, based on American Dye Manufacture Index (ADMI) measurement, is greater than 99% if the pH is maintained at 3.0 with the addition of 1 g l(-1) TiO2. When 10 g l(-1) TiO2 is applied, the oxidation reduction potential (ORP) value is reached to result in an 88% removal of both DOC and color. A model was developed based on the variation of ORP during the photochemical reaction to simulate the decoloring process. The proposed model can be used to predict the color removal efficiency of the UV/TiO2 process.     

以红薯浸泡液为碳源的生物反硝化

为选择低碳氮比污水生物脱氮中合适的碳源,以搅拌罐浸泡淀粉类物质释放碳源,在确定利用红薯浸泡液为碳源后,以浸没式生物滤池为反应器进行生物反硝化实验。实验结果表明:20 g红薯置于2 L自来水中,采用250 r/m in的搅拌速度,搅拌频率为每搅拌3 h停1 h,2 d后得到的浸泡液COD浓度平均为5 921 mg/L,最高可超过7 000 mg/L;将此红薯浸泡液和污水以1∶50的流量比例,采用分别投加的方式进入反应器,污水中总氮、硝酸盐氮、亚硝酸盐氮及氨氮的平均去除率分别为88.6%、91.6%、88.2%和54.8%,出水COD平均在30 mg/L以下;在红薯浸泡液COD浓度为5 700 mg/L左右时,进水中亚硝酸盐氮浓度与硝酸盐氮浓度比为3∶2时总氮去除率为95.3%,当该比例为2∶3时总氮去除率为88.2%。研究表明,红薯浸泡液是一种经济合适的碳源,采用红薯浸泡液作为低碳氮比污水生物处理中反硝化的碳源是可行的。     

一体式A/O反应器中不同碳硫比对除碳脱臭效率的影响

在污水处理领域同步除碳脱臭研究一直是个难题,本实验开发了一种新型同步除碳脱臭一体式A/O反应器,研究了该一体式A/O反应器处理不同碳硫比有机废水时的同步除碳脱臭功能。结果表明,碳硫比为30∶1时,即进水SO24-浓度为133 mg/L,该反应器总COD去除率可达到95%。在进水SO24-浓度不大于400 mg/L时,中间产物臭气硫化氢气可以完全去除,实现了同步除碳脱臭的功能,减少了在有机废水处理过程中的大量臭气的排放。微生物学角度分析,表明污泥中含有大量的硫细菌。     

Modeling the aerobic metabolism of polyphosphate-accumulating organisms enriched with propionate as a carbon source.

In enhanced biological phosphorus removal (EBPR) systems, polyphosphate-accumulating organisms (PAOs) are primarily responsible for removing phosphate from wastewater. Propionate is an abundant carbon substrate in many EBPR plants and has been suggested to provide PAOs an advantage over their carbon competitors--the glycogen-accumulating organisms (GAOs). The aerobic metabolism of PAOs enriched with a propionate carbon source is studied in this paper. A metabolic model is proposed and experimentally validated to characterize the aerobic biochemical transformations by PAOs. The model predicts very well the experimental data obtained from the enriched PAO culture through solid-, liquid-, and gas-phase analyses. This model may be combined with previously formulated metabolic models to better describe the biochemical activity of PAOs with acetate and propionate as the primary carbon sources. Furthermore, it can also facilitate the study of the effect of different carbon sources on PAO-GAO competition.     

Effect of initial pH control on enhanced biological phosphorus removal from wastewater containing acetic and propionic acids

In the literature most of the studies on the effect of pH on enhanced biological phosphorous removal were conducted with the acetate wastewater, and the pH was controlled during the entire anaerobic and aerobic stages. This paper investigated the influence of anaerobic initial pH control, which will be more practical than the entire process pH control strategy, on enhanced biological phosphorus removal from wastewater containing acetic and propionic acids. Typical pH profile showed that both the initial alkaline and acidic pH tended to neutralize due to the consumption of short-chain fatty acid (SCFA) and intracellular pH regulation by polyphosphate accumulating organisms (PAOs). It was observed that the glycogen degradation and polyhydroxyalkanoates (PHA) accumulation decreased with increasing initial pH, which disagreed with previous reports. In the literature the metabolisms of both glycogen and PHA by PAOs in the acetate wastewater were independent of pH. An anaerobic mechanism model was proposed to explain the intra- and extra-cellular pH buffer nature of PAOs, and to address the reasons for increased polyphosphate degradation and decreased PHA synthesis and glycogen degradation at higher pH. The optimal initial pH for higher soluble ortho-phosphorus (SOP) removal efficiency should be controlled between 6.4 and 7.2. This pH control strategy will be easier to use in practice of wastewater treatment plant.     

(AO)_2SBR同步脱氮除磷的研究

以人工配水为研究对象,采用厌氧/好氧/缺氧/好氧交替运行的序批式反应器,研究了(AO)2SBR系统同步脱氮除磷的效果,并结合批式实验讨论了同步脱氮除磷的反应机理。研究结果表明,该系统以厌氧1.5 h、好氧1 h、缺氧3h、好氧0.5 h的方式运行,在DO=2.5 mg/L,SRT=15 d的条件下,具有良好的脱氮除磷效果,配水中的总氮、总磷、COD和总有机碳的去除率分别为96.26%、99.87%、90.46%和85.57%。批式实验表明,合成的内碳源越多,氨氮的硝化越充分,反硝化除磷越多。     

干式厌氧消化过程挥发酸对硫酸盐还原菌的影响

在牛粪干式厌氧消化过程中,通过添加不同挥发酸(乙酸、丙酸、丁酸),考察消化稳定阶段,挥发性脂肪酸的分布特征,挥发性脂肪酸酸组成变化对硫酸盐还原菌(SRB)的影响,微生物种群组成和种群间关系。实验结果表明,挥发性脂肪酸对SRB还原速率的贡献依次为:丙酸丁酸乙酸。相比乙酸和丁酸,添加一定量的丙酸,更有利于激活SRB的活性,从而加强SRB与产甲烷菌(MB)的种间协同,保证厌氧系统的稳定运行。     

内置缺氧区的改良型Pasveer氧化沟工艺脱氮除磷性能研究

针对传统Pasveer氧化沟内缺氧段碳源难以被反硝化菌充分利用的问题,采用内置缺氧区的改良型Pasveer氧化沟工艺,并进行中试规模实验研究,考察了不同内回流比条件下系统的脱氮除磷效果。研究结果表明,在内回流比为200%的情况下,系统的脱氮除磷效果最好,出水TN和TP的浓度分别降至12.7 mg/L和0.34 mg/L,去除率分别达到61.9%和89.2%。内置缺氧区的设置一方面能使有限的碳源充分用于反硝化,另一方面,促使了反硝化吸磷现象的发生,这使得系统在进水碳源较低的情况下仍能够获得上佳的脱氮除磷效果。但是,过高的内回流比会导致好氧区亚硝酸盐的积累,这对生物除磷是不利的。