硝酸盐对磷酸盐还原系统除磷效能的影响

通过改变进水硝酸盐浓度，考察了硝酸盐对缺氧和好氧两种不同氧环境下的磷酸盐还原系统除磷效能的影响。试验结果表明，硝酸盐对两种氧环境下磷酸盐还原系统的除磷效能影响显著。当进水硝酸盐浓度为105~160 mg/L时有利于缺氧条件下的磷酸盐还原。而进水硝酸盐对好氧条件下的磷酸盐还原产生显著抑制作用，并且两者存在显著的负相关（R2=0.982 7）。这种差异主要是由于两种不同氧环境下，硝酸盐对微环境构造的影响不同而造成的。同时，不同浓度的进水硝酸盐还会影响反应器内的pH值，进而影响磷酸盐还原进程。结果表明，偏碱性（pH8左右）有利于两种氧环境下的磷酸盐还原。     

磷酸盐生物还原系统构建过程中磷形态的转化研究

对高浓度生活污水磷酸盐生物还原系统构建过程中的磷平衡和磷形态进行了研究。结果表明,反应器在负荷为1.0 kgCOD/(m3·d)、DO浓度为6 mg/L、温度为30℃、不外排污泥、连续曝气的条件下,运行25 d期间对TP的去除率稳定在85%~93%;生物膜污泥中的聚合磷酸盐含量仅为0.274 mgP/gDS,而结合态磷化氢含量高达3.51×106ngP/kgWS;系统每天对外源磷的去除量为44.2 mg,共损失0.77 g的磷,成功构建了磷酸盐生物还原除磷系统。与接种污泥相比,运行25 d后生物膜污泥中的有机磷(Org-P)和无机磷含量分别减少了3.0和1.43 mgP/gDS;在各种无机形态磷中,水溶性活性磷(H2O-P)、金属结合态磷(NaOH-P)、氧化还原敏感态磷(BD-P)、难溶性的无机和有机态聚合磷(NaOH85-P)含量分别减少了84.1%、13.7%、6.24%、27.3%,钙结合态磷(HCl-P)含量增加了68.9%,据此推断磷形态的转化途径可能是Org-P→H2O-P→NaOH-P→BD-P→NaOH85-P→HCl-P。     

疏松和紧密结合EPS在强化生物除磷中的作用

以实验室A/O-SBR反应器活性污泥为研究对象,从EPS分层的角度研究了厌氧/好氧周期中疏松结合胞外聚合物(LB-EPS)和紧密结合胞外聚合物(TB-EPS)的磷含量和形态及其金属元素含量与类型,明确了LB-EPS和TB-EPS在强化生物除磷(EBPR)中的作用。结果表明,EBPR过程是细菌细胞和TB-EPS共同作用的结果,LB-EPS和TB-EPS在EBPR中发挥不同的作用。LB-EPS中转和滞留正磷酸盐(ortho P),细菌细胞直接释放和吸收ortho P;TB-EPS是磷的主要贮存库,参与了生物聚磷,其聚磷酸盐(poly P)发生了厌氧分解和好氧合成。细菌细胞释放和吸收ortho P以及TB-EPS的poly P厌氧分解和好氧合成过程均伴随着K和Mg的释放与吸收,说明K和Mg是EBPR过程中的重要金属元素。     

ASBBR处理榨菜废水的生物还原除磷效能研究

以高盐、高磷榨菜废水为研究对象,探讨了厌氧序批式生物膜反应器(ASBBR)生物还原磷酸盐的除磷效能,考察了温度、pH、负荷及NO3--N浓度等因素对磷酸盐生物还原除磷的影响.研究表明:温度、pH、负荷及NO3--N浓度对磷酸盐还原除磷效果的影响显著.在水温为30℃、pH值为7.1、负荷为1.0 kgCOD/(m3·d)的条件下,反应器对COD和PO43--P的去除率分别为73.75%和39.85%;当NO3--N为105～160 mg/L时有利于磷酸盐还原除磷.     

反硝化聚磷菌菌剂种子液制备条件及除磷机理

为获取高效反硝化聚磷菌(DNPAOs)菌剂种子液以控制水体富营养化,从安徽省天长市污水处理厂氧化沟活性污泥中分离得到1株具有高效脱氮除磷功能的恶臭假单胞菌B8(Pseudomonas putida sp.)。利用多聚磷酸盐颗粒(Poly-P)染色得到具有高Poly-P含量的B8菌剂种子液。其适宜的培养条件为:pH6.5~7.0,温度30~32℃,溶解氧相当于70%~88%饱和溶解氧(摇床转速120~140r/min),培养时间15~20h。所得的反硝化聚磷菌种子液B8具有良好的同步反硝化除磷效果,对于污水厌氧/缺氧(A/A)处理,其聚磷率、硝酸盐氮去除率分别达到89.73%和53.48%,而经厌氧/好氧(A/O)处理磷去除率最高可达94.09%。通过B8胞外聚合物(EPS)提取与磷去除实验表明其对磷酸盐去除源于B8胞内的吸收,而非胞外的生物吸附。     

泥种对高盐同步脱氮除磷系统快速构建的影响

针对高盐条件下生物脱氮除磷系统构建周期长、构建困难的问题,在前期对高盐榨菜废水磷酸盐生物还原除磷及同步硝化反硝化脱氮技术研究的基础上,探讨高盐榨菜废水基于磷酸盐还原除磷的同步脱氮除磷系统的快速构建方法,重点考察不同城市污水厂的接种污泥对系统构建的影响,并采用PCR-DGGE技术探讨了系统微生物种群结构的变化。在盐度为3%(以NaCl计)、水温为(30±2)℃、DO为3～4 mg/L、负荷为0.5 kgCOD/(m3.d)的条件下,接种不同城市污水厂污泥的反应器在18～30 d内均能够成功构建出同步生物脱氮除磷系统,对COD、PO34--P、NH4+-N、TN的去除率分别达到95%、60%、97%和95%以上,泥种对系统构建的影响不显著。PCR-DGGE研究表明:在系统构建过程中微生物群落结构发生了变化,但与接种污泥微生物种群仍存在56.4%的相似度,表明接种污泥中有部分微生物可以适应高盐环境。     

三种除磷药剂的除磷性能比较

比较了锁磷剂、聚合硫酸铁(PFS)和聚合氯化铝(PAC)的除磷性能.在原水的磷酸盐浓度为1 mg/L(以P计)的条件下,若将磷酸盐浓度降到0.4 mg/L以下,三者的最佳投量分别为150、1和20 mg/L;14 d的监测结果表明,PFS的除磷长效性较差,而锁磷剂和PAC具有较佳的除磷长效性,在富营养化水体除磷应用上更具优势.     

节水与技术创新

一、我国节水、环保技术的现状与弊端我国工业循环冷却水处理技术,是上世纪70年代随着大化肥项目的引进而引入的,主要是磷系配方技术,包括有机磷酸盐、聚磷酸盐、磷酸脂类或聚磷酸盐与聚羧酸盐复配等延伸配方。该技术的基本特点是在工业循环冷却水中     

长期低负荷运行对污水生物除磷的影响

长期低负荷运行是导致城市污水处理厂生物除磷效率降低的主要原因。低负荷下的好氧延时曝气使聚磷菌细胞内的聚 β -羟基丁酸 (PHB)含量下降 ,导致磷的吸收速率和吸磷量下降 ,从而无法有效地吸收细胞外的磷酸盐合成聚磷 ,最终丧失生物除磷能力。通过有效地调整曝气系统不仅可以降低运行费用 ,而且可以保证生物处理系统的稳定性 ,提高生物除磷的效率。     

底物条件对好氧磷酸盐还原除磷效能的影响

通过改变底物条件,考察了初始C/P值、进水PO43--P浓度对好氧磷酸盐还原除磷效能的影响。结果表明,底物条件对好氧磷酸盐还原除磷效能的影响显著,初始C/P值过高或过低均不利于磷酸盐的还原。当初始C/P为100时,SBBR反应器对磷酸盐的去除率达到最高,平均去除率为52.93%,表明磷酸盐还原菌为异养菌。同时,在碳源充足的条件下,增加进水PO43--P浓度可提高对磷酸盐的去除量,并且两者之间以及磷酸盐去除量与COD去除量之间均呈显著的正相关。工艺适用性分析表明,磷酸盐还原除磷工艺适用于处理人畜粪便污水、污泥消化液、榨菜废水等碳源充足的高磷污(废)水。     

Biochemical model for enhanced biological phosphorus removal

Enhanced biological phosphorus (bio-P) removal from wastewater is a promising technology for which the fundamental mechanisms are still unclear. The purpose of this paper is to present a biochemical model that explains bio-P removal mechanisms occurring under anaerobic, aerobic and anoxic conditions of the process. A bio-P bacterium is referred to as one that can store both polyphosphate and carbon (as poly-β-hydroxybutyrate for example). In this communication, observations from the literature are first reviewed and mechanisms of bacterial bioenergetics and membrane transport are summarized. The model for bio-P metabolism under anaerobic, aerobic and anoxic conditions is then presented. The role of polyphosphate under anaerobic conditions is suggested to be as a source of energy both for the reestablishment of the proton motive force, which would be consumed by substrate transport and for substrate storage. The role of the anaerobic zone is to maximize the storage of organic substrates in bio-P bacteria. For this purpose the supply of readily available substrates should be maximized and the presence of electron acceptors (molecular oxygen or oxidized nitrogen) minimized. Under subsequent aerobic or anoxic conditions, bio-P bacteria will accumulate polyphosphates in response to the availability of electron acceptors (oxygen or oxidized nitrogen) for energy production. Carbon reserves in bio-P bacteria should provide energy for growth and for soluble phosphate accumulation as polyphosphate reserves.     

Towards a luxury uptake process via microalgae - Defining the polyphosphate dynamics

Microalgae in waste stabilization ponds (WSP) have been shown to accumulate polyphosphate. This luxury uptake of phosphorus is influenced by the wastewater phosphate concentration, light intensity and temperature, but the dynamics of how these factors affect luxury uptake with respect to time are not understood. With improved understanding of the dynamics of this mechanism and how it could be manipulated, a phosphorus removal process utilizing luxury uptake by microalgae might be developed. In this work, luxury uptake was investigated by chemical extraction of the acid-soluble and acid-insoluble fractions of polyphosphate in the microalgae. The results showed that the initial accumulation and subsequent utilization of both acid-soluble polyphosphate (ASP) and acid-insoluble polyphosphate (AISP) is a function of the wastewater phosphate concentration. It was found that light intensity influenced both the accumulation and utilization of ASP. The temperature influenced the accumulation of AISP. AISP is believed to be a form of phosphorus storage and ASP is involved in metabolism however, the results of this work show that ASP can also act as a short term form of phosphorus storage. To optimize luxury uptake by microalgae a ‘luxury uptake pond’ is proposed where the conditions the microalgae are exposed to can be manipulated. This ‘luxury uptake pond’ would be designed to expose the microalgae to a high phosphate concentration and high light intensity for a short period of time in order to achieve optimal polyphosphate accumulation. Subsequent harvesting would then remove the phosphorus rich microalgae from the system.     

Endogenous processes during long-term starvation in activated sludge performing enhanced biological phosphorus removal

In many biological wastewater treatment systems, bacterial growth and the amount of active biomass are limited by the availability of substrate. Under these low growth conditions, endogenous processes have a significant influence on the amount of active biomass and therefore, the overall system performance. In enhanced biological phosphorus removal (EBPR) systems endogenous processes can also influence the levels of the internal storage compounds of the polyphosphate accumulating organisms (PAO), directly affecting phosphorus removal performance. The purpose of this study was to evaluate the significance of different endogenous processes that occur during the long-term starvation of EBPR sludge under aerobic and anaerobic conditions. Activated sludge obtained from a laboratory sequencing batch reactor was used to perform a series of batch starvation experiments. Under aerobic starvation conditions we observed a significant decay of PAO (first-order decay rate of 0.15/d) together with a rapid utilization of polyhydroxyalkanoates (PHA) and a slower utilization of glycogen and polyphosphate to generate maintenance energy. On the other hand, anaerobic starvation was best described by maintenance processes that rapidly reduce the levels of polyphosphate and glycogen under starvation conditions while no significant decay of PAO was observed. The endogenous utilization of glycogen for maintenance purposes is currently not included in available EBPR models. Our experimental results suggest that mathematical models for in EBPR should differentiate between aerobic and anaerobic endogenous processes, as they influence active biomass and storage products differently.     

Advancing post-anoxic denitrification for biological nutrient removal

The objective of this research was to advance a fundamental understanding of a unique post-anoxic denitrification process for achieving biological nutrient removal (BNR), with an emphasis on elucidating the impacts of surface oxygen transfer (SOT), variable process loadings, and bioreactor operational conditions on nitrogen and phosphorus removal. Two sequencing batch reactors (SBRs) were operated in an anaerobic/aerobic/anoxic mode for over 250 days and fed real municipal wastewater. One SBR was operated with a headspace open to the atmosphere, while the other had a covered liquid surface to prevent surface oxygen transfer. Process performance was assessed for mixed volatile fatty acid (VFA) and acetate-dominated substrate, as well as daily/seasonal variance in influent phosphorus and ammonia loadings. Results demonstrated that post-anoxic BNR can achieve near-complete (>99%) inorganic nitrogen and phosphorus removal, with soluble effluent concentrations less than 1.0 mgN L⁻¹ and 0.14 mgP L⁻¹. Observed specific denitrification rates were in excess of typical endogenous values and exhibited a linear dependence on the glycogen concentration in the biomass. Preventing SOT improved nitrogen removal but had little impact on phosphorus removal under normal loading conditions. However, during periods of low influent ammonia, the covered reactor maintained phosphorus removal performance and showed a greater relative abundance of polyphosphate accumulating organisms (PAOs) as evidenced by quantitative real-time PCR (qPCR). While GAOs were detected in both reactors under all operational conditions, BNR performance was not adversely impacted. Finally, secondary phosphorus release during the post-anoxic period was minimal and only occurred if nitrate/nitrite were depleted post-anoxically.     

Potential phosphorus recovery in a WWTP with the BCFS process: interactions with the biological process

The BCFS process was developed to optimize the activity of denitrifying and P-removing bacteria. In this technology in combination with optimal operating conditions for biological nitrogen removal, chemical precipitation of phosphorus is used to ensure compliance with effluent standards regarding phosphorus. This work addresses the potential of the BCFS technology for phosphorus recovery and the interactions with the biological process. The TUD model calibrated for the Hardenberg WWTP was used. Nitrification was the biological process most influenced by the P stripper operation; however, further research is needed into the effect of limiting phosphate concentrations. Phosphate removal in the anaerobic reactor causes a decrease in the sludge poly-P content. The evaluation of the process operation under dynamic conditions showed that the P stripper use for phosphate recovery does not imply complicated control strategies. The use of the BCFS for phosphate recovery implies a change in the design philosophy not only to achieve the effluent requirements but also to maximize the anaerobic phosphate release and thereby recovery.     

Interactions between calcium precipitation and the polyphosphate-accumulating bacteria metabolism

A sequencing batch reactor that is operated for biological phosphorus removal has been operated under different influent calcium concentrations to study the precipitation process and the possible effects of phosphorus precipitation in the biological phosphorus removal process. Four experiments were carried out under different influent calcium concentrations ranging from 10 to 90 g Ca m(-3). The experimental results and the equilibrium study, which are based on the saturation index calculation, confirm that the process controlling the calcium behaviour is the calcium phosphate precipitation. This precipitation takes place at two stages: initially, precipitation of the amorphous calcium phosphate, and later crystallization of hydroxyapatite. Also the accumulation of phosphorus precipitated was observed when the influent calcium concentration was increased. In all the experiments, the influent wastewater ratio P/COD was kept constant. It has been observed that, at high calcium concentration, the ratio between phosphate release and acetate uptake (P(rel)/Ac(uptake)) decreases. Changes in the polyphosphate-accumulating organism (PAO) population and in the glycogen-accumulating organism (GAO) population during the experimental period were ruled out by means of fluorescence in situ hybridization. These results could suggest that PAO are able to change their metabolic pathways based on external conditions, such as influent calcium concentration. The accumulation of phosphorus precipitated as calcium phosphate at high influent calcium concentration throughout the experimental period confirmed that phosphate precipitation is a process that can affect the PAO metabolism.     

Stability of enhanced biological phosphorus removal and composition of polyphosphate granules

The influence of varying Ca- and Mg-concentration of the influent wastewater on the enhanced biological phosphorus removal was investigated in an anaerobic-aerobic bench-scale plant. The artificial enhancement of the Mg-concentration in the influent from 15 to 24 mg l(-1) and 31 mg l(-1), respectively, caused a raise of the mean P-removal efficiency from 85 to 97%. The P-elimination was very stable in time. A chemical precipitation of magnesium ammonium phosphate could be excluded. The elemental composition of polyphosphate granules was investigated by electron microscopy and energy dispersive X-ray spectroscopy. The elements Ca, Mg and K were the principal metal components of polyphosphate granules. Concerning the metal composition, different types of granules could be distinguished. The quantitative ratios of Ca, Mg and K varied in dependence on the influent concentration of these metals. A relation between the Mg/Ca-ratio of the granules and the efficiency of enhanced biological phosphorus removal can be supposed.     

Biological phosphate removal by activated sludge under defined conditions

A simple, one reactor vessel system, called a fill-and-draw system, was developed for the study of enhanced biological phosphate removal under defined conditions. Sludge was grown in a medium with acetate and glucose as sole energy and carbon sources. The sludge was exposed to cycles with three distinct, consecutive periods; first an anaerobic period, then an aerobic period and finally a settlement period. In the period of settlement one third of the liquid was replaced with fresh medium. Sludge grown under this regime became considerably enriched with polyphosphate-accumulating bacteria. The polyphosphate content reached up to 110 mg P/g dry weight. The amount of polyphosphate in the cells during steady state depended on the acetate:glucose ratio, the nitrate and phosphate concentration in the medium. Highest phosphate accumulation was obtained with an acetate:glucose ratio of 9:1. Intracellular polyphosphate was formed during the aerobic period and was anaerobically hydrolysed and released as phosphate into the medium. In the absence of oxygen and in the presence of 2g acetate-COD/l, 80–90% of phosphate was released by sludge containing 100 mg P/g dry weight. In the absence of acetate only 2–19% of the accumulated phosphate was excreted.     

Calibration of denitrifying activity of polyphosphate accumulating organisms in an extended ASM2d model

This paper presents the results of an experimental study for the modelling and calibration of denitrifying activity of polyphosphate accumulating organisms (PAOs) in full-scale WWTPs that incorporate simultaneous nitrogen and phosphorus removal. The convenience of using different yields under aerobic and anoxic conditions for modelling biological phosphorus removal processes with the ASM2d has been demonstrated. Thus, parameter η_PAO in the model is given a physical meaning and represents the fraction of PAOs that are able to follow the DPAO metabolism. Using stoichiometric relationships, which are based on assumed biochemical pathways, the anoxic yields considered in the extended ASM2d can be obtained as a function of their respective aerobic yields. Thus, this modification does not mean an extra calibration effort to obtain the new parameters. In this work, an off-line calibration methodology has been applied to validate the model, where general relationships among stoichiometric parameters are proposed to avoid increasing the number of parameters to calibrate. The results have been validated through a UCT scheme pilot plant that is fed with municipal wastewater. The good concordance obtained between experimental and simulated values validates the use of anoxic yields as well as the calibration methodology. Deterministic modelling approaches, together with off-line calibration methodologies, are proposed to assist in decision-making about further process optimization in biological phosphate removal, since parameter values obtained by off-line calibration give valuable information about the activated sludge process such as the amount of DPAOs in the system.     

污水强化除磷工艺的现状与未来

对强化生物除磷工艺的基本概念、外加碳源的作用、脱氮除磷的关系、环境影响参数进行了阐述,并介绍了聚磷菌菌群研究的最新进展。最后探讨了如何通过生产鸟粪石(MAP)实现磷元素回收,并围绕污水除磷和回收磷这一课题,提出了研究方向。