Comparison of conventional and inverted A^2/O processes:Phosphorus release and uptake behaviors

Two full-scale systems operated in parallel, a conventional A2/O system consisting of anaerobic, anoxic and oxic compartments in succession and an inverted system consisting of anoxic, anaerobic and oxic compartments without internal recycle, were compared in terms of their phosphorus removal performance, with an emphasis on phosphate （P） release behaviors, using both operational data and simulation results. The inverted system exhibited better long-term phosphorus removal performance （0.2 ± 0.3 vs. 0.7 ±0.7 mg/L）, which should be attributed to the higher P release rate （0.79 vs. 0.60 kg P/（kg MLSS.day）） in the non-aerated compartments. The P release occurred in both the anoxic and anaerobic compartments of the inverted system, resulting in more efficient P release. Although the abundances of the ＇Candidatus Accumulibacter phosphatis＇ population in the two systems were quite similar （（19.1 ＋ 3.27）% and （18.4 ＋ 4.15）% of the total microbe （DAPI stained particles） population in the inverted and conventional systems, respectively, by fluorescence in situ hybridization （FISH））, the high-concentration DAPI staining results show that the abundances of the whole polyphosphate accumulating organisms （PAOs） in the aerobic ends were quite different （the average ratios of the poly-P granules to total microbes （DAPI stained particles） were （45 ±4.18）% and （35 ± 5.39）%, respectively）. Both the operational data and simulation results showed that the inverted system retained more abundant PAO populations due to its special configuration, which permitted efficient P release in the non-aerated compartment and better P removal,

倒置A^2/O工艺的生产性试验研究

为考察倒置A2/O工艺的实际处理效果及影响因素,在某污水处理厂进行了生产性试验。结果表明,对于工业废水占2/3的城市污水而言,倒置A2/O工艺在生产运行中具有较高的去除有机物和脱氮除磷能力;运行中回流比≥2.0,好氧区停留时间为6.0～10.0h,DO为2.0mg/L左右比较合适。整个工艺具有流程简洁、能耗低、运行稳定、抗冲击能力强的特点。

倒置A^2/O工艺的短程生物脱氮中试

在中试规模的倒置A2/O工艺中,考察了通过控制溶解氧浓度实现短程硝化反硝化的效果。试验表明,在溶解氧为0.30.8 mg/L的条件下,可以实现短程硝化反硝化,平均亚硝化率可达64.5%,对TN的平均去除率为66.8%,但易导致严重的污泥膨胀;在低氧(DO=0.30.8 mg/L)与常氧(DO=1.62.5 mg/L)模式交替运行的条件下,可以维持稳定的短程硝化反硝化,平均亚硝化率可达48.4%,对TN的平均去除率为64.3%,对TP的平均去除率可达38.5%,污泥的SVI控制在112 mL/g左右。

倒置A^2／O与改良A^2／O工艺生产性试验比较

以典型高浓度城市污水为处理对象,在生产性试验规模上,比较了不同回流比条件下倒置A2/O工艺与改良A2/O工艺在脱氮除磷效果上的不同,并研究了通过缩短初沉池水力停留时间缓解脱氮除磷碳源矛盾的可行性。试验结果表明,以较低污泥回流比运行的倒置A2/O工艺可以保持较好脱氮除磷效果,与相同污泥回流比而硝化液回流比为300%平行运行的改良A2/O工艺脱氮效果基本相当,但除磷效果优于改良A2/O工艺;提高倒置A2/O工艺污泥回流比至200%左右时,其脱氮除磷效果均优于改良A2/O工艺;通过缩短初沉池水力停留时间可以有效缓解生物脱氮除磷碳源的矛盾,提高系统整体脱氮除磷效果。

仿真模拟改良倒置A^2/O工艺的优化运行策略

以上海嘉定某污水处理厂改良倒置A2/O工艺的调试过程为基础,通过仿真模拟计算,确定了其在不同工况下的最佳运行模式,并优化了最佳模式下的关键运行参数,从而实现达标排放及节能降耗的目的。结果表明,在夏季最佳模式和最优运行参数下,供气量可比优化前减少25%,并且不需要内回流;在冬季最佳模式和最优运行参数下,排泥量减少了17.8%,出水氨氮浓度比优化前低2.3 mg/L。模拟结果对整个污水处理厂的优化运行和节能降耗具有指导意义。

改进倒置A^2/O工艺处理生活污水试验研究

对倒置A2/O工艺进行了缺氧池生物挂膜实验,结果表明,在化粪池出水COD有一定波动情况下,缺氧池COD去除率不仅较高且较稳定,有利于后续硝化反应的进行,提高系统的脱氮效果。同时研究了C/N在缺氧池中对脱氮效果的影响,C/N(质量比)>8.0脱氮效率达80%以上,C/N<6.0脱氮效果较差,证实了C/N是影响反硝化的关键因素。系统进水COD不高,影响了去除效果。

倒置A^2/O脱氮除磷工艺对传统活性污泥法污水厂的改造

为了解决传统活性污泥法处理生活污水存在氮、磷去除率低的问题,本文介绍了倒置A2/O脱氮除磷新工艺的原理及其特点,并采用该工艺对某小型传统活性污泥法污水处理站进行了工艺改造。结果表明,该新工艺对传统活性污泥法污水处理厂进行的改造,可以充分利用原工艺的场地、构筑物及设备,只需少量的改建投资即可达到污水站在保持较高的COD、BOD去除率的同时,出水氮、磷的含量也达到规定的排放要求。

倒置A^2/O工艺生物脱氮效果研究

分别考察了在不同水力停留时间、溶解氧、污泥回流比等条件下,倒置A2/O工艺的脱氮效果和有机物去除效果,结果表明,对于城市生活污水而言,当好氧区水力停留时间为6 h,且好氧区前端溶解氧浓度为3 mg/L、中后端为2 mg/L,污泥回流比为200%时工艺能获得较好的脱氮效果和有机物去除效果。

倒置A^2/O工艺处理城镇河道污水的效能研究

采用连续流的倒置A2/O工艺处理深圳市布吉河水,考察了对COD、NH4+-N、TN、TP的去除效果,以便为新建污水处理厂提供技术参数。结果表明,在总水力停留时间为11 h的条件下,即使在冬季对布吉河水中的污染物仍有良好的去除效果。当进水COD为160～322 mg/L、TN为25.5～64.3 mg/L、TP为2.85～3.96 mg/L、NH 4+-N为24.0～60.2 mg/L时,出水COD为27～63 mg/L、TN为6.46～35.2 mg/L、TP为1.24～2.0 mg/L、NH 4+-N为0.25～29.23 mg/L,平均去除率分别达到82.5%、65.7%、50.1%、88.7%。为进一步降低出水的TP浓度,进行了混凝强化除磷试验。当聚合氯化铝的投量为60 mg/L时,经混凝后出水TP降至0.09～0.48 mg/L,平均为0.32 mg/L,达到了《城镇污水处理厂污染物排放标准》(GB 18918—2002)的一级A标准。

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.

倒置A^(2)/O耦联生物滤池强化生物脱氮除磷的探究

针对传统倒置A^(2)/O工艺(R1)生物脱氮除磷效率不理想的现状,开发了倒置A^(2)/O耦联生物滤池(BAF)(R2)的新工艺,并在中温条件下比较了两工艺对城镇生活废水的脱氮除磷效率。结果表明,稳定运行期R2内出水COD维持在10.7~17.6 mg/L,去除率为92.5%~94.2%,高于R1。延程分析表明,R2内COD主要在缺氧期与厌氧期被消耗。R2内总氮(TN)及总磷(TP)的去除率分别为81.3%~82.8%、85.6%~86.9%,均显著高于R1。机制探究表明,R2强化了硝化过程,使得回流液中硝态氮含量升高,强化了缺氧区的反硝化脱氮过程。在生物除磷方面,R2厌氧期释磷量高于R1,且合成胞内聚合物聚羟基脂肪酸酯(PHA)的最大含量为6.8 mg/g,从而在随后的好氧期产生更多能量用于吸磷。

参数优化对生物絮凝吸附-倒置A^(2)/O组合工艺的影响

采用生物絮凝吸附-倒置A^(2)/O组合工艺处理实际校园生活污水,考察了水力停留时间(HRT)与污泥回流比参数优化对组合工艺脱氮除磷的影响。结果表明:当HRT为7 h,活化污泥回流比为40%时,组合工艺对污水处理效果最佳,对COD的去除率分别为90.98%与91.31%,对氨氮的平均去除率分别为96.02%与96.99%,对TN的平均去除率分别为71.34%与71.23%,对TP的平均去除率分别为87.73%与87.49%,出水水质均能达到国家一级A的排放标准。

Toxicity Reduction of Municipal Wastewater by Anaerobic-anoxic-oxic Process

Objective This study was conducted to optimize the operational parameters of anaerobic-anoxic-oxic （A^2/O） processes to reduce the toxicity of municipal wastewater and evaluate its ability to reduce toxicity. Methods A luminescent bacterium toxicity bioassay was employed to assess the toxicity of influent and effluent of each reactor in the A2/O system. Results The optimum operational parameters for toxicity reduction were as follows： anaerobic hydraulic retention time （HRT） = 2.8 h, anoxic HRT = 2.8 h, aerobic HRT = 6.9 h, sludge retention time （SRT） = 15 days and internal recycle ratio （IRR） = 100%. An important toxicity reduction （%） was observed in the optimized A2/O process, even when the toluene concentration of the influent was 120.7 mg·L^-1. Conclusions The toxicity of municipal wastewater was reduced significantly during the A^2/O process. A^2/O process can be used for toxicity reduction of municipal wastewater under toxic-shock loading.

Full-scale evaluation of reversed A^(2)/O process for removal of multiple pollutants in sewage

This study evaluated the removal of multiple pollutants,i.e.,polybrominated diphenyl ethers(PBDEs),novel halogenated flame retardants(HFRs),sulfonamide antibiotics(SAs),and heavy metals(HMs),by a fullscale reversed A^(2)/O process in a sewage treatment plant(STP)in Guangzhou,China.The reversed A^(2)/O process demonstrated high removal efficiencies(REs)for total PBDEs(60.5%±4.3%),novel HFRs(98.4%±2.8%)and HMs(70.1%±1.2%),and a relatively low RE for SAs(25.0%±2.3%).BDE 209,the dominant PBDE congener,showed a high residual concentration(13.41±5.18 ng/L)in the suspended particulate matter(SPM)of treated effluents.So me novel HFRs,dechlorane plus(DP)and decabromodiphe nyl ethane(DBDPE),were detected in the SPM of the raw sewage(7.50±4.14 ng/L and 11.52±11.65 ng/L,respectively).The removal ofSAs was mainly through biodegradation in the activated sludge bioreactors(ASBs).Ofthe HMs,Mn and Ni exhibited the lowest REs(47.5%±2.2%and 35.0%±2.6%,respectively),while Cr and Cu showed the highest removal(REs>80%).In terms of treatment units in the reversed A^(2)/O process,ASBs showed the highest RE(27.8%)for the multiple pollutants.The information can aid in our understanding of removal properties of STPs on various pollutants and evaluating the ecological/health risks of STPs as point pollutant sources.

西安市某污水处理厂倒置A^2/O工艺改造研究

针对西安市某污水厂一期工程处理能力不足且出水水质无法达到一级A标准的现状,通过对一期工艺的解析和进出水水质的分析,明确了一期倒置A2/O工艺存在缺氧区停留时间不足及污泥处置回流液对水质影响过大的问题,基于一期存在的问题并结合二期扩建工程,提出在好氧池中段增加停留时间为1 h的缺氧段、增加前置缺氧选择池及提高污泥处置效率的工艺改进方案。二期工艺改进建设完成后,出水各项指标均能稳定达到一级A标准。

倒置A^2/O工艺运行效果及优化控制方案

以城市污水处理厂倒置A^2/O工艺为研究对象,介绍了工艺基本情况、主要工艺设计参数及技术特点。对2017—2018年污水处理厂出水的水质进行分析,结果表明:倒置A^2/O工艺可有效去除COD及BOD5,脱氮除磷功能显著。并提出了碳源投加点位、污泥外回流比及曝气池末端DO的优化控制方案。夏、秋季节,控制污泥外回流比为60%~75%、硝化液回流比为100%~150%、曝气池末端ρ(DO)为1.5~3.0 mg/L;冬、春季节控制污泥外回流比为120%~150%、硝化液回流比为200%~250%、曝气池末端ρ(DO)为3.0~5.0 mg/L,可获得较好的污染物去除效果。污水出水ρ(COD)均值为26.1 mg/L,去除率为90.4%;出水ρ(TN)均值为7.69 mg/L,去除率为78.1%;出水ρ(NH^+4-N)均值为0.445 mg/L,去除率为98.3%。通过改变除磷药剂投加点位及建设药剂自动化投加系统的方式优化除磷,实际投加量为2.5 t/d,节省了药剂费用,出水ρ(TP)均值为0.194 mg/L,去除率为96.7%。

白龙港污水厂出水达到一级A的优化运行中试研究

倒置A2/O工艺已广泛应用于新建城镇污水处理厂和老厂脱氮除磷工艺的改造,但在实际运行中常因进水碳源不足和工艺控制不合理,致使出水磷含量无法达到一级A标准。在白龙港污水厂进行中试,研究了混合液回流比、曝气量、进水分流对倒置A2/O工艺除磷效果的影响。试验结果表明,对碳源含量偏低的进水,在保证出水氮浓度达标的前提下适当降低混合液回流比和曝气量,并采用进水分流措施可有效提高除磷效果,出水水质可满足一级A标准的要求。

粪便污水与城市污水合并处理脱氮特性

采用广州市D污水厂倒置A^2／O工艺的模拟反应器，通过单因素试验和正交试验发现，HRT是影响脱氮的最关键因素，为实现高效脱氮，水力停留时间至少应维持8h；在水温28-35℃、粪便污水与城市污水混合比1：300时，最优运行参数如下：泥龄20d、水力停留时间8h、DO质量浓度2．0mg／L、污泥回流比80％、混合液回流比150％。在此工况下运行，NH3-N去除率为97．0％～99．4％，TN去除率为61．4％～68．7％，且出水浓度均可满足《城镇污水处理厂污染物排放标准》一级A标准。

粪便污水与城市污水混合脱氮试验

采用广州市D污水厂倒置A^2/O工艺的模拟装置合并处理粪便污水与城市污水脱氮.结果表明,HRT是脱氮和有机物去除最主要的影响因素,污泥回流比对脱氮影响最小.水温28~35℃时,最优工况确定为氨氮污泥负荷0.018 0 kg NH3-N/kg MLSS.d、SRT 20 d、HRT 8.0 h、DO 2.0 mg.L-1、R 80%r、150%,COD、NH3-N和TN平均去除率分别达到85.5%、98.5%和63.7%,且出水浓度均可满足《城镇污水处理厂污染物排放标准》（GB18918—2002）一级A标准.

粪便污水与城市污水同步脱氮的优化控制

采用倒置A2/O工艺,以实际粪便污水与城市污水同步脱氮为目标进行试验。试验条件下得到,混合污水同步脱氮的临界氨氮污泥负荷为0.019 8 kg.kg-1.d-1;水力停留时间是混合污水脱氮的限制因素;污泥回流比对硝化和反硝化影响最弱;水温28～35℃时,混合污水同步脱氮最佳工况氨氮污泥负荷为0.018 kg.kg-1.d-1、水力停留时间为8 h、溶解氧浓度为2.0 mg.L-1、污泥回流比为80%、混合液回流比为150%、泥龄为20 d。此时,NH4+-N和TN去除率分别为97.0%～99.4%和61.4%～68.7%,出水可达标排放。