Comparative study of two biological nitrogen removal processes:A/O process and step-feeding process

Two biological nitrogen removal processes are compared in the aspect of nitrogen removal, process operation and energy saving. Results show that when the returned sludge ratio is 50% of the inflow rate, the step-feeding process achieves over 80% total nitrogen （TN） removal efficiency, but the TN removal efficiency of the A/O process is only 40%. Moreover, filamentous sludge bulking can be well restrained in the step-feeding process. Given the conditions of a returned sludge ratio of 100% and a nitrifying liquor recycle ratio of 200%, the TN removal efficiency is 78.32% in the A/O process, but the sludge volume index （SVI） value increases to 143 mL/g. In the step-feeding process, the SVI is only 94.4 mL/g when the TN removal efficiency reaches 81. 1%. The step-feeding process has distinct advantages over the A/O process in the aspects of practicability, nitrogen removal and operating stability.

Simultaneous nitrification and denitrification in step feeding biological nitrogen removal process

The simultaneous nitrification and denitrification in step-feeding biological nitrogen removal process were investigated under different influent substrate concentrations and aeration flow rates. Biological occurrence of simultaneous nitrification and denitrification was verified in the aspect of nitrogen mass balance and alkalinity. The experimental results also showed that there was a distinct linear relationship between simultaneous nitrification and denitrification and DO concentration under the conditions of low and high aeration flow rate. In each experimental run the floc sizes of activated sludge were also measured and the results showed that simultaneous nitrification and denitrification could occur with very small size of floc.

Theoretical evaluation on nitrogen removal of step-feed anoxic/oxic activated sludge process

Evaluation on nitrogen removal of step-feed anoxic/oxic activated sludge process at the standpoint of reaction kinetics and process kinetics was conducted. Theoretical biological nitrogen removal efficiency was deduced based on the mass balance of nitrate in the last stage. The comparison of pre-denitrification process and step feed process in the aspects of nitrogen removal efficiency, volume of reactor and building investment was studied, and the results indicated that step-feed anoxic/oxic activated sludge process was superior to pre-denitrification process in these aspects.

Study of control strategy and simulation in anoxic-oxic nitrogen removal process

The control strategy and simulation of external carbon addition were specially studied in an anoxic-oxic(A/O) process with low carbon: nitrogen(C/N) domestic wastewater. The control strategy aimed to adjust the flow rate of external carbon dosage to the anoxic zone, thus the concentration of nitrate plus nitrite(NOx--N) in the anoxic zone was kept closed to the set point. The relationship was studied between the NOx--N concentration in the anoxic zone(S_ NO) and the dosage of external carbon, and the results showed that the removal efficiency of the total nitrogen(TN) could not be largely improved by double dosage of carbon source when S_ NO reached about 2 mg/L. Through keeping S_ NO at the level of about 2 mg/L, the demand of effluent quality could be met and the carbon dosage could be optimized. Based on the Activated Sludge Model No.1(ASM No.1), a simplified mathematical model of external carbon dosage was developed. Simulation results showed that PI controller and feed-forward PI controller both had good dynamic response and steady precision. And feed-forward PI controller had better control effects due to its consideration of influent disturbances.

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.

池塘种稻对养殖水体氮、磷去除效果及对鱼类生长的影响

旨在评估北方养殖池塘中生态浮床种植水稻对水质中氮、磷去除效果及其对养殖鱼类生长的影响。试验选取6个面积均为0.267 hm^(2)的试验池塘,分为试验和对照2个组,每组3个重复。试验组浮床水稻面积占池塘面积20%。试验组和对照组放养鱼类品种、规格、数量、搭配比例、饲料投喂等完全相同。试验期间,每半月监测一次水体总氮(TN)、铵态氮(NH_(4)^(+)-N)、硝态氮(NO_(3)^(-)-N)、磷酸盐(PO_(4)^(3-)-P)、总磷(TP)等水化指标,试验结束后测量各种鱼出池规格,统计各种鱼单位面积产量、总产量、成活率、饲料系数等。结果表明,6月15日试验开始时,试验组和对照组各项水化指标均无差异(P>0.05),7月1日至试验结束,试验组各项水化指标均显著低于对照组(P<0.05)。试验组TN、NH_(4)^(+)-N、NO_(3)^(-)-N、TP、PO_(4)^(3-)-P分别比对照组平均降低55.31%、70.25%、54.61%、68.68%、53.79%。试验结束时,试验组TN、TP分别为0.73 mg/L和0.12 mg/L,均达到了中国池塘养殖尾水排放一级标准。试验组鲫、鲂鱼出池规格和单位面积产量分别显著高于对照组(P<0.05)14.48%、12.68%和12.98%、15.01%,试验组单位面积总产量显著高于对照组(P<0.05)11.59%,试验组各种鱼成活率、鲢、鳙鱼出池规格及单位面积产量与对照组无显著性差异(P>0.05),试验组饲料系数显著低于对照组(P<0.05)7.48%。由此可见,池塘浮床种植水稻对养殖池塘水体中的N、P去除效果显著,并显著提高摄食鱼类产量及饲料利用率。

磁环境下AAO工艺中的微生物群落演替规律

将AAO反应器置于5 mT大小的平均磁场环境,文中研究了磁场对AAO工艺效能的影响,并从分子生物学的角度对其影响机理进行了初步探究。结果表明,在5 mT磁场环境下,AAO工艺启动阶段的平均总氮去除率有较明显提升,比对照组上升6%;AAO反应器启动时间较对照组缩短了5 d;AAO中以固氮螺旋菌(Azospira)为代表的反硝化菌群的相对丰度占比明显提升,丝硫菌属(Thiothrix)的相对丰度占比大幅降低,对污泥膨胀的抑制作用较明显;通过基因功能预测发现磁环境下细胞运动类基因相对丰度相对无磁场条件提升75%,膜运输类基因大幅下降,从而提高了AAO的启动速度,提升了脱氮效能。

曝气生物滤池影响因素及脱氮除磷研究进展

曝气生物滤池(BAF)是一种集吸附、过滤和生物氧化为一体的新型污水生物处理技术。本文介绍了影响BAF运行效果的因素(如填料、水力负荷、气水比、反冲洗、C/N和温度等),综述了BAF在去除水中各类污染物质的最新研究进展,并就该工艺在有机及悬浮物去除、硝化除氨、脱氮除磷、耦合其他工艺等方面所具备的优势与不足进行了阐述,为BAF的发展与应用研究提供一定的科学参考。

小规模高含氮天然气脱氮-液化工艺模拟分析

对于含氮气约为10%、处理量为150 000 m^(3)/d的原料气,当采用常规工艺液化时,不可避免地存在能耗高与LNG储罐安全隐患大等问题。为此,提出脱甲烷塔的塔底加热精馏、塔顶气增压冷凝回流和塔顶气冷凝回流3种脱氮-液化工艺,旨在比选出经济高效、适应性强的脱氮-液化工艺。采用HYSYS软件模拟分析3种脱氮-液化工艺的LNG质量、产量、能耗、排放尾气甲烷含量以及原料气含氮量变化对其适应性,结果发现,塔顶气增压冷凝回流脱氮-液化工艺的甲烷收率最高,达到97.2%;单位能耗最低,达12.81 W/m^(3)原料气;经济效益最好,年收入增加2 076.78万元。因此,该工艺最适合研究原料气的脱氮液化,其分析方法可供类似规模的高含氮天然气脱氮液化工艺比选参考。

脱氮生物滤池在长三角地区城镇污水处理厂中的应用对比分析

选取长三角地区4座城镇污水处理厂中3种典型的脱氮生物滤池,从脱氮滤池设计参数、前后段工艺设计及实际运行情况进行了全面的对比分析。结果表明,滤料是影响滤池形式及运行成本的核心因素,也决定着上下游工艺的选择。在越来越严格排放标准的要求下,脱氮滤池的设计应在调查厂区现状和水质情况的基础上统筹考虑脱氮负荷的分配,保证各个水质指标的稳定达标。最后对实际应用中存在问题及对策进行了总结。

深圳某水质净化厂调试运行关键工艺参数研究

近年来,随着深圳经济的高速发展,片区用水量和污水排放量日益增加,由于配套的污水管网设施不断完善,大量的生活污水和工业废水排入市政污水管,现有的水质净化厂规模已不能满足需求,为满足深圳市治水提质行动方案要求、确保各项规划目标的实现、保证现有配套工程效益的发挥、改善区域水环境,必须扩建某水质净化厂,水质净化厂采用多级AO工艺,出水主要指标执行《地表水环境质量标准》(GB3838-2002)的地表Ⅳ类水标准(TN≤10 mg/L)。经过一段时间的调试,该厂出水COD、NH 3-N、TP和SS稳定达到地表水Ⅳ类标准(出水TN≤10mg/L)。基于实际运行效果,进水配比为1∶0∶0和9∶5∶1,在不同进水配比的运行下总结每段回流比、外循环回流比、总汽水比、污泥龄、各生化池的溶解氧和PAC、PAM、次氯酸钠、乙酸钠药剂的投加量等运行工艺参数并分析运行效果,为水质净化厂的调试运行提供借鉴。

反硝化生物技术在浓盐水脱氮改造中的实践

随着国家和地方环保标准的提高,某石化企业浓盐水处理系统采用“两级臭氧接触池+生物滤池+活性炭滤池”工艺处理后的污水仍不能满足总氮≤15 mg/L的排放标准。因此,在现有处理工艺构筑物的基础上,采用反硝化生物滤池(DNBF)脱氮技术对其进行技术改造,构建出乙酸投加PID控制模型,通过调节DNBF系统C/N、进水TDS、进水温度、控制回流比,使DNBF系统出水硝态氮稳定在8 mg/L左右,经过4 a多的连续运行,外排水质满足国家、地方相关排放标准要求。

多段多级AO工艺处理低碳氮比污水的效能及碳排放分析

在“双碳”背景下,高效处理污水的同时减少碳排放已成为污水处理行业发展的必然要求。多段多级AO工艺处理效果好、脱氮效率高、碳源利用充分、药耗及能耗低,适合低碳氮比城市生活污水的处理。结合工程案例,分析了该工艺在处理低碳氮比污水时的效果,测算了能耗、药耗及碳源利用情况。结果表明,进水碳氮比约为3.0:1时,少量投加碳源情况下,出水总氮质量浓度能达到6.3mg/L,脱氮效果良好。污水处理段碳排放约0.732kgCO_(2)/m^(3),其中生化段碳排放总计约为0.618kgCO_(2)/m^(3),占比约为85%。与脱氮除磷相关的碳排放量约为0.415kgCO_(2)/m^(3),占比约为56.7%,提高脱氮除磷的效率对污水处理的碳减排具有重大意义。该工艺高效低碳的特点,特别适合于南方低碳氮比污水处理,对节能减排具有积极的经济、社会及环境意义。

PN/A工艺应用于主流城市污水处理的研究进展

厌氧氨氧化工艺是一种经济高效的新型生物脱氮工艺,但受限于城市污水特性和自身缺陷,其在主流城市污水处理的应用过程中面临诸多挑战。总结了部分短程硝化-厌氧氨氧化(PN/A)工艺应用于主流城市污水处理的优势和关键问题,重点介绍了相应改进措施,包括城市污水中高负荷有机物的去除、不利生境下功能菌群间的选择性促进与抑制及出水中硝酸盐浓度的降低。并提出了对传统活性污泥工艺进行升级改造、具有无需外加碳源、脱氮效率高等优势的新型PN/A-ED工艺设想,为城市污水处理厂的提标改造和节能减排提供参考借鉴。

氧化还原介体介导厌氧氨氧化生物脱氮的研究进展

厌氧氨氧化(anaerobic ammonium oxidation,Anammox)工艺被认为是一种高效经济且环境友好的生物脱氮技术,是传统生物脱氮工艺的理想替代。然而,该工艺的核心微生物——厌氧氨氧化菌(AnAOB)生长速度缓慢,导致反应器启动时间长,限制了该工艺的实际应用与推广。因此,如何提高AnAOB活性,进一步缩短反应器启动时间成为亟待解决的问题。氧化还原介体(redox mediator,RMs)作为电子载体,通过加速电子传递过程,可增强AnAOB脱氮酶活性和代谢性能,从而提高整体脱氮效果。本文围绕RMs在强化Anammox性能中的作用进行讨论,介绍了RMs的特性、种类及其基本原理,从Anammox性能、胞外聚合物产量、脱氮酶活性及功能菌丰度等方面综述了RMs对Anammox过程的影响,并对其潜在的机理进行了分析和总结,以期为今后的实际应用提供理论依据和参考价值。

BDP(生物倍增)工艺应用于污水处理厂的提标改造

采用BDP(生物倍增)工艺对某污水处理厂进行提标扩建改造工程,工程运行结果表明,该工艺处理效果良好,出水水质稳定,抗冲击负荷能力强,其中COD、BOD5、NH_(3)-N和TP等污染物达到《地表水环境质量标准》(GB3838-2002)中的IV类水标准,TN和SS则满足《城镇污水处理厂污染物排放标准》(GB 18918-2002)中的一级A排放标准。工程实际运行费用为0.94元/m^(3),与国内同类工程相比有一定的运行成本优势。

曝气生物滤池在高标准污水处理厂提标改造中的应用

江苏某市由于区域污染物排放总量的限制,当污水排放量增长后需降低污染物的排放浓度,该市某污水厂因此要进行提标改造,建设规模为1.7×10^(5)m^(3)/d,出水水质由一级A提高至地表“类Ⅲ类水标准”。文中总结了该污水厂提标的设计经验,设计采用“硝化+反硝化+滤布过滤+臭氧-生物活性炭(O_(3)-BAC)+超滤”处理工艺,脱氮处理构筑物采用曝气生物滤池,抗冲击负荷强,运行管理简单,滤池平均36~48 h反冲洗一次,硝化滤池各级出水设置导流板后,反硝化滤池进水溶解氧质量浓度可稳定在4~6 mg/L。单位用地面积为0.15 m^(2)/(m^(3)·d^(-1))。根据2020年—2021年的运行数据,当进水COD_(Cr)、BOD5、SS、氨氮、TN、TP质量浓度为12~26、3.8~7.1、1~6、0.22~2.22、5.34~11.60、0.15~0.40 mg/L时,各污染物平均去除率分别为29%、23%、44%、57%、52%、68%,通过该工艺处理后出水水质稳定达标,为未来污水厂更严格的排放标准提供了升级提标工艺思路和经验借鉴。

缺氧分段式UCT工艺的脱氮除磷效能

在UCT工艺的基础上,提出一种新型缺氧分段式UCT工艺用于高效脱氮除磷。试验考察了新工艺对模拟生活污水的处理效果,并对各个功能单元的氮磷去除能力和微生物群落进行分析。工艺运行结果表明,CODCr、氨氮、TN和TP的平均去除率分别为95.85%、99.37%、83.12%和87.13%。通过氮磷质量平衡发现,前段缺氧池和后段缺氧池均呈现出明显的脱氮能力。同时分段式进水模式有利于系统脱氮能力的提升,从而有效降低回流至厌氧池的NO-3-N浓度,减小NO-3-N对厌氧释磷的不利影响。高通量测序结果揭示了变形菌门(Proteobacteria)和拟杆菌门(Bacteroidota)为优势菌门。在新型UCT工艺中,Candidatus_Competibacter(18.75%~26.43%)、OLB8(7.81%~12.52%)等反硝化菌为优势菌属,Tetrasphaera和Dechloromonas是主要的聚磷菌,有利于实现高效的脱氮除磷。

环丙沙星对短程硝化-厌氧氨氧化工艺脱氮效能的影响

为了研究不同浓度的氟喹诺酮类抗生素环丙沙星对短程硝化-厌氧氨氧化工艺的脱氮效能的影响,采用连续流式反应器进行分阶段长期实验;采用紫外分光光度法、高效液相色谱法及三维荧光光谱法,对不同阶段反应器的脱氮效能、环丙沙星去除率及可溶性微生物产物荧光特性进行表征。结果表明:当环丙沙星的质量浓度为0.1 mg/L时,反应器出水硝态氮的质量浓度由28.71 mg/L增至44.28 mg/L,一段时间后恢复稳定;反应器对环丙沙星的耐药性逐渐增强,恢复稳定期不断缩短;环丙沙星能够改变微生物物种丰富度和多样性以及各属的相对丰度。

城市污水处理中生物脱氮技术的应用及工艺优化路径探析

随着城市化进程的加速,城市污水处理面临越来越严峻的挑战,特别是氮污染问题。生物脱氮技术作为一种高效、环保的处理方法,已经在城市污水处理中得到广泛应用。本文首先分析了生物脱氮技术在城市污水处理中的应用现状,进而探讨了生物脱氮工艺的优化路径;通过对比不同的生物脱氮工艺,提出了针对各类污水处理场景的优化策略,以提升污水处理效果,降低运行成本。