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.

Enhanced nitrogen removal at low temperature with mixed anoxic/oxic process

Different hydraulic retention times(HRTs)were tested in a mixed anoxic/oxic(A/O)system at 5C and 10C to investigate the effects of HRT and carrier on nitrogen removal in wastewater at low temperatures.The results showed that the addition of the fillers improved the treatment effect of each index in the system.With an optimal HRT of 7.5 h at 5C,the removal efficiencies of NHþ4-N and total nitrogen(TN)reached 91.2%and 75.6%,respectively.With an HRT of 6 h at 10C,the removal efficiencies of NHþ4-N and TN were 96.7%and 82.9%,respectively.The results of high-throughput sequencing showed that the addition of the suspended carriers in the aerobic zone could improve the treatment efficiency of nitrogen at low temperatures.The microbial analysis indicated that the addition of the suspended carriers enhanced the enrichment of nitrogen removal bacteria.Nitrospira,Nitrotoga,and Nitrosomonas were found to be the bacteria responsible for nitrification,and their relative concentrations on the biofilm at 5C and 10C accounted for 98.11%,92.79%,and 69.98%of all biological samples,respectively.

基于A^(2)/O工艺污水厂改造与提标工程设计

南方某污水厂提标扩建工程,一期A^(2)/O好氧区采用MBBR工艺改造并增大缺氧区容积;二期提标采用高效沉淀池+纤维转盘滤池+紫外消毒工艺,强化脱氮除磷及SS去除,并对全厂进行除臭设计。提标扩建后总规模12×10^(4)m^(3)/d,直接运行成本约0.63元/m^(3),出水均值为COD 17.10 mg/L、BOD55.40 mg/L、SS 5.80 mg/L、NH_(4)^(+)-N 0.90 mg/L、TN 5.90 mg/L、TP 0.30 mg/L。均优于《城镇污水处理厂污染物排放标准》(GB 18918-2002)一级A标准,其经验可供其他污水厂借鉴。

A-O模式MBBR工艺对村镇社区污水的脱氮效果

采用快速排泥法对硝化型和反硝化型MBBR反应器进行启动,并形成A-O模式工艺处理村镇生活污水。结果显示,通过快速排泥法,可以分别在20 d和10 d内完成硝化生物膜和反硝化生物膜的培养;在填充率为40%时,(20.0±0.5)℃水温条件下填料的平均硝化速率和反硝化速率分别为0.48 kgN/(m^(3)·d)和0.55 kgN/(m^(3)·d);当水温为(16.2±2.4)℃时,不投加外碳源,A-O模式的MBBR工艺出水氨氮和总氮可达到一级A标准;反硝化作用主要发生在缺氧池前端,硝化作用主要发生在好氧池后端。高通量测序结果显示,缺氧池前端反硝化菌主要为异养反硝化菌(相对丰度为19.14%),好氧池从前端到后端,硝化细菌菌属逐渐增加(相对丰度从3.09%增加到11.88%),好氧区填料存在一定比例的反硝化菌属(相对丰度为1.35%~4.11%)。A-O模式纯膜MBBR工艺启动迅速,脱氮效率高,系统简单、易于维护,适用于村镇污水处理。

高原强太阳辐射下A^(2)O工艺活性污泥脱氮机制研究

文章通过横向运行太阳辐射、恒温和室温3套平行A^(2)O装置,分析高原太阳辐射对A^(2)O反应器驯化活性污泥过程中微生物丰度和多样性及代谢的影响。结果表明,当运行到第40天时,太阳辐射A^(2)O反应器的脱氮效果相比于恒温、室温装置总体上较差;太阳辐射A^(2)O系统中的操作分类单元数量为595,呈下降趋势,驯化过程中优势菌属代谢功能以有机物降解、反硝化脱氮为主,代谢途径以碳氮代谢为主;反硝化菌的相对丰度随太阳辐射照射时长的增加而增加。运行到40 d太阳辐射A^(2)O系统菌群多样性要低于恒温和室温系统,某些常见的污泥中的优势菌属相对丰度受到了太阳辐射的抑制,但如norank_f__AKYH767脱氮相关的菌属丰度及其功能基因反而在太阳辐射反应器中得到了强化。

Hydrogeochemical and isotopic assessment of the origin of NO_(3)^(−)and N-NH_(3)contents in the aquifer located in a closed lacustrine volcano-sedimentary basin in the metropolitan area of Mexico City

To explain the presence and spatial distribution of NO_(3)^(−)and N-NH_(3)in the Aquifer of the Metropolitan Area of Mexico City(AMAMC),a hydrogeochemical and isotopic analysis using^(13)C DIC(as well as the stable isotopes^(18)O and^(2)H)in groundwater was conducted.This aquifer is located in an old closed lacustrine volcano-sedimentary basin;some wells hosted in the semi-confined zone contain high N-NH_(3)concentrations,while others present NO_(3)^(−)contents in the recharge zones(hosted in an oxidizing environment).In this study,a change in the isotopic signature(primarily in^(18)O and^(2)H)was observed from the recharge zones to the basin center in some of the wells with high NO_(3)^(−)concentrations,this behavior can be attributed to evaporation during the incorporation of recently infiltrated water.In addition,the results for^(13)C(along with ^(2) H)in wells with the highest N-NH_(3)concentrations exhibited an atypically broad range of values.Results indicated the occurrence of hydrogeochemical and/or biochemical processes in the aquifer(in an oxidizing or reducing environment),such as organic degradation,bacterial decomposition(primarily in the ancient Lake Texcoco and which acts as a natural sink for carbon,nitrogen,sulfur,and phosphorus),besides rock weathering and dissolution,which may be responsible for a very marked isotopic modification of the^(13)C(and,to a lesser extent,2 H).Methanotrophic bacterial activity and methanogenic activity may be related to N-NH_(3)removal processes by oxidation and residual water incorporation respectively,whereas the increase in the NO_(3)^(−)content in some wells is due to the recent contribution of poor-quality water due to contamination.

Effect of soil archaea on N_(2)O emission in alpine permafrost

Soil microbial communities are pivotal in permafrost biogeochemical cycles,yet the variations of abundant and rare microbial taxa and their impacts on greenhouse gas emissions in different seasons,remain elusive,especially in the case of soil archaea.Here,we conducted a study on soil abundant and rare archaeal taxa during the growing and non-growing seasons in the active layer of alpine permafrost in the Qinghai-Tibetan Plateau.The results suggested that,for the archaeal communities in the sub-layer,abundant taxa exhibited higher diversity,while rare taxa maintained a more stable composition from the growing to non-growing season.Water soluble organic carbon and soil porosity were the most significant environmental variables affecting the compositions of abundant and rare taxa,respectively.Stochastic and deterministic processes dominated the assemblies of rare and abundant taxa,respectively.The archaeal ecological network influenced N_(2)O flux through different modules.Rare taxa performed an essential role in stabilizing the network and exerting important effects on N_(2)O flux.Our study provides a pioneering and comprehensive investigation aimed at unravelling the mechanisms by which archaea or other microorganisms influence greenhouse gas emissions in the alpine permafrost.

A/A/O与CASS污水处理工艺碳排放评价与碳减排对策

污水处理行业的碳排放定量评估及碳减排潜力挖掘是实现“双碳目标”的迫切需求.文章采用A/A/O工艺(A厂)和CASS工艺(B厂)两种典型工艺的污水处理厂为研究对象,核算框架以《污水处理厂低碳性能评估技术规范》(CAEPI 49—2022)为主要依据,研究结果表明,A厂总碳排放强度(0.43 kgCO_(2)·m^(-3))比B厂(0.30 kgCO_(2)·m^(-3))高0.13 kg CO_(2)·m^(-3);两厂的间接碳排放均为主要贡献,分别占总碳排放强度的55.4%(A厂)、79.2%(B厂),其中,电耗贡献(A厂34.0%、B厂48.6%)均为间接碳排放的最大占比.相较CASS工艺,A/A/O工艺对COD的去除率高11.3%,对TN的去除率低6.8%,但A/A/O工艺总碳排放强度中CH_(4)占比较CASS工艺多29.5%,药耗方面则低6.8%.降低电耗、药耗等间接碳排放是污水处理行业碳减排主要措施.

A^(2)O工艺活性污泥黏性膨胀原因及控制措施

污泥黏性膨胀问题一直是A^(2)O工艺运行控制的难点。郑州市某污水处理厂在运行过程中出现污泥黏性膨胀问题,造成污泥沉降性能变差,SVI逐渐提升至240 mL/g左右,二沉池泥位持续升高。从进水水质、水温、曝气量、浮渣等多方面综合分析引起污泥膨胀的原因,及时从剩余污泥排放量、污泥龄、溶解氧、回流比、水力停留时间等工艺参数调整运行工艺,使污泥膨胀问题得到一定程度的缓解。为彻底消除生物池浮泥,又通过在二沉池配水井精准投加40 mg/L的阳离子高分子絮凝剂,经过一段时间的药剂助沉,明显提高了污泥沉降性能,SVI也逐渐下降至120 mL/g左右的正常水平,解决了污泥黏性膨胀问题,消除了生物池浮泥,为解决污泥黏性膨胀提供了思路。

A/O工艺与A^(2)/O工艺处理城市污水效果分析

本文采用A/O工艺和A^(2)/O工艺对城市生活污水进行处理,分析对比了两种工艺对COD、氨氮、总氮、总磷的去除效果,重点研究了温度、进水ρ(C)/ρ(N)、进水ρ(C)/ρ(P)对废水中COD去除效果的影响,结果表明:在相同条件下,采用A^(2)/O对城市生活污水中COD、氨氮、总氮、总磷的去除效果要明显优于A/O工艺。在废水COD的去除过程中,A^(2)/O工艺受温度、ρ(C)/ρ(N)和ρ(C)/ρ(P)的影响较小,对COD的去除率整体都在85%以上。但是A/O工艺受温度、ρ(C)/ρ(N)和ρ(C)/ρ(P)变化的影响,COD的去除率随着温度的升高呈现先减小后增加的趋势,随ρ(C)/ρ(N)的增加而逐渐下降,随ρ(C)/ρ(P)的增加呈现先增加后降低的趋势,且对COD的整体去除率低于85%。

焦化废水中COD和氨氮的检测与处理

为解决传统焦化废水治理方法在实际应用中存在治理效果不佳、不稳定以及成本高的问题,在对当前焦化废水治理现状分析的基础上,分析了不同治理方法的优劣势,并重点对A1-A2-O-M工艺应用效果进行分析;提出了A-O-BAF工艺对焦化废水中COD和氨氮处理的思路,并对各个阶段的治理效果进行评估,得出该工艺从治理效果、效率以及成本等方面均强于A1-A2-O-M工艺的结论。

A^(2)O-SBR工艺在城镇污水处理厂中的应用

A^(2)O-SBR工艺为A2O工艺与SBR工艺串联组合,为了探究A^(2)O-SBR工艺在城镇污水处理厂的应用效果,分析广西壮族自治区东兴市城东污水处理厂2021年运行情况,结果表明:厂区出水稳定达标排放,A^(2)O-SBR工艺脱氮除磷效果好;COD、NH_(4)^(+)-N、TP平均去除率为87.05%、97.23%、80.86%,最高去除率为97.55%、98.36%、91.21%;出水浓度相对稳定,A^(2)O-SBR工艺对上述三种污染物的去除率也相对稳定,对NH_(4)^(+)-N效果最好,全年去除率稳定达到95%以上;该污水处理厂平均处理成本0.53元/m^(3)。

HPLC法测定不同防风炮制品中升麻素苷和5-O-甲基维斯阿米醇苷的含量

目的建立防风不同炮制品中升麻素苷和5-O-甲基维斯阿米醇苷的含量测定方法并进行比较。方法采用高效液相色谱法(HPLC),使用Hitachi Lachrom-C_(18)色谱柱(150 mm×4.6 mm,5μm),以甲醇-水溶液(40:60)作为流动相,设定检测波长为254 nm、柱温为30℃、流速为1.0 m L/min,进样量3μL。同时,采用快速水分测定仪测定不同炮制品的水分含量。结果升麻素苷和5-O-甲基维斯阿米醇苷分别在14.75~118.00μg/mL和24.00~192.00μg/mL范围内有良好的线性关系。升麻素苷和5-O-甲基维斯阿米醇苷精密度的相对标准偏差(RSD)分别为0.68%、1.13%,重现性的RSD分别为0.64%、1.74%,平均回收率分别为100.80%,95.65%。防风炮制后升麻素苷和5-O-甲基维斯阿米醇苷的含量均有不同程度的下降,虽然微波炮制炒防风的5-O-甲基维斯阿米醇苷含量要低于传统炮制品,但是微波炮制品含量整体高于传统炮制品,炮制后水分含量明显降低,微波炮制品水分含量整体略高于传统炮制品。结论HPLC法快捷、简便、准确、重复性好,可用于防风不同炮制品的质量控制;防风的微波炮制品有效成分含量较高,水分含量略低。

A^(2)O和MBR组合工艺在寒冷地区污水处理中的应用分析

为进一步探究寒冷地区污水处理效果的提升路径,以一污水处理厂冬季出水水质不达标为研究对象,确定采用A^(2)O (Anaerobic-Anoxic-Oxic,厌氧-缺氧-好氧)工艺与MBR (Membrane Bio-Reactor,膜生物反应器)工艺相结合的方式进行污水处理,在设计整体方案的基础上,对具体的工艺流程及参数等内容进行全面优化设计,以完成工艺设计。从实际运行效果来看,设计的A^(2)O和MBR组合工艺在寒冷地区污水处理中取得相对较优的效果,证明其具有一定的实际应用价值。

H_(2)O分子在五边形BCN上的吸附与解离特性研究

基于密度泛函理论的第一性原理计算方法,研究了H_(2)O分子在五边形BCN上的吸附与解离过程.研究结果表明,五边形BCN结构的B原子是H_(2)O分子的最稳定的活性吸附位点.H_(2)O分子在该活性位点极易解离,其初步解离过程为放热反应且分解势垒仅为0.191 eV,并形成稳定的OH/H产物.深入研究发现,H_(2)O分子初步解离后的五边形BCN表面,可直接分解后续吸附的H_(2)O分子.该研究结果为五边形BCN对H_(2)O分子的吸附解离机制提供理论借鉴.

多级A/O工艺设计及其在应急污水处理工程中的应用

为有效缓解资阳市第二污水处理厂现状处理能力不足导致的污水溢流问题,改善周边水生态环境,新建了规模为5000 m 3/d的应急污水处理工程。该工程采用“多级A/O+磁混凝沉淀”组合工艺,对其中的多级A/O工艺段进行了深化设计,并对本项目的实际运行效果进行了分析。深化设计结果表明,多级A/O反应器级数宜采用2级,流量分配比宜为7∶3,污泥回流比宜为100%。运行期间的监测数据表明,出水指标均满足《四川省岷江、沱江流域水污染物排放标准》(DB51/2311-2016),其中的COD Cr、TP和TN的去除率分别为96.6%、97.6%和87.2%。通过设置初段硝化液回流,充分发挥初级缺氧池的脱氮能力,使多级A/O工艺的脱氮效率得到了强化。该项目采用的组合工艺简单有效,出水效果好,为城市溢流污水的高标准排放提供了一种更优选择。

寒冷地区污水处理厂A^(2)O工艺改良调试与运行效果

为进一步提升寒冷地区A^(2)O污水处理工艺的运行效果,以位于寒冷地区的A污水处理厂为研究案例,研究1种具有多点进水、混合液多点回流特性,且适用于寒冷地区污水处理厂的改良型A^(2)O工艺,并从多个角度着手,确定该工艺的设计要点和运行技术参数等内容。从实际应用效果来看,该改良型A^(2)O工艺在寒冷条件下仍可取得较优的处理效果,可为后续相关工作提供参考。

基于混凝-Fenton-A/O联合工艺的环氧树脂生产废水处理研究

某工业园区的废水原始排放已满足排放标准,但需要满足更严格的纳管要求。为了进一步提高生产废水处理效能,研究采用了混凝-Fenton-A/O联合工艺进行小规模试验。通过对混凝-Fenton-A/O联合工艺处理环氧树脂生产废水指标进行连续检测,出水COD、氨氮、BOD_(5)去除率分别为92.9%、75%、87.7%,出水指标均满足工业废水纳管标准。

改良A/O-垂直流人工湿地组合工艺深度处理畜禽养殖废水研究

针对畜禽养殖废水成分复杂较难处理问题,将传统A/O工艺与人工湿地装置进行改良并组合,利用人工湿地进行深度脱氮除磷,探究了单独启动时各因素的影响作用,确定和讨论了组合工艺最佳处理能力,并分析了人工湿地系统中微生物群落的功能与结构变化.结果表明:改良A/O工艺HRT为12 h,回流比为150%,气水比为5∶1时,处理效果最为理想;人工湿地在HRT为48 h达到最佳去除效果;在最佳工况条件下,组合工艺处理后出水COD、NH_(4)^(+)-N、TN、TP的分别为10.34 mg/L、1.63 mg/L、13.70 mg/L、0.39 mg/L,出水浓度均达到《陕西省黄河流域污水综合排放标准》(DB 61/224-2018)B标标准;根据物种丰富度及层次聚类分析结果可知,人工湿地第二级上行流优势类群Chloroflexi(绿弯菌门)丰富度为16.7%,表明人工湿地形成局部厌氧环境;第三级下行流优势菌群Firmicutes(厚壁菌门)丰富度为18.2%,其主要担负脱氮除磷作用.

ZnO/Vo-(111)Cu_(2)O/NiF光催化材料协同PMS氧化高效去除盐酸环丙沙星

针对盐酸环丙沙星(CIP-HCl)的难降解性,本实验成功合成了以泡沫镍为基底的光催化异质结ZnO/Vo-(111)Cu_(2)O/NiF,该复合材料具有良好的光响应强度,电化学阻抗较小;通过光照产生的能量激活PMS,使其生成具有强氧化性的活性物质SO_(4)^(·-);利用光催化协同PMS氧化共同参与盐酸环丙沙星的高效降解,在20 min内降解效率高达97.5%。