直接种间电子传递对缓解厌氧消化抑制效应的研究进展

厌氧消化是将生物质废弃物进行资源化利用的有效途径之一。然而,复杂的原料性质以及反应器高负荷的运行条件会使厌氧消化过程产生多种抑制效应,易导致反应器运行不稳定,产气效率低等问题。因此,提升厌氧消化反应器运行性能、减缓抑制效应成为当前的研究热点。区别于以氢气和甲酸为媒介的间接种间电子传递（Mediated Interspecies Electron Transfer,MIET）过程,微生物间的直接种间电子传递（Direct Interspecies Electron Transfer,DIET）能够在菌群间直接进行电子转移,传递效率更高。DIET的建立有助于强化厌氧反应的稳定性,提高反应效率,减缓抑制效应。基于此,本论文总结了DIET的研究进展,分析了主要的种间电子传递机制,探讨了DIET对不同类型抑制效应的缓解作用,归纳了DIET潜在微生物的富集效果;在此基础上展望了DIET在减缓厌氧消化抑制效应方面的重点研究方向和应用前景。     

花生壳磁性生物炭对颜料污泥厌氧消化及重金属形态的影响

投加外源添加剂磁性生物炭（Magnetic Biochar,MBC）是解决颜料污泥厌氧消化效率低和重金属钝化效率低的有效途径。该研究选取农业废弃物花生壳制备生物炭（Biochar,BC）,而BC对厌氧消化和重金属钝化的影响有限,对其赋磁改性制得MBC以提升影响效果。设置3组厌氧消化批式试验,A组为对照组,B组投加BC,C组投加MBC,探索花生壳MBC对颜料污泥厌氧消化效率及重金属Cr和Ni钝化的影响。结果表明,MBC投加可有效提升消化系统挥发性脂肪酸（Volatile Fatty Acids,VFAs）的产量,最高VFAs浓度达914.5 mg/L,较对照组（最高浓度603.9 mg/L）提升51.4%。同时MBC可实现生物炭和Fe3O4的双重直接种间电子传递（Direct Interspecies Electron Transfer,DIET）效应的耦合,缓解消化系统的酸化并提高有机物去除率和CH4累积产量。与对照组相比,挥发性固体（Volatile Solid,VS）去除率、累积甲烷产量、平均日甲烷产量和平均日甲烷产率分别提升37.8%、56.3%、56.3%和37.2%。此外,MBC投加可有效降低颜料污泥的重金属生物可利用态分配率和提升钝化效率,与原料相比,Cr的可交换态、可还原态质量占比降低43.6%、61.6%,而可氧化态、残渣态质量占比提升53.2%、243.6%;Ni的可交换态、可还原态质量占比降低41.0%、59.2%,而可氧化态、残渣态质量占比提升65.2%、181.4%。研究结果表明MBC可有效提高颜料污泥厌氧消化效率并降低重金属Cr和Ni的生物利用度,该研究有助于实现颜料污泥的稳定化、无害化、资源化利用。     

污泥厌氧消化过程的流变规律与脱水性能

为阐明厌氧消化过程中污泥流变学与污泥理化性能(脱水性能)之间的关联及低温水解预处理对污泥厌氧消化产气的影响,对常规污泥及低温热水解预处理污泥进行厌氧消化试验,结果表明试验结束时,低温热水解-厌氧消化的挥发性固体(volatile solids, VS)去除水平较常规厌氧消化污泥提高3.7个百分点,低温热水解预处理也使得消化污泥的脱水性提高1.59%;污泥屈服应力分别了降低了64.51%和71.47%;稠度系数分别减小了90.94%和92.83%,污泥流动性增强。整个消化过程VS/总固体(totalsolids,TS)和屈服应力随时间的变化均呈对数下降趋势;通过线性方程拟合和皮尔逊相关性分析表明,屈服应力与VS/TS、屈服应力变化与脱水性能改善两两间的拟合优度(R^2)均大于0.94,表明在厌氧消化过程中屈服应力、屈服应力变化与污泥VS/TS、脱水性能具有较好的线性关系。研究结果从流变学角度为厌氧消化过程中的监控和优化提供新思路和理论依据。     

剩余污泥厌氧消化过程重金属形态转化及生物有效性分析

为研究污泥厌氧消化过程中物理化学性质的变化对典型重金属形态转化的影响,对其农用的可行性及生物有效性进行评估,对取自某城市污水处理厂的剩余污泥进行了序批式厌氧消化实验,在试验过程中测定了污泥理化学性质,采用Tessier分步提取法提取了污泥样品中的典型重金属,并采用电感耦合等离子发射光谱仪（ICP-OES）测定各形态重金属含量及总量。结果表明,厌氧消化过程中重金属的形态发生了显著变化,由不稳定态向比较稳定的残渣态和有机结合态转变,某些重金属形态与污泥理化性质如pH、碱度、VS/TS及氨氮显著相关。厌氧消化可以有效地降低污泥中重金属的潜在迁移能力和生物有效性,经厌氧消化后污泥可以更好地进行土地利用。     

用于污泥厌氧消化的温室-太阳能热水器组合增温系统

利用温室-太阳能热水器组合增温工艺提高和保持厌氧消化反应器的消化温度,实现厌氧消化反应器在中温（春、秋、冬季）和高温（夏季）条件下高效稳定运行。以剩余污泥为原料,考察了该组合工艺一年四季的保温效果和污泥厌氧消化产气性能,并对各季节的能源产出和消耗情况进行对比分析。结果表明：与自然环境下的反应器I相比,温室内反应器II的温度在春夏秋三季分别提高了13.0～28.5℃、15.0～26.5℃和10.7～12.2℃,具有良好的增温和保温效果。春夏秋三季污泥厌氧消化的累积产气量分别提高了176.1%、98.8%和109.9%;总固体（TS）和挥发性固体（VS）去除率分别提高了6.8%～27.1%和7.5%～24.1%。通过能源产出和消耗情况分析,发现反应器II在春夏秋三季度的能源转化效率比反应器I提高了21.0%、38.5%和30.3%,冬季的耗能大于产能,但能保证厌氧消化的持续高效运行。     

碳氮比对猪粪与玉米秸秆混合厌氧消化产沼气性能的影响

厌氧共消化是解决当前单一农业生物质废弃物厌氧消化过程中因碳氮元素比例不平衡而造成系统产能不高的问题的有效途径。该研究以猪粪和玉米秸秆为底物在连续搅拌厌氧消化反应器中进行中温厌氧共消化联产气肥,调控底物C/N分别为13.45(完全以猪粪为底物)、20、25、30、35和300(完全以玉米秸秆为底物),考察了底物C/N对工艺性能的影响。试验结果表明,当底物C/N为25时,厌氧共消化反应系统运行稳定,气肥联产性能最优,其中比产气率、甲烷体积分数和总养分质量浓度分别为514.75 mL/(g·d)、64.01%和660.26 mg/L。该研究为开发农业生物质废弃物高效发酵气肥联产工艺提供了技术参数和实践指导。     

农村生活垃圾半连续式厌氧消化产沼气性能及H2S含量控制

为探究农村生活垃圾厌氧消化过程及对H_2S产量的抑制,采用半连续完全混合式反应器,对农村生活垃圾进行半连续式厌氧消化试验,分析在不同有机负荷下厌氧消化系统中有机质的降解性能、产气性能及稳定性,确定生活垃圾厌氧消化最佳有机负荷。同时设计生活垃圾与浓缩污泥不同配比的序批式厌氧消化试验,观察沼气中H_2S含量的变化。研究结果表明:有机负荷为4 g/(L·d)时,产甲烷率上升最为显著,系统稳定运行且生活垃圾的有机质利用率较高;随着浓缩污泥添加量的增加,H_2S含量降低明显,当生活垃圾与浓缩污泥的VS质量比(VSRSW∶VSCS)为1∶0.25,1∶0.5,1∶0.75时,H_2S的降解率分别达到85.15%,88.18%,96.20%。生活垃圾与浓缩污泥的成分分析得出2种物料的金属含量并无明显差异,但浓缩污泥中的腐殖质含量远远高于生活垃圾,进而判断污泥中的腐殖质含量一定程度的影响厌氧消化系统中H_2S的产量。     

微生物直接种间电子传递:机制及应用

微生物种间电子传递(Interspecies electron transfer,IET)是指电子供体微生物与电子受体微生物之间通过直接或间接方式传递电子形成互营生长关系,从而共同完成单一微生物不能完成的代谢过程的现象。IET分为间接种间电子传递(MediatedIET,MIET)和直接种间电子传递(Direct IET,DIET)。其中,前者一般需要氢、甲酸、核黄素等作为电子载体,而后者是指微生物间通过纳米导线、氧化还原蛋白、导电颗粒等进行直接电子交换。DIET是最新发现的IET方式,DIET的发现改变了微生物互营代谢必须依赖氢/甲酸等能量载体的传统认识。本文在论述MIET的同时,重点阐述了DIET的三种介导机制,列举了参与IET的典型微生物种类,系统介绍了IET在厌氧消化产甲烷、甲烷厌氧氧化、微生物脱氯等重要环境过程中的作用机制及应用潜力,并展望了微生物种间电子传递的未来研究方向。本综述有助于加深对微生物IET发生机制的认识,为理解微生物IET在自然界碳氮等元素循环、温室气体排放、污染物降解等关键生物地球化学过程中的作用提供理论基础,为IET的实际工程应用提供可能。     

厌氧消化在线监控技术及发展方向

厌氧消化作为一种生物降解和产沼气技术,已成为解决农业废弃物面源污染问题的有效途径之一。其发酵过程更是一个复杂的生物转化过程,因此过程监控显得尤为重要。该文系统综述了国内外厌氧消化在线监控技术的发展现状,并提出了需要进一步研究的科学和技术问题。分析表明,目前应用于厌氧消化过程的控制系统主要为:基于嵌入式微控制器监控系统、基于可编程逻辑控制器监控系统及基于工业控制计算机监控系统。为控制系统实时传输采集数据的传感器包括:电化学传感器、光谱学传感器、色谱学传感器等。基于目前所研究内容,该文提出:(1)依据厌氧消化过程的特点,搭建更加精准、稳定、适用范围更广的在线监控系统是该领域研究的核心问题;(2)增加有关物料特性方面监测参数,提高沼气产量和厌氧消化效率应是未来的研究重点。     

污泥林用的生态环境风险分析

结合我国城市污水处理剩余污泥产生、特性及处理处置准入要求,对污泥林用全过程存在的生态环境风险进行了分析与识别,并提出了相应的风险防范措施,为污泥林用的生态环境保护与管理工作提供参考。     

Sequential solar photo-fenton-biological system for the treatment of winery wastewaters

In this study, winery wastewaters are considered for degradation using heterogeneous photo-Fenton as a preliminary step before biotreatment. The heterogeneous photo-Fenton process assisted by solar light is able to partially degrade the organic matter present in winery wastewaters. When an initial hydrogen peroxide concentration of 0.1 M is used over 24 h of treatment, a degradation yield of organic matter (measured as TOC) of around 50% is reached. The later treatment (activated sludge process) allows the elimination of 90% of the initial TOC present in pretreated winery wastewaters without producing nondesired side-effects, such as the bulking phenomenon, which is usually detected when this treatment is used alone. The final effluent contains a concentration of organic matter (measured as COD) of 128 mg O2/L. The coupled system comprising the heterogeneous photo-Fenton process and biological treatment based on activated sludge in simple stage is a real alternative for the treatment of winery wastewater.     

Chemical and Ecotoxicological Assessment of Selected Biologically Activated Sorbents for Treating Wastewater Polluted with Petroleum Products with Special Emphasis on Polycyclic Aromatic Hydrocarbons

A chemical and ecotoxicological assessment of treatment of wastewater that had been polluted with petroleum products using only Activated Sludge (AS) and four biologically activated sorbents (BASs), consisting of activated sludge plus: coal-based activated carbon (-C1), coconut shell-based activated carbon (-C2), zeolite (-Z), and anthracite (-A) were conducted. The efficiency and robustness of the four wastewater treatment systems were evaluated by calculating the reduced total petroleum hydrocarbon (TPH) and polycyclic aromatic hydrocarbon (PAH) contents and the acute ecotoxicity of the effluents. The chemical analysis showed that the combined treatment systems were very effective for reducing the total petroleum hydrocarbon and readily bioavailable PAH contents. The most efficient systems were the BAS-C1 and -C2, which removed 60–88% and 99.5–99.6% of TPH and PAH, respectively. The activated sludge-only treatment was the least effective for purifying the wastewater. Chemical oxygen demand was reduced by >90% by all carbon-based BASs (BAS-C1, BAS-C2 and BAS-A). Shifts in the relative composition of the individual PAHs were identified in samples taken before and after treatment. Algal and bacterial bioassays showed that the toxicities of effluents following treatment by all four systems (except AS for algae) were reduced by more than 80% and 90%, respectively. However, crustacean tests indicated that the carbon-based BASs reduced the toxicity [V _tox(50)] only by 19–67%. Our results indicated that the combination of sorption and biodegradation processes have great potential in the treatment of petroleum products polluted wastewater and is less sensitive for inhibitors of the biological process than treatments in which activated sludge alone is used. The assessment of chemical and ecotoxicological endpoints provided valuable information, but contrasting results for one of the assays indicates that further analysis on the capacity of the different treatment systems is warranted.     

Composting of Residuals Produced in the Catalan Wine Industry

The wine industry in Catalonia (Spain) plays an important role in the economy of the region. In this framework, Miguel Torres S.A. is a well known company specializing in production of high-quality wines and brandy, which possesses its own vineyard. Two of the main solid wastes produced in this kind of industry are: stalk (waste from grape harvesting which is only produced during September and October) and wine sludge from the biological wastewater treatment plant which is steadily generated. A composting process was proposed to treat these two organic wastes for recycling its organic matter content to the vineyard crops. Experiments at laboratory-scale in static composting systems did not show positive results for different stalk:sludge mixtures due to the high moisture content of both wastes. Field composting experiments with windrow methods showed that the thermophilic range of composting could be achieved for a 2:1 stalk:sludge volumetric ratio resulting in a complete sanitation of the material with thermophilic temperature of over 55°C for 28 days. The stability and maturity of the final compost were very high (Dewar self-heating test maturity grade V and static respirometric index 0.10 mg O₂·g Total Organic Matter^?1·h^?1). Due to its seasonal production, stalk storage was necessary. A study of the changes of stalk properties during one year is also presented. Bulk density and water holding capacity decreased with storage time while FAS (Free Air Space) and porosity increased. No remarkable changes in organic matter content were observed. Cocomposting of stalk and wine sludge generated in the wine industry is presented as a sustainable waste management strategy, which produces a sanitized fertilizer suitable for application in the vineyard, closing the organic matter cycle.     

污水处理反硝化除磷-诱导结晶磷回收工艺中除磷微生物特性

为探究反硝化除磷-诱导结晶磷回收工艺中缺氧池污泥释磷、吸磷以及微生物特征,利用荧光原位杂交(fluorescence in situ hybridization,FISH)技术、电子扫描显微镜(scanning electron microscope,SEM)观察了微生物的数量、分布和形态;通过批次试验考察了污泥在厌氧/好氧和厌氧/缺氧2种模式下的释磷和吸磷特征。结果表明:该双污泥系统缺氧池中聚磷菌占总细菌比例的69.7%,明显高于单污泥系统中富集的聚磷菌比例,污泥中的微生物多呈杆状;厌氧/好氧、厌氧/缺氧模式下单位污泥浓度(mixed liquor suspended solids,MLSS)总吸磷量(以PO43--P计)分别为22.84、18.60 mg/g,反硝化聚磷菌(denitrifying polyphosphate-accumulating organisms,DPAO)占聚磷菌(polyphosphate-accumulating organisms,PAO)的比例为81.44%,表明在长期的厌氧/缺氧运行条件下可以富集到以硝酸盐为电子受体的反硝化聚磷菌,同时还存在着仅以氧气为电子受体的聚磷菌;通过pH值和氧化还原电位(oxidation reduction potential,ORP)的实时监测可以快速地了解污水生物处理系统中各类反应的进程,对调控工艺参数有着重要的意义。综上所述,为保证污水生物处理工艺的正常稳定运行,将微生物分析与常规的化学参数分析结合起来考察将是未来发展的必然趋势。     

Application of Adsorption and Ultrafiltration Processes for the Pre-treatment of Several Industrial Wastewater Streams

In this work ultrafiltration (UF) was coupled with suitable minerals and dried activated sludge for the pre-treatment of several industrial wastewater streams. The aim was to decrease heavy metal concentrations to low levels so that wastewater can be safely discharged into municipal sewers or biological wastewater treatment can take place without biomass inhibition problems. Industrial wastewater originating from metal plating, chemical and textile industries was employed. The experiments were conducted in a reactor where the UF membrane module was immersed. UF reduced the amount of heavy metals, but the performance was variable with removal efficiencies ranging from 20 to 99.7?%, depending on the metal type and on the wastewater initial characteristics. The prevailing wastewater characteristics were the pH, the presence of certain anions, the suspended solids concentration and the presence of competing cations. The addition of activated sludge and/or minerals could further increase heavy metal removal through the process of sorption. UF assisted by minerals could achieve variable colour and COD removal ranging from 22 to 94?% and 58 to > 99.9?% respectively. Minerals resulted in membrane fouling mitigation, while sludge adversely impacted on fouling.     

Operational Optimisation of Pilot Scale Biological Nutrient Removal at the Ciudad Real (Spain) Domestic Wastewater Treatment Plant

The aim of this work is optimising operating conditions for a possibleimplementation of a Biological Nutrient Removal (BNR) process in the Wastewater Treatment Plant (WWTP) of Ciudad Real (Spain). Several factors (hydraulic retention times, anaerobic nitrate concentration, sludge age and wastewater biodegradability) were tested using a pilot scale VIP (Virginia Initiative Plant) activated sludge process and domestic wastewater from the full scale plant. Hydraulic retention times used did not cause changes in N and P removal. P removal was adversely affected by anaerobic NO₃ ^- and improved with higher BOD₅/COD ratios in wastewater. Influence of sludge age was very low in P removal, but N removal was mainly affected by this factor. Final operating conditions were selected taking into account their effects over one of both nutrients. COD and SS removal were always successful. N removal was also easily reached and the main difficulty was P removal. P sludge content was very low (2.5–4%) approximately and was also affected by the same factors tested. The main factor to improve P removal was supposed to be the organic wastewater composition. Wastewater characteristics were modified by using different sources from the WWTP. Volatile fatty acids (VFA) addition to the wastewater by using supernatant of the anaerobic sludge digesters seemed to be the best practical solution for a future BNR implementation in the WWTP.     

Stoichiometric modeling of the activated sludge process

A mathematical model of the activated sludge process is solved with consideration given to the wastewater composition. Inclusion of wastewater composition will lead to predictions where N or P may be limiting nutrients. The procedure presented is useful when designing or evaluating the operation of an activated sludge process.