垃圾焚烧发电厂储坑渗滤液与NaOH预处理秸秆混合厌氧消化试验研究

本研究将垃圾焚烧发电厂储坑渗滤液视做可再生资源,其与碱处理后的秸秆进行的中温混合厌氧消化表现出典型的水解酸化和甲烷化过程。高浓度储坑渗滤液能产生相对较高的VFA,可提高系统的产气率和产气量。其产气率比未加入渗滤液的厌氧消化系统高出60.15m L/g VS,总产气量高出1868m L。表明该储坑渗滤液可与碱处理后秸秆混合进行再生能源化利用。     

预处理方法对玉米秸秆利用的影响

分别用化学方法(稀硫酸、氢氧化钠、聚乙二醇-4000、曲拉通X-100)和物理方法(液氮超低温处理)对玉米秸秆进行预处理,比较了预处理后木质纤维素酶降解的效果。结果表明:氢氧化钠和液氮超低温处理的降解效率比较好,生成的糖最多。扫描电镜检测证明预处理后的秸秆物理结构发生了较大改变。对预处理后的秸秆进行发酵产沼气能力比较的结果表明,液氮处理后的秸秆产沼气的量最多。     

易腐垃圾厌氧消化沼液理化性质及VOCs分子特征

解析了易腐垃圾厌氧消化沼液(ADLD)理化性质及其挥发性有机化合物VOCs的分子特征与关联性,以期为沼液资源化利用提供基础性质依据。研究发现,沼液理化指标的季节性差异较小,各沼液的差异较大。不同离子在沼液中的存在形式不同。沼液中的重金属含量远低于国内外相关标准限值。共检测304个VOCs分子,主要是芳香族(30%～83%)、烯烃(5%～44%)类化合物。不同厌氧消化工艺产生沼液的VOCs存在差异,干式厌氧消化沼液中芳香族类VOCs较多(32%～83%),而湿式含有更多的醇(1%～20%)和醚(1%～30%)。从沼液中发现了14种植物敏感性VOCs分子(0.05%～15.42%),如水杨酸甲酯、2-丁酮等,这类化合物可以促进植物生理活性。鉴定出共有化合物(1.09%～41.54%),如香料添加剂、食用香精类化合物等。     

改善污泥厌氧消化性能的预处理技术

厌氧消化是污泥稳定化处理的主要技术之一。通过采用一定的预处理技术,破坏细胞结构,释放有机质,促进污泥的水解速率,从而改善污泥厌氧消化性能。该文综述了几种国内外目前研究较为广泛的预处理技术,主要包括热预处理法、转动球磨法、高压喷射法、超声波预处理法、酸预处理法、碱预处理法和氧化法等技术,并分别探讨了各种技术的作用原理、特点、处理效果及应用前景。     

超声波对污泥脱水及厌氧消化影响的研究进展

超声波技术作为污泥厌氧消化预处理手段被广泛关注.超声波能改变污泥的性质,改善污泥厌氧消化的性能,但是其处理效果受到频率、强度、作用时间和发生方式等因素的影响,只有在合适的条件下,预处理效果才能达到最佳.本文着重介绍了超声波的频率、强度、作用时间和发生方式对污泥脱水性能、污泥沉降性能、微生物活性和污泥产气等多方面的影响.由于脱水性能和厌氧消化的改善所需要超声波的条件不一样,所以有必要通过进一步实验使预处理效果最优化;同时,为了进一步降低能耗,有效利用超声波与其它预处理技术相结合将是未来的研究方向.     

秸秆与猪粪混合高固厌氧消化产气性能及关键微生物分析

高固厌氧消化（HS-AD）是处理木质纤维素类原料和其他高固含率有机原料的有效方式之一。本文以节能高效为出发点,研究秸秆和猪粪为混合原料,两者不同配比（秸秆/猪粪的质量比2∶1、1∶1和1∶2）条件下,反应器的运行情况及关键微生物变化情况。结果表明：原料的配比对高固厌氧消化的产气量有明显影响。相比于其他两组实验,秸秆和猪粪的配比为2∶1时,累计产气量最大为229.66L,最终甲烷含量稳定在60.7%左右,转化为单位VS产甲烷量为131.8mL/g VS。同时,反应过程中液相性质（pH、VFA、TIC）的变化,也说明秸秆和猪粪配比为2∶1时,运行平稳且产气较好。另外,微生物分析结果显示,秸秆和猪粪配比为2∶1的实验组,在实验启动的前期,甲烷八叠球菌（Methanosarcinaceae）的相对丰度较高,并且细菌和古菌群落的丰富度和多样性都优于其他两组。     

豆腐渣厌氧消化产沼气的试验研究

本试验以新鲜豆腐渣为沼气发酵原料,控制厌氧消化温度35±2℃的条件下,采用一次性投料,进行厌氧消化产沼气试验,结果表明:豆腐渣是良好的沼气发酵原料,通过分析消化系统pH值、挥发性脂肪酸(VFA)、日产气量和气体成分的变化可知,在投料比(渣泥质量比)为1∶5、1∶2、1∶1时消化系统的变化是一个正常的水解酸化过程,其单位产气率分别为0.87 L/g TS、1.43 L/g TS、0.93 L/g TS。其中投料比为1∶5的消化系统产生的甲烷含量最高可达81.03%,平均甲烷含量为49.95%。而投料比为2∶1、5∶1的消化系统均出现了酸抑制现象,系统不能顺利进入产甲烷阶段。     

玉米秸秆乙酰化改性对环氧树脂性能的影响

针对玉米秸秆良好的亲水性以及与疏水性环氧树脂相容性差的特点,采用在酸性条件下用乙酸酐对玉米秸秆进行表面疏水改性,研究改性前后玉米秸秆对环氧树脂基复合材料的性能影响。分析了乙酰化改性玉米秸秆红外吸收性质、改性前后C,O元素变化,以及环氧树脂复合材料的力学性能和热性能等。结果表明,乙酰化能成功将亲水性玉米秸秆酯化成疏水性结构,但玉米秸秆纤维素晶型并未完全改变。随着玉米秸秆含量的增加,环氧树脂复合材料的拉伸、弯曲、冲击性能均呈现出先增大后减小的趋势,改性后秸秆与环氧树脂界面相容性增强。秸秆添加量增多,复合材料起始分解温度均降低,残余质量均增加,反应速率提高,固化时间变短。     

秸秆类型及配比变化对污泥厌氧消化中微生物群落的影响

为探讨秸秆类型及配比变化对污泥厌氧消化体系中微生物群落结构的影响,采用16S rRNA高通量测序技术,对污泥-秸秆联合厌氧消化体系中微生物群落进行分析。结果表明：玉米秸秆的添加对体系中pH和挥发性脂肪酸（VFAs）的影响较大,尤其是乙酸。而小麦和水稻秸秆的添加对碱度的影响较大,但当配比增加时体系中的VFAs和乙酸浓度也会增加,特别是1∶1.5（挥发性固体质量比）。通过对微生物群落结构分析发现,秸秆类型及配比的变化能显著提高厌氧体系中水解菌和酸化菌的相对丰度（p＜0.001）,如深古菌门Bathyarchaeota、未识别的_c_深古菌门（norank_p_Bathyarchaeota）、拟杆菌门（Bacteroidetes）、阴沟单胞菌门（Cloacimonetes）、同力菌门（Synergistetes）、未分类的_p_阴沟单胞菌门（unclassified_p_Cloacimonetes）、未识别的_c_拟杆菌门_vadinHA17（norank_c_Bacteroidetes_vadinHA17）、（Christensenellaceae_R-7_group）、未识别的_f_紫单胞菌科（norank_f_ Porphyromonadaceae）、未分类的_f_瘤胃菌科（unclassified_f_Ruminococcaceae）、拟杆菌属（Bacteroides）、丙酸杆菌属（Prolixibacter）、长绳菌属（Longilinea）、纤绳菌属（Leptolinea）等菌群;但对体系中乙酸型产甲烷菌（Methanosaeta）和氢型产甲烷菌（甲烷螺菌属Methanospirillum、甲烷杆菌属Methanobacterium和甲烷短杆菌属Methanobrevibacter）的生长产生抑制作用。同时也发现秸秆的添加对甲基型产甲烷菌（Methanomassiliicoccus）的生长具有显著的促进作用（p＜0.001）,从而影响厌氧体系的产甲烷特性。     

畜禽粪污厌氧消化研究进展

中国是世界最大的畜禽养殖国,面临严重的养殖污染问题,畜禽粪污是导致环境污染的原因。厌氧消化是实现畜禽粪污资源化、无害化和减量化的重要技术,不仅适合于工厂化大规模生产,也适合于小规模的家庭养殖。本文论述了畜禽粪污厌氧处理的研究现状和发展趋势,最后分析了厌氧处理的应用前景。     

Combined pretreatment using CaO and liquid fraction of digestate of rice straw:Anaerobic digestion performance and electron transfer

To improve anaerobic digestion (AD) efficiency of rice straw,solid alkaline CaO and the liquid fraction of digestate (LFD) were used as pretreatment agents of rice straw.The results showed that AD performance of rice straw with CaO-LFD pretreatment was optimal in different pretreatment methods of the CaO + LFD,CaO-LFD,LFD + CaO,CaO,and LFD.The maximum methane yield (314 ml·(g VS)-1) and the highest VFAs concentration (14851 mg·L-1 on day 3) of the CaO-LFD pretreatment group were 81％ and 118％ higher than that of the control group,respectively.Under the action of solid alkaline CaO,the bacteria of Clostridium,Atopostipes,Sphaerochaeta,Tissierella,Thiopseudomonas,Rikenellaceae,and Sedimentibacter could build up co-cultures with the archaeal of Methanosaeta,Methanobacterium,and Methanosarcina performing direct interspecies electron transfer (DIET) and improving AD perfor-mance of rice straw.Therefore,the combined pretreatment using CaO and LFD could not only pretreat rice straw but also stimulate co-cultures of microorganism to establish DIET enhancing AD efficiency.     

餐厨垃圾和厨余垃圾厌氧消化产生沼渣的脱水性能分析

以餐厨垃圾和厨余垃圾为原料进行中温厌氧消化反应,采用含固率(TS)、离心脱水后含固率(CTS)、模化毛细吸水时间(NCST)、过滤比阻(SRF)以及结合水含量(BW)为脱水性能评价指标,研究不同厌氧消化阶段产生沼渣的脱水性能。研究发现:沼渣TS变化范围为3.0%～9.9%,CTS为10.9%～31.0%,NCST为50.8～163.7 s·L·(g TS)^-1,SRF为2.1×10¹³ ～13.8×10¹³ m·kg^-1,BW为2.3～15.1 g·(g TS)^-1。厌氧反应器的累计甲烷产量始终是餐厨垃圾高于厨余垃圾,前者最高可达381 ml·(g VS_added)^-1,而后者仅为280 ml·(g VS_added)^-1;沼渣的脱水性能主要受厌氧消化时间的影响。同时,以餐厨垃圾为原料的沼渣可以达到的脱水程度较高,而以厨余垃圾为原料的沼渣的脱水速率较快;沼渣TS与NCST、SRF和BW脱水指标的两两间相关性显著,而与CTS没有明显相关性。     

水热耦合厌氧消化技术处理餐厨垃圾沼渣沼液及工艺能耗分析

以水热与厌氧消化耦合工艺作为餐厨垃圾沼渣沼液（digestate of food waste,DFW）的处理过程,探究了DFW处理前后的脱水性能及固、液两相产物的特性,分析了工艺过程中的物质流动、能量输入/输出,并评估了能量平衡的影响因素。结果表明,水热处理改善了DFW脱水性能,降低了脱水后的泥饼产量和含水率。温度是影响水热处理效果的主要因素,处理效果随温度的升高明显提升。当水热温度为200℃时,离心后泥饼的产量和含水率降低最为显著,分别从最初的71.83kg/t DFW和88.43%减小至22.11kg/t DFW和76.30%。此外,水热过程促进了DFW有机物质从固相向液相的转移,通过耦合厌氧消化处理工艺生产甲烷,可以有效地回收液相能量。本研究对整个处理工艺进行了全面的物质和能量衡算。水热处理温度的提高增加了加热能量的输入,但减少了后续热干化过程的能量输入,并增加了DFW液相产物的产甲烷潜力。当水热温度为160℃、保温时间为60min时,水热与厌氧消化耦合工艺净能量输入最少（30.75MJ/t DFW）,相比于不采用水热技术处理节省106.48MJ/t DFW。水热过程热能的回收率、脱水后泥饼的含水率、液相产物的产甲烷潜势是影响工艺过程能量净消耗的主要因素,是工艺优化的主要方向。     

Dry anaerobic batch digestion of the organic fraction of municipal solid waste

Anaerobic digestion at high solid concentrations (dry anaerobic digestion) is an attractive method for the stabilization of solid organic wastes. A new concept for dry anaerobic batch digestion (BIOCEL) of the organic fraction of municipal solid waste is presented. The start up of a BIOCEL reactor was studied with several methods of process set up and operation. Dry anaerobic digestion of the pure undiluted organic fraction obtained from a shredding/separation process was not accelerated by partial spatial separation of substrate and methanogenic inoculum (granular sludge) or leachate recycle, or both. With these three methods after 30 days the high organic acids concentration and low pH in the reactor indicated a sour reactor, unable to establish significant methane production. When the organic fraction was digested in combination with compost addition (40% (w/w) of the initial solids) and leachate recycle, the stabilization rate increased significantly. Leachate recycling in combination with partial spatial separation of the substrate/compost mixture and the inoculum showed the shortest lag phase in the methane production and the shortest digestion time. When the digested residue of a completed digestion was applied as the methanogenic inoculum (40% (w/w) of the initial total solids) the digestion time was slightly shorter. It is concluded that dilution with compost had a positive effect on the start up of the dry anaerobic digestion and compensated for a suboptimal amount of initial methanogenic biomass. During the start up of dry anaerobic batch digestion of municipal solid waste the rapid recovery of methane formation from an initial overloading was observed and was found to be the result of a population shift in the methanogenic biomass and the existence of zones in the reactor with more optimal conditions (higher p H, lower organic acids concentration). The observed digestion time was 36 days. Recommendations are given to shorten the period needed, for complete digestion.     

Application of A/O‐MBR for treatment of digestate from anaerobic digestion of cow manure

BACKGROUND: Anaerobic digestion (AD) is widely used as an animal manure bioconversion technology. However, the effluent obtained from the digester during the wet‐AD process requires to be treated carefully before discharge if AD technology is to be developed as an effective and environmentally advantageous animal manure treatment. RESULTS: An anoxic/aerobic‐membrane bioreactor(A/O‐MBR) system has been developed for digestate treatment in an AD system treating cow manure. The performance of the A/O‐MBR system in terms of removal of nitrogen, COD and phosphorus were investigated. Results indicated that the average removal efficiencies of NH₄‐N⁺, COD and PO₄^3?‐P were 98.1%, 96.3% and 76.6%, respectively. The fouled membrane from the A/O‐MBR system was cleaned effectively using NaOH and a 30h soak time. CONCLUSION: This study suggests that it is technically feasible to use the A/O‐MBR for the treatment of digestate from a cow manure AD system, and can provide an environmentally acceptable way for the application of wet‐AD in animal manure treatment. Copyright © 2010 Society of Chemical Industry     

Influence of pH on the acid-phase anaerobic digestion of primary sludge

This study explored the effect of pH on the acid-phase anaerobic digestion of primary sludge. Controlled and uncontrolled pH experiments were conducted using two bench-scale, continuous-flow reactors having different configurations: a completely mixed reactor (CMR) with clarifier and solids recycling, and an upflow anaerobic sludge blanket (UASB) unit. Results indicate that the specific rates of VFA production and COD solubilization, in either system, were not affected by the variation in pH between 4·3 and 5·2, but at higher pH values (5·9–6·2) a significant decline (by 25–30%) in both parameters was observed. Analysis of the degradation behavior of the three important organic classes (carbohydrates, proteins, and lipids) revealed that each class followed an individual trend with respect to pH changes. Acetic acid was the major end-product of acidogenic digestion in both reactors, regardless of pH. The percent VFA distribution did not appear to be influenced by pH variation, except for propionic and butyric acids. Besides VFAs, small amounts of formic acid, ethanol, and lactic acid were also formed at all pH values tested.     

纳米零价铁对厌氧消化影响的反应动力学模型

污泥厌氧消化是污水处理厂实现“碳中和”的关键环节。然而传统厌氧消化技术普遍存在水解不充分、产甲烷效率低的问题,在工程中表现为污泥的甲烷潜势（B₀）低、产甲烷速率（k）低等,从而使得获得的甲烷气通常不能达到量和质的要求。纳米级零价铁（NZVI）基于能够在厌氧条件下析氢（H₂）腐蚀为产甲烷菌提供电子供体及更有利的厌氧环境,而被认为在厌氧消化领域具有潜在的应用前景。就此,通过在厌氧消化体系中投加不同剂量的NZVI（0、100、300、600和1000 mg·L^-1）,以甲烷潜势（B₀）和产甲烷速率（k）为主要评价指标,并基于一级反应动力学模型探讨了NZVI对厌氧消化过程的主要作用机理。研究结果表明,NZVI能够强化厌氧消化过程产甲烷,主要作用机制在于促进微生物细胞破壁,从而提高污泥的水解酸化程度,得到更高的甲烷潜势（B₀）。     

Role of Cu(II) and Zn(II) species on the anaerobic digestion of synthetic activated sludge

The effect of different concentrations of copper or zinc on the anaerobic biodegradability of sludge has been investigated. An attempt has been made to correlate the metal forms with the performance of the digester. The presence of organically-bound copper is indicative of the deteriorated condition of the digester. However, an increased HNO₃ extractable fraction is associated with the failure of the zinc-spiked digesters.     

Influence of phosphate and iron on the extent of calcium carbonate precipitation during anaerobic digestion

The extent to which calcium carbonate deposition in an anaerobic reactor can be reduced by adding inhibitors (phosphate and iron) of calcium carbonate crystal growth was investigated. At several concentrations of the additive, the extent of precipitation was assessed in continuous experiments with laboratory‐scale reactors. In the reactor, phosphate concentrations as low as 0.5–5 mg total‐P dm⁻³ were found to severely inhibit CaCO₃ precipitation. However, iron did not inhibit the deposition of CaCO₃, which was found to be due to the fact that iron, in contrast to phosphate, only inhibits the growth of calcite and not the formation of aragonite. The results led to the conclusion that only additives which inhibit the formation of both aragonite and calcite can be used as effective inhibitors during anaerobic digestion. A chemical equilibrium model was developed and shown to be a useful tool to calculate the extent of calcium carbonate deposition during anaerobic digestion provided the proper apparent solubility product of calcium carbonate can be estimated. © 1999 Society of Chemical Industry