厌氧消化过程的多功能性

本文从厌氧消化的多菌群协同作用和代谢多样性的特征出发,提出了古细菌（产甲烷菌）的“古环境”是由非产甲烷菌代谢所保持和建立的;预示了厌氧消化系统的多功能性。     

厌氧消化技术发展前景广阔

本文报导第八届国际厌氧消化会议的概况,厌氧消化是处理有机废物既省能又产能的技术,正引起国际上的重视。中国是厌氧发酵技术大国。应用厌氧消化技术处理废物,以达到净化环境、获得能源的目的,将在中国有进一步发展的广阔前景。     

微生物组学及其在厌氧消化中的研究进展

我国每年产生大量的有机废弃物,如果处置不当将会对生态、气候以及人类健康造成重大影响。厌氧消化是一种可靠的、绿色的、可持续的有机废弃物处理方式,但由于缺乏准确有效的监测手段,厌氧消化微观过程常常被视为“黑盒”。随着微生物组学的发展,学者们在菌群与运行参数关联性分析、代谢途径分析等方面有了更深入的认识。本文从“三阶段、四菌群”的厌氧消化过程出发,介绍了常用微生物组学的类型,包括:16S rRNA基因组、宏基因组、宏转录组和宏蛋白组;详细阐述了物种组成分析、α多样性分析、OTU相似性分析以及多元统计学分析等6种常用的微生物群落生物信息学分析方法;系统回顾了厌氧消化过程的微生物学研究进展,以期能为分析厌氧消化的微生物群落结构和功能、开发新的厌氧消化工艺和技术提供支持。     

淀粉酶活在厌氧消化过程中的变化研究

本文研究了淀粉酶在厌氧消化过程听变化规律及对沼气形成的影响关系,结果表明,糖化型淀粉酶活性与沼气产量是相关性,酶活高峰期也就是产气高峰,糖化型淀粉酶在此时酶活高达４２１９ｍｇ葡萄糖／１００ｍｌ．ｈｏｕｒ,发酵结束后酶活高于原料中的酶活,其酶主要来自发酵原料。     

厌氧消化法处理畜禽粪的研究

本文报导了２个沼气工程的概况。其一是上海跃进农场的装置１２８ｍ３的上流式厌氧污泥床（ＵＡＳＢ）,该装置于１９８５年建成,已正常运行８年。用于处理２万羽鸡的粪水,２０～２４℃发酵,共产气４５万ｍ３。平均产气率１．３５ｍ３／ｍ３．ｄ。ＣＯＤ去除率８８％。产生的沼气供应１２０户居民使用。其二是上海星火农场沼气站,该站为处理２７００头奶牛的粪便,于１９９１年建成了２７００ｍ３上流式全混合型厌氧消化装置,日处理牛粪便８０吨,鸡粪２０吨,２５～３１℃发酵。至１９９６年底,共产气３６０万ｍ３,供应了３０００户职工及１０个集体单位使用。发酵残留物全部进行了综合利用,不但净化了环境而且创造了较好的经济效益。２个工程长期稳定运行的结果表明,沼气工程的工艺设计先进,设备配套齐全,可为全国畜禽粪的处理提供供鉴。     

大型奶牛场粪便厌氧消化工程的研究

本文报导了大型牛场粪便厌氧消化工程研究的概况。该工程针对牛粪草多、浮渣多的特点设计了除长草、除浮渣装置。以保证了厌氧消化的稳定运行。工程每天可处理奶牛粪便８０余吨、鸡粪及工业发酵废渣２０余吨,生产沼气供应２８６８户职工家庭作燃气使用,平均沼气率为１．２ｍ＾３／ｍ＾３．ｄ。经后处理的发酵残留物被充分利用,制成肥料、绿色营养土和鱼饵,这样既免除了二次污染,又提高了工程的经济效益。该工程为我国大中型沼气     

厨余垃圾厌氧消化合成高附加值化学品的研究进展

厨余垃圾在生活垃圾中占比巨大,已对食品安全、自然资源可持续利用和环境造成了不利影响,故亟须实现厨余垃圾的有效处理及利用。目前处理厨余垃圾最常用的方式主要包括填埋与焚烧,但存在易产生二次污染、耗能大等问题,阻碍了其大规模应用。厨余垃圾具有有机质含量高的特性,通过生物炼制合成高附加值化学品(如有机酸等),不仅可实现产品的清洁生产,也可提高厨余垃圾的经济价值。本文首先概括了国内外厨余垃圾的处理现状及处理方法,其中厌氧消化法可清洁生产高附加值产品,展示出巨大的研究潜力。因此,对厌氧消化厨余垃圾合成化学品进展进行详细综述,最后对构建人工混菌培养体系和生物膜调控在厨余垃圾生物制造领域的应用提出了展望。     

厌氧消化消化残留液中游离氨基酸含量的测定

采用ＧＣ－９Ａ气相色谱仪进行三种不同原料厌氧消化残留液中游离氨基酸珠测定。实验结果表明,鸡粪厌氧消化残留液中游离氨基酸种类最多,且含量较其他两种残留液高,鸡粪残留液更适于再利用。     

餐厨垃圾协同剩余污泥发酵产酸的生物过程与影响因素研究进展

资源化利用是应对餐厨垃圾(Kitchen waste,KW)和剩余污泥(Excess sludge,ES)快速增加的有效方法,而厌氧发酵获得挥发性脂肪酸(Volatile fatty acids,VFAs)是其中的重要方式之一,但单一底物限制了VFAs的高效生产.近年来,不同底物厌氧共发酵产生VFAs被广泛研究与应用,...     

厌氧酸化菌产酸过程研究

以葡萄糖模拟废水为研究对象,在温度37±0．5℃下,通过对不同影响因素下酸化过程的研究,确定水解酸化最佳条件为pH=6．5。重点对此条件下水解酸化过程中产酸速率的动力学进行了推导,通过计算,得出此条件下的动力学常数为V_(max)=8．45~(-1),K_s=1,089mg/L。说明了酸化过程较好氧过程和完全厌氧过程快的理论依据。     

Laboratory scale examination of the effects of overloading on the anaerobic digestion by glycerol

The anaerobic digestion of pure glycerol, which produces a baseline acetic acid to propionic acid ratio of 0.2, was studied in laboratory scale reactors (3 l working volume) at mesophilic temperature (37 °C) with 3000 mg chemical oxygen demand (COD) l⁻¹d⁻¹. During the experiment tVFA and C2-C6 VFA analysis and daily biogas yield measurement were carried out. Following 10 days of a 15% d⁻¹ increase in the organic loading rate (OLR) of 3.0-10.5 g COD l⁻¹d⁻¹, the concentration of propionic acid increased to 6200-8000 mg l⁻¹. Then the inoculum was divided into three parts feeding with 100% glycerol, 50% glycerol + 50% acetic acid, and 50% glycerol + 50% thick stillage, (presented in % of 2.60 g COD l⁻¹d⁻¹ OLR), respectively. The application of co-substrates reduced the recovery period by 5 days compared to feeding with pure glycerol. When the reactors were loaded with glycerol again (10% OLR raise per day) the previously applied co-substrates had a positive effect on the VFA composition and the biogas yield as well.     

The effect of pH on ruminal methanogenesis

Abstract: When a fistulated cow was fed an all forage diet, ruminal pH remained more or less constant (6.7 to 6.9). The ruminal pH of a concentrate-fed cow decreased dramatically in the period soon after feeding, and the pH was as low as 5.45. Mixed ruminal bacteria from the forage-fed cow converted CO₂ and H₂ to methane, but the ruminal fluid from the concentrate-fed cow did not produce methane. When the pH of the ruminal fluid from the concentrate-fed cow was adjusted to pH 7.0, methane was eventually detected, and the absolute rate constant of methane production was as high as the one observed with ruminal fluid from the forage fed cow (0.32 h⁻¹). Based on the zero-time intercepts of methane production, it appeared that the concentrate-fed cow had fewer methanogens than the forage-fed cow. When the mixed ruminal bacteria were incubated in a basal medium containing 100 mM acetate, methanogenesis was pH-dependent, and no methane was detected at pH values less than 6.0. Because the removal of acetic acid completely reversed the inhibition of methanogenesis, it appeared that volatile fatty acids were causing the pH-dependent inhibition. Based on these results, concentrate diets that lower ruminal pH may provide a practical means of decreasing ruminal methane production.     

Electrolysis-enhanced anaerobic digestion of wastewater

This study demonstrates enhanced methane production from wastewater in laboratory-scale anaerobic reactors equipped with electrodes for water electrolysis. The electrodes were installed in the reactor sludge bed and a voltage of 2.8-3.5 V was applied resulting in a continuous supply of oxygen and hydrogen. The oxygen created micro-aerobic conditions, which facilitated hydrolysis of synthetic wastewater and reduced the release of hydrogen sulfide to the biogas. A portion of the hydrogen produced electrolytically escaped to the biogas improving its combustion properties, while another part was converted to methane by hydrogenotrophic methanogens, increasing the net methane production. The presence of oxygen in the biogas was minimized by limiting the applied voltage. At a volumetric energy consumption of 0.2-0.3 Wh/L_R, successful treatment of both low and high strength synthetic wastewaters was demonstrated. Methane production was increased by 10-25% and reactor stability was improved in comparison to a conventional anaerobic reactor.     

Isomerization between n-butyrate and isobutyrate in enrichment cultures

Abstract An isobutyrate-degrading methanogenic enrichment was obtained from a mesophilic anaerobic digester. Studies with growing cells and cell suspensions showed a reversible isomerization between butyrate and isobutyrate, suggesting that butyrate is an intermediate in the anaerobic degradation of isobutyrate. NMR experiments with ¹³C-labelled butyrate demonstrated that this isomerization resulted from the migration of the carboxyl group.     

The effect of detergent on methanogenesis by Methanosarcina barkeri

Abstract both growth and methanogenesis of Methanosarcina barkeri are completely inhibited by sodium dodecylbenzene sulphonate at between 15 and 20 mg·1⁻¹. At lower concentrations growth of cultures was delayed, but no uncoupling of methanogenesis from growth was observed. Higher concentrations of detergent (50 mg·1⁻¹) produced marked alterations in the surface structures of organisms observed in scanning electron micrographs. Thus levels of a detergent common in anaerobic sewage treatment plants can inhibit methanogenesis, the terminal stage in the anaerobic digestion process.     

Saponification of fatty slaughterhouse wastes for enhancing anaerobic biodegradability

The thermochemical pretreatment by saponification of two kinds of fatty slaughterhouse waste – aeroflotation fats and flesh fats from animal carcasses – was studied in order to improve the waste’s anaerobic degradation. The effect of an easily biodegradable compound, ethanol, on raw waste biodegradation was also examined. The aims of the study were to enhance the methanisation of fatty waste and also to show a link between biodegradability and bio-availability. The anaerobic digestion of raw waste, saponified waste and waste with a co-substrate was carried out in batch mode under mesophilic and thermophilic conditions.     

The role of phase separation and feed cycle length in leach beds coupled to methanogenic reactors for digestion of a solid substrate (Part 2): Hydrolysis, acidification and methanogenesis in a two-phase system

The effect of phase separation and batch duration on the trophic stages of anaerobic digestion was assessed for the first time in leach beds coupled to methanogenic reactors digesting maize (Zea mays). The system was operated for consecutive batches of 7, 14 and 28 days for ∼120 days. Hydrolysis rate was higher the shorter the batch, reaching 8.5 gTS_destroyed d⁻¹ in the 7-day system. Phase separation did not affect acidification but methanogenesis was enhanced in the short feed cycle leach beds. Phase separation was inefficient on the 7-day system, where ∼89% of methane was produced in the leach bed. Methane production rate increased with shortening the feed cycle, reaching 3.523 l d⁻¹ average in the 7-day system. Low strength leachate from the leach beds decreased methanogenic activity of methanogenic reactors’ sludges. Enumeration of cellulolytic and methanogenic microorganisms indicated a constant inoculation of leach beds and methanogenic reactors through leachate recirculation.