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。     

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。     

厌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１２８ｍ６３的上流式厌氧污泥床,该装置于１９８５年建成,已正常运行８年。用于处理万羽鸡的粪水,２０－２４℃发酵,共产气４５万ｍ６３。平均产气率１．３５ｍ＾３／ｍ＾３．ｄ。ＣＯＤ去除率８８％。产生的沼气供应１２０户居民使用。     

黑龙江省生物质废弃物厌氧消化产沼气技术现状及发展趋势

面对金融危机,扩大内需,以沼气为核心的农村能源结构的调整和环境的改善是解决农村问题的关键.黑龙江省生物质能源丰富,由于受冬季低温的限制,严重制约了生物质能源的转化,特别是沼气能源的推广应用.低温发酵是制约北方农村沼气的重要的亟待解决的关键问题和技术瓶颈.其核心技术是如何实现低温条件下厌氧消化处理生物质废弃物高效转化,提高沼气的单位产量.本文针对黑龙江省,现有沼气应用技术发展现状及存在的问题,提出了适合寒地的沼气应用的新理论、新技术及新工艺,并对今后的发展趋势进行深入的探讨和分析.     

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。     

添加厨余垃圾对剩余污泥厌氧消化产沼气过程的影响

为提高剩余污泥厌氧消化的沼气产量和甲烷含量,研究了厨余垃圾的不同添加量对剩余污泥厌氧消化性能的影响。结果表明,在35℃下,随着剩余污泥中厨余垃圾添加量的增加,厌氧消化系统中碳氮质量比（C／N）、胞外多聚物（EPS）等生理生化指标均有不同程度的改善。其中当剩余污泥与厨余垃圾质量比为2：1时,混合有机废弃物中沼气产量和甲烷含量均达到最大值,每克挥发性固体（VS）产生了156．56mL沼气,甲烷体积分数为67．52％,分别比剩余污泥单独厌氧消化时的产气量提高了5倍和1．5倍。     

厌氧消化酸抑制研究进展

厌氧消化工艺目前已广泛应用于各类废水的处理处置过程中,但在实际运行中,受消化条件和物料性质的影响,消化系统经常遭受由挥发性脂肪酸积累过多导致的酸抑制问题,引发产气量下降、产甲烷率降低等问题.近年来,有研究者发现,挥发性脂肪酸的种类和浓度及pH、温度是影响酸抑制的主要因素.基于此,相关研究者分别尝试了添加碱性化学药剂和微...     

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。     

城市生物废弃物干式厌氧消化温度实验研究

研究了温度对干式厌氧发酵过程的影响,结果表明温度对pH值影响,高温(55℃)处理pH值迅速达到最低值,中温(35℃)和室温处理相对滞后,室温处理在消化后期出现酸积累现象,pH值维持在较低水平;发酵后期中温处理和高温处理pH值回升.温度对氧化还原电位影响更为明显,氧化还原电位在消化初期下降很快,到达最低点后波动很小.在整个消化过程中的氧化还原电位依次为室温>中温>高温.高温处理VS去除率最高,其值为36.44%;从产气量及甲烷气体含量比较可知,高温处理效率也是最高,其值分别为2548mL、62%,产气时间最长.     

An inexpensive,automatic gas meter for laboratory-scale methane digesters and other gas-evolving systems

A reliable and inexpensive system for measuring gas flow-rates and kinetics which is based on water displacement by gas in a burette is described. It can easily be couple to an acquisition system for data processing. This system allows the gas to be stored without changing the pressure in the gas producing digester and is able to record flow-rates lower than 1 ml · min^?1.     

Investigation of methanogen population structure in biogas reactor by molecular characterization of methyl-coenzyme M reductase A (mcrA) genes

The methanogen community in biogas reactor running on cattle dung was investigated in two different seasons; summer (April, 36 °C) and winter (December, 24 °C), in the year 2004 by a culture-independent approach. Community structure was determined by phylogenetic analyses of 343 and 278 mcrA clones belonging to summer and winter month libraries, respectively. In summer month’s library, 41.7% clones were affiliated to Methanomicrobiales, 30% to Methanosarcinales, 19% to Methanobacteriales, 5% to Methanococcales and a total of 4.3% clones belonged to unclassified euryarchaeotal lineages. In winter month’s library, Methanomicrobiales encompassed 98.6% clones, and Methanobacteriales included 1.4% of total clone diversity. Biogas plant performance data collected during the winter month indicated significant reduction in daily biogas produced as compared to summer month because of lowering in ambient temperature and associated shift in microbial community. Results from this molecular study showed the existence of highly diverse and complex methanogens communities present in biogas plant.     

Comparison of near infra-red spectroscopy, neutral detergent fibre assay and in-vitro organic matter digestibility assay for rapid determination of the biochemical methane potential of meadow grasses

This paper investigates near infra-red spectroscopy (NIRS) as an indirect and rapid method to assess the biochemical methane potential (BMP) of meadow grasses. Additionally analytical methods usually associated with forage analysis, namely, the neutral detergent fibre assay (NDF), and the in-vitro organic matter digestibility assay (IVOMD), were also tested on the meadow grass samples and the applicability of the models in predicting the BMP was studied. Based on these, regression models were obtained using the partial least squares (PLS) method. Various data pre-treatments were also applied to improve the models. Compared to the models based on the NDF and IVOMD predictions of BMP, the model based on the NIRS prediction of BMP gave the best results. This model, with data pre-processed by the mean normalisation method, had an R² value of 0.69, a root mean square error of prediction (RMSEP) of 37.4 and a residual prediction deviation (RPD) of 1.75.     

Molecular analyses of methanogen diversity associated with cattle dung

Methanogen communities were characterized in cattle dung of different ages by using a culture-independent approach. Community structures were determined by the phylogenetic analyses of methyl-coenzyme M reductase A (mcrA) clones of fresh, 8-month-old, and 24-month-old-dry dung samples. The clones in the mcrA libraries of fresh and 8-month old dung samples were identified as belonging to Methanomicrobiales, Methanobacteriales, and Methanosarcinales. However, clones in the library of 24-month-old dung were not affiliated to Methanomicrobiales. Anaerobic digestion of 2-month-old dung produced only 15% less methane compared to fresh dung which indicated the possibility of using dry dung to fuel the biogas plants in areas where unavailability of fresh dung hinders their continuous functioning. Our results first time showed the presence of viable methanogens in dry cattle dung stored for prolonged periods of time.     

Laboratory-scale ultrasound pre-treated digestion of sludge: Heat and energy balance

The objective of this work was to maximize the digestibility of biological sludge to elucidate the feasibility of a new sludge management strategy to recover good quality sludge for agricultural use. The combined effects of organic loading rates (from 0.7 to 2.8 g VS L⁻¹ d⁻¹) and the degree of disintegration by anaerobic digestion of sonicated activated sludge were discussed, and the thermal and energetic balances were evaluated. Despite low sonication inputs, sludge digestion performance improved in terms of solids degradation and biogas production depending on the soluble organic load. The biogas production by sonicated sludge was higher (up to 30%) with respect to the control. Filterability improved during digestion of sonicated sludge at medium OLR due to a significant abatement of the fines. Thermal balances indicated that sonication may be a proper system to guarantee self-sustaining WAS mesophilic digestion. Nevertheless, thickening is a pre-requisite to achieve a positive energy balance.     

Peracetic acid oxidation as an alternative pre-treatment for the anaerobic digestion of waste activated sludge

Anaerobic digestion is generally considered to be an economic and environmentally friendly technology for treating waste activated sludge, but has some limitations, such as the time it takes for the sludge to be digested and also the ineffectiveness of degrading the solids. Various pre-treatment technologies have been suggested to overcome these limitations and to improve the biogas production rate by enhancing the hydrolysis of organic matter. This paper studies the use of peracetic acid for disintegrating sludge as a pre-treatment of anaerobic digestion. It has been proved that this treatment effectively leads to a solubilisation of organic material. A maximum increase in biogas production by 21% is achieved. High dosages of PAA lead to a decrease in biogas production. This is due to the inhibition of the anaerobic micro-organisms by the high VFA-concentrations. The evolution of the various VFAs during digestion is studied and the observed trends support this hypothesis.     

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.     

On-field study of anaerobic digestion full-scale plants (part I): an on-field methodology to determine mass, carbon and nutrients balance

The mass balance (input/output mass flows) of full-scale anaerobic digestion (AD) processes should be known for a series of purposes, e.g. to understand carbon and nutrients balances, to evaluate the contribution of AD processes to elemental cycles, especially when digestates are applied to agricultural land and to measure the biodegradation yields and the process efficiency. In this paper, three alternative methods were studied, to determine the mass balance in full-scale processes, discussing their reliability and applicability. Through a 1-year survey on three full-scale AD plants and through 38 laboratory-scale batch digesters, the congruency of the considered methods was demonstrated and a linear equation was provided that allows calculating the wet weight losses (WL) from the methane produced (MP) by the plant (WL = 41.949 * MP + 20.853, R² = 0.950, p < 0.01). Additionally, this new tool was used to calculate carbon, nitrogen, phosphorous and potassium balances of the three observed AD plants.