厌氧发酵技术在有机垃圾处理方面的应用

根据有机垃圾（可生物降解）的特点及厌氧发酵工艺过程，论述了厌氧发酵技术在有机垃圾处理方面的实际应用价值，说明运用厌氧发酵技术处理有机垃圾是实现固体废弃物资源化、减量化、无害化的新趋势。     

城市有机生活垃圾厌氧发酵处理研究

在适当的PH值和搅拌条件下，研究了反应温度、总固体含量、pH值、碳氮比、碳磷比以及接种物量对有机牛活垃圾厌氧发酵产沼气的影响。实验结果表明：有机生活垃圾厌氧消化产沼气的适宜条件是：反应温度50～55℃，总固体含量23％～28％，pH=6．8～7．4，w(C)／w（N)=(20～30)，w(C)／w(P)=50，60％～75％的生物气，可实现能量回收；发酵剩余物可制有机肥，时间为15～20d。接种物量为25％～30％。在厌氧的条件下，可以制取含甲烷实现物质再利用。有机生活垃圾在厌氧消化反应器的停留时间为15～20d。     

pH值调控对秸秆两阶段厌氧发酵产沼气的影响

两阶段厌氧发酵产沼气是秸秆沼气化利用的重要方式之一。秸秆厌氧发酵过程包括水解产酸和产甲烷两个阶段,水解产酸是秸秆沼气化的限速步骤,也是目前的研究重点。pH值是影响物料水解产酸的重要因素,目前的研究多集中于酸性环境对物料水解产酸的影响,碱性环境对物料水解产酸的影响还未见研究报道。在实验室条件下,每天调节水解产酸反应器发酵液pH值至8.0(T1)、9.5(T2)和11.0(T3),CK在实验过程中不调节水解产酸反应器发酵液pH值,水解产酸反应器排出的水解酸化液直接用蠕动泵泵入产甲烷反应器内产甲烷,分析了发酵过程中水解产酸反应器日产气量、甲烷含量、水解酸化液pH值、COD浓度以及产甲烷反应器产气特性的变化。结果表明:在不调节水解产酸反应器水解酸化液pH值条件下,秸秆两阶段厌氧发酵可以正常进行,秸秆干物质(TS)产气量为281.28mL·g-1,平均甲烷含量为47.36%;T1水解产酸反应器内水解酸化液pH值稳定在7左右,系统累积产气量、总产甲烷量和平均甲烷含量分别较CK大幅增加了24.51%、29.39%和2.5个百分点;T2和T3水解产酸反应器产气明显受到抑制,水解酸化液后续产甲烷亦受到明显抑制,产甲烷反应器累积产气量分别仅为CK的89.97%和17.48%,总产气量仅为T1的67.67%和10.20%;维持水解产酸反应器至碱性条件促进了秸秆中半纤维素的溶出和木质素的破坏,但不利于纤维素的溶出,TS损失率的结果与产气的结果一致。综合以上结果,调节水解产酸反应器水解酸化液pH值至8.0对提高秸秆两阶段厌氧发酵产沼气有明显的促进作用。     

pH对餐厨垃圾厌氧发酵产氢过程的影响

餐厨垃圾具有含水率高、有机物含量高、易腐败等特点,若处理不当,必然造成资源浪费和环境污染。餐厨垃圾减量化、无害化、资源化处理是环境科学领域近年来关注的热点与难点。为解决餐厨垃圾的减量化问题,同时产生清洁能源——氢气,利用自制小型序批式厌氧发酵产氢反应装置,以蒸煮餐厨垃圾为发酵底物,接种污水处理厂剩余污泥进行厌氧发酵产氢,在底物与接种物质量比为4:1,温度为37℃的条件下,研究p H对蒸煮餐厨垃圾厌氧发酵产氢的影响。结果表明,厌氧发酵底物中乙酸和丁酸是挥发性酸(VFA)中主要的组成部分,占总挥发性酸的80%以上,同时含有少量的丙酸,属于典型的丁酸型发酵。初始p H为9.0时,厌氧发酵效果最佳,累积产气量和产氢量最大,分别为748 m L和371 m L;在整个厌氧发酵过程中氢气的体积分数最高可达80.5%,平均产氢速率为10.31 m L·h~(-1),单位产氢量(以VS计)为72.9 m L·g~(-1),总固体(TS)和挥发性固体(VS)的去除率分别高达26.6%和34.4%;脱氢酶的活性呈现出先增强后减弱的趋势,产氢速率与脱氢酶的活性呈正相关;发酵反应进行到16 h时,脱氢酶的活性最好,此时产氢速率最大,为19.2 m L·h~(-1)。因此,调节初始p H为9.0,可以提高餐厨垃圾产氢效率,实现餐厨垃圾减量化和产生清洁能源的双重目标。     

电子垃圾生物浸出的电化学强化机制

电子垃圾的不当处理已造成了严重的环境和健康问题.生物浸出技术具有低成本和环境友好的优点,为电子垃圾的有效资源化提供了一种选择,但是,目前该技术在实际应用中存在耗时长的瓶颈.电子垃圾生物浸出的反应机制、功能微生物的胞外电子传递都涉及到氧化还原反应,因此,电化学反应可提高电子垃圾中金属的生物浸出效率.本文总结了生物浸出过程中常见的功能菌种及其胞外电子传递途径,以此为基础,阐述了通过电势强化、金属阳离子强化、直接电子调控和间接电子调控的电化学强化方法,以期推动电子垃圾资源化的实际应用.     

有机废物好氧发酵腐殖质形成机理及农学效应研究进展

腐殖质是有机废物好氧发酵的重要产物,也是发酵产品品质的重要评价标准。腐殖质含有大量官能团,农学效应显著,可以为作物提供营养,改善土壤理化性质。综述近年来国内外有机废物合成的腐殖质结构特点,探讨了有机废物好氧发酵过程中腐殖质形成机理和演化规律,分析了好氧发酵条件(物料类型、温度、水分、碳氮比、氧含量、p H值、物料粒径、发酵工艺)对腐殖质形成和腐殖化程度的影响,以及腐殖质特征性官能团与保肥性、保水性、抗病性等农学效应的关系。从探明好氧发酵腐殖质形成路径,利用同步辐射显微CT技术(SR-μCT)和软X射线谱学显微光束线分别获得腐殖质团聚体的三维结构域信息和腐殖质元素及化学态信息方面进行展望,将好氧发酵产物腐殖质与农业生产直接关联起来,以期为有机废物好氧资源化技术提供科学依据。     

“厌氧发酵-藻类”法净化有机污水的研究

“厌氧发酵—藻类”法——分别选育耐强酸的厌氧甲烷菌株和耐强碱的螺旋藻,颤藻。采用具有特色的厌氧消化器和藻类净化器工艺,得理CODCr为50000mg/l的高浓度有机污水,出水CODCr降至300mg/l左右,再用藻类净化池进一步处理,即可达到排放标准。其中螺旋藻净化效果已达到日本同类专利水平。 本工艺处理高浓度有机污水,既能获得生物能源甲烷,又可获得含蛋白质60％左右的螺旋藻,可作为精饲料。本法为我国酿造、食品、医药等工业废水的综合治理和利用开辟了新途径。     

城市生活垃圾堆肥在城市绿化上的应用

本文介绍了上海城市生活垃圾堆肥的理化性质及其在活动花坛、屋顶绿化、盆裁花卉和切花生产上的应用研究。结果表明:经无害化处理的城市生活垃圾堆肥疏松多孔、富含大量和微量营养元素,可提高土壤肥力,改善土壤结构、促进植物生长。经过调节 pH 值和增加代换量后,可作为栽培介质,广泛应用于城市绿化,既美化了环境,又为生活垃圾堆肥的应用开辟了新途径。     

垃圾卫生填埋技术

介绍我国第一座现代化城市生活垃圾卫生填埋场－深圳市下坪固体废弃物填埋场的卫生填埋技术设施,如防渗设施、垃圾渗沥液导流设施、场外排水设施和场内清污分流设施等;垃圾卫生填埋工艺技术及作业方法,如分区分层填埋法、单元作业法和高效作业法;垃圾填埋场的环境监测项目及监测成果。     

有机固体废物干法厌氧发酵技术研究综述

干法厌氧发酵技术作为有机固体废物能源化与处置的有效途径,近年来已逐渐成为世界各国农业固体废物资源化技术研究的热点.综述了国内外有关有机固体废物干法厌氧发酵处理技术研究现状,并展望了农业固体废物干法厌氧发酵技术的发展趋势.     

Use of gamma-irradiation pretreatment for enhancement of anaerobic digestibility of sewage sludge

The effects of γ-irradiation pretreatment on anaerobic digestibility of sewage sludge was investigated in this paper. Parameters like solid components, soluble components, and biogas production of anaerobic digestion experiment for sewage sludge were measured. The values of these parameters were compared before and after γ-irradiation pretreatment. Total solid (TS), volatile solid (VS), suspended solid (SS), volatile suspended solid (VSS), and average floc size of samples decreased after γ-irradiation treatment. Besides, floc size distribution of sewage sludge shifted from 80–100 μm to 0–40 μm after γ-irradiation treatment at the doses from 0 to 30 kGy, which indicated the disintegration of sewage sludge. Moreover, microbe cells of sewage sludge were ruptured by γ-irradiation treatment, which resulted in the release of cytoplasm and increase of soluble chemical oxygen demand (SCOD). Both sludge disintegration and microbe cells rupture enhanced the subsequent anaerobic digestion process, which was demonstrated by the increase of accumulated biogas production. Compared with digesters fed with none irradiated sludge, the accumulated biogas production increased 44, 98, and 178 mL for digesters fed sludge irradiated at 2.48, 6.51, and 11.24 kGy, respectively. The results indicated that γ-irradiation pretreatment could effectively enhance anaerobic digestibility of sewage sludge, and correspondingly, could accelerate hydrolysis process, shorten sludge retention time of sludge anaerobic digestion process.     

Increasing the performance of anaerobic digestion: Pilot scale experimental study for thermal hydrolysis of mixed sludge

The performance of a pilot plant operation combining thermal hydrolysis (170°C, 30 min) and anaerobic digestion (AD) was studied, determining the main properties for samples of fresh mixed sludge, hydrolyzed sludge, and digested sludge, in order to quantify the thermal pretreatment performance (disintegration, solubilisation, and dewaterability) and its impact on the anaerobic digestion performance (biodegradability, volatile solids reduction, and digester rheology) and end product characteristics (dewaterability, sanitation, organic and nitrogen content). The disintegration achieved during the thermal treatment enhances the sludge centrifugation, allowing a 70% higher total solids concentration in the feed to anaerobic digestion. The digestion of this sludge generates 40% more biogas in half the time, due to the higher solids removal compared to a conventional digester. The waste generated can be dewatered by centrifugation to 7% dry solids without polymer addition, and is pathogen free.     

Effectiveness of aerobic pretreatment of municipal solid waste for accelerating biogas generation during simulated landfilling

Effect of aerobic pretreatment of MSW on landfill gas generation was investigated. Volatile solid (VS) loss of MSW is an effective and comparable indicator. Chinese MSW requires at least a reduction of VS about 27% (w/w) prior to disposal. Aerobic pretreatment of MSW reduced lag phase more than 90% before methanogenesis. Aerobic pretreatment degree influences quantity of gas generation. This study evaluates the effectiveness of aerobic pretreatment of municipal solid waste (MSW) on reducing lag phase and accelerating biogas generation. Aerobic pretreatment degree (APD) was determined on the basis of reduction in volatile solids (VS) on a wet weight basis. In this study, intermittent aeration (IA) was applied to three reactors as a main aeration mode; since a single reactor was operated under continuous aeration mode. However, the purpose of the experiment was to reduce VS content of waste, irrespective of the comparison between aeration modes. Fresh MSW was first pretreated aerobically with different aeration rates (10, 40, 60 and 85 L/min/m³) for the period of 30–50 days, resulting in VS-loss equivalent to 20%, 27%, 38% and 53% on w/w basis for the wastes A1, A2, A3 and A4, respectively. The cumulative biogas production, calculated based on the modified Gompertz model were 384, 195, 353, 215, and 114 L/kg VS for the wastes A0, A1, A2, A3 and A4, respectively. Untreated waste (A0) showed a long lag phase; whereas the lag phases of pretreated MSW were reduced by more than 90%. Aerobically pretreated wastes reached stable methanogenic phase within 41 days compared to 418 days for untreated waste. The waste mass decreased by about 8% to 27% compared to untreated MSW, indicative that even more MSW could be placed in the same landfill. The study confirmed the effectiveness of aerobic pretreatment of MSW prior to landfilling on reducing lag phase and accelerating biogas generation.     

Impact of Ni(II), Zn(II) and Cd(II) on biogassification of potato waste

A study was conducted on anaerobic digestion of potato waste and cattle manure mixture, inoculated with 12% inoculum and diluted to 1:1 substrate water ratio at 37 +/- 1 degrees C. Initially pH of substrate was found to be 4.5 to 5.0. Lime and sodium bicarbonate solutions were employed to adjust the pH to 7.5. Biogas production continued up to 10 and 7 days, when lime and sodium bicarbonate solutions were used to adjust the pH, respectively. Biogassification potential was studied in response to different ratio of waste and cattle manure. Biogas production rate was higher when potato waste and cattle manure were used in 50:50 ratio. Effect of two different concentrations (2.5 and 5.0 ppm) of three heavy metals viz. (Ni (II), Zn (II) and Cd (II)) on anaerobic digestion of substrate (potato waste--cattle manure, 50:50) was studied. At 2.5 ppm, all the three heavy metals increased biogas production rate over the control value. The percentage increase in biogas production over the control was highest by Cd, followed by Ni and Zn. In all the treatments, methane content of biogas increased with increase in time after feeding. Various physico-chemical parameters viz. total solids, total volatile solids, total organic carbon and chemical oxygen demand considerably declined after 7 days of digestion and decline was greater in presence of heavy metals as compared to control. The physico-chemical parameters revealed maximum decrease in the presence of 2.5-ppm concentrations of heavy metals with the substrate. Among all the three heavy metals employed in the study, Cd++ at 2.5 ppm was found to produce maximum biogas production rate. The use of three heavy metals to enhance biogas production from potato and other horticultural waste is discussed.     

Anaerobic digestion and recycling of kitchen waste: a review

About 1.6 billion tons of food are wasted worldwide annually, calling for advanced methods to recycle food waste into energy and materials. Anaerobic digestion of kitchen waste allows the efficient recovery of energy, and induces low-carbon emissions. Nonetheless, digestion stability and biogas production are variables, due to dietary habits and seasonal diet variations that modify the components of kitchen waste. Another challenge is the recycling of the digestate, which could be partly solved by more efficient reactors of anaerobic digestion. Here, we review the bottlenecks of anaerobic digestion treatment of kitchen waste, with focus on components inhibition, and energy recovery from biogas slurry and residue. We provide rules for the optimal treatment of the organic fraction of kitchen waste, and guidelines to upgrade the anaerobic digestion processes. We propose a strategy using an anaerobic dynamic membrane bioreactor to improve anaerobic digestion of kitchen waste, and a model for the complete transformation and recycling of kitchen waste, based on component properties.

     

城市生活垃圾有机组分厌氧发酵产氢和甲烷

为了提高能源回收效率,采用大米、土豆、生菜、瘦肉、花生油和榕树叶作为实验原料,模拟有机垃圾中普遍存在的淀粉、膳食纤维、蛋白质、脂肪和木质纤维类成分,进行厌氧发酵产氢以及对其剩余物厌氧发酵产甲烷.结果表明.在厌氧发酵产氢阶段,整个过程没有甲烷生成,大米、土豆、生菜、瘦肉、花生油和榕树叶的氢气产率分别为125、103、35、0、5和0 mL g-1(VS),能源回收效率分别为7.9%、6.8%、1.9%、0、0.1%和0.大米、土豆和生菜的氢气浓度分别为34%～59%、41%～56%和37%～70%,整个产氢阶段没有甲烷生成.在厌氧发酵产甲烷阶段,上述原料的甲烷产率分别为232、237、148、278、866和50 mL g-1(VS),生物气中甲烷含量分别为42%～70%、57%～71%、73%～77%、59%～73%、68%～80%和54%～74%.厌氧发酵联产氢气和甲烷整个过程上述原料的能源回收效率分别为56.3%、58.4%、28.8%、39.2%、81.2%和8.8%,总COD去除率分别为72.30%、81.70%、32.63%、47.59%、97.46%和11.29%.图4表5参35     

Developing “precise-acting” strategies for improving anaerobic methanogenesis of organic waste: Insights from the electron transfer system of syntrophic partners

Methanogenesis is the last step in anaerobic digestion, which is usually a rate-limiting step in the biological treatment of organic waste. The low methanogenesis efficiency (low methane production rate, low methane yield, low methane content) substantially limits the development of anaerobic digestion technology. Traditional pretreatment methods and bio-stimulation strategies have impacts on the entire anaerobic system and cannot directly enhance methanogenesis in a targeted manner, which was defined as “broad-acting” strategies in this perspective. Further, we discussed our opinion of methanogenesis process with insights from the electron transfer system of syntrophic partners and provided potential targeted enhancing strategy for high-efficiency electron transfer system. These “precise-acting” strategies are expected to achieve an efficient methanogenesis process and enhance the bio-energy recovery of organic waste.     

麦秸与奶牛场废水高固体混合厌氧发酵产甲烷研究

在实验室条件下,以麦秸和奶牛场废水为原料,设计麦秸与奶牛场废水质量比1∶4(T1)、1∶3(T2)和1∶2(T3)以及对照(麦秸与水质量比1∶4(T4))4个处理,研究发酵过程中日产气量、甲烷含量、发酵前后麦秸理化特性和结构的变化.结果表明,奶牛场废水与麦秸在中温、高固体条件下,厌氧发酵可以正常进行,且产气期延长2周以上,对甲烷含量的影响不大;厌氧发酵初始TS浓度对系统产气的影响较大,麦秸产气量随TS浓度的增加而降低,以T1的产气效果最好,麦秸TS产气量为0.41 L.g-1,较T4提高了17.14%,平均甲烷含量为48.78%;厌氧发酵后,麦秸半纤维素含量大幅降低,纤维素含量少许降低,降低幅度均为T1>T2>T4>T3,木质素含量稍有增加,各处理间无显著差异(P>0.05);FTIR和XRD的结果表明,厌氧发酵后,麦秸纤维素结晶区的相对含量增加,混合发酵可以促进厌氧微生物对麦秸纤维素结晶区的破坏.将麦秸与奶牛场废水(质量比)1∶4混合发酵产沼气是可行的,且促进了厌氧微生物对麦秸有机物的分解破坏,提高了麦秸产气量.     

添加蚓粪对玉米秸秆厌氧发酵产气特性的影响

以玉米秸秆为原料,总固体(TS)含量为50g.kg-1,采用中温35℃批式发酵,考察了添加蚓粪对玉米秸秆厌氧发酵产气的影响。结果表明:玉米秸秆单独发酵时,单位TS产气量为333.3mL.g-1,甲烷产量为202.0mL.g-1,并在反应初期出现酸化现象;蚓粪与玉米秸秆TS质量比为1:1进行发酵时,单位TS产气量为400.0mL.g-1,甲烷产量为269.6mL.g-1,相对于玉米秸秆单独厌氧发酵分别提高了20.0%和35.5%,且反应过程中未出现酸化现象。说明蚓粪适合作为玉米秸秆厌氧发酵产气的添加剂。     

有机化合物厌氧生物降解性的测定和预测

测定有机物厌氧生物降解性的方法包括非特性参数和特性参数测定法。本文着重介绍有机物厌氧生物降解性的筛选测定法，以基团贡献法为基础，不外加其它理化参数的有机物结构与生物降解性关系的预测已经由简单的线性模型发展至专家系统和人工神经网络模型，并显示出极好的应用前景。