Rapid start-up of mesophilic dry anaerobic digestion of kitchen waste in a continuous stirred tank reactor (CSTR)

Under mesophilic conditions (37 °C), a bench-scale experiment of dry fermentation start-up using kitchen waste was conducted in a fed-batch single phase reactor over a period of 40 days. The results showed that (1) comparing biogas production, efficiencies, and methane concentrations, three apparent different stages emerged: adaption, growth, and stability; (2) in adaption and growth stages, daily biogas production was 0–0.2 L/day and 0.2–0.4 L/day, respectively, and the concentration of methane in the biogas was 22.91% and 48.79%, respectively, with a biodegradation rate of approximately 34.72% in the adaption phase and 27.60% during the growth phase; (3) in the stability stage, the biogas production efficiency attained the maximal level and stabilized at approximately 0.6–0.4 L/day and the concentration of methane was 54.32%. Furthermore, the pH fell to 4.15, and the concentration of chemical oxygen demand increased from 51.139 to 119.295 mg/ml.     

Influence of iron,nickel and cobalt on biogas production during the anaerobic fermentation of fresh residual biomass

We have investigated the dependence of the rate of the production of biogas upon the concentration of nickel, cobalt and iron at sub-toxic concentration and monitored its composition as amount of hydrogen, methane and carbon dioxide. The distribution of the added metals between the liquid and solid phase has also been monitored.

The results of our investigations show that the addition of any of the listed metals to the sludge may cause the production of a higher amount of biogas and influence the methane or carbon dioxide percentage. Conversely, the effect on the hydrogen production depends upon the metal added, the age of the active sludge used, and its adaptation to the susbtrate. As a general feature, during the acidogenesis phase, nickel reduces, while iron increases, the percentage of dihydrogen in the biogas, while cobalt has no influence.     

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.     

Influence of iron, nickel and cobalt on biogas production during the anaerobic fermentation of fresh residual biomass

We have investigated the dependence of the rate of the production of biogas upon the concentration of nickel, cobalt and iron at sub-toxic concentration and monitored its composition as amount of hydrogen, methane and carbon dioxide. The distribution of the added metals between the liquid and solid phase has also been monitored.

The results of our investigations show that the addition of any of the listed metals to the sludge may cause the production of a higher amount of biogas and influence the methane or carbon dioxide percentage. Conversely, the effect on the hydrogen production depends upon the metal added, the age of the active sludge used, and its adaptation to the susbtrate. As a general feature, during the acidogenesis phase, nickel reduces, while iron increases, the percentage of dihydrogen in the biogas, while cobalt has no influence.     

广东沼气农业模式的典型调查与思考

回顾了广东沼气发展历程,介绍了广东典型沼气农业模式,包括广东西南部丘陵区典型农户沼气模式,广东东部丘陵区典型农户沼气模式,广东东北部丘陵山区典型农户沼气模式,广东低洼地和积水区农户沼气模式,以及广东规模化养殖场沼气模式,并在此基础上分析了沼气农业模式的空间分布规律、沼气模式和经济发展的关系以及沼气发展的系统工程。     

福州市郊泉头村沼气生态工程建设及其效益分析

应用生态学和系统论的原理，把可利用的生物物质通过沼气厌氧发酵形成良性生态循环系统。这样既解决了农村能源，保护了森林资源和植被，又解决了环境保护等问题。同时，把种植业和养殖业有机地结合起来，取得了综合效益。福州市郊泉头村生态工程建设从１９８６年起经过８年的试点，采用了沼气多级发酵工艺，成功地建造了沼气生态系统工程，促进了生产的发展，１９９３年产值达６８００万元，人均产值９３４００元，成为福州市重点商品猪基地之一和菜篮子工程项目。     

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。     

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.     

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.     

城市有机生活垃圾溶胞处理对其厌氧消化的影响机理

由于城市有机生活垃圾成分的复杂性和厌氧消化的限速步骤的影响,导致厌氧发酵的速度比较缓慢、产气量较少和工艺不稳定等问题。文章综述了国内外有机生活垃圾的各种溶胞处理技术,如物理法、化学法、生物法及其联合处理等方法,以便改善发酵物料的性质,消除厌氧发酵的限速步骤。研究认为,通过溶胞处理能够改善有机垃圾的物理化学性质如发酵物料的溶解度、酸碱度等,提高微生物对难降解有机物的分解,增加可溶性COD和挥发性酸的浓度,优化发酵细菌的代谢途径以及产物的组成等,从而增加生物气产量,缩短水力停留时间,强化厌氧发酵过程,减轻了后续处理的负担。     

秸秆干发酵沼气增产研究

研究了复合菌剂预处理秸秆和添加沼气发酵促进剂对秸秆干发酵的影响.结果表明,秸秆经菌剂预处理后的产气量比不加菌剂预处理(对照)提高29.54%;在菌剂预处理过的秸秆中加入促进剂,其产气量比对照提高35.28%,比单纯菌剂预处理提高4.43%.另外,菌剂预处理过的秸秆的TOC降解率和纤维素降解率分别比对照高136.32%和47.68%;秸秆经菌剂预处理后再添加促进剂的TOC降解率、纤维素降解率分别比对照高169.58%和49.62%,比单纯菌剂预处理高14.07%和3.36%.图2表1参8     

Effect of different gas releasing methods on anaerobic fermentative hydrogen production in batch cultures

Decreasing hydrogen partial pressure can not only increase the activity of the hydrogen enzyme but also decrease the products inhibition, so it is an appropriate method to enhance the fermentative hydrogen production from anaerobic mixed culture. The effect of biogas release method on anaerobic fermentative hydrogen production in batch culture system was compared, i.e., Owen method with intermediately release, continuous releasing method, and continuous releasing+ CO₂ absorbing. The experimental results showed that, at 35°C, initial pH 7.0 and glucose concentration of 10 g·L^-1, the hydrogen production was only 28 mL when releasing gas by Owen method, while it increased two times when releasing the biogas continuously. The cumulative hydrogen production could reach 155 mL when carbon dioxide in the gas stream was continuously absorbed by 1 mol·L^-1 NaOH. The results showed that acetate was dominated, accounting for 43% in the dissolved fermentation products in Owen method, whereas the butyrate predominated and reached 47%–53% of the total liquid end products when releasing gas continuously. It is concluded that the homoacetogenesis could be suppressed when absorbing CO₂ in the gas phase in fermentative hydrogen production system.     

Efficient adsorption of carbon dioxide and methane on activated carbon prepared from glycerol with potassium acetate

In the context of global warming and the energy crisis, emissions to the atmosphere of greenhouse gases such as carbon dioxide (CO₂) and methane (CH₄) should be reduced, and biomethane from landfill biogas should be recycled. For this, there is a need for affordable technologies to capture carbon dioxide, such as adsorption of biogas on activated carbon produced from industrial wastes. Here we converted glycerol, a largely available by-product from biodiesel production, into activated carbon with the first use of potassium acetate as an activating agent. We studied adsorption of CO₂ and CH₄ on activated carbon. The results show that activated carbon adsorb CO₂ up to 20% activated carbon weight at 250 kPa, and 9% at atmospheric pressure. This is explained by high specific surface areas up to 1115 m²g⁻¹. Moreover, selectivity values up to 10.6 are observed for the separation of CO₂/CH₄. We also found that the equivalent CO₂ emissions from activated carbon synthesis are easily neutralized by their use, even in a small biogas production unit.

     

化学前处理——改善城市污水污泥厌氧消化处理的有效途径

城市污水污泥在厌氧消化时，时间长，且产气量较低，利用化学试剂ＮａｏＨ或Ｃａ（ＯＨ２）对污泥进行前处理，可以促进污泥水解，使之易于消化，从而提高污泥的消化效率，本文介绍了化学前处理方法的基本原理，分析了化学前处理对产气率、甲烷产率、ｐＨ值，基质去除率等方面的有益影响以及化学药剂的投加量。     

城市污泥超声波处理技术

较全面的介绍了超声波处理污泥的效果，以及目前取得的研究进展，并简要讨论了今后的发展趋势。在适当的操作条件下，超声波可以迅速改变污泥结构，释放菌胶团包含水，从而促进污泥减量化和稳定化。高强度的处理也可以加快污泥水解、提高污泥可生化性、提高沼气产量。同时可消毒有害病菌。     

Anaerobic degradation of coconut husk leachate using UASB-reactor

Reffing of coconut husk, the majorprocess in quality coir fibre extraction, causes serious pollution with brackish water lagoons of Kerala. An attempt is made to treat the coconut husk leachate by using a laboratory scale UASB-reactor The experiment was conducted with loading of leachate from 1 kg of fresh coconut husk. The anaerobic treatment was done continuously The parameters like VFA, pH, COD and polyphenols were analysed regularly during the evaluation of the reactor performance. The polyphenol, VFA and COD were diminished gradually with time. The pH of the reactor during the study was found to be in the range of 6-8. The biogas production was increased with loading and about 82% of the total COD/kg husk could be converted to biogas. The maximum polyphenol loading in the reactor was reached to about 298.51 mg/l of husk.     

两相厌氧发酵互花米草的特性

利用两相(固态水解酸化相+湿式发酵产甲烷相)发酵互花米草,通过尿素的添加来调整厌氧发酵互花米草的碳氮比,考察两相厌氧发酵互花米草的特性;并利用FTIR考察水解发酵前后互花米草结构的变化.研究结果表明,由于固态水解渗滤液对尿素的淋滤,产生高浓度的氨氮溶液,抑制了湿式发酵产甲烷反应器中的甲烷菌;通过53 d的两相发酵互花米草,单位挥发性固体(VS)累积产气量仅为98.6 mL.g-1(0℃),转化率是理论产气量的17.5%;游离性氨(FA)浓度超过55 mg.L-1,就会严重抑制高温甲烷菌;红外光谱分析表明,石灰堆沤预处理对互花米草结构改变较小;只有大幅度的强化预处理,才能显著提高互花米草发酵的产气量.     

五里塘生态农场有机废弃物的资源化生态工艺

上海市松江县五里塘生态农场以沼气工程、氧化沟和鱼塘围网养鸭为主的生态工程,有效地利用了农场产生的大量禽畜粪便并解决了沼液,沼渣的二次污染问题;在沼气池上建玻璃温室保温,使沼气池能正常越冬从而得以周年运转.生态工程的建立,取得了良好的经济、生态和环境效益.     

铜鼓岭自然保护区及其周围地区资源管理技术探讨

本文在对海南岛铜鼓岭自然保护区实际调查的基础上,为解决保护区管理中的一些主要问题,提出一些能够发挥当地热带自然条件优势、合理且持续利用自然资源的技术途径,即建立一个以沼气发酵为中心枢纽,将种植业、养殖业、加工业及人类生活能源等有机相联的综合生产系统。这将改善保护区缓冲区及其周围地区退化土地的生产力,提高经济、社会和环境三个效益,从而促进对核心区的有效管理和保护。