餐厨垃圾半连续乙醇型酸化两相厌氧消化产甲烷性能研究
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摘要
为了解乙醇型两相厌氧消化系统性能,该研究构建了以接种酵母菌产乙醇同时产酸为特征的餐厨垃圾两相厌氧消化系统(乙醇型两相),并开展系统的进料有机负荷率由2.0 g/(L·d)逐渐提高至6.0 g/(L·d)的半连续厌氧发酵产甲烷试验。结果表明:乙醇型两相在5.0 g/(L·d)时甲烷产率为421.52 mL/g,比传统两相厌氧消化系统的394.48 mL/g,提高了6.8%。乙醇型的醇化/酸化相的水解产物中乙醇占33.4%,这有利于水解物料进入甲烷相后保持该相pH值及厌氧消化的稳定运行。与传统两相相比,乙醇型两相系统的醇化/酸化相水力停留时间减少了60%,系统的有效容积减少了10.6%,容积产甲烷率提高了18.3%。说明乙醇型两相比传统型两相系统在产甲烷性能方面具有明显的优势,且有提高系统稳定性的潜力。
A novel semi-continuous two-phase anaerobic digestion(AD) system characterized by methanogenesis from alcoholization was constructed, and the organic loading rate of the system was gradually increased from 2.0 to 6.0 g/(L·d).According to the previous research results, the HRT(hydrodynamic retention time) of the first phase of the alcoholization/acidification type semi-continuous two-phase AD system was set for 2 d. Compared to the first phase of the traditional two-phase anaerobic digestion, the HRT was set for 2, 5, and 8 days, respectively. After 25 days of continuous operation, the change tendencies of acetic acid, propionic acid, butyric acid, etc. in the first phase hydrolysis products were analyzed under a certain OLR(organic loading rate). The results showed that when the acidification phase residence time was 5 and 8 days, the hydrolysis acidification effect of the system was better than that at 2 days, which may be due to the stable state of the acidified bacteria microbial community in the system. Therefore, in this experiment, 5 days was selected as the hydraulic retention time of the acidified phase. The methanogenic phase volume of the two systems was 8 L and the hydraulic retention time was 25 d. The results showed that 5.0 g/(L·d) was the maximum OLR for stable operation of the two systems in the study. By comparing the alcoholization/acidification type system with the traditional two-phase anaerobic digestion system,when the maximum OLR of the system reached 5.0 g/(L·d), the methane yield of the alcoholization/acidification type system reached 421.52 mL/g, which was 6.8% higher than that of the traditional system(394.48 mL/g). In this study, the TVFA(total volatile fatty acid)/alkalinity ratio was a more sensitive indicator than the p H value to detect the operating state of the methanogenic phase. The ethanol concentration in the first phase of the alcoholization/acidification type system accounted for 33.4%, which was beneficial to maintain the pH value and the stable operation of anaerobic digestion after the materials in the first phase entered to the second phase. Compared with the traditional two-phase anaerobic digestion system, the alcoholization/acidification type system had a shorter first phase hydraulic retention time of 2 days. Moreover, comparing with the traditional two-phase system, the volume methanogenesis rate of alcoholization/acidification type system was increased by 18.3%. All of the results showed that the alcoholization/acidification type system had obvious advantages in the methanogenic performance compared with the traditional system. And it also had the potential to improve system stability and reduce the scale of the plant and save the energy required for hydrolysis acidification in industrial applications. By comparing the first phase of the two systems, it could be found that the total amount of hydrolyzed products in the two groups was close when the OLR was 3.0 and 4.0 g/(L·d). When the OLR increased to 5.0 g/(L·d), the ethanol proportion in the first phase of the alcoholization/acidification type system was higher than that in the traditional two-phase system. Meanwhile, the propionic acid concentration was lower than that of the traditional two-phase system. Propionic acid was a substance which was more difficult to be degraded by methanogens in all volatile fatty acids, and its accumulation in the methanogenic phase inhibited the activity of methanogens. These results showed that it was beneficial to keep a stable pH value and alkalinity environment for the methanogenic phase, which ensured the advantage to improve the stability of the anaerobic system.
A novel semi-continuous two-phase anaerobic digestion(AD) system characterized by methanogenesis from alcoholization was constructed, and the organic loading rate of the system was gradually increased from 2.0 to 6.0 g/(L·d).According to the previous research results, the HRT(hydrodynamic retention time) of the first phase of the alcoholization/acidification type semi-continuous two-phase AD system was set for 2 d. Compared to the first phase of the traditional two-phase anaerobic digestion, the HRT was set for 2, 5, and 8 days, respectively. After 25 days of continuous operation, the change tendencies of acetic acid, propionic acid, butyric acid, etc. in the first phase hydrolysis products were analyzed under a certain OLR(organic loading rate). The results showed that when the acidification phase residence time was 5 and 8 days, the hydrolysis acidification effect of the system was better than that at 2 days, which may be due to the stable state of the acidified bacteria microbial community in the system. Therefore, in this experiment, 5 days was selected as the hydraulic retention time of the acidified phase. The methanogenic phase volume of the two systems was 8 L and the hydraulic retention time was 25 d. The results showed that 5.0 g/(L·d) was the maximum OLR for stable operation of the two systems in the study. By comparing the alcoholization/acidification type system with the traditional two-phase anaerobic digestion system,when the maximum OLR of the system reached 5.0 g/(L·d), the methane yield of the alcoholization/acidification type system reached 421.52 mL/g, which was 6.8% higher than that of the traditional system(394.48 mL/g). In this study, the TVFA(total volatile fatty acid)/alkalinity ratio was a more sensitive indicator than the p H value to detect the operating state of the methanogenic phase. The ethanol concentration in the first phase of the alcoholization/acidification type system accounted for 33.4%, which was beneficial to maintain the pH value and the stable operation of anaerobic digestion after the materials in the first phase entered to the second phase. Compared with the traditional two-phase anaerobic digestion system, the alcoholization/acidification type system had a shorter first phase hydraulic retention time of 2 days. Moreover, comparing with the traditional two-phase system, the volume methanogenesis rate of alcoholization/acidification type system was increased by 18.3%. All of the results showed that the alcoholization/acidification type system had obvious advantages in the methanogenic performance compared with the traditional system. And it also had the potential to improve system stability and reduce the scale of the plant and save the energy required for hydrolysis acidification in industrial applications. By comparing the first phase of the two systems, it could be found that the total amount of hydrolyzed products in the two groups was close when the OLR was 3.0 and 4.0 g/(L·d). When the OLR increased to 5.0 g/(L·d), the ethanol proportion in the first phase of the alcoholization/acidification type system was higher than that in the traditional two-phase system. Meanwhile, the propionic acid concentration was lower than that of the traditional two-phase system. Propionic acid was a substance which was more difficult to be degraded by methanogens in all volatile fatty acids, and its accumulation in the methanogenic phase inhibited the activity of methanogens. These results showed that it was beneficial to keep a stable pH value and alkalinity environment for the methanogenic phase, which ensured the advantage to improve the stability of the anaerobic system.
引文
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[21]高明,马鸿志,苏伟,等.糟液循环对开放式餐厨垃圾乙醇发酵的影响及工艺改进[J].中国环境科学,2015(12):3721-3727.Gao Ming,Ma Hongzhi,Su Wei,et al.Effects of distillery waste recycling on open ethanol fermentation from kitchen garbage and technological enhancement[J].China Environmental Science2015(12):3721-3727.(in Chinese with English abstract)
[22]Yu Miao,Gao Ming,Wang Lihong,et al.Kinetic modelling and synergistic impact evaluation for the anaerobic co-digestion of distillers’grains and food waste by ethanol pre-fermentation[J].Environmental Science and Pollution Research,2018,25(30):30281-30291.
[23]Voelklein M A,Jacob A,O Shea R,et al.Assessment of increasing loading rate on two-stage digestion of food waste[J].Bioresource Technology,2016,202:172-180.
[24]Patinvoh Regina J,Kalantar Mehrjerdi Adib,Sárvári Horváth Ilona,et al.Dry fermentation of manure with straw in continuous plug flow reactor:Reactor development and process stability at different loading rates[J].Bioresource Technology,2017,224:197-205.
[25]Li Dong,Ran Yi,Chen Lin,et al.Instability diagnosis and syntrophic acetate oxidation during thermophilic digestion of vegetable waste[J].Water Research,2018,139:263-271.
[26]Li Dong,Chen Lin,Liu Xiaofeng,et al.Instability mechanisms and early warning indicators for mesophilic anaerobic digestion of vegetable waste[J].Bioresource Technology,2017,245:90-97.
[27]Wang Yuanyuan,Zhang Yanlin,Wang Jianbo,et al.Effects of volatile fatty acid concentrations on methane yield and methanogenic bacteria[J].Biomass and Bioenergy,2009,33(5):848-853.
[2]Ma Hongzhi,Xing Yi,Yu Miao,et al.Feasibility of converting lactic acid to ethanol in food waste fermentation by immobilized lactate oxidase[J].Applied Energy,2014,129:89-93.
[3]Ren Yuanyuan,Yu Miao,Wu Chuanfu,et al.Acomprehensive review on food waste anaerobic digestion:Research updates and tendencies[J].Bioresource Technology,2018,247:1069-1076.
[4]许勇.餐厨垃圾两相厌氧发酵性能的研究[D].哈尔滨:东北林业大学,2014.Xu Yong.Performance of Two-Phase Anaerobic Fermentation of Food Waste[D].Harbin:Northeast Forestry University,2014.(in Chinese with English abstract)
[5]Kawai Minako,Nagao Norio,Tajima Nobuaki,et al.The effect of the labile organic fraction in food waste and the substrate/inoculum ratio on anaerobic digestion for a reliable methane yield[J].Bioresource Technology,2014,157:174-180.
[6]Zhang Cunsheng,Su Haijia,Baeyens Jan,et al.Reviewing the anaerobic digestion of food waste for biogas production[J].Renewable and Sustainable Energy Reviews,2014,38:383-392.
[7]Lee Eunyoung,Cumberbatch Jewel,Wang Meng,et al.Kinetic parameter estimation model for anaerobic co-digestion of waste activated sludge and microalgae[J].Bioresource Technology,2017,228:9-17.
[8]Wu Chuanfu,Wang Qunhui,Yu Miao,et al.Effect of ethanol prefermentation and inoculum-to-substrate ratio on methane yield from food waste and distillers’grains[J].Applied Energy,2015,155:846-853.
[9]Zhao Nana,Yu Miao,Wang Qunhui,et al.Effect of ethanol and lactic acid pre-fermentation on putrefactive bacteria suppression,hydrolysis,and methanogenesis of food waste[J]Energy&Fuels,2016,30(4):2982-2989.
[10]Yu Miao,Wu Chuanfu,Wang Qunhui,et al.Ethanol prefermentation of food waste in sequencing batch methane fermentation for improved buffering capacity and microbial community analysis[J].Bioresource Technology,2018,248(Part A):187-193.
[11]American Public Health Association,American Water Works Association,Farber Lawrence.Standard Methods for the Examination of Water and Wastewater[M].18th edition.Washington:American Public Health Association,1992.
[12]Wu Chuanfu,Huang Qiqi,Yu Miao,et al.Effects of digestate recirculation on a two-stage anaerobic digestion system,particularly focusing on metabolite correlation analysis[J].Bioresource Technology,2018,251:40-48.
[13]Wu Chuanfu,Wang Qunhui,Xiang Juan,et al.Enhanced productions and recoveries of ethanol and methane from food waste by a three-Stage process[J].Energy&Fuels,2015,29(10):6494-6500.
[14]孙绪顺,褚春凤,李春杰.反相高效液相色谱测定厌氧反应上清液中挥发性脂肪酸[J].净水技术,2009,28(5):64-66.Sun Xushun,Chu Chunfeng,Li Chunjie.Determination of volatile fatty acids in anaerobic reaction by high performance liquid chromatography[J].Water Puification Technology,2009,28(5):64-66.(in Chinese with English abstract)
[15]沼气中甲烷和二氧化碳的测定.气相色谱法:NY/T 1700-2009[S],2009.
[16]Zuo Zhuang,Wu Shubiao,Qi Xiangyang,et al.Performance enhancement of leaf vegetable waste in two-stage anaerobic systems under high organic loading rate:Role of recirculation and hydraulic retention time[J].Applied Energy,2015,147:279-286.
[17]Wang Haoyu,Tao Yu,Temudo Margarida,et al.Biomethanation from enzymatically hydrolyzed brewer’s spent grain:Impact of rapid increase in loadings[J].Bioresource Technology,2015,190:167-174.
[18]Nielfa A,Cano R,Fdz-Polanco M.Theoretical methane production generated by the co-digestion of organic fraction municipal solid waste and biological sludge[J].Biotechnology Reports,2015,5:14-21.
[19]Vavilin V A,Fernandez B,Palatsi J,et al.Hydrolysis kinetics in anaerobic degradation of particulate organic material:An overview[J].Waste Management,2008,28(6):939-951.
[20]Wang Kun,Yin Jun,Shen Dongsheng,et al.Anaerobic digestion of food waste for volatile fatty acids(VFAs)production with different types of inoculum:Effect of pH[J].Bioresource Technology,2014,161:395-401.
[21]高明,马鸿志,苏伟,等.糟液循环对开放式餐厨垃圾乙醇发酵的影响及工艺改进[J].中国环境科学,2015(12):3721-3727.Gao Ming,Ma Hongzhi,Su Wei,et al.Effects of distillery waste recycling on open ethanol fermentation from kitchen garbage and technological enhancement[J].China Environmental Science2015(12):3721-3727.(in Chinese with English abstract)
[22]Yu Miao,Gao Ming,Wang Lihong,et al.Kinetic modelling and synergistic impact evaluation for the anaerobic co-digestion of distillers’grains and food waste by ethanol pre-fermentation[J].Environmental Science and Pollution Research,2018,25(30):30281-30291.
[23]Voelklein M A,Jacob A,O Shea R,et al.Assessment of increasing loading rate on two-stage digestion of food waste[J].Bioresource Technology,2016,202:172-180.
[24]Patinvoh Regina J,Kalantar Mehrjerdi Adib,Sárvári Horváth Ilona,et al.Dry fermentation of manure with straw in continuous plug flow reactor:Reactor development and process stability at different loading rates[J].Bioresource Technology,2017,224:197-205.
[25]Li Dong,Ran Yi,Chen Lin,et al.Instability diagnosis and syntrophic acetate oxidation during thermophilic digestion of vegetable waste[J].Water Research,2018,139:263-271.
[26]Li Dong,Chen Lin,Liu Xiaofeng,et al.Instability mechanisms and early warning indicators for mesophilic anaerobic digestion of vegetable waste[J].Bioresource Technology,2017,245:90-97.
[27]Wang Yuanyuan,Zhang Yanlin,Wang Jianbo,et al.Effects of volatile fatty acid concentrations on methane yield and methanogenic bacteria[J].Biomass and Bioenergy,2009,33(5):848-853.