Study On Hydrogen Production By Anaerobic Fermentation Of Kitchen Waste Mixed With Surplus Sludge

With rapid development of industries and improved urban living standards,kitchen waste and surplus sludge and other organic solid wastes have increasedheavily. Organic solid waste treatment is becoming a problem but at the same timeproviding a rich source of raw materials for anaerobic fermentation to producehydrogen. This helps in the reduction of waste and production of clean energy.Currently many studies focus on separation of kitchen and surplus sludge assubstrate for fermentation to produce hydrogen. Only a few studies are concernedwith combined kitchen and surplus sludge waste to produce hydrogen. This paperfocuses on combined kitchen waste and surplus sludge waste as substrate forfermentation. The experiment was carried out in a self-designed anaerobicsequencing batch type device with temperature controlled at37±1℃and rotationspeed at120±1r/min. The effects of different mixing ratios, initial pH and processpH on hydrogen production on combined waste was examined. I analyze VFAscomposition, dehydrogenase enzyme activity, morphology and16S rDNA florasequence in the substrate of producing hydrogen and further explore its effectmechanism The results were as follows:(1) The suitable mixing ratio and pH cab increase the effect of microbialhydrogen production by anaerobic fermentation. At37℃, kitchen waste/surplussludge ration of4:1and initial pH of9.0, the best production rate is72.9mlH2/g·VSand simultaneous VS and TS removal rates are34%and26.6%respectively. Thefastest hydrogen production was observed when pH was between6.0and7.0andfurther control process at pH6.5hydrogen production rate can be increased to85.46ml H2/g·VS with the system removing41.8%and31.0%VS and TSrespectively. This indicate an increase in hydrogen production rate by17.2%. VSand TS removal rate increased by7.8%and4.4%respectively.(2) VFAs is an important intermediate in the anaerobic fermentation process.The concentration and composition tend to response the method to producehydrogen and hydrogen production effect. The main components of VFAs inanaerobic fermentation liquor phase are butyric acid and acetic acid with a smallamount of propionic acid which is typical of butyric acid type fermentation.(3) Dehydrogenase enzyme activity is directly related to hydrogen production process’s hydrogenase. At initial pH9.0without pH control process of fermentationat fastest rate of hydrogen production, dehydrogenase enzyme activity was29.5mg/(l·h-1); When pH was controlled6.5, the dehydrogenase enzyme activity was33.1mg/(l·h-1), The compared with initial pH9.0shows an improvement of12.2%.(4) Identification of16S rDNA flora sequences can be intuitive reflect the typesof dominant bacteria in the hydrogen production by anaerobic fermentation. Atinitial pH of9.0, when the hydrogen production was faster, the dominant bacteria inthe substrate mainly include Clostridium chauvoei, Clostridium bifermentans,Clostridium perfringens. And at pH6.5during fastest hydrogen production rate themain was Clostridium perfringens.