Anaerobic Biochemical Treatment And Hydrogen Production Factors Of Waste Food

Currently, waste food generation rate is increasing year by year. Considered the domestic lack of waste food recycling technology, the low rate of waste food recycling rate and other issues, this paper used the basic principles of anaerobic fermentation, took waste food as a substrate, carried out the study on anaerobic biochemical treatment to produce syngas which was rich in hydrogen, explored the characteristic of hydrogen production and the influencing factors in the fermentation process, and explored the feasibility and technical factors of using wate food to produce syngas which was rich in hydrogen by fermentation.This paper carried out the experiments of waste food hydrolyzing and hydrogen production by anaerobic fermentation, analyzed the process of waste food transforming to hydrogen, discussed the effects of temperature, stirring speed, strain and strain pretreatment conditions and other operating factors to hydrogen production. On the basis of the selection of the optimum inoculums, by comparing the concentration of CODcr, reducing sugar, NH3-N, TP in the process of fermentation, and ultimately optimized the best operating conditions.The results showed that the temperature played a very important role in the course of anaerobic fermentation, when the temperature was35℃, it became the most conducive to catering anaerobic fermentation of waste food smoothly. In the course of fermentation, necessary mixing to the fermentation broth played a positive role to promote the production of hydrogen, reasonable stirring speed was advantageous to increase the efficiency of hydrogen production, but the stirring speed should not be too fast, otherwise it would completely destroy the anaerobic process. Through comparing, it was found that when used waste food to produce hydrogen by fermentation, and when the reaction temperature was controlled in35℃and the stirring speed was held at400r/min, the largest producing hydrogen yield could be obtained, among them, the hydrogen concentration was39.93%, the cumulative amount of hydrogen production could reach394.5mL. In addition, in the system of producing hydrogen from anaerobic fermentation of waste food, the inoculation of activated sludge and pickled cabbage liquid and other bacteria could further promote the occurrence of hydrogen. Among them, the number of hydrogen-producing bacteria in activated sludge was relative higher and more suitable for the process of hydrogen production by fermentation. As hydrogen producing strains, before used activated sludge to inoculate, necessary pretreatment to activated sludge had positive significance to promote the fermentation to produce hydrogen reaction. The pretreatment of the activated sludge included acid treatment, alkali treatment and heat treatment. Heat treatment by appropriate temperature, reasonable acid treatment and alkali treatment all could improve the activity of hydrogen producing bacteria, so as to improve the total volume of gas production and hydrogen production of waste food hydrolysate. Among them, the best heat treatment temperature was80℃, the best heat treatment time was10min, the best pH value of acid treatment was4and the best pH value of alkali pretreatment was12. Through comparing, it was found that after activated sludge was pretreated by alkali which pH was12for fermentation system, the hydrogen production effect was best, the hydrogen concentration was43.24%, the cumulative hydrogen production could reach495.1mL. And when used acid which pH value was4to treat activated sludge as inoculation for anaerobic fermentation, the hydrogen content in the syngas could reach42.2%, the cumulative hydrogen production could reach422mL. After activated sludge was treated by heat pretreatment with10min and80℃for anaerobic fermentation, could obtain the syngas which hydrogen content was38.67%, and the cumulative hydrogen production was402.17mL.