Effect Of Ultrasonic Pretreatment On Two-phase Anaerobic Digestion Of Food Waste And Sewage Sludge

Foodwaste and sewage sludge are both part of the organic solid waste in the city.With the rapid development of economy and urbanization advancement,a large quantity of sewage sludge and foodwaste generated.If not properly treated that will have a bad influence on the surrounding environment.Anaerobic fermentation as an effective way to realize the resource utilization of organic solid waste,which has become the focus of research in domestic and overseas.In order to strengthen the traditional sludge and foodwaste anaerobic co-digestion efficiency,an experiment of two-stage anaerobic digestion of foodwaste and sludge was investigated in optimize conditions.The main results were as follows:(1)Ultrasonic pretreatment improved the production of hydrolysis acid in primary dynamic fermentation and also promoted the degradation of nitrogen organic matter.It had little effect on the pH value,which can realize the separation of methanogenic and acidogenic phase;Ultrasonic pretreatment can improved fermentation gas production rate and gas production,there were more than 80% H2 in both group and had little effect on the gas composition.(2)The change of VFAs,pH and NH3-N concentration index showed that the ultrasonic pretreatment had little effect on the stable operation of the secondary co-digestion system of foodwaste and sludge,but can save 7~10d of the system stable operation time.(3)Different secondary fermentation dosing rate has a certain influence on the effects of ultrasonic pretreatment,there was no significant difference between the ultrasonic and control group of organic removal and gas production in the dosing rate of 8% secondary fermentation,but required more energy of degradation of 1gVS compared to control group.when the dosing rate was 10% and 12%,the removal rates of SCOD,TS and VS in ultrasound group were higher than those in control group,methane yield compared with the control group increased by 12.5% and13%,respectively,The needed energy of degradation of 1gVS were both lower than that of the control group.(4)The optimum condition of this experiment:In the secondary co-fermentation dosing rate of 12%,and the foodwaste pretreated(10 min,1.2W/mL),the required of system stable time was about 40 days,total VS removal rate was 63.0%,gas production rate was 801.46(mL/(gVS·d)),methane yield of up to 641.84(mLCH4/(gVS·d)),least energy was needed to degradation per gram VS,which was highestbenefits for the economic.