Research On Anaerobic Thermophilic Digestion Of Kitchen Waste With High Solid Content

Kitchen waste is a kind of organic waste in the resident's life expends,accounting for about half of the urban domestic garbage,which will cause various environmental problems with improper disposal.Due to characteristics of high moisture content,rich organic matter content and high solid content,it can be converted into renewable energy like methane and hydrogen by anaerobic digestion process.This paper,based on the experiment,researched the hydrolysis acidification process of dry anaerobic digestion under thermophilic condition and evaluated the codigestion of kitchen waste and stalk,explorated of the operating conditions on the batch phase dry anaerobic digestion system under thermophilic condition.Base on the former study,a kind of dry anaerobic digestion reactor for kitchen waste is designed.The main conclusions are as follows:?1?The kitchen waste from Ningbo Kaseen Ecology Co.Ltd is the high-solid material after pretreatment of three-phase separation.Through transport,mechanical sorting,high temperature sterilization,mechanical dehydration,and three-phase separation,the properties of the kitchen waste change a lot with TS content 25%³5%,temperature nearly 60 degrees and a high biodegradability,which are suitable for dry anaerobic digestion under thermophilic conditon.?2?This paper also analyzes the hydrolysis acidification process of dry anaerobic fermentation for kitchen waste under thermophilic condition by controlling feedstock to inoculum rates and gives the optimal rate and period for hydrolysis acidification.In order to make full use of the resources and improve the fermentation processing capacity,the acidizing fluid in the retention tank was chosen as the inoculum.The test shows that,when feedstock to inoculum rate is 10%,the kitchen waste reaches a maximum VFA concentration after 15 days' hydrolysis acidification,and the concentration ratio of acetic is about 60%,while the content of propionic acid is relatively low,and the greatest degree of fermentation is obtained.Finally,considering the efficiency of processing and anaerobic digestion,in the two-phase anaerobic digestion test,we suggest that the HRT is better to control in less than 10 days in the hydrolysis acidification stage.?3?The performance co-digestion of kitchen waste and stalk is discussed.To improve the material performance of hydrolysis acidification and methane production,by changing C/N ratio to 20 through mixing the stalk,we make the ratio test on kitchen waste of thermophilic dry anaerobic digestion.In the stage of hydrolysis acidification,the period is prolonged because of the continuous digestion of the fiber lignin in the stalk.In the methane production phase,the methane production capacity is much higher in the anaerobic digestion which kitchen waste is as the single source.The content of methane is 60.72% in the co-digestion study,much higher than the control group.Finally,considering the production practice,though it can greatly reduce the organic loading of the kitchen waste,the efficiency in the mixed fermentation doesn't improve obviously.Therefore,we don't take the mixed fermentation of stalk and kitchen waste into consideration.?4?This paper proposes an analysis of the operating conditions for batch two-phase dry anaerobic digestion under thermophilic condition.The experiment is stimulated by small load dosing materials,gradually increasing the organic loading to observe the processing impact that different loading makes to kitchen waste.The result indicates that,when the volume load is 4.55 kg-VS·m^-3·d^-112.75 kg-VS·m^-3·d^-1,daily average methane production shows a trend of rising first and decreasing afterward;When the organic loading is 12.75 kgVS·m^-3·d^-1,the daily average methane production reaches the highest value to 16303 mL.