Study On Characteristics And Anaerobic Digestion Performance Of Kitchen Waste

Kitchen waste as the main component of municipal waste with high-moisture and high-organic has become one of the key environmental problems. Anaerobic digestion was considered a most promising alternative for handing this kind of waste due to waste reduction and clean energy production.The kitchen waste production and treatment in Beijing was investigated firstly, qualitative and quantitative data on kitchen waste production characteristic disposal ways and cost were attained. The results showed that most of kitchen waste was directly landfilled or for feeding livestock illegally. Therefore, anaerobic digestion treatment of kitchen waste was necessary and important.The characteristics of kitchen waste with three meals and four seasons were determined, the results indicated that three kinds of kitchen waste showed significant differences. VS/TS,C,N,crude protein and crude fat of breakfast kitchen waste were lower than lunch and dinner waste while the content of soluble sugar and salt were higher. Kitchen waste in different quarters had no significant difference in the nature, VS/TS maintained at 70% -80%, total nitrogen content was between 2% and 3%. The total soluble sugar was the most in all the oranic compounds, followed by fats, proteins, fiber.This article evaluated the batch fermentation of different VS concentration kitchen waste with and without pH adjustion at 35℃.The results showed that maximum oraganic concentration can reach 25gVS·L-1 without pH adjustion and highest biogas yield 938.6mL-gVS-1 was achieved at 20gVS·L-1. It can reach 45gVS·L-1 with pH adjustion and the highest biogas yield was 991.0 mL-gVS-1 at 16gVS·L-1. Methane content had been increased in the different extents with pH adjustion. The effects of different inoculum proportion on the anaerobic digestion performance was studied. Appropriate inoculum (F/M=0.36) can shorten the reaction time and obtain good biogas production.CSTR digestor was introduced to evalue one-phase anaerobic digestion performance of continuous feed kitchen waste and impact of different HRT was studied. The maximum loading rate can reach 2.75gVS·L-1.d-1.when HRT was 30d, the optimal biogas generation was 787.0mL-gVS-1·d-1 at 2.25 gVS·L-1·d-1.When the feed concentration was fixed,2.5gVS·L-1·d-1 was achieved as the highest loading rate while the highest biogas yield was 723.9 mL-gVS-1·d-1 at 2.25gVS·L-1·-d-1. As the loading rate increased, adequate HRT was needed to ensure enough micro-organisms for decomposting organic matters.