Gases Production Characteristics And Odor Control Of Aquatic Products Processing Factory Sludge Composting

Before vermicomposting, the mixture of sludge and corn stalks needs to bepre-composted, which may cause odorous gases pollution and nitrogen loss issue inthe process. This study is on the aquatic products processing factory sludge fromQingdao. This kind of sludge is of high nitrogen content, and stinks. To reduce odorpollution during the pre-composting, two different methods are explored, includingcomposting parameters control and ammonia removal effectively. The producing rateand concentration of ammonia and other gases during the process are analyzed, andthe effects of some factors on the odors produced in the compost are learned bychanging some operating parameters, such as C to N ratio, the moisture content andtemperature. The compost maturity can be evaluated by inoculating earthworms. Theoptimal combination of parameters is determined, considering pre-composting periodand its cost. The feasibility of removing ammonia by biofiltration is verified, and theinfluences of the operating parameters on the biofilter removal performance.(1) The aquatic plants sludge and corn stalks are mixed to pre-compost beforevermicomposting. C to N ratio(17,24,31,37), the temperature(15℃,25℃,35℃), themoisture content of the composting material (55%,65%,75%)are changed in thecomposting process to regulate the release of ammonia. With the increase of the C toN ratio, ammonia volatilization reduce. The ratio of31:1is determined as the mostappropriate in the pre-composting process. Ammonia generation rate increases withthe moisture content, but excess water resultes in composting anaerobic conditions,and therefore the initial moisture content of55%is treated as the optimal. Composttemperature greatly affectes the rate of release of ammonia. And the temperature risesto a certain range, the effect weakens. At low temperature,ammonia volatilization islow, but it makes composting process slow down, which meant the feasible ambienttemperature is25℃.(2) The mixture of ammonia with nitrogen or air is used to simulate the odor producedfrom high nitrogen sludge composting process. The odor passes through thebiofiltration with the vermicompost as media to estimate the effect on the ammonia removal efficiency. The influence of the volume load of ammonia, the carrier gastype, media components and temperatures on the performance of biofiltration isanalyzed, and the appropriate process parameters are determined. The experimentalresults indicate that the biofiltration performed well and the ammonia removalefficiency can reach100%. The ammonia is carried by air,with the flow rate of10mL·min-1and the volume load is43~86g·m-3·h-1.The media in the column is using a1:1by volume mixture of ceramic and vermicompost at the temperatures of37℃,when the media removes ammonia efficiently and steadily.