| Biofiltration is currently one of the most used gas treatment technology, especially for biodegradable emissions. In comparison to traditional physical and chemical removal method, biodegradation method has several advantages of simple operation, cost effective, and no secondary pollution. The three main types of bioreactors are biofilter, biotrickling tilter and bioscrubber, however, biofilter is a hot area for low concentration and high flow industrial waste gas. As the carrier of microorganism’s apposition growth and substrate transmission, the filler is the heart of the process and its performance determines the purification effect directly. In this study, an innovative biological filler was composited in embedding fixation method with the powders of cow dung compost, cement, perlite and vegetable fiber mixed in certain proportion. Then the cylindrical granules were performed with flat film extrusion method, and the dimensions could be adjusted. Then the physicochemical properties of filter were assessed. Finally, the simulating H2S and NOX were used to evaluated the purification performance. The main experiment results are as follows:(l)The filler was mainly composted of water glass chose as adhesive, cow compost acted as nutrients and microorganisms source, porous perlite and vegetable fiber used as slight skeleton, cement selected as resisting binder and CaCO3served as pH buffer. Then the size of cow compost was20-40mesh and the finally mass ration of1:1for cement and perlite,7%for vegetable fiber and28%for water glass.(2)The results of physical and chemical properties evaluation of the new filler showed that, the average size of (?)12×20mm, compressive strength of427.3N, bulk density of471Kg/m3moisture holding capacity, specific surface area is3.91m2/g, porosity of38-41%, pH of10.5, alkaline.(3)The accumulating release rate of TOC and TN was only1.58%and4.02%after extraction14times, and the accumulating release amount is1.6mg·g-1filler0.24mg·g-1filler, which showed the composite filler could release nutrients slowly, besides, the filler could maintain good adhesive property in damp and hot environment for a long time.(4)The filler had good pH buffer capacity, and the pH dropped from10.7to9.2slowly in90d.(5)The composite could short start-up period remarkably for it carrying function microorganisms and the biological amount was2.9×104CFU/g.(6)During the normal operation of biofilter experiment, the elimination capacity of BF1and BF2differed largely, but BF1could adapt the fluctuation of contaminate strongly and the removal of the load could be1666.2mg/(m3-h) when the inlet H2S load increased from0mg/(m3-h) to1680mg/(m3·h). The relationship between inlet load and removal load was nearly linear relationship when the inlet load was lower than1419mg/(m3-h). The removal kinetics has been studied, and the Ks and Vm of composite filler were21.9308mg/m3and12.8g(H2S)/(m3d) respectively.(7)The maximum removal capacities of BF1and BF2were1593mg/(m3-h) and542mg/(m3-h) when the inlet load of simulating NOx increasing slowly, and the removal effective was93.15%and61.8%, respectively. The system could recover to normal condition after2-3d when the BF1was idle shutdown for30days. In the condition of high inlet loading and short residence time, the removal capacity of composite filler was higher than the sterilized filler. |
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