Study On The Application Of Biochar Filler For Odorous Gas Purification

The source of malodorous gases is relatively wide,mainly due to industrial and livestock production,environmental treatment projects,and daily life of human beings.Its olfactory threshold is very low,so low concentrations of malodorous gases can also interfere with people's mental state.At present,malodorous gas treatment methods mainly include physical methods,chemical methods,and biological deodorization methods.Biological deodorization is an environmentally friendly deodorization technology.Developing low-cost,high-efficiency deodorant fillers is one of the key ways to improving this technology.The new type of filler biochar which had appeared in recent years can be taken from the municipal sewage treatment plant residual sludge and agricultural and forestry waste as raw materials,and is made by dry distillation carbonization technology;it has the advantages of simple production process and low production cost.At present,there are few pilot tests and engineering studies on biochar in the purification of exhaust pollutants.In this study,biochar was used as a biological drip filter packing to carry out pilot tests.The research results were summarized from the experiment,which provided some experience for the application of biochar in waste gas treatment engineering.Advice was also provided for the fate of sludge dry distillation products?biochar?.Based on this,this paper used the biochar produced by a certain company as an experimental material to carry out pilot experiments.Biochar and bamboo charcoal were used as fillers respectively to compare the removal efficiency of VOCs?using CH₃SH as a character?and H₂S and NH₃ in different stages of biological deodorization.Then through the data of the pilot test to determine the pre-commissioning time of the equipment?contains the time required for the microbe to hang the film?,the residence time of the exhaust gas in the biological drip filter tower,and other relevant design parameters to complete the exhaust gas engineering design of a printing and dyeing textile enterprise sewage treatment station.The main research conclusions are as follows:1.Comparative study on the removal efficiency of VOCs,H₂S and NH₃ by biochar and bamboo charcoal in different stages:?1?The bio-deodorization device at the start-up stage:The removal rates of bamboo charcoal and biochar to H₂S reached 90%and 88%,the removal rates of NH₃ reached 89%and 87%.The removal rate of VOCs by bamboo charcoal filler was slightly higher than that of biochar,reaching 65%,and the removal rate of biochar filler was 57%.?2?Bio-deodorization device commissioning operation phase:The removal rates of H₂S for both fillers were above 95%,and the removal rates for NH₃ were above 94%,and both had certain impact load resistance.The removal of VOCs by the two kinds of fillers could be divided into two steps:When the pollutant load was small in the early stage of the experiment,the adsorption was dominant and the biodegradation as an assist,the removal effect was better,which can reach 80%.The pollutant load increaseed in the later stage of the experiment,the biodegradation was dominant and the adsorption effect as an assist,and the removal was sharply reduced,and the minimum reduced to 15%.?3?Stable operation stage:The removal effect of biochar filler on H₂S was better than that of bamboo charcoal filler,and the difference in removal efficiency between the two was0%-31.7%.With the increase of residence time,the removal effect of biochar fillers on VOCs was better than that of bamboo charcoal fillers,and the difference in removal efficiency was2.4%.The removal efficiency of the two fillers for different concentrations of NH₃ was similar,and the difference in removal efficiency between the two was 0.5%-2.4%.2.To conduct a pilot test of the biological trickling filter for determine the design parameters:?1?The debugging time of the microbial membrane in the biological drip filter tower was more than 8 days,commissioning time was more than 15 days.?2?For exhaust gases in which most of the components are readily soluble in water,a pretreatment step of washing and humidification may be provided to reduce the residence time in the biological trickling filter.?3?Through unit cost accounting,the unit cost of removing carbon dioxide from biochar fillers was lower than that of bamboo charcoal fillers.3.The use of biochar-bamboo charcoal as a filler had a certain degradation effect on the malodorous gases?H₂S,NH₃,VOCs?produced by the printing and dyeing enterprise sewage treatment station:the removal rate of H₂S was about 97.1%-98.9%,and NH₃ was about90.4%-93.5%,VOCs were about 59.9%-68.0%,and the removal rate of CH₃SH in VOCs was about 98.3%-99.3%.The removal rate of this demonstration project were higher than that of two similar engineering cases?where the NH₃ removal effect was similar to the composite deodorization engineering case?and was similar to the two similar experimental studies.Therefore,biochar is a new type of filler for biological deodorization system,which is feasible for purifying NH₃,H₂S,CH₃SH and VOCs.