Experimental Research On Filler Modification And The Purification Process Operation Conditions Of NO_x In Bio-trickling Filter

There were a lot of problems in traditional technology which purfying waste gasby biological trickling filter, such as limited purification efficiency, unsteady processoperation, packing had a short serviceable cycle and so on. In the paper, experimentstudy on these problems. Selected advantage of denitrifying denitrfier bacteria, thesurface of activated carbon filler was modified, process operation conditions whichremoving waste gas by biological trickling filter were determined.Screened several denitrification bacterial strain that from the activated sludge ofsewage treatment plant after cultivate, then separated and affinitied a degrade nitratenitrogen easily bacterial. The surface of activated carbon filler was modified throughusing different soaking time and concentration of nitric acid or sodium hydroxide asmodifier. By analyzing the physico-chemical properties and attached biomass ofactivated carbon under different modification conditions, the modification conditionwas optimized. The results showed that the modification effect of sodium hydroxidewith concentration of1mol/L soak24hours was the best. Under this condition, thegeneral characteristics of activated carbon filler such as morphology and densitychanged a little after modification. However, the specific surface area of activatedcarbon increased2times, which is more suitable for the growth of microorganism andwith a maximum of biomass, the biomass as high as1.55mol/L, and the film formingcycle was shortened2days. The bacterial density where the circulated fluids ofbio-trickling filter after modification steady maintained between0.9and1.2in theprocess of formation biofilm. Various forms of nitrogen changed rapidly and stably, and the denitrification was more thorough in the process. Control the process operatingconditions: temperature,30~35℃, quantity of flushing liquid,0.32L/h, the circulatedfluids pH,7.0~8.0. The results pointed out that the removal efficiency of NO_xinbio-trickling filter used the best modification conditions was significantly improvedabout10%than before modification and stabilized more than85%, this occurred whenthe inlet concentration of NO_xslowly increased from350mg/m~3to2700mg/m~3, inletquantity was1.5L/min, empty bed residence time was60s, the height of thebio-trickling filter was30m. The result also indicated that the bio-trickling filtersystem operated more stable and has a stronger resistance impact capacity than thatbefore modification. According to the experiment research, modified filler has asignificant influence on the effect of operation when the biological trickling filterpurifies pollutants.