RESUMO
Sampling of triethylamine in the cold-box unit in an auto-manufacturing company in Iran has indicated the average concentration of 430 mg/m[3] in the emission duct. In this study a biotrickling filter was used for treatment of triethylamine in air stream. Triethylamine removal efficiency [K/L] pattern was evaluated by changing volumetric loading [L], superficial gas velocity [U[o]], empty bed gas retention time [EBRT] and recirculation liquid flow rate [V[L]], while operating at constant temperature of 25 +/- 1 Degree C. For finding the effect of EBRT on the triethylamine removal efficiency, tests were performed at EBRT of 156 s, 52s and 31s and a constant liquid recirculation velocity of 3.466 m[3]/m[2]/h. Results showded that for a test period of 65 days, triethylamine removal efficiencies of more than 98% were obtained for EBRT of 156s and loading rates of less than 48 g/m[3]/h. With an EBRT of 52s removal efficiencies of > 90% were obtained for loadings of < 57 g/m[3]/h and maximum removal capacity was 53.4 g/m[3]/h at volumetric loading of 64 g/m[3]/h. Also with an EBRT of 31 s the maximum removal capacity was 53.6 g/m[3]/h at volumetric loading of 68 g/m[3]/h. Thus in the range of implemented EBRTs the proper absorption of triethylamine from gas to liquid phase took place and the elimination efficiency was shown to be dependent on microorganisms activity rate. The effect of liquid flow rate on the triethylamine removal efficiency was investigated by changing VL in the range of 3.46 to 10.40 m[3]/m[2]/h at EBRT=31 s and influent triethylamine concentration of 600 mg/m[3]. Results showed that the triethylamine removal efficiency was nearly independent of the liquid recirculation rate
Assuntos
Gases , Volatilização , Filtros de Ar , Poluição do ArRESUMO
Nitrogen compounds such as triethylamine are odorants generally found in chemical plants and foundries in which cold-box cores are made. In this study, the efficiency of biofiltration of triethylamine [TEA] vapor was evaluated. Experiments were conducted in two 6-L biofilters arranged in three stages and packed with inoculated compost - wood chips [40:60v/v] as the filter medium. The seed inoculum was obtained from municipal activated sludge. Tests were made to compare effects of initial temperature [30-/+1°C, biofilter A] and [23-/+2 °C, biofilter B] on the performance of the biofilter. TEA elimination rate pattern was evaluated by changing loading rates [6-138 gm-3h-1 and hydraulic retention times [40-60 s] while operating at constant temperature and humidity at 50-55%. Results showed that organic loading rates [OLR] of up to 114.4 gin-3h-1 [biofilter A] and 90.56 gin-3h-1 [biofilter B] could be handled without any apparent indication of maximum elimination capacity and substrate inhibition. The elimination capacity of biofilters could reach up to 72 gm-311-1[biofilter A] and 613 gm-3h [biofilter B]. When the loading of TEA exceeded the critical values, substrate inhibition occurred and the elimination capacity decreased. However, the requirement of keeping the pressure drop below 4 cm water gauge per meter of bed height to avoid operational problems warranted lower than maximum capacity operation. The optimal OLR values of 90-114 gm3h-1 are suggested for hydraulic retention time value of 48 s and temperature of 30-/+1°C. Under these conditions, elimination capacity of 71-/+3 gm-3h-land removal efficiency of 81-/+14% was achieved