Treatment of Styrene and Acrylonitrile in Air Streams by Full-scale Biotrickling Filters
This research focuses on the performance of a full-scale biotrickling filter (BTF) for treating a vented gas from an ABS (acrylonitrile-butadiene-styrene) resin plant. The BTF was constructed by reinforced concrete with a size of 5 m in width, 9 m in length, and 3.5 m in height. It consists of six individual chambers with packing materials of 4.6m in length and 4.2m in width for each. The vented gas contains styrene (SM) and acrylonitrile (AN) as two major components and has an average flow rate of 43,000 m3/h (720 m3/min) and a temperature range of 40-53¢J.
Three test protocols have been studied to understand the effects of changing scrubbing method, types of packing materials, and amounts of packing materials on the pollutant removal efficacy. Two different instruments (portable FID and laboratory GC) were used to measure the VOC concentrations for both the inlet and outlet of the BTF. Many parameters were monitored for trend analysis, including gas flow rate, empty-bed gas retention time, system temperature, inlet and outlet VOC concentrations, VOC mass flow rate, organic loading, VOC removal efficiency, recirculation water volume, VOC concentration in the recirculation water, and mass flow rate of the recirculation water. These data were analyzed for discussing the technical feasibility of using BTF as an air pollution control unit for petrochemical industry.
Experimental results showed that the third protocol using PVC packing materials (installed with 4.6m in length, 4.2 in width, and 0.6m in height for each of the 6 chambers) was the best setup for the target VOC removal. Without adding any special seed and supplementary nutrient, effluent of the wastewater treatment unit of the plant was introduced into the BTF as the recirculation water (pH 7-8.5, volumetric flow rate 15-30 m3/h, and temperature was 35-50¢J). A range of VOC removal efficiencies of 8.6-41% (equivalent to volumetric elimination rates of K = 41-949 g/m3.h) was obtained with loadings of L = 469-3015 g/m3.h based on the GC data. The elimination rates were 41-949 and 27.4-562 g/m3.h, respectively, for AN and SM corresponding to loadings of 121-1104 and 818-1756 g/m3.h for the two components. An average removal efficiency (K/L) of 24.5% was obtained for AN and SM regardless of the magnitude of the loading. Distribution of VOC removal was 13% by biofilms and the rest by the recirculation water. Microbiological tests revealed that Nematods was the most dominating species at high loadings and Trachelophyllum sp. was the most dominating species at lower loadings. It was also estimated that a total operating cost of NT$ 23,920/day is required and that is equivalent to a cost of NT$ 34.1 for eliminating 1 kg of VOCs from the waste gas.
The data showed that the VOC loading (469-3015 g/m3.h, average 1808 g/m3.h) to the BTF was much higher than the normal design value of 30-60g/m3.h. It is suggested that a pre-treatment unit should be added into the system to lower the organic loading before the waste stream enters the BTF. In addition, the makeup recirculation water should be increased to foster the bacteria growth and to improve the absorption of VOCs from the waste gas.
Advisor:Ming-Shen Chou; Richard Hung; Ming-Mu Kao
School:National Sun Yat-Sen University
School Location:China - Taiwan
Source Type:Master's Thesis
Keywords:biotrickling filter voc acryloniprile styrene
Date of Publication:06/20/2001