No abstract

This paper presents a study on the biofiltration of styrene by using two inorganic filtering materials. The effects of styrene inlet load and nitrogen concentration present in the nutrient solution on biofilter performance were studied. The styrene inlet concentration was varied from 65 to 1115 parts per million by volume (ppmv), whereas the contaminated airflow rate was fixed at 1 m 3 /hr. The nitrogen concentration in nutrient solution was varied from 1 to 4 gN/L. The maximum elimination capacity obtained was 105 g/m 3 -hr, which corresponded to a removal efficiency of 80% for a styrene inlet load of 130 g/m 3 -hr. This study shows that the nitrogen content in the nutrient solution affects the removal rate of styrene, with an optimal nitrogen concentration of 3 gN/L. The performance comparison between two different inorganic bed types was undertaken and a comparative study on biofiltration of two aromatic compounds, styrene and toluene, is also presented.

Studies show that agricultural and animal feeding operations (AFOs) contribute a considerable amount of ammonia (NH 3 ) to the atmosphere. Agricultural NH 3 emissions are recognized as an important air quality issue. Biological decomposition of manure from dairy operations results in emissions of NH 3 and other gases. There is a need to determine NH 3 emission factors (EFs) to compile annual NH 3 inventories. NH 3 emissions should be estimated from different ground-level area sources (GLAS) including open-lots (cows on earthen corrals), free-stalls (cows in barns), manure composting sites, primary and secondary lagoons, separated solids, and milking parlors. A protocol using flux chambers was used to determine NH 3 EFs from different GLAS of a free-stall dairy in central Texas. Data including NH 3 emissions from GLAS were collected during winter and summer seasons. NH 3 concentration measurements were made using chemiluminescence-based analyzers. The EFs for the free-stall dairy were estimated as 11 Ϯ 4.9 (confidence interval [CI]) kg-NH 3 ⅐ yr Ϫ1 ⅐ head Ϫ1 for summer and 4.7 Ϯ 4.9 kg-NH 3 ⅐ yr Ϫ1 ⅐ head Ϫ1 for winter. The estimated annual NH 3 EF was 8.4 Ϯ 4.9 kg-NH 3 ⅐ yr Ϫ1 ⅐ head Ϫ1 for this free-stall dairy. This seasonal difference was attributed to temperature, loading rate of dairy waste, and manure bacterial activity of GLAS. In winter, composted manure and free-stalls contributed nearly 77% of the total NH 3 emissions for the dairy; however, in summer, two lagoons at the dairy contributed 65% of the overall NH 3 emissions.