Biofiltration of Acetic Acid Vapours Using Filtering Bed Compost from Poultry Manure - Pruning Residues - Rice Husks

Abstract

Volatile organic compounds (VOCs) are generated by important economic activities such as: Chemical production plants, industrial areas, agricultural and livestock farms and waste treatment plants. These VOCs could generate annoyance and repercussions on health of the employees and the surrounding communities. Biofiltration is one of the most efficient biological technologies to eliminate these contaminants on streams with medium concentrations and high flows. Moreover, it has several advantages related to low costs of implementation and maintenance. In this work, packing materials were obtained through a composting process carried out under controlled conditions. Poultry manure (PM) as main substrate and pruning residues (PR) or rice husks (RH) as bulking materials were used during composting. Two isolated acrylic barrels (210L) with automatized aeration were used as composters. These systems were fed with PM:PR and PM:RH in a volume ratio of 1:1 to obtain two different composts used as packing materials. A biofiltration battery was used to evaluate acetic acid removal efficiency from an air stream through the composting beds. The material moisture was fixed in 50% w.w. and the system assessment was carried out using an empty bed retention time of 66 s. The biofiltration system was exposed to concentrations in the range of 7,240 to 14,480 ppm. The removal efficiency, of both biofilters, during the experiment was in the range of 77.1 to 99.9 %. The low pollutant removal was associated with a high initial VOCs concentration in the gas stream. Nevertheless, the pruning residues bed showed a better operative performance to the transient conditions evaluated.