Minimum-cost biofilters for reducing odours and other aerial emissions from livestock buildings .2. A model to analyse the influence of design parameters on annual costs

A model to optimize the design of biofilters for livestock buildings is presented. This was developed from four sub-models covering biofilter size, biological performance, pressure drop and costs. The sub-model for biological performance predicts that for a specified duty, residence time multiplied by effective surface area of packing is constant. Hence direct comparison of different packing media can be made without the need to quantify the difficult parameter of odour. Five different packing media were compared, based on given inputs. The model predicts that peat and heather, a common packing medium, is the cheapest packing when fewer than 5000 broilers are housed. (C) 1996 Silsoe Research Institute