Economic feasibility of irradiation-composting plant of sewage sludge

Design and cost analysis were made for a sewage sludge treatment plant (capacity 25-200 ton sludge/day) with an electron accelerator. Dewatered sludge is spread on a rolling drum through a flat nozzle and disinfected by electron irradiation with a dose of 5 kGy. Composting of the irradiated sludge is also made at the optimum temperature for 3 days. The accelerating voltage of electron and capacity of the accelerator are 1. 5 MV and 15 kW, respectively. Total volume of the fermentor is about one third of that of conventional composting process because the irradiation makes the time of composting shorter. The cost of sludge treatment is almost the same as that of conventional method.