Odour control with biological air washers

Abstract

Odour nuisance caused by livestock and poultry farms is becoming a real problem in Holland. By installing biological air-scrubbers in the ventilation of the exhaust system, the air can be made dust-free, and the odour components can be reduced. In this way the complaints of neighbours can be eliminated. In the air-scrubbers the ventilation air is brought into contact with a large surface over water by using an inert material. The water is recirculated over the filter material. It is important that the surface of the water changes often. Activated sludge from a sewage plant is added to the circulating water. The reduction of smell is from 60 to 85% according to organoleptic and chemical analysis and depends on such different parameters as the initial amount of smell, the filter medium in the scrubber and the overflow of the circulation water. A description is given of the biological air washer, types of packing material used, circulation pumps and water distribution. Some of the theoretical aspects such as water consumption and mechanism of the air washer are discussed, together with a cost study. The wash-water contains nitrite and nitrate as a result of biological activity. Future research is indicated.