Sustainable intensive livestock production demands manure and exhaust air treatment technologies

Intensive livestock production is connected with a number of environmental effects, including discharges to soils and surface waters and emissions to the atmosphere. In areas with a high livestock density the low availability of nearby arable land, together with the preferred use of chemical fertilizer by arable farmers, results in high off-farm disposal costs for manure. Furthermore, ammonia abatement technologies, such as treatment of exhaust air, are important as ammonia emissions may account up to a quarter of the total nitrogen flux. Firstly, the paper describes and discusses the development of manure treatment in the Netherlands since the 1970’s. Manure treatment processes that result in products that compete with and replace the use of chemical fertilizers can (partly) close the nutrient cycle again. From this point of view aerobic treatment of manure (nitrification/denitrification) can not be considered sustainable as nitrogen is taken out of the cycle at high environmental costs. Secondly, the state-of-the-art of techniques for treatment of exhaust air is presented. Besides ammonia, application of air treatment may also reduce environmental emissions of odour and particulate matter (dust). Both manure treatment and treatment of exhaust air are considered essential for sustainable livestock operations in areas with a high livestock density.