Waste Not, Want Not: Managing Livestock Waste for Income and the Environment
The world-wide intensification of livestock industries poses major challenges for waste disposal. For example, the total solids wastes discharged from livestock farms in China exceeded 1.7 billion tons in 1997, with a further 20 billion tons of waste water being discharged to the environment — only 10% of these wastes were treated! A key element of sustainable development is Cleaner Production. Cleaner Production is an approach in which wastes are handled in such a way that environmental pollution is avoided. Cleaner Production practices include waste minimisation, pollution prevention, recycling and community-based environmental approaches. An increase in the production of livestock products means an increase in the production of livestock wastes and, consequently, an increase in the potential for environmental pollution. The applications of the principles of Cleaner Production for four types of livestock waste are discussed in this paper. With wool-scouring wastes, the process streams are segregated in order to separate the raw wool contaminants so that the dirt and wool wax can either be composted to produce either a soil conditioner or a premium potting mix, or used as a fuel. The water-soluble contaminants can then be used as a source of potassium. The treated water can be recycled to the washing process, thereby eliminating aqueous discharges completely. The pollution propensity of the wastes produced in the leather industry can be reduced by methods such as converting waste hair into a fertiliser, recycling chrome liquor and reducing salt discharges through hide drying technologies. In order to facilitate the adoption of Cleaner Production technologies with piggery wastes in the Pacific Island countries, participatory methods and action research are being used to encourage community involvement. Nutrient audits of farms using farmyard manure applications to improve crop yields showed that Indian farmers under-fertilised their crops, whereas Australian farmers overfertilised them.