Evolution of physical and chemical parameters during co-composting of swine solid fraction manure using different turning strategies

Composting is not a new technology in livestock farms. Generally animal manure composting is carried out with basic methodology, without controlling the main characteristics of the feedstock and the process conditions (Bernal, 2008). Composting of organic residues promotes the maturation and partial humification of organic matter up to complete stabilisation. This process depends on characteristics of organic materials and process management. Environmental impact of intensive breeding makes treatment techniques of liquid manure very popular. Liquid-solid separation of liquid manure is the most simple of these techniques. It consists of the separation of the solid fraction from the liquids. This process splits the nitrogen content into two different materials that can be stored and managed separately, permitting different agronomical use. The solid fraction can be successfully composted to achieve stabilization of the organic matter and to improve the agronomical value of the material. High efficiency separator devices produce a solid fraction with low C/N ratio (Almela, 2005). However this product can lead to important ammonia (NH3) emissions during composting process. This paper reports the results of investigations on the evolution of characteristics of the same initial mixture of solid fraction of swine manure and untreated sawdust composted with a turning and non-turning composting process.