Co-composting of chicken manure, alperujo, olive leaves/pruning and cereal straw at full-scale: Compost quality assessment and odour emission

Abstract

Co-composting is a simple and inexpensive alternative for stabilizing and reducing jointly different biodegradable waste. In this study, the feasibility of co-composting chicken manure (CM), alperujo (AL), olive leaves/pruning (OL) and cereal straw (CS) was evaluated at full-scale. The different areas of a composting plant such as fermentation area, composting area and leachate lagoon, were evaluated from physico-chemical, respirometric and olfactometric points of view. The compostable mixture was previously subjected to anaerobic fermentative pretreatment to hydrolyse the non-easy biodegradable organic matter and favour the subsequent composting process. The physico-chemical, respirometric and olfactometric characterization of the composted mixture showed a high-quality final product characterized by a 57 % average organic matter content, an adequate metal content (Compost type A) and a suitable microbiological stability (SOURmax value of 14mmol O2/kg VSh), complying with current national legislation for use as fertilizer in agriculture. Furthermore, the average global odour emission rate of the composting plant was 5.16 ouE/kg, considering the total mass of the compostable mixture and the time required to be treated. Finally, the leachate collected from different treatments of the compostable mixture was found to be a stabilized organic liquid waste with a high nutrient content, useful for wetting composting piles.