A review on treatment processes of chicken manure

Abstract

The poultry industry is a fast-growing industry fuelled by overwhelming customer demand. Of the different poultry meat options, chicken is arguably the most popular as it is the second most staple food item in Malaysia after rice. Consequently, due to the overwhelming demand for chicken meat, chicken manure is produced in abundance. In fact, a chicken produces 80 g to 100 g of manure daily, corresponding to 3-4% of its body weight. Utilizing the raw manure as an organic fertilizer without any prior treatment results in adverse environmental consequences as this common practice acts as a vector for propagation of pathogens, attracting flies and pests as well as contributing to odour problems. Treatment methods using pesticides, effective microorganisms and daily collection and disposal have been adopted by the farmers but these techniques are relatively costly and associated with potential environmental threats. Other techniques such as composting, pyrolysis, gasification, anaerobic digestion, hydrothermal liquefaction and torrefaction are drawing interest due to their ability to convert waste to value-added products. Approximately, 77,209 tonnes of chicken manure produced per day in Malaysia in 2014 can potentially generate up to 3.86 million m3 of methane from anaerobic digestion, equivalent to potential generation of 139.5 TJ of heat or 38.7 GWh of electricity theoretically. This paper reviews the technical and practical aspects of the techniques mentioned above in terms of operation, performance and limitations. This paper also examines the preferential treatment techniques in relation to the product outputs with good market potential while being environmentally sustainable.