Treatment of piggery waste in an ectopic microbial fermentation system and safety evaluation of generated organic fertilizer

Abstract BACKGROUND With the development of China’s livestock breeding industry, a large amount of waste was discharged and the local environment was seriously polluted. In this research, treatment performance of piggery waste in an ectopic fermentation system (EFS) using different padding materials and safety evaluation of generated organic fertilizer were studied in a pilot experiment. RESULTS During the whole fermentation process, temperature in the EFS fluctuated with addition of fresh feces and its consumption, and the pH value varied between 6.5 and 9.5. The absorption coefficient of pig breeding wastewater and feces per kilogram of padding (maize straw) at the end was 2.52 and 1.88, respectively. Bacteria played a major role in decomposing organic matter, and its number was basically maintained at 10 7 –10 8 orders of magnitude. The C:N ratio in two EFS beds decreased gradually and was below 14:1 at the end, indicating the maturity of fermentation. Moreover, operation of the EFS with addition of rice husk/coconut shell mixture was more stable than that of EFS with maize straw. After fermentation, the heavy metal, total nutrient content, ascaris egg mortality and fecal coliform population of the generated organic fertilizer from two fermentation beds all met the limits of the Organic Fertilizer Standard of China, and the seed germination index of the product increased. CONCLUSIONS EFS employing maize straw or rice husk/coconut shell mixture as padding material can be used to treat both solid and liquid waste from pig farms. EFS technology reduced the biotoxicity of piggery waste. © 2022 Society of Chemical Industry (SCI).