Improving pig manure aerobic composting quality by using carbonaceous amendment with different particle sizes

Abstract: Aerobic composting is an important technical approach to the harmless and resource utilization of livestock and poultry waste. In actual composting, a certain amount of auxiliary materials should be added to promote the effective operation of aerobic composting. At present, the auxiliary materials are divided into activity and inertia from the angle of participating in the fermentation process, while the effect of active auxiliary materials on improving the structure of the reactor is not obvious, and the disadvantage of inert auxiliary material was that it could not regulate the carbon nitrogen ratio of the material. In order to realize the auxiliary material with diversity of function such as regulating the chemical properties of compost material, improving the heap structure, etc. Woodland waste such as branches, were used in this study, and non-sufficiently carbonized by biomass carbonization equipment, which was used as carbonaceous amendment (CA) to improve the quality and technology of manure aerobic composting. The granule surface of CA material was carbon, and the interior was still wood structure. The feedstocks for composting were mainly pig manure and edible fungus residues. Three treatments included the CK (pig manure and edible fungus residue compost), B1 and B2 (60% of edible fungus residue (volume ratio) in the CK treatment was replaced by the CA with particle size of 1-2 and 6-7 cm, respectively). The composting treatments were in triplicate and lasted for 30 days. The changes of parameters such as temperature, ammonia volatilization, nitrous oxide emission, pH value and EC value were monitored. Days heating up to 55 ℃ for the first time, nitrogen loss rate, C/N change rate, seed germination index and the recovery rate of auxiliary materials were selected as the evaluation indexes, the application effect of CA in composting was analyzed by the fuzzy evaluation method. The results showed that, compared with control, CA could obviously promote the rapid increase of the heap temperature, reduce the days heating up to 55℃ for the first time by 4 to 11 days, significantly raise compost accumulated temperature. The heating and warming effect of B2 treatment was better than that of B1 treatment. After 30 days of composting, the total ammonia volatilization amount of three treatments (CK, B1, B2) were 605.41, 374.94, 303.68 mg/kg, and the accumulated amount of nitrous oxide emission was 35.80, 49.53, 74.94 mg/kg, respectively. The nitrogen loss rates of B1 and B2 treatments were decreased by 16.13% and 22.81%. The decrease of nitrogen loss in composting was mainly due to the effective control of NH3 volatilization. The CA auxiliary materials reduced the EC value of the compost, significantly improved the C/N change rate and the seed germination index. By the comprehensive comparison of various parameters and fuzzy evaluation results, the composting effect of B2 treatment was better than that of B1 treatment. CA could effectively promote the decomposition of pig manure and improve the quality of compost products, the suitable particle size for aerobic composting process with high temperature was 6-7 cm.