Full-Scale Composting of Different Mixtures with Meal from Dead Pigs: Process Monitoring, Compost Quality and Toxicity

Abstract

Abundant by-products of large swine industries, such as slaughterhouse sludge and carcasses, require adequate treatment to prevent negative effects of their direct disposal in the open environment. This study is aimed to evaluate the efficiency of composting using meal from dead pigs through physicochemical analyses and phytotoxic assays. Five treatments were tested, all including 50% sawdust: T1, with 50% slaughterhouse sludge (control); T2, with 20% slaughterhouse sludge and 30% meal from dead pigs; T3, with 10% slaughterhouse sludge and 40% meal from dead pigs; T4, with 20% organic stabilizing compost and 30% meal from dead pigs and T5, with 30% organic stabilizing compost and 20% meal from dead pigs. The phytotoxicity assays used lettuce, cucumber, celia, soybean, rice and wheat as bioindicators. Inclusion of meal from dead pigs was related to reduction in pH, C/N ratio, humidity and temperatures inside the pile, although thermophilic peaks lasted longer than 50 days and the final composts showed high content of nitrogen and phosphorous. The germination of bioindicators was reduced in all tested treatments, compared to the control. The composts from treatments that included meal from dead pigs presented acceptable nutrient content, which may indicate their use as organic fertilizers. However, after 4 months, all bioindicators in contact with such composts presented impaired germination.

Cattle Manure Compost Properties with the Addition of Dead Broiler Carcass as Nitrogen Sources

“…Overall, the nitrogen content of the compost produced is less than the provisions of the Indonesian compost standard SNI: 19-7030-2004, where the minimum nitrogen content in compost is 0.4%. Total N content in this result was contra with the previous study [23,24] that the utilization of the swine carcasses could significantly increase the total N content of matured compost. Low compost nitrogen content was suspected due to the release of volatilization gas during the compost turning process.…”

Life cycle inventory for an organic swine waste treatment system

“…Pampuro et al [ 26 ] presented similar results with a pH of 6.9 in compost obtained from SFS in a static composting system. The moisture content at all sampling points was lower (72.8, 7.1 and 85.7%, respectively) compared to the recommended minimum (35%) for commercial compost; this problem occurs when the materials used in composting already have a humidity close to that ideal for composting [ 17 ] between 50 and 60% [ 56 , 57 ]. In addition, during composting, a large amount of water is lost, and the moisture content decreases [ 57 ]; it is necessary to monitor the process so that the compost can be kept within optimal ranges.…”

“…Guidoni et al [ 17 ] evaluated the efficiency of composting dead pigs and loading agents (sawdust, slaughterhouse sludge, and stabilized compost) in different volumes for 120 days. They obtained a compost with a pH of 7.6, electrical conductivity (EC) of 3.8 mS/cm, total nitrogen (N tot ) of 6.1%, and total phosphorus (P tot ) of 3.0%, although it was toxic when applied to different tested seeds.…”

Comportamento de micro-organismos patogênicos durante processo de compostagem de carcaças de suínos

“…Após 24 dias do início do processo, o material foi revolvido, o que promoveu a oxigenação do sistema e consequentemente a reativação do processo de decomposição, comprovado pela elevação da temperatura acima de 50 ºC (Figura 1). O processo de revolvimento é recomendado em outros estudos (Schloss et al, 2000;Guidoni et al, 2021) e frequentemente um processo adotado por produtores rurais em granjas avícolas sendo este manejo útil para situações similares. Um perfil de variação da temperatura semelhante foi observado por Lashermes et al (2012), e justifica-se por conta das dimensões da composteira, onde experimentos em escala laboratorial podem perder calor para o ambiente com mais facilidade (Lashermes et al 2012).…”