Application of Cleaner Production Methodology to Evaluate the Generation of Bioenergy in a Small Swine Farm

Abstract

The swine production is an animal husbandry activity of great commercial importance in Brazil although the environmental organization considers the confined systems of low environmental quality and high polluter potential since it generates a great amount of waste and consumes a high amount of water. Against that background, the aim of this work was to apply the Cleaner Production (CP) methodology in a small swine farm with the purpose of identifying the bottlenecks of processes (considering environmental impacts) and propose sustainable and safe solutions. Based on the first results this research analyzed the economical and environmental feasibility of biogas production, due to the implementation of anaerobic digestions system. To achieve the first goal of this work, the authors developed a schematic flowchart of the process, then identified and evaluated the environmental impacts, to finally select the specific stages necessaries to implement CP actions. The main short and long term actions proposed were: the installations of a septic tank; the improvement of the drainage system; the installation of a hydrometer and a powered watch; the implementation of safety standards to storage chemical and medical products, the improvement of the residues management and the implementation of a biological treatment for the sewage which can be combined to a cogeneration system to produce electricity from the biogas. The technical feasibility study for the implementation of an efficient cogeneration system from the biogas has been developed considering three specific mathematics models (MM): 1st MM: Ratio between animal waste (manure generation) and amount of the biogas produced; 2nd MM: Ratio between the concentration of volatile solids (VS) from animal waste and amount of the biogas produced and 3rd MM: Empirical correlation between the amount of methane produced and the waste digested in the anaerobic reactor, considering influent Biological Oxygen Demand (BOD) value. The VS and BOD methods seem to be the most proper models and had close values for the predictions of biogas produced. According to these results the use of biogas for the energy cogeneration seems to be economically and environmentally practicable.