Effects of Combined Technologies on Environmental Prevention against Livestock Pollution in Biogas Projects

To resolve the contradiction between livestock development and environmental pollution, anaerobic fermentation in biogas projects has been used for more missions, such as co-generation of heat and power, production of anaerobic digested fertilizer for the prevention and control of livestock pollution. The aim of this work was to investigate the effects of combined technologies on biogas slurry treatment. Chemical flocculation can remove the total solids (TS), chemical oxygen demand (CODcr), total phosphorus (TP), and total nitrogen (TN) at rates of 89.4%, 95.9%, 98.0% and 73.9%, respectively. However, removal of ammonia nitrogen (NH4+ N) (37.1%) and soluble potassium (3.4%) is poor. A facultative oxidation pond can remove NH4+ N and soluble K at rates of 63.5% and 47.5%, respectively. In addition, an ecological forest can remove NH4+ N, soluble K, and TP at rates of 93.1%, 54.9%, and 70%, respectively. Heavy metal pollution is effectively controlled through the whole workflow. Ultraviolet disinfection is still required for pathogen elimination, although the combined processing has a remarkable impact on the removal of fecal coliforms and total coliforms.