Evaluating the quality of biogas sludge after pretreatment by Fenton process and dewatering for organic fertilizer formulation
Abstract
Biogas sludge is rich in nutrients and can be used as fertilizers after resolving the limits such as high pH, large amount of water, containing volatile N that is easily lost into the environment, and pathogens. This study investigates the effectiveness of iron-rich biogas sludge pretreatment using Fenton method to increase biodegradability and dewatering efficiency to recover condensed sludge as a raw material for fertilizer production. The results showed that Fenton oxidation process improved the quality of sludge by adjusting pH and reducing pathogenic microorganisms in sludge. The humidification - dehumidification process effectively removed water at 70oC (36.6%) and helped to enrich nutrients in the biogas sludge. The condensed sludge remained significant amounts of nutrients (3089.2 mg/L of TKN, 37.3 mg/L of P2O5 and 21.8 mg/L of K2O). The water recovered from the humidification - dehumidification process contained significant amount of TKN (651.2 mg/L), which can be reused for composting process.
