Case Studies in Chemical and Environmental Engineering (Jun 2023)
Combination of biochar filtration and ozonation processes in livestock wastewater treatment and application for soil cultivation
Abstract
The livestock wastewater after being digested anaerobically in the biogas tank still contains high concentrations of organic substances, nutrients, antibiotics and other pollutants which could affect seriously the surrounding environment. In this study, the swine wastewater, after being digested anaerobically in the biogas tank, was further treated in 3 different processes: biochar filtration, ozonation, and combination of both (filtration + ozonation). Biochar material made from biomass residue of mango leaves was analyzed for testing the adsorption capacity of the wastewater by the techniques such as scanning electron microscope (SEM), Fourier Transform Infrared (FTIR), surface area and pore size (Barrett-Joyner-Halenda-BJH). The post-treated wastewater and adsorbed biochar were then applied for the soil cultivation by monitoring the growth of Lactuca sativa. The results showed that the simultaneous biochar filtration and ozonation processes performed the best removal of Chemical Oxigen Demand (COD), Biochemical Oxygen Demand (BOD5), Total Suspended Solids (TSS), total nitrogen (TN), total phosphorous (TP), total potassium (TK), total organic carbon (TOC), and ammonium (N–NH4+) of 84.2%. 92.7%, 80.8%, 93.3%, 76.0%, 80.4%, 90% and 53.7%, respectively. The analysis of SEM, FTIR, and BJH images also indicated that the biochar had a high adsorption capacity of livestock wastewater after being digested anaerobically in the biogas tank. The use of adsorbed biochar as an organic fertilizer was proved to be useful for cultivation of Lactuca sativa. By the combination of local biomass residue and the reuse post-treated materials, the study has proved the benefit of the sustainable economy model for the low income families in the rural areas, particularly in Vietnam.
