A Study on Organics and Nutrients Removal Mechanisms in Livestock Wastewater Treatment Using EGSB

Abstract

An advanced way of treating livestock wastewater made use of both Autothermal Thermophilic Aerobic Digestion (ATAD), as a pre-step, and Expanded Granular Sludge Blanket (EGSB), as the post-step. As a result, the chemical oxygen demand (COD) concentration flowing out of the post step, including the EGSB, was 89mg/ℓ, while the suspended solid (SS) concentration was 28mg/ℓ, and the total nitrogen (TN) and total phosphorus (TP) concentrations were 62mg/ℓ and 5.7mg/ℓ, respectively. To maintain a high temperature in the ATAD reactor without external heating, the characteristics of influent were found to be very critical. The temperature of the ATAD reactor was significantly elevated only when the influent TSS was more 50,000mg/ℓ. The EGSB reactor was fed with increasingly higher livestock wastewater loading rates up to 6kg chemical oxygen demand (COD)/ m3/day and an average of 84.7% of the COD and 85.4% of the SS were removed in EGSB. Biogas was generated on the 47th day of operation in the EGSB after startup and its production increased at a rapid rate. The methane percentage within the biogas was initially low but it also increased rapidly, up to 73%. When the HRTs were 0.5-3 days, the COD removal efficiency was over 80%, but did show a increase as the HRT increased to 3 days.