Assessment of Rice Straw–Derived Biochar for Livestock Wastewater Treatment

The use of rice straw for biochar production has been widely proved as a great alternative energy source, which not only is cheaper than other commercial coals but also helps mitigation of climate change. In this study, the rice straw–derived biochar was assessed as a sorption material used for livestock wastewater treatment, which has not much been studied so far. The biochar derived from rice straw had moisture content of 4.9 ± 0.5 %, bulk density of 0.38 ± 0.03 g/cm3, iodine number of 958.0 ± 37.0 mg/g, and pH was determined at 7.6 ± 0.1. The optimal contact time, biochar mass concentration, and pH were determined as 3.0 h, 4.0 g/L, and 9.0, respectively. The COD and BOD5 removal efficiencies were up to 40.0% via the batch experiment. However, the column test results showed the higher removal efficiencies which were 79.0 ± 6.1% for COD and 84.0 ± 2.5% for BOD5 with the influent COD concentration of 373.0 ± 8.0 mg/L and BOD5 concentration of 240.0 ± 3.0 mg/L. The effluent all met the current livestock wastewater discharge standard of Vietnam (QCVN 62-MT:2016/BTNMT). These findings indicate the potential of using straw-derived biochar as a good material for removing organic pollutants from livestock wastewater.