Improved Algal Sludge Methane Production and Dewaterability by Zerovalent Iron-Assisted Fermentation

This study investigated the methane production improvement of algal sludge by zerovalent iron (ZVI)-assisted anaerobic digestion. The zerovalent iron added were 0.5, 2, 5, 10, and 20 g·ZVI/g·TS (total solid). The results indicated that the addition of ZVI at 2, 5, 10, and 20 g·ZVI/g·TS has improved the methane production 1.07, 1.24, 1.41, and 1.46 times as compared with no ZVI added. The dewaterability of treated algal sludge has improved 1.06, 1.08, 1.08, and 1.11 times as compared with no ZVI addition. The biochemical methane production test results fitted to both one-substrate and two-substrate models. The one-substrate model indicated that the hydrolysis rate k has increased 8.21, 7.07, 9.39, 3.50, and 5.07 times as compared with R1 where no ZVI was added. The two-substrate model implied that the rapid hydrolysis rate k _rapid values were 5.23, 4.5, 5.98, 2.23, and 3.23 times as compared with R1. The one-substrate model predicted that the value of methane production was in high correlation with the actual value (R ² > 0.98). The addition of ZVI in algal sludge for methane production without an extra pretreatment process has improved the hydrolysis rate and methane production. This has the potential to be developed as an effective and economic technology in resource recovery from algal sludge.