Enhancing methane production from algae anaerobic digestion using diatomite

An innovative technology using diatomite to enhance methane production from anaerobic algae digestion was proposed in this study. The results of biochemical methane production (BMP) tests showed that 1, 2, 5 g/L of diatomite addition increased methane production by 22.5 +/- 7.1%, 30.6 +/- 5.1% and 32.8 +/- 7.2% (p = 0.001, 0.0002, and 0.0002) compared to the control. In continuous operation experiments over 136 days, the parameters of digester containing volatile solid (VS) destruction and daily methane yield were increased by 31.2% and 32.1% with diatomite (5 g/L) addition. The addition of diatomite improved the solubilization, hydrolysis, acidification, and methanation processes in the anaerobic algae digestion, and the abundances of most key microorganisms (e.g., Methanosaeta sp. and Syntrophomonas sp.) involved in anaerobic digestion also increased correspondingly. The mechanism studies revealed that diatomite with strong conductivity could act as an electron shuttle, contributing to the increasing electron transfer efficiency for methane production. The novel strategy proposed in this study might bring significant economic and environmental benefits to algae treatment for energy recovery.