Integrated biohydrogen production and dairy manure wastewater treatment via a microalgae platform

Abstract

The present study aimed to investigate the feasibility of sustainable biohydrogen production from dairy manure wastewater using a microalgae platform to achieve simultaneous wastewater treatment and clean energy production. Compared to single-stage microalgae cultivation, two-stage cultivation of indigenous wastewater bacteria and carbohydrate-rich microalgae Chlorella vulgaris ESP-6 achieved satisfactory removal of nutrients and chemical oxygen demand. The resulting biomass, with high carbohydrate content (48.8 ± 2.3%), was used as alternative feedstock for biohydrogen production by Clostridium butyricum CGS5 via dark fermentation after thermal acid pretreatment. The implementation of an automatic pH control strategy significantly promoted H2 generation, resulting in a hydrogen yield of 211 mL/g VS and a maximum productivity of 391.1 mL/L/h. To the best of our knowledge, this is the first integrated study of dairy manure wastewater treatment and biohydrogen production with high H2 yield and productivity comparable to those reported in the literature.