Polydimethyldiallylammonium chloride inhibits dark fermentative hydrogen production from waste activated sludge

PDDA (polydimethyldiallylammonium chloride) is an excellent flocculant for wastewater purification, but it is unclear whether it poses a threat to waste activated sludge hydrogen production. Herein, the effect and underlying mechanism of PDDA on sludge dark fermentation was investigated. Based on the results, PDDA inhibits hydrogen production.It reduces the cumulative hydrogen production.PDDA impeded the entire dark fermentation process by inhibiting key enzyme activities, and inhibits hydrogen-producing processes such as hydrolysis and acidification more strongly than hydrogen-consuming processes. In addition, PDDA crowded out dominant bacteria such as Firmicutes sp. by enriching other microorganisms such as denitrifying bacteria, thus inhibiting hydrogen production by the acetate pathway. This study examines the potential impact of PDDA on sludge treatment.