Unraveling the role of polyferric chloride in anaerobic digestion of waste activated sludge

This study explored the effect of polyferric chloride (PFC) as a flocculant on waste activated sludge anaerobic digestion. The results verified that PFC has an inhibitory effect on methane production during anaerobic digestion. PFC with a concentration of 40 g/kg total suspended solids reduced methane production from 195 +/- 2.10 to 156 +/- 1.50 L/kg volatile suspended solids, a decrease of 20.0 +/- 0.09%. PFC released hydroxyl polymers and Fe(III). Hydroxy polymers aggregated sludge flocs and hindered the release of dissolved organic matter. Fe (III) induced dissimilar iron reduction processes to contend with methyl-CoM for electrons, thereby further reducing methane production. In addition, PFC enriched iron-reducing bacteria and reduced the abundance of methanogens, resulting in microbial communities that are not conducive to methane production. This article puts forward innovative insights on the role of PFC in biological sludge treatment, which is expected to guide the flocculant selection during wastewater treatment.

Automated summary

The study showed that polyferric chloride (PFC) has an inhibitory effect on methane production during waste activated sludge anaerobic digestion. PFC released hydroxy polymers and Fe(III), leading to a decrease in methane production by inducing dissimilar iron reduction processes and altering microbial communities. This innovative insight could guide flocculant selection in wastewater treatment.