Simultaneous nitrogen and phosphorus control from alkali and zeolite sludge fermentation process: Mechanism and application

Abstract

Sludge alkali fermentation (NaOH treatment) can achieve a substantial production of volatile fatty acids (VFAs) while releasing a large amount of ammonia nitrogen (NH4+-N) and phosphorus (PO43--P). To address these issues, a combination of zeolite and NaOH/Ca(OH)2 mixed alkali fermentation was proposed. The results demonstrated that the concentration of PO43--P with mixed alkali treatment was 17.9 mg/L, whereas it was 109.21 mg/L for the NaOH treatment group. At the 8th day, the VFAs production was 1.42 times higher than the control group when using NaOH/Ca(OH)2 mixed alkali treatment. Furthermore, the addition of zeolite strengthened the fermentation by adsorbing NH4+-N. Besides, the sludge after fermentation had good dehydration performance and increased microbial community diversity and richness. Macellibacteroides, Proteiniclasticum, Exiguobacterium, Sporacetigenium and Bacillus were the dominant microorganisms with zeolite treatment. Zeolite combined with mixed alkali induced metabolic changes and the abundances of amino acid and carbohydrate metabolisms were the highest.