Autotroph

Environmental chemistry

Biomass (ecology)

Engineering

Nutrient

Nitrification

Organic chemistry

Chemistry

Ecology

Metabolite

Activated sludge

Chlorella vulgaris

Food science

Environmental science

Bacteria

Pulp and paper industry

Nitrogen

Genetics

Biochemistry

Algae

Sewage treatment

Botany

Biology

Aeration

Environmental engineering

Wastewater

Journal of Cleaner Production

Wastewater treatment based on algae-bacteria consortia is expected to find use among other biological processes. In this report, the effects of the inoculation ratios of a Chlorella vulgaris and nitrifier-enriched-activated-sludge (NAS) consortium on nutrient removal, carbon capture, and metabolite generation were investigated under autotrophic conditions. The maximum NH4+-N removal (100%) was observed within 7 days in a photo-bioreactor containing 10% C. vulgaris: 90% NAS (w/w); this consortium is referred to as B10. The maximum PO43--P removal (87.5%) was observed in a pure culture of C. vulgaris after 14 days. Due to the fast nitrification achieved using B10, this system showed the highest nitrate accumulation value of 19.73 mg NO3−-N/L at the end of the experiment. The DO concentration in B10 reached 4 mg/L due to the photosynthetic activity of C. vulgaris, providing appropriate conditions for the NAS. Among all the tested consortium ratios, B90 (90%:10% C. vulgaris/NAS, w/w) showed the highest carbon capture (156 mg), while B10 captured only 43.2 mg of carbon. Furthermore, metabolite analysis showed a positive correlation between the proportion of C. vulgaris and the generation of metabolites in the cultures. A trade-off was observed between nutrient removal and carbon capture in C. vulgaris and NAS co-cultures. Overall, our study shows that the aeration system in conventional nitrification processes could be replaced by a cleaner process based on microalgae, resulting in enhanced nutrient removal, increased carbon capture, reduced metabolite generation, and a decrease in excess sludge production.

Interaction between Chlorella vulgaris and nitrifying-enriched activated sludge in the treatment of wastewater with low C/N ratio