Anaerobic digestion

Methane

Engineering

Anaerobic exercise

Ecology

Biology

Chromatography

Botany

Food science

Digestion (alchemy)

Physiology

Environmental engineering

Organic chemistry

Biomass (ecology)

Agronomy

Effluent

Environmental science

Volatilisation

Chemistry

Nutrient

Pulp and paper industry

Microorganisms

This study investigated nutrient removal from anaerobic digestion effluent by cultivating mixed-culture microalgae enriched from anaerobic sludge under different pH conditions: RUC (uncontrolled), R7-8 (maintained at 7-8), and R<8 (maintained below 8). Significant amounts of NH4+-N were lost by volatilization in RUC cultures due to increased pH values (≤8.6) during the early period of cultivation. The pH control strategies significantly affected the biological NH4+-N removal (highest in R7-8), microalgal growth (highest in R7-8), biomass settleability (highest in R<8), and microalgal growth relative to bacteria (highest in R<8) in the cultures. Parachlorella completely dominated the microalgal communities in the inoculum and all of the cultures, and grew well at highly acidic pH (<3) induced by culture acidification with microalgal growth. Microalgae-associated bacterial community structure developed very differently among the cultures. The findings call for more attention to the influence and control of pH changes during cultivation in microalgal treatment of anaerobic digestion effluent.

Effects of Different pH Control Strategies on Microalgae Cultivation and Nutrient Removal from Anaerobic Digestion Effluent