10:45 AM - 12:15 PM
[AGE28-P08] Nutrient conservation achieved through mixing regime improves the microalgal wastewater treatment and diminishes the net environmental impact
Keywords:Microalgae, Wastewater treatment, Mixing regime, Nutrient conservation, Non-negative environmental impact
Photobioreactors (PBR) offer promising alternative to activated sludge process (ASP) with environmental benefits, as well as among other microalgae wastewater treatment technologies (MWTT) such as raceway ponds with high biomass productivity and pollutant removal. However, commonly practised modus operandi (aeration) for PBR would render the environmental benefits of MWTT, if it is prone to gaseous emissions like ASPs. In this context there is wider knowledge gap in decision making for environmentally benign modus operandi of PBR-MWTT.
Therefore, the present work utilized two modus operandi, aeration and mechanical mixing (non-aeration), for comparative evaluation. The experiments conducted with dominant microalgae:bacterial (M:B) inoculation ratio (60:40), demonstrated higher M:B ratio (78:21) within mixing regime, as essential nutrients (dissolved inorganic carbon and ammoniacal nitrogen) were conserved within the wastewater. The lower M:B ratio (36:63) was obtained during aeration regime, as these nutrients were transformed into CO2 and NH3 and emitted to the environment. The nutrient conservation mechanism within mixing regime enhanced microalgae growth (30%), metal removal, and exhibited carbon negative global warming potential (-0.0451 kg CO2 eqm-3), along with overall non-negative environmental impact. Overall, this study reveals a previously overlooked yet significant contribution of nutrient conservation achieved through mixing regime for holistic wastewater treatment.
Therefore, the present work utilized two modus operandi, aeration and mechanical mixing (non-aeration), for comparative evaluation. The experiments conducted with dominant microalgae:bacterial (M:B) inoculation ratio (60:40), demonstrated higher M:B ratio (78:21) within mixing regime, as essential nutrients (dissolved inorganic carbon and ammoniacal nitrogen) were conserved within the wastewater. The lower M:B ratio (36:63) was obtained during aeration regime, as these nutrients were transformed into CO2 and NH3 and emitted to the environment. The nutrient conservation mechanism within mixing regime enhanced microalgae growth (30%), metal removal, and exhibited carbon negative global warming potential (-0.0451 kg CO2 eqm-3), along with overall non-negative environmental impact. Overall, this study reveals a previously overlooked yet significant contribution of nutrient conservation achieved through mixing regime for holistic wastewater treatment.