Associate Professor
Department of Environmental Engineering
NED University of Engineering & Technology
University Road, Karachi
Pakistan
Engine performance and emission characteristics of biofuels (biodiesel and bioethanol)
Thermochemical treatments of biomass (pyrolysis, torrefaction, gasification and combustion)
Biofuels production (biogas, biodiesel, bioethanol, biohydrogen and bio-pellets)
Hydrothermal liquefaction of biomass
Solar drying of agricultural residues and food crops
Carbon capture through microalgae cultivation
Raceway Pond to Treat Domestic Wastewater and Microalgae Biomass Production
Untreated wastewater is a major environmental issue, leading to pollution in aquatic and marine ecosystems worldwide. Thus, treating wastewater before its disposal is critical to protecting aquatic and marine ecosystems from pollutants. The objective of this study was to develop a sustainable, efficient method for treating domestic wastewater, using mixed microalgae to remove organic and inorganic pollutants. Moreover, microalgal biomass productivity was studied for its utilization to produce sustainable biodiesel fuel. A locally designed and fabricated raceway pond was used for this research work, where five experiments were conducted with different ratios of wastewater and microalgae culture by vol/ vol (i.e., 90:10; 80:20; 70:30; 60:40 and 50:50) respectively. The experimental results showed that (90:10) ratio was most efficient in reducing the inorganic contaminants (nitrates and orthophosphate) as compared to other experiments with nitrates and orthophosphate removal efficiency of 48.88% and 51.30% respectively. While biomass productivity and chemical oxygen demand (COD) removal were 38.41% and 35.61 % respectively. The previous literature results are comparable with current study showing microalgae photobioreactors removal rate of nutrients from wastewater ranged from 72 to 75% for nitrogen and 36 to 64% for phosphorus. Statistical analysis by using one-way ANOVA showed that the reduction of nutrients (nitrates and orthophosphates) and biomass productivity were found highly significant in all experiments. Disposing of treated wastewater through a raceway pond containing microalgae is a sustainable solution, and treated domestic wastewater discharged into water bodies will have the optimal dissolved oxygen level essential for healthy aquatic / marine life without negatively impacting the biological cycle. Microalgae biomass is a very promising and sustainable energy source that has the ability to replace fossil fuels with biofuels. Microalgae cultivation helps in CO2 sequestration and removal of inorganic contaminants in wastewater.
Keywords: Microalgae; Raceway Pond; Wastewater treatment; Biodiesel; Nutrients