Removal of nitrogen and phosphorus from municipal wastewater effluent using Chlorella vulgaris and its growth kinetics

Chlorella vulgaris was used for the removal of residual ammonia/ammonium ion (NH3/NH4+) and orthophosphate ion (PO43-) from secondary wastewater effluent collected from a municipal wastewater treatment plant. The uptake rates for nitrogen and phosphorus were studied with different initial algal cell densities and the addition of CO2 gas for pH control and supply of inorganic carbon. Our result showed that typical NH3/NH4+ and PO43- concentrations could be readily removed within 48 h. It was found that the culture with an initial algal cell density of ∼350 mg/L and CO2 gas supply could significantly enhance both the rates of cell growth and nutrient uptake. The Monod equation well described the algal cell growth under substrate-limiting conditions, and could be used for the design and operation of photobioreactors for potential tertiary wastewater treatment.