Effect of l-glutamic acid on the growth and ammonium removal from ammonium solution and natural wastewater by Chlorella vulgaris NTM06

The main objective of this laboratory scale experiment was to study the effect of l-glutamic acid on the growth in media and removal of ammonium from ammonium solution and natural wastewater by Chlorella vulgaris NTM06. It was observed that higher levels (1.0% and 1.5%) of l-glutamic acid compared to control (0% l-glutamic acid) negatively affected growth of C. vulgaris NTM06 and enhanced removal of ammonium from ammonium solution as well as natural wastewater. After 24 h of incubation, 99% of 169.3 mg NH4+–N/l was removed from ammonium solution by 1.5% l-glutamic acid treated C. vulgairs NTM06 cultures; removal in case of control was 70%. In case of natural wastewaters with initial ammonium concentrations of 1550, 775, 310 and 155 mg NH4+–N/l, removal after 48 h of incubation were 60%, 88%, 61% and 55% respectively. Ammonium removals from ammonium solutions of pH 4.0–8.0 were similar, whereas adsorption of ammonium ions on to the surface of dead C. vulgaris NTM06 cells was around 11%. Compared to dark, cultures incubated under the light showed higher initial removal of ammonium, however, after 24 h, differences were not significant. Further research on the role of l-glutamic acid in micro-algal treatment of wastewater and its combination with other approaches such as co-immobilization of micro-algae with other organisms, starvation of micro-algal cells and the use of polymers is recommended.