This study investigated the effect of NH4 + concentrations on microalgae growth by appling mixotrophic microalgae chlorella vulgaris in order to treat anaerobic digested food waste leachate. The growth rate and final microalgae growth were an order as 400 > 100 > 800 > 1300 mg-N/L. As results, The growth rate and final growth of microalgae were highest at ammonia concentration of 400 mg-N/L, On the other hand microalgae growth was inhibited when ammonia concentrations were over 800 mg-N/L. high concentrations of nitrogen over 800 mg-N/L interrupt the growth of microalgae. All of nitrogen and phosphorus were removed by microalgae at the ammonia concentration of 100~400 mg-N/L. In addition, when ammonia concentration was over 800 mg-N/L, the removal of nitrogen and phosphorus was limited mainly due to the microalgae growth limit. It was possible to treat anaerobic digested food waste leachate with mixotrophic microalgae when the ammonia concentration was controlled below 400 mg-N/L.

This study investigated the semi-continuous and continuous cultivation of microalgae-sludge for artificial digested food wastes leachate treatment, and the effect of hydraulic retention times(HRT) on microalgae growth and nutrient removal. In this study, two reactors were examined the HRTs from 4 to 1 day, the Chlorella vulgaris cell density of semi-continuous and continuous cultivation reached a maximum value at HRT 3 day, then decreasing HRT to 2 day and 1 day the Chlorella vulgaris cell density was decreased. The maximum Chlorella vulgaris cell density in semi-continuous cultivation was 1.4 times higher than continuous cultivation. The maximum NH4-N, PO4-P removal efficiency was 100%, 75.7% with HRT of 3 day in semi-continuous cultivation, while 96.5%, 65.7% with HRT of 4 day in continuous cultivation. These results indicate that semi-continuous cultivation is more suitable than continuous cultivation. And the effect of increased light intensity from 100 μmol/m²/s to 400 μmol/m²/s was also evaluated, as the result, increased light intensity improved Chlorella vulgaris cell growth and nutrient removal.