Effects of dilution and pretreatment on nutrient removal and biomass production of Chlorella vulgaris in kitchen wastewater

Abstract

This research investigated the effect of kitchen wastewater (KWW) concentrations and pretreatment methods on Chlorella vulgaris biomass production, lipid content and nutrient removal. This study was divided into two separate experiments. The first experiment determined the appropriate dilution rate of KWW for the growth of microalgae, sterilized KWW was varied between 25%, 50%, 75%, and 100%(v/v). The result indicated that 50%(v/v) showed the highest nutrient removal by 90.23%, 85.87%, and 80.64% of sCOD, TKN, and TP, respectively. The highest biomass and lipid content were obtained with 50%(v/v) (1.447 g/L, 37.9%). The second experiment was to find an effective physical pretreatment method, which separated the biotic contaminant, non-sterilized KWW was diluted 50%(v/v) and filtered with different mesh size filters (150 μm, 50 μm, and 30 μm) compared with sterilized KWW as a control sample. The result indicated that pretreatment with 50 μm filtration was found highest nutrient removal by 90.51%, 84.74%, and 77.50% of sCOD, TKN, and TP, respectively. The highest biomass and lipid content were obtained with 50 μm filtration (1.496 g/L, 39.4%). Our results support the hypothesis that the optimal dilution and proper filtration of KWW helps create more favorable environment for microalgal growth.

Graphical Abstract

STATEMENT OF NOVELTY

The application of microalgae in actual wastewater treatment was the improper amount of nutrients and the presence of biotic contaminant in the non-sterilized wastewater, which is inhibit the microalgae growth. Hence, it is necessary to develop the technique for controlling biotic contamination and appropriately diluting wastewater to enable full-scale microalgae cultivation in the future.

Keywords:

• Chlorella vulgaris
• dilution
• kitchen wastewater
• pretreatment method
• zooplankton

Acknowledgments

The authors extend their appreciation to the staff members for their collaboration, assistance in sampling, and contribution to data collection.

Additional information

Funding

This work was financially supported by a grant from the Faculty of Engineering, Srinakharinwirot University, Thailand (No.540/2019).