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Cultivating Chlorella sp. in a Pilot-Scale Photobioreactor Using Centrate Wastewater for Microalgae Biomass Production and Wastewater Nutrient Removal
- Min, Min, Wang, Liang, Li, Yecong, Mohr, Michael J., Hu, Bing, Zhou, Wenguang, Chen, Paul, Ruan, Roger
- Applied biochemistry and biotechnology 2011 v.165 no.1 pp. 123-137
- Chlorella, bioenergy, biomass production, carbon, carbon dioxide, chemical oxygen demand, light intensity, microalgae, nitrogen, nutrient content, nutrients, phosphorus, total suspended solids, wastewater, wastewater treatment
- This study is concerned with a novel mass microalgae production system which, for the first time, uses “centrate”, a concentrated wastewater stream, to produce microalgal biomass for energy production. Centrate contains a high level of nutrients that support algal growth. The objective of this study was to investigate the growth characteristics of a locally isolated microalgae strain Chlorella sp. in centrate and its ability to remove nutrients from centrate. A pilot-scale photobioreactor (PBR) was constructed at a local wastewater treatment plant. The system was tested under different harvesting rates and exogenous CO2 levels with the local strain of Chlorella sp. Under low light conditions (25 μmol·m-2s-1) the system can produce 34.6 and 17.7 g·m-2day-1 biomass in terms of total suspended solids and volatile suspended solids, respectively. At a one fourth harvesting rate, reduction of chemical oxygen demand, total Kjeldahl nitrogen, and soluble total phosphorus were 70%, 61%, and 61%, respectively. The addition of CO2 to the system did not exhibit a positive effect on biomass productivity or nutrient removal in centrate which is an organic carbon rich medium. The unique PBR system is highly scalable and provides a great opportunity for biomass production coupled with wastewater treatment.