Sub-pilot scale cultivation of Tetradesmus dimorphus in wastewater for biomass production and nutrients removal: Effects of photoperiod, CO2 concentration and aeration intensity

Abstract

The potential of microalgae in wastewater treatment and resource utilization has received considerable interest. For better outcomes in large-scale cultivations, it is usually essential to optimize the microalgal culture parameters in a sub-pilot cultivation system. Herein, a series of experiments were carried out to investigate the effects of photoperiod, CO2 concentration and aeration intensity on nutrients removal and biomass production of Tetradesmus dimorphus under the 50 L culture scale. The results showed that the removal rates of chemical oxygen demand (CODcr), NH4+-N and total phosphorus (TP) in primary effluent (PE) were 93.9 %, 92.3 % and 84.8 %, respectively. Compared with 15 h:9 h (15 h light and 9 h dark cycle), the maximum Chlorophyll-a content of 2797.78 mg/m3 was reached at 24 h:0 h. The maximum microalgae biomass (OD680 = 0.56) was obtained when the CO2 concentration was 200 mL/min, but CO2 enrichment inhibited nitrogen removal. At optimal aeration intensity (60 L/h), the highest chlorophyll-a content was recorded on day 3. The removal rates of NH4+-N and TP were 92.1 % and 89.7 %, respectively.