Biomass production of a Scenedesmus sp. under phosphorous-starvation cultivation condition.

Microalgae-based bioenergy has gained extensive attention, but the consumption of non-renewable resource such as phosphorous is inevitable in the production of its feedstock. In this work, the minimal phosphorous consumption for algal biomass production of Scenedesmus sp. LX1 was investigated by monitoring the growth and nutrient uptake under two different cultivation modes: phosphorous-starvation and luxury-nutrient. The results showed that continuous nitrogen and phosphorous feeding in luxury-nutrient mode had no stimulating effect on biomass productivity at the nutrient level in this study, TN: 245 mg L(-1), TP: 5.4 mg L(-1). However, the sustained growth of biomass after the exhaust of phosphate in phosphorous-starvation mode led to significant increase in the biomass yield of phosphorous up to 160 g biomass/g -P, which was nearly six times more than that with nutrient feeding. To minimize phosphorous resource consumption in production of algal biomass, a phosphorous-starvation cultivation mode is proposed.

Culture of Scenedesmus sp. LX1 in the modified effluent of a wastewater treatment plant of an electric factory by photo-membrane bioreactor.

To investigate the coupled technology for advanced wastewater treatment and microalgal biomass production, a photo-membrane bioreactor was constructed. The microalga Scenedesmus sp. LX1 was cultured in the bioreactor using liquor prepared from the effluent of an electronic device factory. The algal cell growth, nitrate nitrogen removal, orthophosphate phosphorus removal were investigated. When cultured with batch operation, the average specific growth rate was about 0.09 d(-1), and low nitrogen (N), phosphorus (P) concentrations in the liquor were achieved. However, under continuous operation with an inflow of 60 Lh(-1), the average specific growth rate was only 0.02 d(-1), and removal rates of 100% for orthophosphate P and 46% for nitrate N were achieved. With the inflow of 120 Lh(-1), the accumulated metal ions in the bioreactor adversely affected the algal cells. The algal cells were much easier to settle, and the removal efficiency for N and P decreased.