Using surfactants for controlling rotifer contamination in mass cultivation of Chlorella pyrenoidosa

Abstract Frequent microzooplankton contamination such as rotifers in Chlorella mass culture often causes devastating effects on biomass production. In this study, five surfactants were used to control contamination by a rotifer, Brachionus calyciflorus, in Chlorella pyrenoidosa XQ-20044 cultures. Laboratory results showed that the minimal effective concentrations of surfactants for complete control of B. calyciflorus were 7.5, 10, 10, 10, and 15 mg L−1 for primary alcohol ethoxylate, sodium dodecylbenzene sulfonate, sodium alcohol ether sulfate, coconut diethanolamide, and sodium dodecyl sulfate, respectively. However, only 10 mg L−1 sodium dodecylbenzene sulfonate and 7.5–10 mg L−1 primary alcohol ethoxylate had no negative effects on algal growth. Moreover, in a 5 m2 open raceway pond, 10 mg L−1 sodium dodecylbenzene sulfonate ensured swift and total elimination of rotifers, while the final dry weight of the algae reached >0.74 g L−1 whereas the cost of using sodium dodecylbenzene sulfonate was only $ 0.014. The results of this study indicated that sodium dodecylbenzene sulfonate approach is fast-acting, highly effective, and a low-cost treatment. Therefore, sodium dodecylbenzene sulfonate has great potential for biological contamination control in microalgae mass culture without a negative impact on algal growth.