Use of microalgae for the treatment of black and odorous water: Purification effects and optimization of treatment conditions

Abstract

In this study, three strains of microalgae, including Scenedesmus sp. LX1, Navicula pelliculosa and Cyclotella sp., were selected to investigate their treatment effects on black and odorous water and their growth potential, after which the optimal treatment conditions were obtained. All three strains, especially Navicula, have been shown to be effective at removing pollutants from black and odorous water samples. The removal rate of ammonia nitrogen (NH4+-N) and total phosphorus (TP) from the water samples treated by Navicula could reach up to 100%, and total nitrogen (TN) and chemical oxygen demand (COD) were cut by 66.67 ± 2.30% and 81.82 ± 2.10%, respectively. After treatment with Navicula, the dissolved oxygen (DO) and the oxidation-reduction potential (ORP) values of the water samples significantly improved, and the pH value was closest to neutrality. The samples treated with Navicula exhibited the best water quality. All three microalgae could grow in black and odorous water samples with different growth characteristics, among which Navicula, with more moderate growth characteristics, was considered to have greater application potential than the other two strains for the future treatment of black and odorous water. To promote the ability of Navicula to purify black and odorous water, the optimal conditions to allow Navicula to promote pollutant removal for water purification were determined to be an initial algal density of 2.50 × 105 cells mL−1, a temperature of 10.60 °C and a light intensity of 2437.5 lx using a Box-Behnken design of response surface methodology.