Efficiency investigation of chlorella vulgaris algae in removal of nitrogen, phosphorus and chemical oxygen demand from municipal and industrial wastewaters

Human activities, especially in construction and agriculture, introduce large amounts of nitrogen, phosphorus and organic matter into aquatic ecosystems.

In this study, municipal and industrial wastewater samples were obtained from wastewater treatment plant No. 1 of Parkand Abad and wastewater treatment plant of Kalat industrial park, respectively. Before starting the reactor, wastewater samples were allowed to settle for 2 h to remove coarse suspended solids and then sterilizes in autoclave. Chlorella vulgaris was purchased from Jahad Daneshgahi of Mashhad and grown in specific culture media under temperature 25±2°C, photoperiod of 14 h light and 10 h dark, monochrome light with intensity of 5000±350 lux, pH of 7-8.5 and time of 10 d. Then 1 L of the above solution were transferred to three 10 L reactors loaded with municipal, industrial and culture media and aerated under sterile conditions in the presence of light for 10 d. In predetermined time intervals (each 2 d), 100 mL sample were taken from reactors and COD, total phosphorous, total nitrogen, pH and chlorophyll a measured.

Removal efficiency of COD, total nitrogen, and phosphorus in municipal, industrial and culture media by Chlorella vulgaris was 63.69, 12.52, and 13.79%, 66.57, 34, and 50.18%, respectively. According to results, the efficacy of algae for removal of COD was higher than other parameters, while that for total nitrogen was lowest. Efficacy of algae for removing pollutants from industrial was better than those in domestic wastewater.

The results of this study showed that municipal and industrial media could be a suitable culture media for growing Chlorella vulgaris algae. It also has the ability to remove nutrients from wastewaters.