Investigation of pH Effect on Optical Membrane Bioreactor Performance in Biomass Growth and Nutrient Removal from Municipal Wastewater

Document Type : Research Paper


1 PhD. Student, Dept. of Environment, Faculty of Environment, Tonekabon Branch, Islamic Azad University, Tonekabon, Iran

2 Assoc. Prof., Dept. of Environment, Faculty of Environment, Tonekabon Branch, Islamic Azad University, Tonekabon, Iran

3 Assist. Prof., Dept. of Chemical Engineering, Faculty of Petroleum and Chemical Engineering, Science and Research Branch, Islamic Azad University, Tehran, Iran

4 Assist. Prof., Dept. of Environment, Faculty of Environment, Tonekabon Branch, Islamic Azad University, Tonekabon, Iran


Municipal wastewater treatment and algal biomass production are simultaneously new and efficient methods in the treatment industry. Using artificial culture medium, urban wastewater is used as a food source for microalgae. Cultivation of microalgae in wastewater is an important step in wastewater treatment that, in addition to wastewater treatment, simultaneous production of biomass is done which can be used for many purposes and is of great value. Method: in the present study, the effect of initial pH on the performance of membrane photobioreactor in biomass growth and nutrient removal from municipal wastewater was investigated. In this study, first Chlorella vulgaris microalgae in a membrane optical bioreactor with a light intensity of 300 μmol photons m-2. s-1 in the 24-hour light cycle and an initial concentration of 1 g/L dry weight of microalgae in the initial three pH (4, 7 and 10) were cultivated. Then, due to the direct relationship between microalgae growth and nutrient removal, the best initial pH in nitrate and phosphate removal from municipal wastewater was investigated. According to the results, microalgae were adapted to municipal effluent after 9 days and at the initial pH of 7, the highest growth rate of microalgae equal to 2.37 g dry weight per liter, and removal of nitrate and phosphate were 88 and 87%, respectively. Also, on the 15th day at the same initial pH, the highest amount of nitrate and phosphate removal from municipal effluent was 92% and 91%, respectively. The results show that the regulation of the initial pH of microalgae can have an undeniable effect on the growth of microalgae. It also has a significant effect on the removal of nitrate and phosphate from municipal wastewater through the cultivation of microalgae. By optimizing the initial pH, this removal percentage has increased.


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