Background: The treatment of sewage water is an important problem faced by many cities
across India. Conventional methods are costly and require high space, therefore, there is a need to develop
an eco-friendly and cost effective technique for the treatment of sewage water.
Methods: The present work deals with the treatment of sewage water using three different microalgae
cultures in combination with the Membrane Bioreactor (MBR). Open raceway pond was used to grow
microalgae (three species) in presence of sunlight (12:12 h light-dark cycle) with continuous monitoring
of nutrients and organic matter depletion for 5 days. Algal growth was measured using hemocytometer.
Nutrients and organic matter uptake was measured using standard APHA & TOC analyzer respectively.
The grown algal biomass was dewatered using three different membrane modules.
Results: The effect of various operating parameters such as the concentration of microalgae, types of
membranes (viz. ceramic, polysulfone and polyacrylonitrile (PAN)), and transmembrane pressure, on
the quality of treated water was investigated in detail. During the operation, various process parameters
such as nutrients uptake, pH and organic matters were monitored. It was found that at higher initial biomass
concentration (5x106 cells/ml), the rate of the nutrients uptake was maximum for all the three cultures,
and PAN membrane gave the highest permeate flux with less fouling compared to other membranes.
Conclusion: Efficient biomass production and high quality permeate water was achieved together by
the combination of microalgae and membrane bioreactor system.