Harvesting of Microalgal Biomass Using Moringa Oleifera as Natural Coagulant: A Cost-Effective Approach

Abstract

Microalgae has been considered one of the most promising 3rd generation biofuel sources. Nevertheless, the commercialization of this biomass has not been successful in developing countries due to the energy-intensive harvesting process. The aim of the present study is to find a suitable coagulant which is locally available, costeffective, non-toxic, and environmentally friendly. In this regard, Moringa Oleifera (MO) seed powder, locally known as Shojne in Bangladesh, is used as natural coagulant to fulfil the present crisis. However, the harvesting efficiency and coagulant properties of MO were evaluated through jar-test, where wastewater grown microalgae, cultured in a photobioreactor (PBR), was used. This study optimized the harvesting parameters such as coagulant dose, mixing rate, and mixing time. As those parameters have a significant impact on the microalgae harvesting process. Low mixing rate and mixing time have better performance with coagulant dose varied from 10-70 mg/L. The highest harvesting efficiency of 83% microalgae recovery was achieved at 20 rpm for 10 minutes with coagulant dose of 70 mg/L. The MO seeds are recommended to be prospective coagulants for both water treatment and microalgae harvesting. Journal of Engineering Science 13(1), 2022, 51-59