Review of Challenges for Algae-Based Wastewater Treatment: Strain Selection, Wastewater Characteristics, Abiotic, and Biotic Factors

Abstract

This paper will focus on the challenges associated with algae-based wastewater treatment (ABWWT). To elucidate the issue, this review will investigate the following: (1) microalgal strain selection, (2) wastewater characteristics, and (3) the effect of various biotic and abiotic factors. Mostly, monocultures of microalgae are used in wastewater treatment (WWT), but microalgae–bacteria consortia have received significant attention recently. Their interaction mechanisms and the sheer number of possible combinations pose a significant challenge in the strain selection. Various types of wastewaters have varying nutrient loads and different types of biochemical composition, which affect the efficiency of their treatment process significantly. Because microalgae are photosynthetic organisms, environmental factors, such as light, temperature, and pH play a significant role in the phycoremediation of wastewater. Light intensity and its duration, the maintenance of optimum temperature, and pH range pose major challenges in ABWWT. In addition to abiotic factors, biotic factors, such as biopollutants that include pathogenic microorganisms greatly affect the quality of treated wastewater. Their proper detection and elimination is a significant requirement in the wastewater process. Therefore, this paper will carry out a critical review of all the previously mentioned key challenges, which act as an impediment in the large scale implementation of ABWWT.