Microalgal-induced remediation of wastewaters loaded with organic and inorganic pollutants: An overview

The recent surge in industrialization has intensified the accumulation of various types of organic and inorganic pollutants due to the illegal dumping of partially and/or untreated wastewater effluents in the environment. The pollutants emitted by several industries pose serious risk to the environment, animals and human beings. Management and diminution of these hazardous organic pollutants have become an incipient research interest. Traditional physiochemical methods are energy intensive and produce secondary pollutants. So, bioremediation via microalgae has appeared to be an eco-friendly and sustainable technique to curb the adverse effects of organic and inorganic contaminants because microalgae can degrade complex organic compounds and convert them into simpler and non-toxic substances without the release of secondary pollutants. Even some of the organic pollutants can be exploited by microalgae as a source of carbon in mixotrophic cultivation. Literature survey has revealed that use of the latest modification techniques for microalgae such as immobilization (on alginate, carrageena and agar), pigment-extraction, and pretreatment (with acids) have enhaced their bioremedial po-tential. Moreover, microalgal components i.e., biopolymers and extracellular polymeric substances (EPS) can potentially be exploited in the biosorption of pollutants. Though bioremediation of wastewaters by microalgae is quite well-studied realm but some aspects like structural and functional responses of microalgae toward pollutant derivatives/by-products (formed during biodegradation), use of genetic engineering to improve the tolerance of microalgae against higher concentrations of polluatans, and harvesting cost reduction, and monitoring of pa-rameters at large-scale still need more focus. This review discusses the accumulation of different types of pol-lutants into the environment through various sources and the mechanisms used by microalgae to degrade commonly occurring organic and inorganic pollutants.

Automated summary

The recent surge in industrialization has led to the accumulation of different types of pollutants in the environment due to illegal dumping of wastewater. Microalgae bioremediation has emerged as an eco-friendly technique to degrade organic compounds and convert them into non-toxic substances without producing secondary pollutants. Modification techniques such as immobilization and pigment-extraction have enhanced the bioremediation potential of microalgae. However, further research is needed to study the structural and functional responses of microalgae towards pollutant by-products, engineering microalgae to tolerate higher pollutant concentrations, reducing harvesting costs, and monitoring parameters at a large scale.