Bioremediation of nutrients and heavy metals from wastewater by microalgal cells: Mechanism and kinetics

Abstract

Conventional chemical and physical treatment methods applied for the treatment of wastewater tend to be complicated, energy demanding and expensive. Biological waste treatment process involving microalgae provides an economical, sustainable and alternate means of advanced wastewater treatment process coupled with simultaneous recovery of nutrients and manufacture of commercially valuable products like single-cell protein, biofuel, etc. Updated information regarding the advancements made in the treatment process, mechanism and kinetic models involved in nutrient removal by microalgae are provided in this review. Advancements such ultrasonic treatment, use of algal-bacterial symbiosis system, blending of two different wastewater and use of photo-sequencing batch bioreactors for the treatment of municipal, domestic, livestock and industrial wastewater are discussed in brief. The present work focuses mainly on the primary mechanisms involved in the assimilation of nitrogen, carbon and phosphorus inside the microalgal cell. Not only a brief description of metal-ion uptake by processes such as ion exchange, complex formation, precipitation and physical adsorption and role of the plasma membrane, cell wall, vacuoles, chloroplast and mitochondria is discussed in this investigation, but also the various kinetic models of nutrient removal such as Stover-Kincannon, Michaelis-Menten, Gompertz model and Luedeking-Piret model with their experimental curve fitting results obtained from microalgal cell-mediated treatment process are also discussed. © Springer Nature Singapore Pte Ltd. 2019.