Combination of Advanced Oxidation Processes and Microalgae Aiming at Recalcitrant Wastewater Treatment and Algal Biomass Production: a Review

Abstract

Recalcitrant wastewaters are hardly biodegradable. Therefore, these wastewaters must be treated prior to their disposal into water bodies. Advanced oxidation processes (AOP) represent promising alternative treatments since they are capable of improving their biodegradability. However, AOP treatments may be expensive and demand high energy consumption, especially when a complete mineralization of organic pollutants is expected. For this reason, AOP are often associated with other treatment methods. The microalgae-based wastewater treatment is a remarkable environmentally friendly technology since, in addition to the wastewater remediation, it can provide microalgae biomass to be used as feedstock for biofuel production. This review summarizes the current knowledge regarding the use of combined AOP and microalgae treatment aiming at both wastewater remediation and algal biomass production. Additionally, an integrated flowsheet of remediation of recalcitrant wastewater (using AOP and microalgae) and exploitation of microalgal biomass is proposed as an additional contribution of this paper. Scientific publications from 2009 to 2019 available in the Web of Science databases were reviewed. 1255 papers were selected, 328 papers were reviewed after screening, and 76 were actually included. The number of studies that encompass combinations of AOP and microalgae treatment are very scarce. The ozonation is the pretreatment most often utilized for pollutant oxidation and disinfection of recalcitrant wastewaters. The review of these articles shows that the harvested microalgae biomass from recalcitrant wastewaters pretreated by AOP has potential to be used as feedstock for biofuel production. Highlights • Remediation of recalcitrant wastewater by AOP and microalgae combined treatment. • Biomass from recalcitrant wastewaters pretreated by AOP can produce biofuels. • There are few studies about AOP and microalgae combined treatment. • A layout for recalcitrant effluent remediation and biomass exploitation is proposed.