Comparative Bioremediation Efficiency of Selected Microalgae in Industrial Wastewater Treatment

Abstract

This study evaluated the bioremediation potential of four freshwater algae—Microcystis aeruginosa, Eudorina elegans, Chlorella vulgaris, and Oedogonium grande—grown in industrial effluents from rubber, paint, Coca-Cola, and Guinness industries. Effluent remediation was assessed over a four-week exposure period using electrical conductivity, phosphate concentration, and dissolved oxygen as performance indicators. Removal efficiencies (%) were calculated to quantify treatment effectiveness. All algae significantly reduced ionic and nutrient loads, with electrical conductivity reductions ranging from 46.7–72.0% and phosphate removal reaching 100% in Coca-Cola effluent. Conductivity reduction was most pronounced in rubber effluent, with Oedogonium grande (71.91%) and Microcystis aeruginosa (72%) showing superior ionic removal, while all algae performed poorly in high-salinity beverage effluents. Phosphate removal was substantial across effluents, reaching complete removal (100%) in Coca-Cola effluent by M. aeruginosa and Ch. vulgaris. Dissolved oxygen increased consistently across treatments. Results demonstrated strong effluent-specific responses. Chlorella vulgaris consistently exhibited the highest overall bioremediation efficiency across effluents, while Oedogonium grande performed optimally in nutrient-rich brewery wastewater. Two-way ANOVA revealed significant effects of algal species and effluent type on removal efficiencies, with post-hoc comparisons confirming species-specific responses. The findings highlight functional specialization among algal taxa, with filamentous forms excelling in low-ionic effluents and unicellular green algae performing best under nutrient-rich conditions. The findings demonstrate the strong potential of micro-algae for low-cost, sustainable treatment of industrial effluents and support their application in effluent-specific bioremediation strategies. The study confirms the feasibility of algae-based effluent polishing and supports the strategic selection of algal species based on effluent chemistry. These results provide a scientific basis for integrating algal bioremediation into sustainable industrial wastewater management.