Enhancing domestic wastewater treatment through four chlorophyta strains-based phycoremediation: nutrient removal efficiency and algal physiology.

Abstract

Phycoremediation is a promising solution for environmentally sustainable wastewater treatment. However, its effectiveness depends on the selection of suitable microalgae species. In this study, four algal species (Chlorella sorokiniana, Chlorella vulgaris, Scenedesmus ecornis, and Strombomonas sp.) were evaluated for their ability to remove pollutants from secondary treated domestic wastewater using multi-soil-layering (MSL) technology. Among the four strains tested, Chlorella sorokiniana exhibited the highest algal density (2.832 ± 0.187 × 10⁷ cells/mL) and outperformed other species with phosphorus, nitrogen, and COD removal rates exceeding 82.01%, 63.64%, and 61.09% respectively. In addition, Chlorella sorokiniana had a higher total chlorophyll content of 31.11 µg. L^-1 (Chl a: 15.47 ± 0.148 µg. L^-1; Chl b: 15.642 ± 0.052 µg. L^-1) than other species. Physiological analyses of proline and glycine betaine indicated that the two Chlorella strains experienced lower stress levels, which facilitated an accelerated bioremediation process compared to other Chlorophyta, namely Scenedesmus ecornis and Strombomonas sp. The efficiency of C. sorokiniana in the treatment of secondary treated wastewater from MSL, combined with its maximum biomass production, underlines its potential for industrial application. Consequently, there is a compelling interest in evaluating C. sorokiniana within a prototype as a prelude to industrial development.