Performance of blue green algae in mitigation of reactive dye industrial wastewater

Abstract

Rapid industrialization and urban expansion contributed to escalating environmental pollution globally. Despite economic benefits, the textile industry is flawed by its substantial effluent discharge. This study pioneers the investigation of Spirulina platensis's treatment efficiency and growth kinetics for mitigating reactive dye-based textile industry wastewater (TIWW) at concentrations of 20 %, 40 %, 60 %, 80 %, and raw with mass balance and stoichiometric analysis. Growth analysis showed peak biomass production on the 15th day for all concentrations, with similar patterns to the control, highlighting Spirulina platensis's adaptability in TIWW. This resulted in maximum color and Chemical Oxygen Demand (COD) removal of 42.65 ± 0.85 % and 79.45 ± 1.59 %, respectively, observed on the 15th day in raw TIWW with biomass productivity reaching 0.032 ± 0.001 gL⁻¹ day⁻¹ and a specific growth rate of 0.141 ± 0.003 day⁻¹. Furthermore, the highest removal percentages for nitrate, ammonia, and phosphate were observed, reaching 98.23 ± 0.19 %, 87.68 ± 1.75 %, and 68.29 ± 1.36 %, respectively. Interestingly, Spirulina platensis facilitated the removal of metals as well, with removal percentages of 55.56 ± 1.11 % for Cu(II), 68.97 ± 1.38 % for Th(IV), 100 % for Mo(VI), and 100 % for Sr(II) after treatment. Mass balance and stoichiometric calculations were employed to elucidate the underlying chemical transformations involved in these processes, resulting in a biomass yield of 0.185 g biomass/g COD. Hence, reactive dye-based TIWW was effectively treated by Spirulina platensis, which also acts as a suitable nutrient-rich medium. The results of this study demonstrate the potential of Spirulina platensis as a sustainable and effective method for treating textile industry wastewater.