No abstract

This study evaluated the bioremediation potential of two marine microalgae Chlorella sp. and Phormidium sp., both individually and in consortium, to reduce various pollutants in tannery wastewater (TW). The microalgae were grown in hazardous 100% TW for 20 days, and the reductions in biochemical oxygen demand (BOD), chemical oxygen demand (COD), total nitrogen (TN), total phosphorous (TP), chromium (Cr) and total dissolved solids (TDS) of the wastewater monitored periodically. Both marine isolates reduced the BOD and COD by ≥90% in the consortium and by over 80% individually. Concentrations of TN and TP were reduced by 91.16% and 88%, respectively, by the consortium. Removal/biosorption efficiencies for chromium ranged from 90.17-94.45%. Notably, the TDS, the most difficult to deal with, were reduced by >50% within 20 days by the consortium. The novel consortium developed in this study reduced most of the ecologically harmful components in the TW to within the permissible limits of discharge in about 5 to 15 days of treatment. Thus, both the tested marine strains of Chlorella and Phormidium sp. are promising for bioremediating/detoxifying TW and adequately improve the water quality for safe discharge into open water bodies, in particular when used as a consortium.

The potential of the marine microalgal isolate Phormidium sp. to detoxify/reduce various pollutants from a highly hazardous mixed industrial effluent (MIE) is evaluated. The microalgae are grown in the MIE at 30% (v/v%) strength for 21 days under controlled environmental conditions. The reductions/changes in concentrations of biochemical oxygen demand (BOD), chemical oxygen demand (COD), nitrate, nitrite, total phosphate, and toxic metals (chromium, nickel, manganese, copper) are monitored. Notably, the isolate grew quite well, reducing the levels of BOD by 93% and those of COD by 71% in 6 to 9 days. Concentrations of other measured contaminants are also reduced to within the permissible limits of discharge. Higher rates of hatchability in Artemia salina cysts and survivability of its hatchlings are observed in the algae‐treated wastewater than in the untreated wastewater, indicating safe discharge of the wastewater. These observations are valuable, as they indicate that many environmental strains of microalgae possess the potential to detoxify certain hazardous MIEs and can adequately improve the quality of water for reuse/discharge, thereby safeguarding our natural environments from the detrimental effects of direct disposal.