Efficient treatment of tannery wastewater through aeration, coagulation, and algal pond

Abstract

Background: Tannery wastewater effluents contain many toxic and carcinogenic heavy metals and physiochemical parameters that need to be removed before these effluents enter in the main water bodies or rivers. In this study, the effluents from the tannery industry are treated through aeration, coagulation, and Chlorella vulgaris pond treatment processes for the removal of physiochemical: parameters only.

Methods: The effect of removal efficiencies (%) was studied on the physicochemical parameters, including salinity, electrical conductivity (EC), total dissolved solids (TDS), turbidity, total suspended solids (TSS), biochemical oxygen demand (BOD), and chemical oxygen demand (COD).

Results: The key results showed that the removal of EC, TDS, turbidity, TSS, BOD, and COD was 80.2%, 67%, 81%, 80.8%, 68.6%, and 100%, respectively, in raw wastewater treatment having 25, 50, and 70 g of algae C. vulgaris doses. The removal efficiencies (%) of salinity, EC, TDS, turbidity, TSS, BOD, and COD were 83%, 87.1%, 77.1%, 80%, 40%, 97%, and 98%, respectively, during coagulated wastewater treatment with three doses of algae. The observed improvement in treated wastewater indicated that the removal efficiencies (%) of salinity, EC, TDS, turbidity, TSS, BOD, and COD were 85.7%, 39.3%, 81.3%, 67.8%, 50.3%, 97%, and 98%, with C. vulgaris.

Conclusion: This study confirmed that the treatment of tannery wastewater by these processes increased the pollutant removal efficiencies as all the physiochemical parameters were exceeding the permissible limits.

Results contribution in future: This research will be helpful to treat the industrial wastewaters or effluents before it further mixes up in the main water streams. In this way, water quality will be better, aquatic life will be saved, and further researchers can analyze more ways for efficient treatments as they have a baseline data through this study findings.

Practitioner points: One of the most pollutant sources in terms of both physical and chemical parameters is the produced wastewater from tannery industries. The effluents from tannery industry are treated through aeration, coagulation, and algae ponds treatment processes. These treatment made the tannery wastewater as environmental friendly.

Keywords: Chlorella vulgaris; biochemical oxygen demand (BOD); chemical oxygen demand (COD); electrical conductivity (EC)|; salinity; tannery wastewater; total dissolved solids (TDS); total suspended solids (TSS); turbidity.