Potential use of Foundry sand and Furnace blast sand for fabrication of visibly active composite to promote circular economy/waste-management for treating real agro-industrial wastewater.

Abstract

A two-step process of coagulation/flocculation followed by a simultaneous dual process (photocatalysis + photo-Fenton) is developed to treat real pulp and paper (P and P) industry wastewater. The rigid stout color wastewater was treated using a sunlight-responsive and cost-effective Fe-TiO2 composite using recirculating photoreactor with a total working volume of 4L. The key point of this study is that the treatment is done in very less time (90 min) and it incorporates the idea of circular economy, as the composite is fabricated out of industrial rejects. The further intensification of the process was done by proper process optimization of both approaches. With an initial concentration of stout color (0.78 AU) and COD (2200 mg/L), the optimized conditions gave a good reduction in % color and % COD i.e. 64.1% and 41.8% (1280 mg/l) after coagulation/flocculation and 89.74% and 53.12% (600 mg/l) after dual respectively. The composite was characterized by using various techniques like FESEM/EDAX, UV-vis DRS, XRD, etc. to check the catalyst composition, complexes formed between Fe-TiO2, and the catalyst intactness in both fresh and 50 times recycled composite. A trapping study was also performed using various quenchers to confirm that OH• plays a major role in the present study amongst other radicals produced where 55-60% drop in color removal was seen. In order to foresee the commercial use of this study, the process' cost was also estimated.