Application of combined hydrodynamic cavitation and Fenton reagent for COD reduction of cellulosic fiber industry effluents

Abstract

The present work demonstrates the implementation of combined approach of hydrodynamic cavitation reactor and Fenton oxidation process for the treatment of three cellulosic fiber (CF) industry effluent streams using pilot scale reactor with operation at 500 L developed at an industrial site. In order to assess the techno-economic viability of the combined hydrodynamic cavitation (HC) and Fenton oxidation process, various sets of experimental runs were carried out. Effect of type of treatment approach, one step and stepwise addition of oxidants, number of cavitation passes, and finally the type of effluent varying in terms of initial chemical oxygen demand (COD) on the efficacy of treatment were studied. Based on the results, HC + Fenton oxidation scheme was demonstrated to be a viable option for the treatment of CF industry effluent streams. HC + Fenton treatment rapidly reduced COD, achieving almost 90 % reduction in just 10 min, highlighting its efficiency in industrial wastewater treatment. The treatment achieved substantial reduction in residual COD levels with actual value as up to 1000 mg/L COD in effluent-I, up to 150 mg/L COD in effluent-II, and up to 100 mg/L COD in effluent-III. The study also explored the operating cost expenditure (Opex) of the proposed system required to demonstrate it at a commercial level, including the cost of chemicals and electricity. The COD reduction cost evaluated were INR 140–230/kg COD depending on the effluent. The main highlight of the article is the practical demonstration at the manufacturing unit including the operating cost calculations.