Hybrid Treatment of Hospital Wastewater Combining Continuous Flow Electrochemical Coagulation Coupled with Adsorption

摘要

Hybrid treatment technology in recent time is seen as novel treatment technology for treatment of various types of wastewaters. Over the past few decades, electrochemical treatment coupled with adsorption for wastewater treatment has gained much attention. Raw hospital wastewater (HWW) was treated coupling continuous flow electrochemical coagulation (ECC) and adsorption for removal of pollutants/contaminants chemical oxygen demand (COD), colour, and total dissolved solids (TDS). The electrochemical treatments in continuous mode were carried out for applied voltage of 12 and 18 V using A1 and SS electrodes for flow rates 6 Lph, 4 Lph, 2 Lph, and 1 Lph coupled with adsorption. COD removal of 79.4 and 75.26 were obtained at 90 min ET for 12 and 18 V using Al electrodes with corresponding colour removal of 77.15 and 74.49 and TDS residual concentration of 452 mg/L (12 V) (45.14 removal) and 431 mg/L (18 V) (47.69 removal) from its initial concentration C_0 of 824 mg/L respectively. Similarly, continuous ECC studies using SS electrodes showed maximum COD removal of 75.26 and 73.85 for 12 and 18 V at 90 min ET for flow rate 1 Lph. Colour removal of 77.15 and 74.46 was observed at the end of 330 min ET with simultaneous TDS concentration reduction of 423 mg/L (48.66 removal) and 408 mg/L (50.48 removal) respectively. The initial COD and colour concentration before ECC were 768 mg/L and 0.404 (absorb-ance). The breakthrough capacity for Al electrodes was comparable with SS electrodes ranging from 73 to 107.78 g/L. Adsorption kinetics showed that the Adam Bhorat model constants increased with increase in flow rates with pollutant removal controlled by external mass transfer. The ECC + adsorption coupled hybrid treatment process showed disinfection potential by destruction of the microbial mass by both Al and SS electrodes. At the end of the electrochemical treatment, the agar plate count was< 10 CFU/mL for Al and<5 CFU/mL for SS electrodes. The operating cost of the hybrid process is 41.65 and 50.95 INR/m~3 of HWW treated for the desired 75-80 COD removal using Al and SS electrodes. The ECC coupled adsorption process showed its effectiveness and may be successfully applied for the treatment.