Treatment of greywater using waste biomass derived activated carbons and integrated sand column

Abstract

Utilization of greywater can reduce water stress if, it is used as an alternative source of water for non-potable use, but it requires careful treatment to remove the contaminants including micropollutants associated with the use of a large number of personal care products. The present paper deals with the batch as well as continuous adsorption study for the treatment of greywater using activated carbons prepared from sawdust, sugarcane bagasse and pine needles. Characterization of adsorbents were done through sophisticated instruments such as FE-SEM, FTIR and BET. The optimum conditions in batch mode for the removal of contaminants are found as pH 7, contact time 240 min. and adsorbent dose 8 g/L with initial COD of greywater as 554 mg/L and BOD as 120 mg/L. For isotherms study, models such as Langmuir, Freundlich and Temkin were used whereas for kinetic study pseudo-first-order, pseudo-second-order and Elovich models were investigated to validate the experimental data. The column adsorption study has been performed to carry out breakthrough analysis of the column bed with respect to COD and BOD removal. To understand the behaviour of breakthrough curves three models viz. Bohart-Adams, Yoon-Nelson and Thomas models have been tested. Out of these adsorbents, the sawdust activated carbon is found to be more efficient. To maintain the concentration of pollutants in treated water below the permissible limit as per CPCB (Central pollution control board), India, a coupled unit of sand and the adsorbent column was investigated in continuous mode. The present investigation appears to be highly competitive to the published literature.