Removal of disinfection by-product precursors from natural water using coagulation and subsequent adsorption

Abstract

A critical task in drinking water treatment is the removal of natural organic matter (NOM), particularly during the rainy season when a lot of organic matter is transported by run of the water bodies. In order to increase the NOM removal; synthetic chemical coagulants were used as coagulants. However, they have been associated with Alzheimer and are carcinogenic. The application of natural coagulants (green compounds) has become a responsibility to guarantee the health of the population. The aim of this study was to evaluate the removal efficiency of disinfection by-product precursors by coagulation and activated carbon adsorption. Coagulation was studied by Moringa stenopetala and activated carbon adsorption was tested with Vachellia abyssinica. The experimental procedure employs first treating the raw water sample with Moringa stenopetala and filtering the coagulated supernatant water. Then this filtered supernatant was prepared for activated carbon adsorption test and any removal improvement by activated carbon adsorption over that of coagulation was assessed. The dose of the coagulant was selected as 10,20,30,40 and 50mg/L and that of the adsorbent dose was selected as 0.01, 0.02, 0.04, 0.1 and 0.2g. The finding shows that there is afraction of DBP precursor that was not amenable under coagulation, especially at higher coagulant doses indicating that part of the very reactive component of DBP precursors or SUVA to form disininfection by-product wasn’t removed sufficiently resulting high THMFP in the coagulation treated samples. On the other hand subsequent application of activated carbon adsorption improved the removal efficiency on the DOC and SUVA concentration over that of coagulation with avery minimal concentration of THMFP