Performance of Agroindustrial Wastes for Removal of Disinfection By-products From Water

The aim of the present work was to use agroindustrial wastes as alternative adsorbents for the removal of trihalomethanes (THMs). SEM micrographs of sugar cane bagasse and coconut mesocarp samples showed a high degree of particle agglomeration, with particle sizes of 114.4 +/- 74.0 mu m, while the sugar cane bagasse particles were larger (557.3 +/- 169.5 mu m). The pyrogram obtained for sugar cane bagasse revealed the presence of many compounds with different functional groups containing oxygen atoms. In the case of the coconut mesocarp, the range of oxygenated functional groups was smaller. The adsorption processes showed fast kinetics, with equilibrium reached after around 240 min of contact. Adsorption tests revealed different selectivities of the biomass adsorption sites for the THMs. Adsorption percentages obtained with coconut mesocarp ranged from 49.2 +/- 2.57 to 71.9 +/- 1.88 %, while the values obtained for sugar cane bagasse were between 31.8 +/- 1.08 and 67.4 +/- 1.27 %. The orders of removal (significant at p<0.05) were as follows: CHCl3>CHBrCl2>CHBr2Cl>CHBr3 (using sugar cane bagasse) and CHBr2Cl>CHBrCl2>CHCl3>CHBr3 (using coconut mesocarp). Use of the sugar cane bagasse resulted in high removal percentages of chloroform (51.1 %) and dichlorobromoform (42.3 %) in the first 5 min of contact, showing that this biomass had greater affinity for trihalomethane compounds with more chlorine atoms in their structures. This finding has considerable environmental importance, given that these are the two commonest compounds found in water distribution networks.