The potential of Zeolitic Volcanic Tuff to remove manganese and iron from water.

Abstract

The study investigated the potential of zeolitic volcanic tuff (chokaa) to remove iron and manganese from water. A series of batch experiments were conducted to ascertain this potential. Iron removal was favoured by small particle sizes of sorbent, high temperature and low pH. Batch studies carried out at low pH, using sorbent particles of size O.3mm- O.6mm indicted that about 93% of the iron was removed from the solution. On the other hand, manganese removal was favoured by small particle size of the sorbent and high pH. Batch studies carried out at a pH of 9 using sorbent particle size of O.3mm- O.6mm indicted that over 75% of the manganese was removed from the solution. Further study showed that the two cations can be removed at normal operating condition of neutral pH, but the sample had to be treated first with potassium permanganate before passing it through a column. Results from column studies carried out at a pH of 7.35, which was the normal pH of the sample and initial iron concentration of 3.7mgll, and initial manganese concentration of O.6mgll, indicated that up to around 98 bed volumes, the percentage removal for iron and manganese were 92% and 87% respectively. The cost associated with removal of iron and manganese ions from water using a column packed with zeolitic volcanic tuff is reasonably low and the system practically viable. Sorption kinetic studies strongly indicated that the sorption process was governed by intra- particle diffusion.