Removal of iron and manganese from groundwater based on iron bacteria's activities

Abstract

With regard to growing potable water quality standards, iron and manganese removal from underground water has become a problem of today in the Lithuanian water works. The analysis of groundwater, treated for drinking purposes in Lithuania show, that it contains too much iron and manganese, which quantity at some (in Nida, Preila, Daugai, Moletai, Sirvintos) places exceeds the Lithuanian hygienically acceptable standards up to six times following the value of iron concentration and to four times of manganese concentration [Diliunas 1999]. Now the most advanced method for removal of the mentio¬ned substances is nonreagent technologies, where the important role is the on biological oxidation [Mouchet 1992, Bohm 1995]. This kind of process is new not only in Lithuania, but also in other countries, since its principles were developed only in the last decade [Sakalau-skas 1999, Karosas 2001]. The results of experimental investigations of Lithuanian scientists [Karosas 2001, Salteniene 2003] in Vilnius, Viriai, Kirtimai, Sereikiskes, Kaunas Petra-siunai waterworks (1996-2002) show that non-reagent iron and manganese removal is an attractive process for Lithuanian groundwater types. But capabilities of the present technology are still not fully revealed. There are not established and not optimised such technological parameters of biological oxidation as filtration rate, duration and intensity of filter bac-kwashing. Dependency of activity of iron bacteria's on the mentioned factors is not fully examined yet and not used, what is urgent nowadays.