DBPapers
DOI: 10.5593/SGEM2014/B31/S12.063

NATURALLY IRON-RICH GROUNDWATER IN SOUTH-EASTERN ESTONIA: PROBLEM RELATED TO THE FULFILLING THE DRINKING WATER QUALITY REQUIREMENTS

M. Hiiob, E. Karro, M. Uppin, A. Marandi
Wednesday 1 October 2014 by Libadmin2014

References: 14th International Multidisciplinary Scientific GeoConference SGEM 2014, www.sgem.org, SGEM2014 Conference Proceedings, ISBN 978-619-7105-13-1 / ISSN 1314-2704, June 19-25, 2014, Book 3, Vol. 1, 487-494 pp

ABSTRACT
Groundwater abstracted from the sand- and siltstones of the Middle Devonian (D2) aquifer system is the main source of drinking water in southern Estonia. Naturally high iron (Fe) concentrations are the greatest problem in this region, complicating to fulfil the EU requirements concerning the drinking water quality. The content of Fetot exceeds the limit value of 0.2 mg/l set to the drinking water (98/83/EC) in 80% of the analyses. In places the Fetot concentrations up to 26 mg/l have been detected. High Fetot concentrations are mainly caused by high Fe2+ contents in groundwater, referring to the domination of reducing conditions in aquifer system. In order to produce high-quality drinking water 4 different water treatment systems were used in 9 studied water treatment plants. Filter materials such as Manganese Greensand, Nevtraco and quartz sand were combined with aeration. The results of the study show that Fetot content in abstracted groundwater (0.12-3.60 mg/l) was reduced to the level of 0.02-0.34 mg/l during the purification process. The systems with pre-aeration remove iron effectively, thus while the oxygen-poor conditions prevail in the D2 aquifer system, pre-aeration is needed in order to increase the effectiveness of the purification process.

Keywords: water treatment, iron, Middle Devonian aquifer system, Estonia