Artificial groundwater recharge (AGR) is used in the drinking water industry to supplement groundwater resources and minimize the use of chemicals in water treatment. The process involves infiltration of lake or river water through a designated, natural sandy formation (esker). In Finland, the surface waters contain high concentrations of peatland-originated humic substances. Thus, the artificial recharge process results in the conduction of large quantities of natural organic matter (NOM) into the subsurface. A high proportion of NOM is removed during passage of the recharged water through the esker. The mechanisms of NOM removal are a combination of adsorption and biodegradation. This study aims to improve the understanding of NOM biodegradation during AGR and to assess whether real-time online monitoring can be used to enhance AGR production and NOM removal. In cooperation with the Universities of Helsinki and Jyväskylä, chemical and microbial dynamics were monitored at an existing site during the re-introduction of surface water, after a period of recharge with chemically treated water. Ground state monitoring of one virgin recharge site has been completed, and full scale monitoring of a second virgin site before and during surface waters infiltration is ongoing. Laboratory work aims to clarify characteristics of groundwater microorganisms that are likely to affect the extent of NOM degradation during AGR.
Responsible persons: Professor Jaakko Puhakka, PhD Kathryn Wakeman
Researchers: MSc Tech Johanna Ojala, BSc Tech Titta Hagelin
Funding: TEKES (80 %), Tavase Oy, Turun Seudun Vesi Oy, Pöyry Environment Oy, FCG Planeko Oy Programme
Schedule: 11/2008 – 04/2011