Managed aquifer recharge in South Africa (MARSA)

Managed aquifer recharge (MAR), the purposeful recharge of water to aquifers for subsequent recovery, is used globally to replenish over-exploited groundwater resources and to prevent saltwater intrusion. Due to increased water shortage worldwide, there is a growing interest in using unconventional water resources for MAR such as reclaimed water or surface water impaired by wastewater discharges. This, however, raises major concerns related to pollution of our drinking water resources. MARSA is a new Danish-South African research project aiming at developing MAR technologies allowing a broader span of water resources to be used for MAR, including storm water, river water, saline water, and even treated wastewater. It is hypothesised that improved removal of organic pollutants, nitrogen species, antibiotic resistance, and pathogens can be achieved by establishment of reactive barriers or creation of different redox environments through injection of oxidizing agents to anaerobic aquifers during recharge. In MARSA we will carry out feasibility studies, as flow-through columns, first in Denmark and later in South Africa, to investigate the capacity of South African aquifer sediments to remove organic pollutants, nitrogen species, antibiotic resistance genes, and pathogens. Then, based on these studies, MAR options will be further investigated at field conditions in South Africa using real source water from MAR sites. For this presentation we will give an overview of the MARSA-project and show results from previous feasibility studies investigating the potential of reactive barriers to remove organic micropollutants and ammonium. These studies have shown that establishment of reactive barriers will cause oxygen depletion, but also more efficient ammonium and organic micro-pollutant removal. MARSA is funded by the DANIDA fellowship centre, Ministry of Foreign Affairs of Denmark. Project no. 20-M03GEUS.