Natural Attenuation of Emerging Pharmaceuticals by Bank Filtration in Addressing Regional Groundwater Management Issues - Dimkic et al. page 02

In Vojvodina, nearly 70% of groundwater is abstracted from deep, regional aquifers. The over-exploitation problem has been present in the Bačka and Banat regions since the early 1980’s, when the rate of abstraction for public and industrial water supply exceeded natural recharge of the BWC. The impact of over-exploitation is primarily seen in declining groundwater levels in the wider
areas of groundwater sources (resulting in increasing abstraction costs), declining yield, and in some cases local land subsidence. Extreme drawdowns were recorded in the wider zones of water sources; lowering of piezometric head in the past 3 decades is present in the regions of north Bačka and north Banat (between 20 and 30 metres) (Figure 3).


A forecast of the effects of future groundwater abstraction at the current rate (roughly 4.5 m3/s) or higher showed that that there will be a further decline in groundwater levels, in some areas by several dozen meters (JCI, 2000). Figure 4 shows drawdown forecasts for a moderate increase in the rate of abstraction through the year 2030.
The quality of groundwater in Bačka, Banat and Srem is characterized by distinctive inequality, ranging from acceptable water quality to water that requires a high level of treatment. Groundwater chemistry in central Bačka is characterized by elevated concentrations of organic substances, arsenic, iron and manganese, while in the catchment area of the Tisa and in western Bačka (Odžaci), KMnO4 demand is greater than, andeven as high as 100 mg/L (the prescribed limit value is 8 mg/L).
Other characteristics of this groundwater include permanently elevated iron concentrations, sometimes as high as 3 mg/L,and the absence of manganese, nitrite and nitrate.

Based on recorded values, there are several areas with extremely high arsenic concentrations (> 50 µg/L): northern, western and southern Backa, and northern and central Banat (Figure 5 and Table 1).
A relatively narrow zone between the towns of Zrenjanin and Žitište (central Banat), is characterized by highly-mineralized groundwater (in excess of 1200 mg/L), and high concentrations of iron (generally 0.4 but also above 2 mg/L), arsenic (up to 200 µg/L), and the ammonium ion (over 2 mg/L), as well as significantly high Natural Organic Matter (NOM) levels in groundwater (with KMnO4 demand occasionally exceeding 200 mg/L). Over the past decade, major efforts were made (especially in the Town of Zrenjanin) to find a suitable technology for the treatment of this groundwater; 9 pilot plants were installed and tested but the results were not satisfactory. A highly complex technology (aeration, flocculation/sedimentation, ozonation, multilayer filtration and disinfection, and in some cases reverse osmosis) is required to treat this groundwater (Stauder, 2007).