Priority substances in the groundwater of the Neogene Middle Posavina region and proposal for nano-geopolymer-based remediation techniques

The physicochemical characterization of the groundwater from the southern part of the Pannonian Basin of the Neogene age was investigated. High concentrations of manganese and nitrate as well as selected polycyclic aromatic hydrocarbons (PAHs) above legislation were monitored as the main challenges. The novel cost-effective nano-geopolymer remediation technique for groundwater purification was proposed due to the existing conventional one. Organic and inorganic parameters were conducted on adapted pollution indices: the Nemerow and the single-factor pollution index, the ecological risk factor as well as the chosen rations of particular PAHs (pyrolytic or petrogenic origin) for water. The statistical factor analysis of the principal component analysis grouping of Ca and Mg ions in the groundwater suggests the dissolution of sedimentary rocks, mostly limestone. The high correlation between SO₄²⁻, KMnO₄ cons. and TOC indicates point source pollution, originating from the leakage of municipal wastewater pipes. Chloride, Al, Zn and the total phosphorus in the solution have both a crustal and anthropogenic origin. The concentrations of SO₄²⁻, Mg, Na, K and Cl are extremely low. Cost-effective technologies, such as high-performance clay minerals, zeolites and calcium–aluminum–silicate–hydrates, were selected for manganese removal, e.g., clinoptilolite (natural zeolite), one of the highest in this class with an adsorption capacity equal to 4.22 mg/g. An important aspect related to this research is the inclusion of, e.g., manganese as the complexing agent and of chlorides in the second Watch List which lies under the Water Framework Directive. Graphic abstract: [Figure not available: see fulltext.].