Evaluation of the removal efficiency of ammonium and some heavy metals from agricultural wastewater on the zeolitic substrate of an experimental wastewater treatment plant

This study is intended to evaluate the adsorptive potential of clinoptilolite zeolite, used as a filter medium in an experimental wastewater treatment plant for agricultural interests. Samples of technological water and wastewater from agricultural households and microfarms in Transylvania were analyzed, before and after filtration using natural zeolite from Rupea (ZNR) and Turbidex. The tests included the determination of pH, electrical conductivity, ammonium, and some heavy metals (Fe, Cr, Mn, Co, Ni, Cu, Zn, Cd, and Pb) for the characterization of the technological water/wastewater and the zeolite removal efficiency. The evolution of pH had an increasing trend, due to the alkalinity of the zeolite material, with similar values (7.2–7.4) before and after filtration of both water and with larger oscillations for wastewater (6.0–9.4). Electrical conductivity values decreased after both water (from 848 to 492 μS/cm) and wastewater (from 1277 to 933 μS/cm) filtration, correlating with increased alkalinity. The filtration media had a good adsorptive potential, with ZNR values being slightly higher than those of Turbidex‘s for NH4+ (88.02% and 86.85%, respectively) and ranked differently for heavy metals: Zn (72.45%) > Fe (66.45%) > Cu (43.76%) > Mn (43.69%) and Fe (67.41%) > Mn (65.65%) > Zn (60.84%) > Cu (56.08%), respectively.