From wastewater to irrigation water: adsorption of microbial, NH4+ and heavy metals pollution through a clinoptilolite bed laminar flux

Human pressure on environment is an increasing problem all over the world. Excess of nutrients (P, N), organic contaminants (PAH, PCB, pesticides) and heavy metals (Cu, Ni, Zn, Pb, Cd, etc.) are often affecting water canals because of several discharges form human activities. The monitoring of a “good Ecological Status” of natural waters is required by the European Waterframe Directive (2000/60CE) and some limits concerning organics, metals and microorganisms, are required in order to use water for potable or irrigation purposes or for reusing wastewater in natural water systems. Natural zeolites are interesting low cost sorbents which have been studied since the last decades because of their high ion exchange capacity between a liquid and a porous phase (Kocaoba et at. 2006) but also for their capacity to entrap microorganisms in their microporous structure (Chen et al. 2005). Among zeolite species, clinoptilolite is a natural zeolite comprising a microporous arrangement of silica and alumina tetrahedral, forming a tabular monoclinic tectosilicate crystals and it has a high attractive selectivity for certain heavy metal cations, such as Pb, Cu, Zn, Cd and it can be used as an ion exchanger for the removal of ammonium ions (Stylianou et al. 2006). In this study clinoptilolite (ECOLIN) has been tested for its capacity to detoxify and depollute the out flow wastewater from an old waste treatment plant.