6. Application efficiency of natural zeolite in water treatment
Wastewaters obtained from processes of many industries contain pollutants (inorganic cations, anions, oils, organic matter, etc.) have a toxic effect on the ecosystem. It is necessary to treat the metal contaminated wastewater prior to discharge into the environment and the removal of these pollutants requires economically justifiable and efficient technologies and techniques [4].
Natural zeolitesin wastewater treatmentare quiteeffective in comparisonwith other methods. The conditionsof purification process are very important for wastewater treatment. Thus possible regeneration of thezeolite, re-use of the zeolite and re-use of the obtainedconcentratemetalions after regeneration of the zeolite, verypositivelyimpacton the environmentwithout creatingnewwaste. Table8shows theefficiency of the removalof metalcations fromwastewaterusing naturalzeolitewhich is supplementedwith otherphysical andchemical methods. The efficiencyof removingmetalionsfrom wastewatersdependson many factorssuch asinitial concentrationof metalionsin wastewater, the pH value of the system, the possibility of formation ofmetalhydroxylanion, previouschemical andthermalmodificationof zeoliteand the amountof water thatshould bepurified. Besides the already mentioned properties (selectivity, capacity, etc.) natural zeolites have excellent resistance to chemical, biological, mechanical or thermal changes.