Application of natural zeolite in treatment of leachate obtained from mercury contaminated soil : bachelor thesis

Rudnik Idrija u Sloveniji bio je značajan antropogeni izvor žive. Iako je još 1995. godine proizvodnja u rudniku prestala, zbog neučinkovitog pečenja rude tlo u okolici Idrije je vrlo onečišćeno živom čija koncentracija doseže i do 10 000 mg Hg/kg. U tako krškom području živa se površinskim i oborinskim vodama može isprati u dublje slojeve tla te može doći do podzemnih voda. Budući da je živa jedan od najtoksičnijih metala, nužno je pronaći učinkovitu, a isplativu metodu za uklanjanje žive iz onečišćenih voda. U ovome radu ispitana je učinkovitost prirodnog zeolita klinoptilolita veličine čestica 0,6 - 0,8 mm u obradi eluata dobivenog ispiranjem živom onečišćenog tla s područja Idrije. Najveći učinak uklanjanja dobiven je u eluatima s najnižom koncentracijom ukupne žive, koja se smanjila do ispod maksimalno dopuštenih koncentracija. Najveća ravnotežna količina vezane ukupne žive po jedinici mase zeolita postignuta je u eluatima s najvećom koncentracijom ukupne žive te opada smanjenjem početne koncentracije. Prirodni zeolit klinoptilolit može se uspješno primjeniti u obradi voda onečišćenih živom, posebice u slučaju niskih početnih koncentracija ukupne žive. Međutim, u svrhu povećanja učinkovitosti prirodnog zeolita za uklanjanje ukupne žive nužno je poboljšati njegova površinska svojstva za adsorpciju različitih ionskih i organskih vrsta, što se najčešće postiže modifikacijom organskim surfaktantima. The Idrija mine in Slovenia was a significant anthropogenic source of mercury. Although the production in the mine stopped in 1995, the soil in surrounding of Idrija is highly polluted with mercury due to the inefficient ore roasting, so the concentration reaches even up to 10 000 mg Hg/kg. In such karst area, surface and rain waters can leach mercury from contaminated soil to deeper soil layers and then into groundwater. Since mercury is one of the most toxic metals, it is necessary to find an efficient, cost- effective method for its removal from contaminated waters. This paper investigated the efficiency of the natural zeolite clinoptilolite of particle size 0.6 - 0.8 mm in the treatment of the leachate obtained by leaching the mercury contaminated soil of Idrija district. The highest removal efficiency has been obtained in leachates with the lowest concentration of total mercury, which has been decreased to below the maximum permissible concentration. The highest equilibrium quantity of removed total mercury per unit of the zeolite mass has been achieved in the leachates with the highest concentration of total mercury, and decreased by decreasing in initial concentration. The natural zeolite clinoptilolite can be successfully applied for the treatment of mercury contaminated waters, especially in the case of low initial total mercury concentrations. However, in order to increase the efficiency of natural zeolite for total mercury removal, it is necessary to improve the surface properties of zeolite for adsorption of various ionic and organic species, which is most commonly achieved by modification with organic surfactants.