ZeoLIFE project has been conceived to test an innovative integrated zeolitite cycle aimed at reducing the NH4+ content in livestock effluents and correct agricultural soils, with improvement of the yield and economization of water for irrigation and fertilizers, leading to a reduction of surface water and groundwater pollution and excessive exploitation of the water resource. Natural zeolitites are rocks containing more than 50% of zeolites, a kind of minerals with peculiar physical and chemical properties, like high and selective cation exchange capacity (CEC), molecular adsorption and reversible dehydration. Zeolitites are capable to uptake NH4+ from solutions and to release it gradually to the roots of the plants. The project proposes an open-field experimentation of an integrated zeolitite cycle, for 2 year of cultivation. It foresees the construction of a prototype tank for swine manure treatment, where an appropriate quantity of natural K-zeolitite (Italian chabasite zeolitite) will be added and mechanically mixed. The zeolitite will then be left still to reach cationic equilibrium with the manure: in a time span of 12-18 hours it will subtract by selective cationic exchange a considerable amount of NH4+ from the liquid. The NH4+-charged zeolitite will then be removed and added to parcels of land, where it will release the nutrients only through cationic exchange induced by humic acids of plant roots and in proportion of the real needs of the cultures. A surface of about 6 ha will be divided into various parcels. Control parcels will be cultivated and irrigated in traditional way; other parcels will be added with natural zeolitites and one will be mixed with NH4+-charged zeolites from the prototype tank. In the parcels amended with zeolitites both fertilization and irrigation water will be reduced by 30 and 50% respectively. A reduction of nitrate content in groundwater and surface waters is expected without any decrease of the yield. Prototype working parameters need to be estimated in order to optimize the production of NH4+-charged zeolitites to be put in the experimental fields. In bench scale reactors a series of experiments were performed to test the exchange capacity of natural zeolites in contact with the manure solution. Each experiment was performed in triplicate, each time varying one single parameter (mixing time, zeolitite/manure ratio, resting time). Over the whole duration of the experiment, samples of manure were taken from each of the reactor vessels at increasing time intervals, each sample were analyzed for NH4+ by ISE electrochemical sensor, for the quantification of the ammonium exchanged on chabasite. Results show that a zeolitite/manure ratio of 25 gr/l, a mixing time of 45 minutes and a resting time of 12 hours allow the zeolitite to take the maximum amount of ammonium from the solution, up to 30 mg/g. After zeolitite addition each parcel will be monitored by periodic groundwater and surface water sampling and by a series of permanent devices, installed before the beginning of experimentation. The permanent monitoring stations include: a piezometer for groundwater sampling, multiple lysimeters for interstitial water sampling, a datalogger for physical-chemical parameter monitoring and interstitial water quantification, and an evaporimeter. An automated meteorological station has been also installed in order to quantify rainfalls and sun irradiation for water balance.
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