WATER POLLUTION REDUCTION AND WATER SAVING USING A NATURAL ZEOLITITE CYCLE

ZeoLIFE project has been conceived to test an innovative integrated zeolitite cycle having the aim to reduce 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 fresh 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. Agriculture, that on average wastes 50% of the available freshwater, is at the base of the economy of the Ferrara Province; the intensive utilization of land and the indiscriminate use of chemical nitrate fertilizers (NPKs), however, generated various punctual and diffuse sources of pollution, mainly causing nitrate concentration in surface and ground waters and subsequent eutrophication of coastal swampy areas and lagoons. Thanks to the use of strategic materials like zeolitites this project aims to demonstrate how the effects of nitrate pollution deriving both from cattle breeding and from agriculture can be mitigated and contemporarily how chemical fertilization and water for irrigation can be reduced obtaining an improvement of the yield. Manure is used as fertilizer but its NH4 content is very high; only a minor amount of NH4 is taken by plant roots, whereas the most of it is quickly nitrified and washed away by rainfalls, going into ground- and freshwater. Zeolitite treatment of manure reduces its NH4 content making its eventual re-utilization or disposal appropriate according to the limits of law. NH4-charged zeolitite added to agricultural soils allow to reduce chemical and organic fertilization and water for irrigation of at least the 30%. Moreover, the expected climate changes will result in a worsening of the extreme weather events, like droughts and heavy rains. The consequent progressive desertification of lands will be reduced by zeolitite addition to soils, due to their intrinsic fertilizing power and high water retention capacity, not affected by weather events. The project proposes an open-field experimentation of the integrated zeolitite cycle, for a 2 year of cultivation. It foresees the construction of a prototype of a tank for swine manure treatment, where an appropriate quantity of natural K-zeolitite (chabasite) will be added and mechanically mixed. The zeolitite will then be left still to reach cationic equilibrium with the manure and in a time span of 12-18 hours it will subtract by selective cationic exchange a considerable amount of NH4 from the liquid. The charged zeolitite will then be removed and added to the experimental parcel of land, where it will release its NH4, K and water contents only through cationic exchange induced by humic acids of plant roots and in proportion of the real needs of the cultures, allowing a reduction of the use of water for irrigation and of NPKs and, by consequence, of the excessive transfer of NH4 into the whole water system. The reduction of NH4 in the hydrologic system will be verified by monitoring all changes in the chemistry of groundwater and surface water. The reduction of fertilization and irrigation water, and the improvement of the yield for different types of cultures will also be taken into account by comparing parcels where the zeolitite has been added with adjacent control fields cultivated and irrigated in the traditional way.