RECYCLING OF CALCIUM-SILICATE MATERIAL AFTER WASTEWATER FILTRATION TO AGRICULTURE - SOIL CONDITION IMPACT

Reactive filter materials aimed at phosphorus (P) recovery is a novel method for on-site wastewater treatment. Once the bed filter is no longer effective, the sorbent must be replaced and can then be recycled as a soil amendment to agriculture. This study investigated the short-term effects of such amendments in a field with a wheat crop in order to evaluate the risks and/or potential benefits of this disposal option. The developed product Polonite (manufactured from Opoka) was used as a model filter sorbent in the field trial. Rates corresponding to approximately 6 and 8 tons per hectare were applied. In the short-term, this amending did not affect soil physical and sorption properties. The rate of Polonite used here, as P source for wheat was irrelevant in this kind of soil. The usefulness of this disposal option of exhausted filter material is discussed.