| Abstract: | Biologically purified wastewater in ten doses of 50 and 400 mm per year was given into sand-filled lysimeters of 1 m2 area and 1 m depth which were vegetated with Lolium perenne (forage rye) and green maize all the year round. The experimental results gained in the course of five summer half-years and four winter half-years were evaluated with respect to the purification efficiency of the soil-plant system. The results demonstrate a high efficiency of the system with mean annual elimination performances of 86 and 40% for BOD5, and COD-Cr, resp., as well as 49, 86 and 52% for N, P and K, resp., at mean concentrations in mg/l for BOD5?1.3, COD-Cr?34.1, N?18.1, P?0.4 and K?9 in the percolating water from a soil depth of 1 m. The lysimeters which had been supplied with wastewater were not treated with mineral fertilizer. Intermingling with 1 kg/m2 straw brings about an increase of the loads of K and P as well as COD-Cr in the percolating water and a reduction of the N-loads, besides an increase in yield. All in all, for four years the performance has been stable without any temporal trend. |
