Doświadczenia związane z wykorzystaniem wikliny Salix viminalis w usuwaniu zanieczyszczeń z wód i ścieków

W pracy przedstawiono obecne doświadczenia związane z wykorzysta-niem wikliny do usuwania zanieczyszczeń ze źródeł punktowych i obszarowych oraz do utylizacji osadów ściekowych

Willow (Salix) is a very popular plant in Poland, a symbol of Polish country-side. It is used for weaving baskets, for production of wicker furniture and for reinforcement of river and lake embankments. It is also a pioneer plant in land reclamation process (dunes, excavations etc.). These practical applications of Salix were taken into account when a conception of willow plantations watered with sewage was developed. New application of Salix is using it as an energy resource. In the article the up to date experiences with application of willow for removal of pollutants from point and aerial sources and for sewage sludge utilization are described. At the zoo in Oliwa, along the bed of the Rynaszewski Stream, the main inflow of the Jelitkowski Stream, a set of 5 hygrophyte facilities was constructed for decreasing the load of organic nitrogen and elimination of faecal coli bacteria. The willow buffer zones were located at the edges of the ponds and along the stream bed. The willow buffer zones were located at the edges of the ponds and along the stream bed. The experiences show the buffer willow zones can be used for removal of pollutants from aerial sources. Laboratory experiments were carried out in order to evaluate the effectiveness of pollutants removal from sewage. The seedlings of willow (Salix viminalis) were grown in PE pots, filled with sand. The highest removal efficiency of pollutants (nitrogen, phosphorus, BOD5 and COD)was observed in the pots irrigated with biologically treated sewage and the lowest removal efficiency was observed for the pot without plants. Nine individual household WWTPs with horizontal flow of sewage (HF-CW), inhabited with Salix viminalis, working as the second stage of treatment were analysed. The plants were located near Ciechanow, Lublin and in Lubiejewo near Ostrołęka. On the basis of laboratory and field experiments it was proved that Salix viminalis can be applied for treatment of sewage in individual household treatment plants. Application of willow results in the increase of treatment efficiency in comparison to soil filters. Sewage sludge utilization in a willow plantation in the WWTP Swarzewo. The investigations were carried out at the pilot willow bed (2400 m2 area), planted with Salix viminalis. Sewage sludge from the WWTP Swarzewo was then discharged to the bed - in 3 years time the thickness of discharged sludge layer reached 1 m. Studies show willow plantations can be applied for sewage sludge utilization. In the years 2002÷2003 in southern Sweden the content of heavy metals in soil and biomass in several willow plantations was analysed. All analysed plantations had been irrigated with sewage sludge in the past. The assimilability of metals by the aboveground tissues of willow was analysed with regard to the content of metals in discharged sludge. It was found out that in case of cadmium the uptake by plants was 10 times higher than the content in sludge. On the basis of investigation results and statistical analyses it was postulated that the yearly doses of 9÷10 t d.m. of sludge/ha will exclude potential cadmium accumulation in soil.