EFFECTIVENESS OF RECLAMATION OF SODA WASTE DISPOSAL SITE AT JANIKOWO USING SEWAGE SLUDGE

Abstract

There are numerous reclamation technologies based on sewage sludge treatment, however, one that is most purposeful consists in applying the sludge in order to achieve green cover (bioremediation with plants) on fine grained waste disposal sites which have a high potential for soil formation on the one hand, but on the other, are highly vulnerable to erosive action of wind and atmospheric precipitation. The technological waste at the Janikowo Soda Plant has liquid consistence, contains fine-grained (dust-like) and water soluble calcium compounds, and is highly alkaline and saline. The waste was disposed and dehydrated in the large-area earthen ponds elevated beyond the ground level. The combined surface of all the exploited settling ponds (with roads and escarpments jointly) exceeds 105 ha. Dehydration by infiltration and evaporation was a source of unrestricted dust emissions from the drying and dry surfaces of the waste site. Urgent action was then deemed necessary to manage the high risk of nuisance dust to the local population, technical infrastructure, engines and cars. Consequently, it was decided that the best way to manage nuisance dust would be to create a thick and permanent vegetal cover on the waste site. The vegetal cover would also limit salt infiltration from the disposal site to groundwater and to adjacent agricultural land, and contribute to improving the local landscape values. Treatment with adequately high (appropriate for reclamation purposes) doses of sewage sludge and sowing of plants which have a high growth potential and nutrient demand resulted in the quick establishment of green cover on the waste disposal site. The contents of mineral elements in plants and in the top layer of the ground reclaimed were analyzed starting from the year 2000 onwards until the year 2013. The chemical composition of sewage sludge was systematically analyzed as well. No excessive contents were found of main elements neither of heavy metals in both plants and grounds. The vegetation was mown twice during the vegetation season and clippings were stacked in prisms. The biomass after humification was spread as an organic fertilizer throughout the area under reclamation. The present advanced stage of development of vegetal cover and soils on the waste site provides opportunities for cultivation of economic crops that may be used for fertilizer and energy production or for other industrial purposes.