USING ABUNDANT WASTE AND NATURAL MATERIALS FOR SOIL AND GROUNDWATER PROTECTION AGAINST CONTAMINATION WITH HEAVY METALS

Abstract

Sewage sludge (biosolids) application on land as a fertilizer and soil improver, and high-volume sulfidic mining waste disposal and use as a common fill are anthropogenic activities that increasingly contribute to heavy metal enrichment of soil and ground water. (i) Sewage sludge (SS) use in agriculture appears to be the most attractive and cost effective, but at the same time a controversial disposal outlet due to concentration of all kinds of anthropogenic pollutants, of these the heavy metal content has been of the major concern for many years. While large industries in principle achieved required source control of heavy metals in this field, small artisan enterprises ( e. g. metal electroplating, vehicle repair workshops, etc), still contribute significantly to the heavy metal loads in SS. Experiments on metal sorption onto natural organic matter ( NOM) such as high-moor peats and SS in batch and flow-through systems from different, low-pH, polymetallic electroplating waste solutions (EPW) revealed high viability of this process. Use of small amounts of organogenic materials, preferably waste such as SS as a sorbent to be incinerated after use, could greatly and at almost no costs improve quality of bulk SS to enable its environmentally sustainable use in agriculture. (ii) Emission of heavy metals and sulfate loads from other objects of concern (sulfidic mining waste dumps and civil engineering constructions) in all stages of their construction and in the post-closure period can be successfully attenuated with use of fly ash ( FA) from coal-fired power plants that is another abundant bulk waste, and the aforementioned organogenic materials. Excellent insulating properties of properly placed FA: water dense mixtures with respect to air penetration (1-2 orders of magnitude higher than that of natural cohesive soils) can be utilized in protective layers in order to prevent access of air as a major reagent in sulfide oxidation resulting in heavy metals release and migration with leachate. These means can efficiently protect ground waters against long-term contamination by leachate from sulfidic waste, usually lasting for decades. The presented applications of waste materials comply with the nowadays policies and strategies focused on waste reuse and natural resources protection, with the sustainable development as a major target.