APPLICATION OF SLUDGES FOR REMEDIATION OF CONTAMINATED SOIL ENVIRONMENT

摘要

As we pointed out, the problem of sewage sludge disposal in Poland is difficult to solve in the short term. It is evident that the use of sewage sludge for agricultural purposes and reclamation work is not as widespread as in the USA and in European countries. This is primarily because of sludge quality, but it is also important that there is no comprehensive and clear set of legal regulations to be used as guidelines for its use. It must be emphasized that the legal system in Poland allows the use of sludge for such purposes, although the criteria for use are not much different from criteria accepted in other countries. The primary difference lies in the bureaucracy surrounding approvals and administrative decision making. Conflicts of interest, competency issues and duplication of relevant laws and regulations slow down the process considerably. These problems also tend to inhibit wider implementation for the use of sludge by thwarting useful initiatives before they get under way. From a practical point of view, the poor quality of sewage sludge often found in industrial areas in the Katowice region automatically eliminates them from agricultural use. It seems that the only valid solution for the intelligent management of sewage sludge in such regions would be to use them for the stabilization and revegetation of industrial waste lands. The results of our research indicate that sewage sludges can be successfully used for the reclamation of toxic smelter waste as an alternative to traditional methods such as topsoiling. Sewage sludge has many benefits, one of the most important being that it is cost effective as compared to traditional methods. This is primarily because transportation costs are reduced along with the cost of revegetation. At the same time, the problem of sludge land filling is also solved. Regarding metal waste, the main roadblocks we are facing come from salinity and the high content of heavy metals in a mobile form. This problem is further enhanced by spatial variability which forces us to decide the application rates of sludge and lime specifically for each given site, and here even within one pile. GIS methods and grid sampling are useful tools for achieving this. A crucial factor for successful revegetation of zinc- and lead-contaminated smelter waste sites in Silesia is their salinity. High concentrations of metals in their soluble form are only of secondary importance because their mobility can be reduced by appropriate forms and doses of lime. For waste characterized by medium salinity such as Welz waste the recommended rate of sludge should not be higher than 300 dry tons per hectare under average conditions. Waste which demonstrates higher salinity, such as Doerschel waste, must be treated differently. Capping such waste with less toxic waste - ideally lime waste - followed by sludge application and grass seeding has great potential. Similar methods can be used for other types of waste treatments such as mining spoil which is addressed in other publications. An integral part of a biosolid reclamation project is the selection of grass species and cultivars that are resistant to toxicity. The appropriate selection creates conditions for good coverage of an area and limits the movement of toxic elements into the terrestrial ecosystem. The metal content in the biomass of selected species also inhibits the impact of metals on the health conditions of organisms/animals returning to reclaimed areas. It is encouraging that the results of this project seem to have implementation potential and have been well recieved by both local authorities and industry in Silesia. This technology similarly seems to have potential for the entire Central and Eastern European region where lands have been degraded. As a byproduct of this study, a set of guidelines and procedures is in the process of being developed which will address not only current laws and regulations, but appropriate management practices and solutions as a