Determination of metal content in sewage sludge and sewage sludge ash to find opportunities to use them in the construction industry

Sewage sludge management is becoming an increasing problem in developed and developing countries. Due to their physicochemical properties (mainly high content of heavy metals) a safe method of utilization is sought. Considering environmental protection, energy recycling, reduction in use of the raw materials and the possibility of immobilization hazardous substances, the use of ashes in building materials becomes a very good way of utilization. Both unprocessed sewage sludge and ashes after their thermal utilization can be used in the construction industry. Before using sediments and ashes, it is necessary to analyze the content of heavy metals, because they can have a negative effect, for example, on cement-stabilized products. The purpose of this work was to determine selected metals (Cd, Cu, Ni, Pb, Zn, Cr, Mg, Mn, Fe) in the primary, dehydrated, digested, excess sludge and ash after his incineration to check and compare heavy metal content. The obtained data can be used to optimize the production process of cement products that contain sewage sludge at differ form, and confirm the environmental safety of proposed approaches.