| Popis: |
The worldwide increase in sewage sludge (SS) production is the result of increasing urbanization, which requires research and development and finding appropriate ways to manage and dispose of SS in accordance with environmental laws and economic justification. In the absence of an optimal disposal solution for this type of waste in many countries worldwide, recent research points to the use of SS as an energy source (incineration, gasification, pyrolysis) or use in the construction industry, among others. For example, the use of dry sewage sludge (DSS) and sewage sludge ash (SSA) from the thermal treatment process as an alternative substitute material for natural raw materials in the production of fired clay bricks in the construction industry is mentioned among others. In this study, clay was used as a base for the production of bricks using SS dried in a conventional drying process (CDSS) and SS from microwave dried sewage sludge (MDSS) from two wastewater treatment plants in the Republic of Croatia (Zagreb and Karlovac). The SS dried by the two methods were used in mass fractions of 5, 10 and 20 wt% for the production of bricks. The physicochemical and mineralogical composition of CDSS and MDSS was determined and the influence on the mechanical properties of the modified bricks was investigated. The bricks made from MDSS generally exhibited better properties than those made from CDSS. There is no significant change in the chemical and environmental properties of the control brick (without the addition of SS), and the new brick product with the addition of CDSS and MDSS is environmentally acceptable from this point of view, with equal acceptance. A more significant difference occurs in the mechanical properties, e.g. compressive strength, where the addition of a lower percentage of SS (5%) is preferred, with a slight advantage for MDSS. |
