engleski

Effect of lime addition during sewage sludge treatment on characteristics of resulting SSA when it is used in cementitious materials

Final disposal of sewage sludge is important not only in terms of satisfying the regulations, but the aspect of choosing the optimal wastewater treatment technology, including the sludge treatment. In most EU countries, significant amounts of stabilized and dehydrated sludge are incinerated, and sewage sludge ash (SSA) is generated as a byproduct. At the same time, lime is one of the commonly used additives in the sewage sludge treatment primarily to stabilize the sludge. In doing so, the question arose how desirable is such addition of lime if the sludge is subsequently incinerated, and the generated ash is further used in the production of cementitious materials. A series of mortars were prepared where 10-20% of the cement fraction was replaced by SSA. Since all three types of analysed SSA (without lime, with lime added during sludge stabilization and with extra lime added during sludge incineration) yielded nearly same results, it can be concluded that if sludge incineration variant is accepted, lime addition during sludge treatment is unnecessary even from the standpoint of preserving the pozzolanic properties of the resulting ash. Results of the research carried out on cement mortars point to the great possibilities of SSA incorporation in concrete industry.

cement mortar ; lime ; pozzolanic material ; sewage sludge ash ; sludge stabilization

This work has been fully supported by Croatian Science Foundation under the project "7927 - Reuse of sewage sludge in concrete industry – from infrastructure to innovative construction products".