The aim of this research was to determine how best to utilize two environmentally challenging types of
waste: sewage sludge, and a particular type of waste ash, biomass ash, which is obtained from biomass
combustion processes. The results of the performed research have shown that liquid sewage sludge can,
in fact, be successfully stabilized with biomass ash, so that a stable composite material can be obtained,
having a compressive strength within the range between 0.5 to 2.5 MPa, with “Controlled Low-Strength
Material” properties. During the stabilization process, the microbial activity of sewage sludge is inhibited,
due to raised pH levels and temperatures.