Incorporation of biosolids in fired clay bricks

In Australia, thousands of tonnes of biosolids are produced and millions of dollars expended for their management annually. Biosolids are derived from wastewater sludge which is the major solid component collected from the wastewater treatment process. This study investigated the incorporation of biosolids into fired clay bricks. Geotechnical characteristics of three biosolids samples produced from Eastern Wastewater Treatment Plant (ETP) in Melbourne were investigated to assess their suitability as a partial replacement material for the clay in fired-clay bricks. Results of classification tests including liquid limit, plastic limit and sieve analysis indicated that the three biosolids samples are silty clayey sand with low to high plasticity. Linear shrinkage of biosolids samples varied from 10% to 15% and organic content from 6% to 14%. Control clay bricks with 0% biosolids and clay-biosolids bricks with 25% by weight biosolids were made and properties including compressive strength, shrinkage, density, initial rate of absorption (IRA), water absorption, thermal conductivity and other properties were determined. The overall results of this preliminary study are promising. Some of the results of this stage of this investigation are presented and discussed in this paper.