A study of gas emissions during the firing process from bricks incorporating biosolids

Abstract

This paper investigates the five different gas emissions during the firing process of clay bricks and bricks incorporating biosolids. In this study, three different biosolids produced at the Western Treatment Plant and Eastern Treatment Plant, Melbourne, were used as an alternative raw material to the conventional brick soil to produce bricks. Three sets of bricks were manufactured incorporating 25% of biosolids by weight. Initially, three biosolids samples and brick soil were characterised by their chemical and mineral compositions, organic content and particle size distribution. Brick samples were fired in a tube furnace at a temperature of 1050 °C for three hours. Five different gas emissions - SO₂, CO₂, NO, CO, and HCN - were measured at different temperatures throughout the firing process. The results indicated that all the gas emissions were increased with the addition of biosolids. The energy input and production based factors were developed based on the experimental results, which were then used in the life cycle assessment of biosolids-amended bricks. The cradle-to-gate results of life cycle assessment revealed that the production of biosolids bricks reduced environmental impacts for all impact categories except water depletion impact when compared to conventional bricks.

Keywords: Biosolids; Bricks; Gas emissions; Life cycle assessment; Recycling.