Fired-clay bricks incorporating biosolids: Comparative life-cycle assessment

A comparative life cycle assessment (LCA) was undertaken to evaluate the environmental impacts of fired-clay bricks incorporating biosolids from Melbourne Water's Victorian Eastern Treatment Plant (ETP) and Western Treatment Plant (WTP). The scope of this comparative LCA study ranges from "cradle to gate", and involves the brick soil and biosolids extraction, transportation, crushing and proportioning, grinding and screening, shaping, drying, firing, and packaging. The energy used during the firing process of the biosolids-amended bricks, concentrate of gas emission and emission factors was quantified experimentally at the laboratory scale. The potential environmental impacts were analysed and compared by means of the ReCipe mid-point LCA method using SimaPro 8.0.5.13. The results of the life-cycle impact assessment (LCIA) showed that the incorporation of biosolids into bricks was environmentally favourable and a promising alternative approach with respect to most of the environmental impacts except water depletion, which was mainly due to the higher water demand of biosolids-amended bricks during the shaping process. In addition, bricks incorporating ETP biosolids showed a relatively higher potential for ozone depletion and acidification because of the higher fuel usage for ETP biosolids transportation compared to that of brick soil and WTP biosolids. In addition, a sensitivity analysis was carried out to address the impact of the assumptions and variables used in the LCA model on the final comparative LCIA results. Furthermore, a comparative uncertainty analysis was conducted to assess the effect of uncertainty in the inventory data on the results of the LCIA indicators. The methods used in this study and discussed in this paper can be used for the LCA of different construction materials.