Stabilization of tannery filter press effluent sludge in brick production for sustainable use

In leather processing, wastewater is directed to the effluent treatment plant for treatment before being discharged into the surface water. This study focuses on the fabrication of construction materials using filter press tannery effluent sludge (FPTES) and soil to manage solid waste generated in the tannery. The FPTES was mixed at various ratios (0-9%) with soil at increments of 1% to fabricate bricks. The fabricated bricks were sun-dried, oven-dried (103 ± 2 °C), and finally burned at 1000 °C in an automated brick field. The engineering properties of fabricated bricks were analyzed. The results showed that bricks made with 4% FPTES had good strength (15.9 MPa), absorbed a reasonable amount of water (14.7%), shrank a little (2.3%), lost some weight (9.8%), and had a suitable density (1.8 g/cm³) without any surface issues, meeting the category brick "A" standards set by ASTM and Bangladesh (BDS). The XRF analysis of FPTES identified the base elements required for brick production, whereas the SEM micrograph of FPTES-incorporated bricks confirmed a smooth, compact structure within the FPTES-soil matrix. Moreover, the NEN 7345 analysis showed lower levels of leached heavy metals from FPTES-incorporated bricks, well below the permissible limit. The incorporation of 4% FPTES resulted in a saving of USD 0.012/brick and a 25.8% reduction in energy consumption per brick. Incorporating FPTES into brick production is a feasible way to minimize environmental hazards.