Reuse of desalination sludge for brick making

Increasingly stringent environmental pressures in Australia encourage alternative solutions towards waste management. A study was carried out to determine the potential reuse of desalination sludge as a brick making material. Desalination sludge was dried and grinded into a fine powder before being mixed with clay at different ratios corresponding to 0%, 10%, 20%, 30% and 40% dried desalination sludge content by weight. The optimum moisture content was determined for each mixture to ensure the bricks were made to their maximum density, thus maintaining sample consistency. Three bricks (10 cm x 10 cm x 10 cm) were made from each of the 0%, 10%, and 20% mixtures to determine their compressive strength, whereas four brick samples were prepared from 0%, 10%, 20%, 30%, and 40% mixtures to determine initial rate of absorption (IRA), lime pitting and potential to efflorescence. It was found that the compressive strength decreased with increasing dried desalination sludge content in comparison with the control bricks (0% sludge). The average compressive strength reduced from 8 MPa, to 3 MPa and 2 MPa for the 0%, 10% and 20% sludge bricks respectively. The IRA tests show steadily increasing IRA values with increasing sludge content. Bricks that did not contain any sludge had an average IRA value of 8.1 kg/m2min, whereas bricks containing 40% dried desalination sludge had an average value of 14.6 kg/m2min. No efflorescence or lime pitting were observed for any of the brick samples.