Dewatering of sludge obtained by neutralisation from sulfuric-acid waste solutions

The aim of this paper was to investigate the possibility of removing the liquid phase from the sludge using the mechanical dewatering methods. The sludge was obtained by neutralization of sulfuric acid waste solution from the process of copper electrolysis, using 1M Ca (OH)2 with and without addition of FeCl3 and AlCl3 as coagulants. Classical method of filtration by gravity and vacuum filtration method were used for tests of sludge dewatering process in the laboratory conditions. Solution volume, amount of sample, dewatering duration was measured during the experiments. The obtained results, presented in this paper, showed that using the vacuum filtration method, high of sludge sample was reduced for 75%, which is almost three times higher value compared to the results obtained using the gravity filtration. Data relating to the time of filtration, using different methods, show that in application of vacuum filtration method the dewatering time is almost 200 times faster compared to the time dewatering with gravity filtration. The shortest settling time was registered for the sludge that was obtained by neutralization process without coagulants addition.