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

Abstract

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.

Cilj ovog rada bio je da se ispita mogućnost uklanjanja tečne faze iz mulja metodama mehaničkog odvodnjavanja. Mulj je dobijen neutralizacijom sumporno-kiselih otpadnih rastvora iz procesa elektrolize bakra, korišćenjem 1M Ca(OH)2 sa i bez dodataka FeCl3 i AlCl3 kao koagulanata. Metoda klasične filtracije pod uticajem gravitacije i metoda vakuumske filtracije, korišćene su za ispitivanja procesa odvodnjavanja mulja u laboratorijskim uslovima. Tokom eksperimenata merena je zapremina rastvora, visina uzoraka, trajanje odvodnjavanja. Dobijeni rezultati prikazani u ovom radu pokazali su da je vakuumskom filtracijom postignuto smanjenje visine mulja od 75 % što predstavlja gotovo 3 puta veću vrednost u odnosu na rezultate dobijene klasičnom filtracijom. Podaci koji se odnose na vreme filtracije primenom različitih metoda, pokazuju da je primenom vakuumske filtracione metode vreme odvodnjavanja gotovo 200 puta kraće u odnosu na vreme odvodnjavanja klasičnom filtracijom. Najkraće vreme bistrenja suspenzije registrovano je kod mulja dobijenog procesom neutralizacije bez dodataka koagulanata.