Effects of calcium chloride and poly(N,N-dimethylaminoethyl methacrylate) on the filtration rate of a bentonite suspension and the examination of the filtration mechanism

•Cationic polymer and electrolyte were used as flocculants of bentonite suspension.•The filtration rate increased by using both cationic polymer and electrolyte.•Bentonite aggregates became larger by using flocculants.•The resistance of filter cake with flocculants decreased.•The filtration rate increased with increasing the porosity of bentonite cake.