Affiliations: Department of Materials of Science and Engineering,
University of Science and Technology of China, Hefei 230026, China | School of Chemistry and Chemical Engineering, Anhui
University, Hefei 230039, China | National Key Laboratory of Transient Physics, Nanjing
210094, China | Great Wall New Century Membrane Technology
Corporation, Hefei 230601, China
Abstract: The oily wastewater generated from pretreatment unit of
electrocoating industry contains oils, phosphate, organic solvents, and
surfactants. In order to improve the removal efficiencies of phosphate and
oils, to mitigate the membrane fouling, coagulation for ceramic membrane
microfiltration of oily wastewater was performed. The results of filtration
tests show that the membrane fouling decreased and the permeate flux and
quality increased with coagulation as pretreatment. At the coagulant Ca
(OH)_2 dosage of 900 mg/L, the removal efficiency of
phosphate was increased from 46.4% without coagulation to 99.6%; the removal of
COD and oils were 97.0% and 99.8%, respectively. And the permeate flux was
about 70% greater than that when Ca(OH)_2 was not used. The
permeate obtained from coagulation and microfiltration can be reused as make-up
water, and the recommended operation conditions for pilot and industrial
application are transmembrane pressure of 0.10 MPa and cross-flow velocity of 5
m/s. The comparison results show that 0.2μm ZrO_2
microfilter with coagulation could be used to perform the filtration rather
than conventional ultrafilter, with very substantial gain in flux and removal
efficiency of phosphate.
