Ceramic microfiltration membrane development from rice husk waste and kaolin and application as pre-treatment of paper industry effluent

The paper processing industry is characterized as one of the three largest producers of wastewater of significant environmental contamination. In order to minimize impacts on water resources and comply with the standards required by legislation, advanced treatment solutions are needed. The present study developed a ceramic microfiltration membrane based on 60% of rice husk ash waste and 40% of kaolinitic clay to pretreat a raw effluent of paper industries. The membrane was obtained by uniaxial compression (27MPa) in an electric press, with subsequent sintering at 1,220(degrees)C for 1 hour. Base formulation materials were characterized by chemical and physical analyses. The membrane presented apparent porosity of 34.59%, density of 1,30 g.cm(-3) , diameter and thickness linear retraction of 1.7 and 2.5%, respectively, fire loss of 9.3% and a good chemical stability at acid and base solution. Hydraulic permeability corresponded to 11.3 x 10(-3) m(3)/m(2) s MPa-1 , with a hydraulic pore diameter to 2.29 mu m and average pore size of 1.727 mu m. The characterization of the raw effluent showed high levels of COD (1,125.4 mg.L-1), turbidity (1,300 UNT), and color (253.8 UC). The filtration study indicated good results of membrane efficiency, with removal of turbidity (99.3%), COD (95.7%), color (83.0%), phenolic compounds (82.1%), and solids (85.1 to 90%). The rice husk ash accomplished the function as pore-form agent and adsorbent of phenolic compounds and represented a promising alternative for incorporating the waste into the production cycle.