Ceramic Membranes Prepared from a Silicate and Clay-mineral Mixture for Treatment of Oily Wastewater

Abstract

The application of ceramic membranes is limited by the high cost of raw materials and the sintering process at high temperatures. To overcome these drawbacks, the present study investigated both the preparation of ceramic membranes using cost-effective raw materials and the possibility of recycling the membranes for the treatment of oily wastewater. Ceramic membranes with a pore size of 0.29–0.67 μm were prepared successfully at temperatures as low as 1000–1100°C by a simple pressing route using lowcost base materials including diatomite, kaolin, bentonite, talc, sodium borate, and barium carbonate. The typical steady-state flux, fouling resistance, and oil-rejection rate of the low-cost virgin membranes sintered at 1000°C were 2.5 × 10−5 m3m−2s−1 at 303 kPa, 63.5%, and 84.1%, respectively, with a feed oil concentration of 600 mg/L. A simple burn-out process of the used membranes at 600°C in air resulted in >95% recovery of the specific surface area (SSA) of the virgin membranes, a significantly increased steady-state flux, decreased fouling resistance, and increased oil-rejection rate. The typical steady-state flux, fouling resistance, and oil-rejection rate of the low-cost ceramic membrane sintered at 1000°C and subsequently heat treated at 600°C for 1 h in air after the first filtration were 5.4 × 10−5 m3m−2s−1 at 303 kPa, 27.1%, and 92.9%, respectively, with a feed oil concentration of 600 mg/L. The present results suggest that the low-cost ceramic membranes used for oily wastewater filtration can be recycled by simple heat-treatment at 600°C in air. As the fouling resistance of the low-cost ceramic membranes decreased with a decrease in pore size, the preferred pore size of the membranes for oily wastewater filtration is <0.4 μm.

Processing of alumina‐coated glass‐bonded silicon carbide membranes for oily wastewater treatment

“…A laboratory‐made dead‐end filtration set‐up was used for the oily water filtration tests. Details of the set‐up are described in a previous paper . The membrane diameter and thickness were 4.60×10 −2 m and 3.00×10 −3 m, respectively.…”

“…With changing regulations and limited availability of fresh water, treatments for water produced by oil operations and oily wastewaters have gained increasing interest . Conventional approaches for treating oily wastewaters have included de‐emulsification, gravity separation and skimming, coagulation, dissolved air flotation, and flocculation .…”

“…Membrane separation can effectively meet those standards. Mullite, mullite‐Al 2 O 3 composites, TiO 2 ‐coated mullite, ZrO 2 ‐coated Al 2 O 3, Al 2 O 3 ‐coated Al 2 O 3, zeolite‐coated Al 2 O 3, TiO 2 ‐coated Al 2 O 3, clay, and diatomite‐clay composite membranes have all been investigated for the treatment of oily wastewater. However, the literature barely mentions the application of SiC membranes for oily wastewater treatment.…”

“…With changing regulations and limited availability of fresh water, treatments for water produced by oil operations and oily wastewaters have gained increasing interest. [32][33][34] Conventional approaches for treating oily wastewaters have included de-emulsification, gravity separation and skimming, coagulation, dissolved air flotation, and flocculation. [35][36][37] The small quantity of oil remaining in the water after the conventional methods must be reduced to an acceptable limit before the water can be discharged into seas or rivers.…”

“…Membrane separation can effectively meet those standards. Mullite, 38 clay, 44,45 and diatomite-clay composite membranes 34,46 have all been investigated for the treatment of oily wastewater. However, the literature barely mentions the application of SiC membranes for oily wastewater treatment.…”