Mohd Hafiz Puteh

Ammonium-Nitrogen Recovery from Wastewater by Struvite Crystallization Technology

Struvite crystallization is one of the sustainable approaches for recovering ammonium nitrogen (NH4-N) from wastewater in the form of a valuable material, in parallel with improving wastewater treatment efficiency. Focusing on NH4-N recovery, this review discusses the factors influencing struvite crystallization including the effect of foreign elements. It is shown that more than 95% of NH4-N could be recovered in the form of struvite, a magnesium-ammonium phosphate (MAP) salt, from some kinds of wastewater. This review emphasizes the role of utilizing alternative sources of Mg and P in improving the process sustainability. Additionally, it also explains how the MAP precipitation process could result with significant reduction of other pollutants contributing to total organic carbon, of color and turbidity, which support MAP integration with other treatment methods. The main options of lowering MAP recovery cost are presented; it was shown that applying low-cost materials of both Mg and P could save more than 65% of the process’s cost. Finally, the future research directions to improve NH4-N recovery are pointed out.

Fabrication and characterization of affordable hydrophobic ceramic hollow fibre membrane for contacting processes

Affordable hydrophobic hollow fibre membranes were prepared using kaolin and alumina based ceramic powders via a combined phase inversion and sintering technique, followed by a grafting with fluoroalkylsilane (FAS). The crux of the matter in this paper is to study the changes in the properties of the hollow fibre membranes (gas permeation, mechanical strength, pore size, porosity, tortuosity, morphology, and contact angle) by the addition of alumina (Al2O3) to the pure kaolin with mono or multiparticle sizes. By varying the overall loading and particle size of alumina addition, different morphologies of the membranes were obtained due to the differences in the path lengths during phase inversion process for each solvent and nonsolvent exchange. The successful grafting with FAS was evidenced by the increase in contact angle from nearly equal to zero degree before grafting to 140° after grafting. Kaolin–alumina-4, one of the hollow fibres fabricated in this work, achieved a mean pore size of 0.25 μm with the bending strength of 96.4 MPa and high nitrogen permeance of 2.3×10-5 mol·m-2·Pa-1·s-1, which makes the hollow fibre most suitable for the membrane contactor application.

The adsorptive removal of chromium (VI) in aqueous solution by novel natural zeolite based hollow fibre ceramic membrane

Adsorption is one of the most efficient ways to remove heavy metal from wastewater. In this study, the adsorptive removal of hexavalent chromium, Cr (VI) from aqueous solution was investigated using natural zeolite, clinoptilolite, in the form of hollow fibre ceramic membrane (HFCM). The HFCM sample was prepared using phase inversion-based extrusion technique and followed by sintering process at different sintering temperatures in the range of 900-1050 °C. The fabricated HFCM was characterised using scanning electron microscopy (SEM), contact angle, water permeability, and mechanical strength for all HFCMs sintered at different temperatures. The adsorption and filtration test of Cr (VI) were performed using an in-house water permeation set up with a dead-end cross-flow permeation test. An asymmetric structure with sponge- and finger-like structures across the cross-section of HFCM was observed using SEM. Based on the characterisation data, 1050 °C was chosen to be the best sintering temperature as the water permeability and mechanical strength of this HFCM were 29.14 L/m2∙h and 50.92 MPa, respectively. The performance of the HFCM in adsorption/filtration was 44% of Cr (VI) removal at the Cr (VI) concentration of 40 mg/L and pH 4. In addition, the mathematical model was also performed in simulating the experimental data obtained from this study. All in all, the natural zeolite-based HFCM has a potential as a single-step Cr (VI) removal by membrane adsorption for the wastewater treatment.

Fabrikasi membran seramik kos rendah berasaskan zeolit melalui kaedah penyongsangan fasa dan sinteran

The usage of ceramic membranes is gaining enormous attention due to their higher selectivity, permeation rate, and chemical and thermal stability as compared to the polymeric membrane. Owing to the fact of these superior properties, the search of a low-cost ceramic membrane is still in demand. To date, the fabrication of ceramic membrane using natural zeolite as the membrane ceramic loading has yet to be explored. Thus, this study aims to develop natural zeolite (Clinoptilolite) as the ceramic source in the fabrication of low-cost hollow fibre ceramic membrane (HFCM) via phase inversion and sintering techniques. Several fabrication parameters were also studied namely air gap distance, bore fluid flow rate and sintering temperature throughout this research. The best ceramic membrane was fabricated using 5 cm air-gap distance, 13 mL min-1 of bore fluid flow rate and 1000 °C of sintering temperature. The acceptable strength and morphological behaviour of finger-like and sponge-like voids were found to be an advantageous characteristic of the fabricated membrane. The cheap and yet abundant raw ceramic material as well as low sintering temperature are eventually reduced the cost of membrane production.