Fabrication and characterization of coated ceramic membranes from natural sources for water treatment applications

This study aimed to fabricate ceramic membranes for water treatment applications using natural and costeffective materials. This is the first-time white clay, Arabic gum, and marble powder were used in ceramic membranes. Two ceramic membranes were fabricated using an extrusion process: substrate A and substrate B. The JMP software (Version 15) was used to obtain the optimal recipes for the two substrates, which were white clay (62.7 %), silica flour (32.3 %), and Arabic gum (5 %) for substrate A and white clay (63 %), silica flour (26.8 %), and marble powder (10.2 %) for substrate B. Additionally, the effect of waste glass in the coating layer on the separation rate was examined. The ceramic membranes were analysed using various techniques, including X-ray fluorescence (XRF), X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), laser diffraction particle size analysis, thermogravimetric analysis (TGA), and a universal testing machine. The morphologies of the membranes were observed using scan electron microscopy (SEM), and their chemical resistances were evaluated. The flux across the substrates was measured using a crossflow filtration system, and it was found that substrate B had a higher flux (116 L/m2 h) than substrate A (77 L/m2 h). This was probably due to its higher porosity (34 %) compared to substrate A (29 %). Substrate A, with a coating layer (CO-2), exhibited the highest removal efficiency of approximately 99.2 % for synthetic feed water composed of tap water and bentonite clay, with an average particle size of 1.1 μm and turbidity of 13 ± 0.2 NTU. The costs of ceramic membranes A and B were estimated to be approximately 51 and 47 USD/m2 , respectively. Their cost-effectiveness results from the use of low-cost materials that do not require high sintering temperatures. This study demonstrates that these ceramic membranes are not only affordable but also possess desirable properties for water treatment applications

Development of Red Clay Ultrafiltration Membranes for Oil-Water Separation

In this study, a red clay/nano-activated carbon membrane was investigated for the removal of oil from industrial wastewater. The sintering temperature was minimized using CaF2 powder as a binder. The fabricated membrane was characterized by its mechanical properties, average pore size, and hydrophilicity. A contact angle of 67.3° and membrane spore size of 95.46 nm were obtained. The prepared membrane was tested by a cross-flow filtration process using an oil-water emulsion, and showed a promising permeate flux and oil rejection results. During the separation of oil from water, the flux increased from 191.38 to 284.99 L/m2 on increasing the applied pressure from 3 to 6 bar. In addition, high water permeability was obtained for the fabricated membrane at low operating pressure. However, the membrane flux decreased from 490.28 to 367.32 L/m2·h due to oil deposition on the membrane surface; regardless, the maximum oil rejection was 99.96% at an oil concentration of 80 NTU and a pressure of 5 bar. The fabricated membrane was negatively charged, as were the oil droplets, thereby facilitating membrane purification through backwashing. The obtained ceramic membrane functioned well as a hydrophilic membrane and showed potential for use in oil wastewater treatment

Performance optimisation of microbial fuel cell for wastewater treatment and sustainable clean energy generation using response surface methodology

In this study, response surface methodology (RSM), coupled with central composite design (CCD), are applied to optimise the performance of a microbial fuel cell (MFC) as a function of three main factors of commercialisation. Pt, as the main obstacle for commercialisation in the range of 0.1–0.5 mg/cm2, degree of sulphonation in SPEEK, as a new proton exchange membrane in the range of 20–80%, and rate of aeration of cathode between 10 and 150 ml/min were optimised to identify a more commercial MFC. The single maximum response of power density and COD removal and simultaneous maximisation of both responses were obtained at the corresponding optimal independent variables. The results show that the optimised condition for power density and COD removal is at DS 68% and aeration of 121.62 ml/min. However, the pt load differs and is 0.42 mg/cm2 for produced power density and 0.28 mg/cm2 for COD removal. The maximum produced power density in the optimised situation was 58.19 mW/m2 while the maximum COD removal in the optimised condition was 94.8%. However, once we optimised both at the same time i.e., the power generation and COD removal, the degree of sulphonation (DS) was 68%, Pt load was 0.35 mg/cm2 and the aeration rate was 121.62 ml/min, which resulted in a power production of about 57.06 mW/m2 and COD removal of 92.7%. Keywords: Wastewater treatment, Sustainable energy, Microbial fuel cell, Optimisation, Response surface methodolog

Preparation of Polybenzimidazole Hollow-Fiber Membranes for Reverse Osmosis and Nanofiltration by Changing the Spinning Air Gap

High-performance polybenzimidazole (PBI) hollow-fiber membranes (HFMs) were fabricated through a continuous dry-jet wet spinning process at SRI International. By adjusting the spinning air gap from 4″ (10.2 cm) to 0.5″ (1.3 cm), the HFM pore sizes were enlarged dramatically without any significant change of the fiber dimensional size and barrier layer thickness. When fabricated with an air gap of 2.5″ (6.4 cm) and a surface modified by NaClO solution, the PBI HFM performance was comparable to that of a commercial reverse osmosis (RO) HFM product from Toyobo in terms of salt (NaCl) rejection and water permeability. The PBI RO HFM was positively surface charged in acidic conditions (pH < 7), which enhanced salt rejection via the Donnan effect. With an air gap of 1.5″ (3.8 cm), the PBI HFM rejected MgSO4 and Na2SO4 above 95%, a result that compares favorably with that achieved by nanofiltration. In addition, the PBI HFM has a defect-free structure with an ultra-thin barrier layer and porous sublayer. We believe PBI HFMs are ideal for water purification and can be readily commercialized

Sulfonated poly ether ether ketone with different degree of sulphonation in microbial fuel cell: Application study and economical analysis

A microbial fuel cell (MFC) is a device for the simultaneous treatment of wastewater and the generation of electricity with the aid of microorganisms as a biocatalyst. Membranes play an important role in the power generation of microbial fuel cells. Nafion 117, the most common proton exchange membrane (PEM), is expensive and this is the main obstacle for commercialization of MFC. In this study, four kinds of sulphonated poly ether ether ketone (SPEEK) with different degrees of sulphonation (DS) referred to hereafter as SPEEK 1 (DS = 20.8%), SPEEK 2 (DS = 41%), SPEEK 3 (DS = 63.6%), and SPEEK 4 (DS = 76%), were fabricated, characterized and applied in an MFC. The membranes were characterized by thermogravimetric analysis TGA) and differential scanning calorimetry (DSC) and their morphologies were observed by scanning electron microscopy (SEM). The degree of sulphonation was determined by nuclear magnetic resonance (NMR). Then the membranes were applied to the MFC system. The results indicated that the power produced by MFC with SPEEK 3 (68.64 mW/m) was higher than with the other SPEEK membranes while it was lower than with Nafion 117 (74.8 mW/m). SPEEK3 also had the highest chemical oxygen demand removal (91%) and coulombic efficiency (26%) compared to other SPEEK membranes. The cost evaluation suggests that application of SPEEK 3 is more cost effective than applications of the other types of SPEEK and Nafion 117, due to its high power density generation per cost

Simultaneous organics, sulphate and salt removal in a microbial desalination cell with an insight into microbial communities

Microbial desalination cells (MDCs) are known among the bioelectrochemical systems for their green and cost-effective application in salt removal. However, the low efficiency of desalination compared to other chemical and membrane-based methods still holding this technology in laboratory and requiring further research and development (R&D) to establish actual plants. This study focused on integrating different applicable functions in one setup to promote applying MDCs in actual scale. In this research, the behavior of the MDC upon applying different salt concentrations in the desalination chamber was studied. Moreover, salt, sulphate and organic matter removal in acetate and sulphate-fed MDCs (A.MDC and S.MDC) were investigated. 10, 20 and 35 g/l of salt were successfully removed by using MDC technology. Sulphate removal of 72% was achieved within the S.MDC setup while similar current productions were observed in both A.MDC and S.MDC. Higher COD removal (88%) was recorded in S.MDC compared to 65% in A.MDC. Furthermore, the microbial communities were characterized and Rubrivivax was identified as the dominant genus in A.MDC while Desulfobulbus, Geobacter and Desulfovibrio were the most abundant genera in S.MDC setup

Treatment of two different water resources in desalination and microbial fuel cell processes by poly sulfone/sulfonated poly ether ether ketone hybrid membrane

The PS (Polysulfone)/SPEEK (sulfonated poly ether ether ketone) hybrid membranes were fabricated and modified with low and high DS (degrees of sulfonation) for the desalination of brackish water and proton exchange membrane in microbial fuel cell. The results illustrated that SPEEK has changed the morphology of membranes and increase their hydrophilicity. PS/SPEEK with lower DS (29%) had the rejection percentage of 62% for NaCl and 68% for MgSO4; while it was 67% and 81% for PS/SPEEK (76%) at 4 bars. Furthermore, the water flux for PS at 10 bar was 12.41 L m-2 h-1. It was four times higher for PS/SPEEK (29%) which means 49.5 L m-2 h-1 and 13 times higher for PS/SPEEK (76%) with means 157.76 L m-2 h-1. However, in MFC (microbial fuel cell), the highest power production was 97.47 mW/m2 by PS/SPEEK (29%) followed by 41.42 mW/m2 for PS/SPEEK (76%), and 9.4 mW/m2 for PS. This revealed that the sulfonation of PEEK (poly ether ether ketone) made it a better additive for PS for desalination, because it created a membrane with higher hydrophilicity, better pore size and better for salt rejection. Although for the separator, the degree of sulfonation was limited; otherwise it made a membrane to transfer some of the unwanted ions

Power generation and wastewater treatment using a novel SPEEK nanocomposite membrane in a dual chamber microbial fuel cell

In this paper, the performance of two common and two self-fabricated proton exchange membranes were compared. Nafion 112 and Nafion 117, which are two of the most common proton exchange membranes that can be used in all fuel cell systems, were compared to SPEEK and SP/CC/TAP. The results showed that at lower COD such as 2000 mg/l, Nafion 117 has the highest performance in terms of power production and COD removal, while once the COD of wastewater goes up to 5000 mg/l, SP/CC/TAP has approximately the same performance as Nafion 117. The membranes were characterized by FESEM, while the degree of sulfonation was measured by NMR. The oxidation activity of microorganisms was measure by cyclic voltammetry (CV). Also, the attachment of bacteria onto the anode electrode was observed by SEM, which showed that different bacteria from the media with a mixed culture inoculum had attached to the anode electrode

Power generation and wastewater treatment using a novel SPEEK nanocomposite membrane in a dual chamber microbial fuel cell

In this paper, the performance of two common and two self-fabricated proton exchange membranes were compared. Nafion 112 and Nafion 117, which are two of the most common proton exchange membranes that can be used in all fuel cell systems, were compared to SPEEK and SP/CC/TAP. The results showed that at lower COD such as 2000 mg/l, Nafion 117 has the highest performance in terms of power production and COD removal, while once the COD of wastewater goes up to 5000 mg/l, SP/CC/TAP has approximately the same performance as Nafion 117. The membranes were characterized by FESEM, while the degree of sulfonation was measured by NMR. The oxidation activity of microorganisms was measure by cyclic voltammetry (CV). Also, the attachment of bacteria onto the anode electrode was observed by SEM, which showed that different bacteria from the media with a mixed culture inoculum had attached to the anode electrode