Membrane Reactor For Wastewater Treatment Research Articles

Performance Evaluation of Polymeric Membrane Permeability Characteristics Using Different Aqueous Solutions

In the last decade the application of membrane separation technology is more increasing. The membrane in water purification and wastewater treatment is essential separation process used for water reclamation. The production of new membrane types with different permeable characteristics and performances allows them to be fitted in different membrane modules that can be used in the membrane filtration. The water characteristics are important for the membrane performance. It can seriously affect the permeability characteristics and increase the fouling on the membrane surface. In wastewater treatment, the characteristics of the aqueous influent can reduce the permeability of the membrane and the process efficiency of the membrane bioreactor (MBR). The aim of this paper is to explore the effect of different aqueous solutions on membrane permeability using dead end filtration process. For this purpose, NaCl solution with different concentration were prepared and the effect of the concentration polarization on the membrane was observed. The constructed membrane module was also tested with real water sample and the membrane permeability was analyzed. In this experiment a polymeric membrane produced from polyether sulphonate (PES), with diameter of 5.0 cm and pore size of 0.04 µm was assembled in a constructed module for dead-end filtration. The module was constructed in a way that would allow turbulence of the solution on the membrane surface. The following working parameters were examined: transmembrane pressure (TMP), the types of solutions, the working temperature, and the influence of agitation on the feeding to the specific membrane flux and permeability. The results showed that the membrane permeability is affected by the water organic and inorganic constituents and in the process of design of membrane reactor for wastewater treatment, the water composition should be taken in consideration.

Phosphorus-doped g-C3N4 integrated photocatalytic membrane reactor for wastewater treatment

Photocatalytic membrane reactors (PMRs) have been widely used in wastewater treatment over the past few years. In this study, P-doped g-C3N4 (PCN), a metal-free, visible light (Vis)-driven photocatalyst, was prepared and coated on an Al2O3 substrate followed by integration with an inorganic Al2O3 hollow fiber membrane module for use as a PMR. The 10 wt % of PCN exhibited the highest degradation activity for methyl blue (MB) removal under Vis irradiation because the C sites and vacancies within the heptazine rings of the CN units were substituted with P to improve charge separation and reduce the number of unpaired electrons. The PMR exhibits higher efficiency and stability in the removal of MB, methyl orange, phenol solution, and a mixture of the three organic compounds than do individual hollow fiber membranes or photocatalysis systems. The TOC (total organic carbon) analysis revealed that more than 92% of the phenol was decomposed and mineralized in the PMR, which also had a MB removal efficiency of greater than 90% when repeatedly used for four times. These results indicate that the PMR developed in this study is highly active and stable, and can serve as a promising system for effective removal of organic pollutants in wastewater.

Antifouling performance and mechanisms in an electrochemical ceramic membrane reactor for wastewater treatment

Membrane fouling remains as a critical issue limiting the widespread applications of membrane-based technologies for water and wastewater treatment. In this work, an electrochemical ceramic membrane reactor (ECMR), in which ceramic membrane with built-in Ti mesh acted as cathode/filter and Ti/SnO2-Sb-Ce as anodes, was developed for mitigating membrane fouling during wastewater treatment. Linear sweep voltammetry (LSV) and electrochemical impedance spectroscopy (EIS) of Ti/SnO2-Sb-Ce electrode demonstrated favorable electrochemical properties. Filtration tests with influent wastewater containing 50 mg/L sodium alginate (SA) showed that TMP increase rate for the ECMR was decreased by 23.9–72.7% compared to the control, dependent on the exertion modes of electric field in this reactor. It was found that all the oxidants contributed to the enhanced antifouling performance of the ECMR due to in-situ membrane cleaning effects while the hydrogen peroxide and active chlorine (ClT) played a more important role compared to superoxide anions and hydroxyl radicals. SA was oxidized to a smaller size after reacting with reactive oxygen species (ROS) and ClT, benefiting the mitigation of membrane fouling in ECMR.

Polydopamine-Coated Porous Substrates as a Platform for Mineralized β-FeOOH Nanorods with Photocatalysis under Sunlight.

Immobilization of photo-Fenton catalysts on porous materials is crucial to the efficiency and stability for water purification. Here we report polydopamine (PDA)-coated porous substrates as a platform for in situ mineralizing β-FeOOH nanorods with enhanced photocatalytic performance under sunlight. The PDA coating plays multiple roles as an adhesive interface, a medium inducing mineral generation, and an electron transfer layer. The mineralized β-FeOOH nanorods perfectly wrap various porous substrates and are stable on the substrates that have a PDA coating. The immobilized β-FeOOH nanorods have been shown to be efficient for degrading dyes in water via a photo-Fenton reaction. The degradation efficiency reaches approximately 100% in 60 min when the reaction was carried out with H2O2 under visible light, and it remains higher than 90% after five cycles. We demonstrate that the PDA coating promotes electron transfer to reduce the electron-hole recombination rate. As a result, the β-FeOOH nanorods wrapped on the PDA-coated substrates show enhanced photocatalytic performance under direct sunlight in the presence of H2O2. Moreover, this versatile platform using porous materials as the substrate is useful in fabricating β-FeOOH nanorods-based membrane reactor for wastewater treatment.

Development of a Novel Bioelectrochemical Membrane Reactor for Wastewater Treatment

A novel bioelectrochemical membrane reactor (BEMR), which takes advantage of a membrane bioreactor (MBR) and microbial fuel cells (MFC), is developed for wastewater treatment and energy recovery. In this system, stainless steel mesh with biofilm formed on it serves as both the cathode and the filtration material. Oxygen reduction reactions are effectively catalyzed by the microorganisms attached on the mesh. The effluent turbidity from the BEMR system was low during most of the operation period, and the chemical oxygen demand and NH(4)(+)-N removal efficiencies averaged 92.4% and 95.6%, respectively. With an increase in hydraulic retention time and a decrease in loading rate, the system performance was enhanced. In this BEMR process, a maximum power density of 4.35 W/m(3) and a current density of 18.32 A/m(3) were obtained at a hydraulic retention time of 150 min and external resister of 100 Ω. The Coulombic efficiency was 8.2%. Though the power density and current density of the BEMR system were not very high, compared with other high-output MFC systems, electricity recovery could be further enhanced through optimizing the operation conditions and BEMR configurations. Results clearly indicate that this innovative system holds great promise for efficient treatment of wastewater and energy recovery.

Study and Preparation of Electrocatalytic Ceramic Membrane Electrode

The novel electrochemical membrane reactor for wastewater treatment was designed and introduced. As the key part of the electromembrane reactor, the tubular membrane electrode was prepared and researched. The tubular inorganic ceramic membrane was endowed with electroconductivity by the deposition of pyrolytic carbon from propylene by chemical vapor deposition. The electrocatalytic property of the membrane electrode was realized through dip-coating with chloroplatinic acid solution, drying and hydrogen reduction in order that the electrocatalyst of reduced platinum can be supported. The SEM characterization and water flux test of the membrane electrode show that membrane separation and electrocatalysis can be integrated together.