Effects of coagulant residuals on polyamide membrane performance

Reverse osmosis and nanofiltration systems are continuously challenged with biofouling of polyamide membranes that are used almost exclusively for these desalination techniques. Traditionally, pretreatment and reactive membrane cleanings are employed as biofouling control methods. This in-depth review paper discusses the mechanisms of membrane biofouling and effects on performance. Current industrial disinfection techniques are reviewed, including chlorine and other chemical and non-chemical alternatives to chlorine. Operational techniques such as reactive membrane cleaning are also covered. Based on this review, there are three suggested areas of additional research offering promising, polyamide membrane-targeted biofouling minimization that are discussed. One area is membrane modification. Modification using surface coatings with inclusion of various nanoparticles, and graphene oxide within the polymer or membrane matrix, are covered. This work is in the infancy stage and shows promise for minimizing the contributions of current membranes themselves in promoting biofouling, as well as creating oxidant-resistant membranes. Another area of suggested research is chemical disinfectants for possible application directly on the membrane. Likely disinfectants discussed herein include nitric oxide donor compounds, dichloroisocyanurate, and chlorine dioxide. Finally, proactive cleaning, which aims to control the extent of biofouling by cleaning before it negatively affects membrane performance, shows potential for low- to middle-risk systems.

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Long-Term Stable Metal Organic Framework (MOF) Based Mixed Matrix Membranes for Ultrafiltration

10.26434/chemrxiv.13399367 ◽

2020 ◽

Author(s):

Muayad Al-shaeli ◽

Stefan J. D. Smith ◽

Shanxue Jiang ◽

Huanting Wang ◽

Kaisong Zhang ◽

...

Keyword(s):

Contact Angle ◽

Water Contact Angle ◽

Mixed Matrix Membranes ◽

Recovery Ratio ◽

Mixed Matrix ◽

Water Contact ◽

Membrane Performance ◽

Metal Organic ◽

Matrix Membranes

In this study, novel <a>mixed matrix polyethersulfone (PES) membranes</a> were synthesized by using two different kinds of metal organic frameworks (MOFs), namely UiO-66 and UiO-66-NH2. The composite membranes were characterised by SEM, EDX, FTIR, PXRD, water contact angle, porosity, pore size, etc. Membrane performance was investigated by water permeation flux, flux recovery ratio, fouling resistance and anti-fouling performance. The stability test was also conducted for the prepared mixed matrix membranes. A higher reduction in the water contact angle was observed after adding both MOFs to the PES and sulfonated PES membranes compared to pristine PES membranes. An enhancement in membrane performance was observed by embedding the MOF into PES membrane matrix, which may be attributed to the super-hydrophilic porous structure of UiO-66-NH2 nanoparticles and hydrophilic structure of UiO-66 nanoparticles that could accelerate the exchange rate between solvent and non-solvent during the phase inversion process. By adding the MOFs into PES matrix, the flux recovery ratio was increased greatly (more than 99% for most mixed matrix membranes). The mixed matrix membranes showed higher resistance to protein adsorption compared to pristine PES membranes. After immersing the membranes in water for 3 months, 6 months and 12 months, both MOFs were stable and retained their structure. This study indicates that UiO-66 and UiO-66-NH2 are great candidates for designing long-term stable mixed matrix membranes with higher anti-fouling performance.

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Gravity-Driven Membrane Reactor for Decentralized Wastewater Treatment: Effect of Reactor Configuration and Cleaning Protocol

Membranes ◽

10.3390/membranes11060388 ◽

2021 ◽

Vol 11 (6) ◽

pp. 388

Author(s):

Ihtisham Ul Haq Shami ◽

Bing Wu

Keyword(s):

Wastewater Treatment ◽

Municipal Wastewater ◽

Economic Feasibility ◽

Reactor Configuration ◽

Membrane Performance ◽

Decentralized Wastewater Treatment ◽

Water Head ◽

Cake Layer ◽

Gravity Driven ◽

Cleaning Protocol

In this study, three gravity-driven membrane (GDM) reactors with flat sheet membrane modules and various biocarriers (synthetic fibers, lava stones, and sands) were operated for municipal wastewater treatment. The effects of water head, periodically cleaning protocol, and operation temperature on the GDM reactor performance were illustrated in terms of membrane performance and water quality. The results indicated that: (1) the cake layer fouling was predominant (>~85%), regardless of reactor configuration and operation conditions; (2) under lower water head, variable water head benefited in achieving higher permeate fluxes due to effective relaxation of the compacted cake layers; (3) the short-term chemical cleaning (30–60 min per 3–4 days) improved membrane performance, especially when additional physical shear force was implemented; (4) the lower temperature had negligible effect on the GDM reactors packed with Icelandic lava stones and sands. Furthermore, the wastewater treatment costs of the three GDM reactors were estimated, ranging between 0.31 and 0.37 EUR/m3, which was greatly lower than that of conventional membrane bioreactors under lower population scenarios. This sheds light on the technical and economic feasibility of biocarrier-facilitated GDM systems for decentralized wastewater treatment in Iceland.

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Impact of pretreatment on RO membrane organic fouling: composition and adhesion of tertiary wastewater effluent organic matter

Environmental Science Water Research & Technology ◽

10.1039/d0ew01098g ◽

2021 ◽

Author(s):

Nadine Siebdrath ◽

Bertram Skibinski ◽

Shiju Abraham ◽

Roy Bernstein ◽

Robert Berger ◽

...

Keyword(s):

Organic Matter ◽

Wastewater Effluent ◽

Effluent Organic Matter ◽

Membrane Performance ◽

Organic Fouling ◽

Ro Membrane

Organic fouling in RO desalination of tertiary wastewater is of major concern in the decline in membrane performance.

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Polyamide membrane with nanocluster assembly structure for desalination

Journal of Membrane Science ◽

10.1016/j.memsci.2021.119230 ◽

2021 ◽

Vol 628 ◽

pp. 119230

Author(s):

Shuhao Wang ◽

Shaosuo Bing ◽

Yunhao Li ◽

Yong Zhou ◽

Lin Zhang ◽

...

Keyword(s):

Assembly Structure ◽

Polyamide Membrane

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Dye Separation and Antibacterial Activities of Polyaniline Thin Film-Coated Poly(phenyl sulfone) Membranes

Membranes ◽

10.3390/membranes11010025 ◽

2020 ◽

Vol 11 (1) ◽

pp. 25

Author(s):

Javed Alam ◽

Arun Kumar Shukla ◽

Mohammad Azam Ansari ◽

Fekri Abdulraqeb Ahmed Ali ◽

Mansour Alhoshan

Keyword(s):

Zeta Potential ◽

Surface Properties ◽

Antibacterial Activities ◽

Pani Film ◽

Force Microscopy ◽

Water Permeation ◽

Membrane Pores ◽

Membrane Performance ◽

Phenyl Sulfone ◽

The Impact

We fabricated a nanofiltration membrane consisting of a polyaniline (PANI) film on a polyphenylsulfone (PPSU) substrate membrane. The PANI film acted as a potent separation enhancer and antimicrobial coating. The membrane was analyzed via scanning electron microscopy and atomic force microscopy to examine its morphology, topography, contact angle, and zeta potential. We aimed to investigate the impact of the PANI film on the surface properties of the membrane. Membrane performance was then evaluated in terms of water permeation and rejection of methylene blue (MB), an organic dye. Coating the PPSU membrane with a PANI film imparted significant advantages, including finely tuned nanometer-scale membrane pores and tailored surface properties, including increased hydrophilicity and zeta potential. The PANI film also significantly enhanced separation of the MB dye. The PANI-coated membrane rejected over 90% of MB with little compromise in membrane permeability. The PANI film also enhanced the antimicrobial activity of the membrane. The bacteriostasis (BR) values of PANI-coated PPSU membranes after six and sixteen hours of incubation with Escherichia coli were 63.5% and 95.2%, respectively. The BR values of PANI-coated PPSU membranes after six and sixteen hours of incubation with Staphylococcus aureus were 70.6% and 88.0%, respectively.

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