Investigation of pilot scale manufacturing of polysulfone (PSf) membranes by wet phase inversion method

Membranes are used as a support layer for the fabrication of thin film composite membranes. Sup- port layer properties can affect many performance parameters of TFC membranes such as flux, rejection, morphology and stability against pressure. Although studies in lab scale fabrication exist, investigation the pilot scale polysulfone membrane fabrication has not been done. In this study, opti- mization of polysulfone support membranes fabrication was conducted in pilot scale. Coagulation bath temperature; casting speed and solution content were selected as main parameters for the opti- mization. Membrane surface properties were investigated in details with SEM and pore size dis- tribution. Membrane performance were determined with permeability experiments. Differences in pilot scale and lab scale membrane manufacturing were observed and compared with literature. On the contrary to literature it was found that, coagulation bath temperature has exact opposite effect in pilot scale membrane formation compared to lab scale studies. 10°C drop (from 25°C to 15°C) in coagulation bath temperature decreased mean pore size of membranes from 27 nm to 8 nm and per- meability from 464 l/m2h to 100 l/m2h while everything else was kept constant

Marmara Seawater Desalination by Membrane Distillation: Direct Consumption Assessment of Produced Drinking Water

Drinking water was produced from Marmara seawater by membrane distillation (MD). The best operating conditions were determined by batch experiments as: 0.45 μm PTFE, 30°C distillate temperature and temperature difference, and 270–360 L/h cross‐flow rates in feed‐distillate. Seawater desalination was carried out with 99.93% solute rejection and 17.2 L/m2h permeate flux in 66% concentration ratio by lab‐scale pilot system. Since the desalinated water contained no organic carbon, turbidity, and nitrate, it seemed to be very suitable for immediate service with quality of 7.3 pH, clear, odor‐free, 76.0 µS/cm, 47.1 mg TDS/L, <0.001 color, and 0.01 mg boron/L. The product water lacked of vital cations, especially Na+, K+, Ca2+, Mg2+ that are essentials for promoting osmotic balanced body liquid and healthy development. A holistic management approach towards satisfying specific water quality requirements in direct service of MD effluents to human consumption was proposed that jointly included in injecting into urban potable water, adding appropriate chemicals into the effluent, and mixing effluents with raw or concentrated seawater (1:250/1:1000 for Marmara seawater) or brackish natural waters under hygienic precautions

Graphene integrated polymeric membranes for ultrafiltration

Graphene has the potential to re-define the pore parameters of a conventional ultrafiltration membrane. Due to its flexibility, mechanical strength and atomic thickness, graphene provides a platform for nano/sub nanometer pores for ionic filtration. In this work we would like to present the mechanisms involved in graphene integration/transfer with a polymer substrate, the overall effects of graphene on the properties of the membrane and initial results on textile dye filtration using these membranes. In addition we also would like to present how water nanodroplets can be live imaged under a Transmission Electron Microscope (TEM) using graphene as a TEM window. This method can pave a way for new generation nanofluidic devices where bio-molecules can be imaged in their natural state. Nanodroplet condensation and water bubble dynamics have been observed and recorded by this method

The Effect of Sequential and Simultaneous Supplementation of Waste-Derived Volatile Fatty Acids and Methanol as Alternative Carbon Source Blend for Wastewater Denitrification

Supplementation of alternative carbon sources is a technological bottleneck, particularly in post-denitrification processes due to stringent effluent nitrogen levels. This study focuses on enhancing the sustainability of wastewater treatment practices by partially replacing conventionally used fossil-derived methanol with organic waste-derived volatile fatty acids (VFAs) in moving bed biofilm reactors (MBBRs). In this regards, results of denitrification batch assays with sequential or simultaneous addition of VFA effluent from acidogenic fermentation of potato starch residue (AD-VFAPPL) and chicken manure (AD-VFACKM), simulated synthetic VFAs solutions (sVFAs), and methanol as carbon source were presented and discussed. Although methanol has proven superior in the conversion of nitrate to nitrite, VFAs are more effective when it comes to reducing nitrite. Although solely added AD-VFAPPL had a slower denitrification capability (0.56 ± 0.13 mgNOx-N removed/m2/day) than methanol (1.04 ± 0.46 mgNOx-N removed/m2/day), up to 50% of the methanol can be replaced by waste-derived AD-VFAPPL and achieve comparable performance (1.08 ± 0.07 mgNOx-N removed/m2/day) with the pure methanol. This proves that the co-addition of VFAs together with methanol can fully compete with pure methanol in performance, providing a promising opportunity for wastewater treatment plants to potentially reduce their carbon footprint and become more sustainable in practice while benefiting from recovered nutrients from waste

Potential of food waste-derived volatile fatty acids as alternative carbon source for denitrifying moving bed biofilm reactors

Fossil-based materials such as methanol are frequently used in the denitrification process of advanced biological wastewater treatment as external carbon source. Volatile fatty acids (VFAs) produced by anaerobic digestion of food waste, are sustainable compounds with the potential to act as carbon sources for denitrification, reducing carbon footprint and material costs. In this study, the effectiveness of food waste-derived VFAs (AD-VFA) was investigated in the post-denitrification process in comparison with synthetic VFA and methanol as carbon sources. Acetic acid had the highest rate of disappearance among single tested VFAs with a denitrification rate of 0.44 g NOx-N removed/m2/day, indicating a preferential utilization pattern. While AD-VFA had a denitrification rate of 0.61 mg NOx-N removed/m2/day, sVFA had a rate of 0.57 mg NOx-N removed/m2/day, indicating that impurities in AD-VFA did not play substantial role in denitrification. AD-VFA proved to be promising carbon source alternative for denitrification in wastewater treatment plants

Photothermal electrospun nanofibers containing polydopamine-coated halloysite nanotubes as antibacterial air filters

Antibacterial air filter media offer an important solution to indoor air pollution from bioaerosols, which pose a serious threat to global public health. In this study, we introduced an antibacterial air filter based on nanofibers functionalized with a photothermal agent, which deactivates bacteria upon near-infrared (NIR) irradiation. Halloysite nanotube (HNT) clay nanoparticles coated with polydopamine (PDA), which heat up when exposed to NIR light, were utilized as photothermal agents to be incorporated into polyacrylonitrile (PAN) nanofibers. The resulting PAN/HNT-PDA nanofibers reached 102 °C after 2 min of NIR irradiation and physically destroyed Staphylococcus aureus (S. aureus) cells that were in contact with the nanofibers. In a simulated air filtration test system, photothermal nanofibers demonstrated a bioaerosol filtration efficiency of 99.97% and a quality factor of 0.14 Pa-1. 107S. aureus cells captured on the nanofibers were killed via a 10 min NIR-light irradiation, whereas the light-activated antibacterial properties of the nanofibers were maintained over 5 bioaerosol flow/NIR-treatment cycles. The photothermal agent-containing electrospun nanofibers presented here have a strong potential for aerosol removal as light-activated antibacterial air filters

Influence of ageing on the catalytic activity of MnO2 sludge for oxidation of Mn(II)

Manganese can be present in natural water in concentrations exceeding 10mg/l. If not treated well, Mn(II) ions can easily escape through the water treatment systems. Mn(II) in the distribution systems could form manganese dioxide, which is insoluble in water, causing several problems such as water discoloration, turbidity, metallic taste, odour, corrosion and biofouling. Oxidation is a common method for Mn(II) removal. Oxidation process can become more efficient with catalytic effects of several substances. High Mn(IV) concentrations can be maintained only by sludge recycle which eventually leads to sludge ages as high as 10days. The aim of this study was to determine whether ageing of MnO2 sludge affects its catalytic effect on the oxidation of manganese by aeration. In order to reach this aim, five different groups of experiments were carried out by MnO2 sludge aged for a period of 0-10days. It has been demonstrated that the catalytic effect of MnO2 sludge on the oxidation of manganese, contrary to what is commonly expected, aeration increases with increasing sludge age. It has been concluded that, catalytic oxidation rate constant, k(cat) obtained from the batch systems can safely be used in design of continuous flow Mn(II) oxidation reactors with sludge recycle. As a result, the catalytic effect of MnO2 sludge on the Mn(II) oxidation by aeration increases with increasing sludge age up to approximately fourth day

Towards maximum value creation from potato protein liquor: volatile fatty acids production from fungal cultivation effluent

The cornerstones of an efficient circular waste management strategy aiming for enhanced resource efficiency are maximizing organic waste valorization and improving residual conversion to biochemicals. In this regard, this study focuses on the production of volatile fatty acids (VFAs) from the effluent of fungi biomass cultivation on low-grade residues from the potato starch industry with batch and semi-continuous membrane bioreactors (MBRs) containing the effluent of already fermented potato protein liquor (FPPL) inoculated with chicken and cow manure. The effect of pH in the batch experiments on the production and yield of VFAs during acidogenic digestion was evaluated. Rapid generation of VFAs at a concentration of up to 11.8 g/L could be successfully achieved in the MBR. Under the optimal conditions, a high yield of 0.65 g VFAs/g VSfed was obtained for the organic loading rate (OLR) of 1 g VS/L/d using FPPL substrate and chicken manure as inoculum. The results show that the application of sequential multi-step bioconversion of potato starch industry residues has the potential to increase the variety of value-added products generated from a single organic residue while enhancing nutrient recovery capacity.

Interfacially polymerized thin-film composite membranes: impact of support layer pore size on active layer polymerization and seawater desalination performance

This study focuses on the structure-property relationship of interfacially polymerized thin-film composite (TFC) membranes. The impact of the polysulfone support layer on the polymerization of the polyamide active layer is investigated systematically and the resulting membrane surface morphology is related to RO separation performance under seawater desalination conditions. Six different TFC membranes with support layers having average pore sizes ranging from 18 nm to 120 nm were fabricated. Cross-flow RO tests showed that salt rejection systematically increased from 80.5% to 99.0% with decreasing support layer pore size. Scanning electron microscopy at high resolution revealed that the ridge-and-valley structure was more pronounced for active layers of TFC membranes prepared with support layers having larger pores. Convective monomer transport during interfacial polymerization is discussed as a possible reason behind the formation of ear- and ridge-like protuberances, of which the latter can apparently be damaging to the inner active layer