Membrane Bioreactors for Waste gas Treatment

Producción CientíficaIn the chapter on “Membrane Bioreactors for Waste Gas Treatment” an overview of recent progress in this field is given. In contrast with waste water treatment, membrane systems for waste gas treatment are still in the exploratory stage, although advantages are obvious: in membrane systems the air and aqueous phase are separated, which allows better performance for hydrophobic compounds. The bottleneck, however, is the scaling up of the system. In this chapter the basics of membrane permeation; reactor configuration; results of lab and pilot scale membrane waste gas treatment studies; microbiological aspects and modeling are discussed and future perspectives are presented

Electrochemistry of lead and lead alloy anodes in lead-acid batteries for photovoltaic energy storage.

The performance of lead-acid batteries for energy storage in photovoltaic/diesel/battery hybrid systems strongly depends on several electrochemical and/or operational factors such as the alloying elements incorporated in the electrode plates, the addition of expander materials to the anode or to the electrolyte, temperature, and the charging regime of the battery. In this study, the influences of the above mentioned factors on battery performance were investigated using cyclic voltammetry and potentiostatic transient techniques supplemented by surface analysis techniques including scanning electron microscopy (SEM) and x-ray photoelectron spectroscopy (XPS). The behaviour of binary lead-calcium and lead-antimony, and ternary lead-calcium-tin and lead-antimony-selenium alloy anodes were compared to that of the pure lead anode. In addition, the effect of ammonium ligno-sulphonate (ALS), as an expander added to the electrolyte, on the anode behaviour, was studied at room (23\sp\circC) and cold (0\sp\circC) temperatures

Promotion of life in senior's dancing group

There is an increasing interest for business organizations to engage into the global inter-firm alliance nowadays. The companies are striving for accessing the opportunities created by emerging markets, diversification of the products’ offer or the access to lower cost inputs (Barnes, et al., 2010). However, along with the benefits, there are also risks that the inter-firm alliances are challenged with. Those risks are represented by various forms of opportunistic behavior, which might be further caused by business partners (Williamson, 1975). The companies that decide to engage into inter-firm alliance need to invest in the implementation of control mechanisms that will protect them against opportunistic behavior. The preventing exante mechanisms can be implemented prior to the official start of cooperation while the cause ex-post mechanisms are applied during further stage of the collaboration. However, due to the cost of these implementations, companies cannot afford employing every available control mechanism. They need to select only the ones that their benefits exceed their costs. One of the main factors that influence the selection process of control mechanisms is the level of knowledge sensitivity of a product. The main objective of this master thesis is to determine how the level of knowledge sensitivity of a product influences the selection of ex-ante control mechanisms

Ex-ante Control Mechanisms against Opportunistic Behavior regarding Knowledge Sensitivity of Product (Comparative Case Study)

There is an increasing interest for business organizations to engage into the global inter-firm alliance nowadays. The companies are striving for accessing the opportunities created by emerging markets, diversification of the products’ offer or the access to lower cost inputs (Barnes, et al., 2010). However, along with the benefits, there are also risks that the inter-firm alliances are challenged with. Those risks are represented by various forms of opportunistic behavior, which might be further caused by business partners (Williamson, 1975). The companies that decide to engage into inter-firm alliance need to invest in the implementation of control mechanisms that will protect them against opportunistic behavior. The preventing exante mechanisms can be implemented prior to the official start of cooperation while the cause ex-post mechanisms are applied during further stage of the collaboration. However, due to the cost of these implementations, companies cannot afford employing every available control mechanism. They need to select only the ones that their benefits exceed their costs. One of the main factors that influence the selection process of control mechanisms is the level of knowledge sensitivity of a product. The main objective of this master thesis is to determine how the level of knowledge sensitivity of a product influences the selection of ex-ante control mechanisms

Effects of pressure ratio and pressure difference on the gas permeation properties of rubbery and glassy membranes

The dependence of permeance and ideal separation factor on pressure ratio and pressure difference across the membrane was studied for a rubbery and a glassy membrane. The membranes tested included commercially available silicone rubber and polyimide. The experimental gases included helium, oxygen, and nitrogen. The experiments were performed using an automated constant volume gas permeation system where the rise of the downstream pressure was accurately converted into permeance using a computer program. All experiments were performed at room temperature.The results indicated that the permeance of the rubbery membrane increased with pressure ratio and decreased with pressure difference. The ideal separation factors of the three experimental gases were not affected by pressure ratio, but increased with pressure difference. On the other hand, the permeance and ideal separation factors of the gases through the glassy membrane remained unaffected by either pressure ratio or pressure difference

Negatively charged polyethersulfone hollow fiber nanofiltration membrane for the removal of bisphenol A from wastewater

Removal of endocrine disrupting compound (viz., bisphenolA, BPA) by laboratory-fabricated hollowfiberpolyethersulfone (PES) nanofiltration (NF) membranes have been investigated. The tailor made charged PES hollow fiber NF membranes have been developed by blending negativelycharged surface modifying macromolecule (cSMM). It is resulted more than 90% removal of BPA, mainly due to negativelycharged properties of the membrane and the negativelycharged solute under the influence of higher pH feed water matrix. The PES hollowfiber modified by blending cSMM is associated with sulfonic groups, confirmed by energy dispersive X-ray and Fourier transform infrared analysis. The blending of cSMM has successfully modified PES hollowfiber which is resulted twice better removal of BPA compared to the unmodified PES

Asymmetric membranes by a two-stage gelation technique for gas separation: formation and characterization

Asymmetric gas separation membranes with dense and defect-free skin layer can be prepared by controlling the location of liquid\ub1liquid demixing gap in a ternary phase diagram, and by controlling the residence time in the gel region. For this purpose, polymer solutions of polysulfone in NMP were immersed in polyethylene glycol (PEG) prior to transferring to a water bath. It was believed that a coating layer of PEG retards the liquid\ub1liquid phase separation and controls the demixing of the solution. The investigations indicated that an optimum residence time in the PEG bath existed, which led to the formation of a defect-free, and consequently, a selective skin layer. The skin formation mechanism was discussed in terms of gelation and liquid\ub1liquid phase separation. Also, nodular structure formation was interpreted in the view of spinodal decomposition and the second liquid\ub1liquid phase separation in the water bath. In addition, Micro-Raman spectroscopy was used to investigate the composition change across the interface of the precipitated phase during phase inversion process. The difference in gelation process and liquid\ub1liquid phase separation was observed spectroscopically. The results are incorporated into a discussion of the skin formation of asymmetric membrane.NRC publication: Ye

Characterization and performance of proton exchange membranes for direct methanol fuel cell: Blending of sulfonated poly(ether ether ketone) with charged surface modifying macromolecule

Modification of sulfonated poly(ether ether ketone) (SPEEK) membrane was attempted by blending charged surface modifying macromolecule (cSMM). The modified membrane was tested for direct methanol fuel cell (DMFC) application; i.e. a SPEEK/cSMM blend membrane was compared to a SPEEK membrane and a Nafion 112 membrane for the thermal and mechanical stability, methanol permeability, and proton conductivity. Thermal and mechanical stability of the blended membrane were slightly reduced from the SPEEK membrane but still higher than the Nafion 112 membrane. The blend membrane was found to be promising for DMFC applications because of its lower methanol diffusivity (2.75×10−7 cm2 s−1) and higher proton conductivity (6.4×10−3 Scm−1), than the SPEEK membrane. A plausible explanation was given for the favorable effect of cSMM blendin