Film breakers prevent migration of aqueous potassium hydroxide in fuel cells

Electrolyte film breakers made from polytetrafluoroethylene are installed in the reactant and water vapor removal outlets of each cell and sealed by elastomers. Use of these devices in the water vapor removal cavity outlets prevents loss of KOH solution through film migration during water removal

Practical application of ferrate(VI) for water and wastewater treatment: site study’s approach

This paper presents the work aiming to validate the practical feasibility of ferrate(VI) used as an alternative to the existing coagulant (e.g., ferric chloride/sulphate) for both drinking water and domestic sewage treatment via series of pilot plant trials. For drinking water treatment, a ferrate(VI) dose of 0.1 mg/L can achieve 93% and 97% particle removal (in terms of particle counting) after the filtration for raw water and for the ozonized water, respectively, which is satisfied to the treated water quality requirement for the particles’ removal. Moreover, ferrate(VI) can remove 10% metformin, benzotriazole and acesulfam from raw water but FeCl3 with ozonation can’t. When treating domestic sewage at pilot scale trials, ferrate(VI) demonstrated encouraging performance as well, at a very lower dose range, 0.1–0.2 mg Fe/L, ferrate(VI) achieved better performance in comparison with high dosed ferric sulphate. This will reduce chemical demand and sludge production and therefore results in a low operating cost and generates substantial cost saving in treating sewage. Keywords: BOD removal, Coagulation, COD removal, Drinking water treatment, Ferrate(VI), Micro pollutant reduction, Particle removal, Phosphorous removal, Sewage treatmen

The survey of removal of suspended solids from river at flooding period by plain sedimentation process

The most important of surface sources of water in the large city are rivers. The turbidity and flow rate of rivers is a constantly changing phenomenon in the seasons from year. During rainy period, the run off carries with it silt, clay and sand which make a severe increasing in turbidity to over 1000NTU. The increasing of turbidity causes which the water plant treatment receives the more solides.However; in order to protection of plant units must apply pretreatment processes. In this research, the effectiveness of settling process in order to removal of TSS from raw water was studied. The beginning of the work, lab-scale pilot designed which consisted of a raw water preparation container; the settling column was made of Plexiglas with 2m height, 20cm diameter and the six of sampling ports. The settling column filled with the raw water associated with sediments of river. At defined time steps (30-60-90-120-150-180 min) samples were taken out from the bottom of the column (180cm under water surface). The temperature of water was in the range of 15 to 18oC during experiments. The results showed that between the increasing of TSS removal and settling time, a direct and significant relative (p<0/01) was obtained by Pearson, s correlation coefficient. Also with increasing the depth, the removal efficiency of TSS and turbidity decreased. In the settling time of 30min, 2640mg/L of TSS concentration, the depths of 30 and 180cm, systematically, the TSS removal 92.42% and 80.47% was obtained. when the initial TSS concentration increase to 27640mg/L (the most concentration of TSS), with increasing SOR from 25m/d to 60m/d, the total removal efficiency decreased from 99.2% to 92.2%, and with the TSS of concentration equals to 2640mg/L, the rate of total removal efficiency decreased from 97.2% to 95.7%. The results showed that the rising of SOR and TSS concentration, decreased the total removal efficiency. Also, these are an opposite and significant relative (p<0/05) between the removal of TSS and initial concentration of TSS

Exploratory analysis of excitation-emission matrix fluorescence spectra with self-organizing maps as a basis for determination of organic matter removal efficiency at water treatment works

In the paper, the self-organizing map (SOM) was employed for the exploratory analysis of fluorescence excitation-emission data characterizing organic matter removal efficiency at 16 water treatment works in the UK. Fluorescence spectroscopy was used to assess organic matter removal efficiency between raw and partially treated (clarified) water to provide an indication of the potential for disinfection by-products formation. Fluorescence spectroscopy was utilized to evaluate quantitative and qualitative properties of organic matter removal. However, the substantial amount of fluorescence data generated impeded the interpretation process. Therefore a robust SOM technique was used to examine the fluorescence data and to reveal patterns in data distribution and correlations between organic matter properties and fluorescence variables. It was found that the SOM provided a good discrimination between water treatment sites on the base of spectral properties of organic matter. The distances between the units of the SOM map were indicative of the similarity of the fluorescence samples and thus demonstrated the relative changes in organic matter content between raw and clarified water. The higher efficiency of organic matter removal was demonstrated for the larger distances between raw and clarified samples on the map. It was also shown that organic matter removal was highly dependent on the raw water fluorescence properties, with higher efficiencies for higher emission wavelengths in visible and UV humic-like fluorescence centers

Removal of Carbamazepine from Drinking Water

Due to the increasing prevalence of prescription medication over the past few decades, pharmaceuticals have accumulated in various water sources. This has become a public health concern because many pharmaceuticals have limited research on the effects of chronic low-level exposure. According to the World’s Health Organization (WHO), traces of pharmaceuticals products have been reported in different water sources such as surface waters, wastewater, groundwater, and drinking water.[1] One pharmaceutical of interest that has been detected in water sources is carbamazepine. Carbamazepine is a common pharmaceutical prescribed for the treatment of seizure disorders, neuropathic pain, and various psychological disorders. It’s mechanism of action is “sodium channel blocking,” which is the impairment of conduction of sodium ions in sodium channels. This, in effect, reduces nervous-system conductivity in key areas related to the treated disorders mentioned above.[2] Carbamazepine is also not easily biodegradable and current conventional treatment methods in some drinking water and wastewater facilities do not adequately remove carbamazepine and other pharmaceuticals from treated water. While carbamazepine is not federally regulated by the Environmental Protection Agency (EPA) under the Safe Water Drinking Act (SWDA) at this time, it does have the potential for producing adverse health effects in humans. Therefore, being proactive in finding ways to remove carbamazepine and compounds like it should be encouraged. The Carbamaza-Clean team designed a bench scale unit as well as an in-home treatment system using granular activated carbon (GAC) to effectively remove carbamazepine from water. GAC was chosen for this design because it is inexpensive and does not create byproducts that are harmful to human health. Several experiments were conducted to determine the efficiency of the removal of carbamazepine using two different GACs: coconut shell GAC (CSGAC) and bituminous coal GAC (BGAC). A packed bed column was constructed to determine if both carbons could reduce the concentration of carbamazepine from 1 ppm to 1 ppb or lower. The CSGAC packed bed was able to lower the concentration below 1 ppb at a packed bed length of 4.4 ft, while the BGAC only required half that (2.2 ft). Both carbons can remove carbamazepine to the desired concentration; however, the costs vary. An economic analysis was performed to determine the costs of the carbons. The CSGAC system would cost $990 for the first year and$589.68 for each following year. The BGAC system would cost $639 for the first two years, and then$200 every two years following the initial capital investment

Influence of operating parameters on the biodegradation of steroid estrogens and nonylphenolic compounds during biological wastewater treatment processes

This document is the unedited author's version of a Submitted Work that was subsequently accepted for publication in Environmental Science & Technology, copyright © American Chemical Society after peer review. To access the final edited and published work see http://pubs.acs.org/doi/abs/10.1021/es901612v.This study investigated operational factors influencing the removal of steroid estrogens and nonylphenolic compounds in two sewage treatment works, one a nitrifying/denitrifying activated sludge plant and the other a nitrifying/denitrifying activated sludge plant with phosphorus removal. Removal efficiencies of >90% for steroid estrogens and for longer chain nonylphenol ethoxylates (NP4−12EO) were observed at both works, which had equal sludge ages of 13 days. However, the biological activity in terms of milligrams of estrogen removed per day per tonne of biomass was found to be 50−60% more efficient in the nitrifying/denitrifying activated sludge works compared to the works which additionally incorporated phosphorus removal. A temperature reduction of 6 °C had no impact on the removal of free estrogens, but removal of the conjugated estrone-3-sulfate was reduced by 20%. The apparent biomass sorption (LogKp) values were greater in the nitrifying/denitrifying works than those in the nitrifying/denitrifying works with phosphorus removal for both steroid estrogens and nonylphenolic compounds possibly indicating a different cell surface structure and therefore microbial population. The difference in biological activity (mg tonne−1 d−1) identified in this study, of up to seven times, suggests that there is the potential for enhancing the removal of estrogens and nonylphenols if more detailed knowledge of the factors responsible for these differences can be identified and maximized, thus potentially improving the quality of receiving waters.Public Utilities Board (Singapore), Anglian Water Ltd, Severn Trent Water Ltd, Thames Water Utilities Ltd, United Utilities 393 Plc and Yorkshire Water Services

A parametric evaluation of the removal as(III) and as(V) from aqueous water by red mud

In the present study, removal of arsenide (As(III)) and arsenate As(V) ions from water/wastewater by adsorption on red mud is investigated. Laboratory experiments were carried out to analyze removal capacity of the adsorbents, to achieve adsorption isotherms and kinetic parameters. Optimum doses of adsorbents, pH dependence of solutions, and contact time have been discussed. This study proposes the potential adsorbent material for water/wastewater which is contaminated with As species

Mechanistic modeling of pollutant removal, temperature, and evaporation in chemical air scrubbers

Chemical air scrubbers reduce the concentration of water-soluble components such as ammonia from the outgoing ventilation air through absorption in water, followed by chemical conversions and removal of the end products. A mechanistic model for a countercurrent air scrubber was set up. Mass balances for ammonia, hydrogen sulfide, nitrous oxide, and methane were implemented, as well as the water mass balance and heat balances. The model was validated against experimental data from a conventional fattening pig housing facility. The effect of influent characteristics, design parameters, and control handles on the removal efficiency, the temperature profile, and the water evaporation rate were investigated through simulation. The model was able to describe the behavior of a countercurrent chemical air scrubber

Dairy waste water treatment by combining ozonation and nanofiltration

The aim of this investigation was to examine the applicability of the membrane technique and the effect of preozonation in dairy waste water treatment technology. The best degree of surfactant removal from model anionic surfactant solution by nanofiltration was achieved at 20 degrees C and 40 bar. Investigations on the effects of ozone treatment of the waste water indicated that preozonation decreased the flux and increased the chemical oxygen demand and surfactant removal efficiency. Ozone treatment enhanced the biodegradability of the retentate from 68.8% to 96.4%

Application of hydrophobic fluorinated silicon oxide nanoparticle coating on electrodynamic screen (EDS) films for enhancing self-cleaning function of solar collectors

Optical surfaces, which are exposed to outdoor environmental conditions, are susceptible to dust deposition. Sunlight incident on the surface of photovoltaic (PV) modules is attenuated by the dust layer accumulation on the front surface of the modules. Energy-yield decrease by dust layer accumulation, called soiling losses, can be 5 to 40 percent annually unless the modules are cleaned frequently. Cleaning the optical surface with water is generally used in solar plants, which causes an unsustainable demand for freshwater in semi arid and desert areas. Adhesion of soil on the front surface of solar collectors plays a major role in the cleaning process. For low water cleaning, the module surface is often coated with an anti-soiling coating. If the surface is made hydrophilic, water can wet the surface most effectively making the cleaning process efficient, but requiring a low amount of water. If the surface is made hydrophobic, the surface energy is decreased reducing the adhesion force; the cleaning can be performed even with a lesser amount of water or with an application of an external removal force, such as wind. Major problems with the application of anti-soiling coatings are their environmental durability, poor adhesion of the coating on the surface and low resistance to abrasion. Since the removal of dust still requires spraying of water to the PV modules, the coatings get removed within a short period. Similarly, another dust removal method that does not require water for cleaning PV modules, is the Electrodynamic Screen (EDS) film, which consists of series of parallel transparent electrodes embedded within two transparent dielectric films and laminated on the surface of the solar collectors. When the electrodes are activated film by applied voltage pulses there will be a traveling electric field on the EDS surface, then the dust particles on the film surface gets charged electrostatically and are removed by Coulomb forces applied by the electric field. The EDS film application is an elective removal of the dust particles from the PV module surface without requiring any water or mechanical forces. However, the applied Coulomb force cannot overcome the dust adhesion force when the particles are smaller than 2 m in diameter or if the capillary adhesion forces are present because of the high humidity environment. The objective of the thesis is to decrease the particle adhesion forces of the EDS film surface by the application of a hydrophobic coating so that the dust removal efficiency is enhanced for moving small particles. To improve EDS film based dust-removal performance it is necessary to have the coating non-conductive and optically transparent and hydrophobic for the effective application electrostatic removal mechanisms. The hydrophobic coating would reduce the surface energy and hence the dust adhesion force, assisting the self-cleaning effect, which would not require any water consumption. Since water-based cleaning is no longer needed for dust removal when the EDS film surface is modified with hydrophobic surface properties, the durability of the coating would improve. We describe here a synthesis of a hydrophobic fluorinated silicon oxide nanoparticle coating on the EDS films for enhancing the self-cleaning function of solar collectors. We used dip-coating method to apply a single-layer hydrophobic silicon oxide nanoparticle film with a large static water contact angle on the EDS film surface. silicon oxide was prepared by the sol-gel method using Tetraethylorthosilicate (TEOS) and ammonium hydroxide as a precursor anda catalyst. The suspension was treated with 3-aminopropyltriethoxysilane (APS) and 1H,1H,2H,2H-perfluorodecyltriethoxysilane (FAS-17) to modify the surface of the coating, which greatly improved the hydrophobicity, and thus gave the coating the desired self-cleaning property. We used polyurethane (PU) as a binder between the substrate and coating to enhance the durability of the lm in outdoors applications. Experimental data on the optical transmittance, adhesion of the hydrophobic film on the glass surface of the EDS lm, and the dust removal efficiency are presented. The average optical transmission efficiency (TE) decreased from 93.43 to 89.78 percent and the output power restoration (OPR) of the solar panels laminated with EDS film with SH coating increased from 98.3 to 99.19 percent. Possible improvements to the hydrophobic coating process and its durability and future research needs are discussed