Spelling suggestions: "subject:"activated barbon"" "subject:"activated darbon""
131 |
Removal of Organic Matters from Domestic Wastewater Using GAC Trickling FilterLin, Ze-min 07 July 2012 (has links)
Because of high intense population is in Taiwan, households water use requires a considerable amount. It is substantially reduce daily water use to share primary water resources, if we can reclaim domestic wastewater properly and make it support. Currently, reclaiming water is an emerging requirement for management and application. If we can adequately monitor and treat reclaimed water, reducing environmental contaminants, costs, and environmental feedback is possible.
The study treated domestic wastewater of Feng-Shan river using GAC trickling filter with two column in a series and the removal efficiency of organic carbon was observed. The experimental results indicated that removal efficiency of organic carbon concentration was decreased as the empty-bed contact time (EBCT) increased. The best average removal efficiency of TOC and DOC was about 72% and 78%. According to the TOC removal rates using GAC at different temperatures, the TOC removal rates at room temperature and 4¢Jwere respectively 95% and 90% in the first column of the experiment and 85% and 80% in the second column. The removal rates of dissolved organic carbon (DOC) using GAC folter system at room temperature and 4¢J were respectively 95% and 90% in the first column of the experiment and 90% and 87% in the second column. Obviously,the TOC removal rate treated using GAC filter system at room temperature was superior to that treated at 4¢J
In comparing treated water and recycled water,most of the water quality parameters (temperature¡BSuspended solids¡BBOD¡BCOD¡BpH) were to meet recycled water quality standards.However, the system due to use GAC trickling filter system treatment that easily decrease dissolved oxygen in treated water but conductivity in treated water without changes. These two water parameters were failed to meet the recycled water standards.
By the way, we found trained GAC through SEM irradiation the biofilm area of trained GAC surface at 25¢Jwas superior to that treated at 4¢J. It corresponds to the removal efficiency of organic carbon, the removal efficiency of 25¢J was higher than result of 4¢J. Therefore, a certain relationship between the biofilm area and removal efficiency of organic carbon is existed in this work.
|
132 |
Kinetic Modeling of the Adsorption of Mercury Chloride Vapor on Spherical Activated Carbon by Thermogravimetric AnaylysisCHEN, WEI-CHIN 25 August 2004 (has links)
This study investigated the adsorptive capacity and isotherm of HgCl2 onto spherical activated carbons (SAC) via thermogravimetric analysis (TGA). Activated carbon injection (ACI) is thought as the best available control technology (BACT) for mercury removal from flue gas. There are two major forms of vapor-phase mercury, Hgo and Hg2+, of which HgCl2 accounts for 60-95% of total mercury. Mercury emitted from the incineration of municipal solid wastes (MSW) could cause severely adverse effects on human health and ecosystem since it exists mainly in vapor phase due to high vapor pressure. Although the adsorptive capacity of HgCl2 onto activated carbon has been studied in previous adsorption column tests, only a few studies have thoroughly investigated the adsorption isotherms of HgCl2 onto SAC.
Equilibrium and kinetic studies are important towards obtaining a better understanding of mercury adsorption. Many investigations have addressed the relationship between sorption kinetics and equilibrium for different adsorbent/adsorbate combinations. For the removal of vapor-phase mercury, several bench-pilot, and full-scale tests have be proceeded to examine the influence of carbon types, carbon structures, carbon surface characteristics, injection methods (dry or wet), amount of carbon injected, and flue gas temperature on mercury removal. In addition, the dynamics of spherical activated carbons (SAC) adsorbers for the uptake of gas-phase mercury was evaluated as a function of temperature, influent concentration of mercury, and empty-bed residence time. However, only a few studies investigated the adsorption isotherms of HgCl2 onto activated carbons.
In this study, TGA was applied to obtain the adsorptive capacity of HgCl2 onto SAC with adsorption temperature (30~150oC) and influent HgCl2 concentration (50~1,000£gg/m3). Experimental results indicated that the adsorptive capacity of HgCl2 onto SAC was 0.67and 0.20 mg/gC at 30¡B70 and 150oC, respectively. This study investigated the adsorptive capacity of HgCl2 vapor onto SAC via TGA analysis. Experimental results indicated that the adsorptive capacity of SAC decreased with the increase of the adsorption temperature. Furthermore, the results suggested that that the adsorption of SAC on HgCl2 vapor was favorable equilibrium at 30 and 70¢J and unfavorable equilibrium at 150¢J. In comparison of the experimental data with isotherm equations, Freundlich isotherm fitted the experimental results better than Langmuir isotherm. The model simulations were found to fit very well to the high concentration experimental kinetic data for both adsorption and desorptionusing two adjust parameter, effective diffusivity, and the Freundlich isothermexponent.¡@The extracted model parameter, effective diffusivity and n, were then used to predict the experimental kinetic data for the same combination at other concentrations.
|
133 |
Wet Scrubbing and Activated-carbon Adsorption of Odorous Compounds in Vented Gases from Food-cooking OperationsChen, Cheng-wei 26 June 2006 (has links)
In this study, wet scrubbing and activated-carbon adsorption technologies were tested to investigate their abilities to remove total hydrocarbons (THCs) and other odorous compounds in the effluent gas from food-cooking operations such as frying, toasting, grilling, and steaming.
A full-scale scrubber (gas-liquid contacting cross section 0.58 m¡Ñ0.50 m, height 0.80 m) was used in the present study for testing its performance on removing odorous compounds from a gas stream of 102 m3/min drawn from a Japanese-type grilling restaurant located in the Kaohsiung city. The scrubbing liquid had a flow rate of 67.2 L/min which is equivalent to a liquid/gas ratio of (L/G) 0.0065 m3 liquid/(m3 gas). Tap water, aqueous sodium hypochlorite solution, and aqueous hydrogen peroxide solution were used as scrubbing liquids. For the activated carbon tests, a 2-cm i.d. glass column packed with 20 g activated carbon which gives a packing height of 10.5 cm was used to obtain the adsorption isotherms by introducing a 15 L/min gas stream drawn from an oven toasting sausage. The gas flow resulted in a superficial gas velocity of 1.06 m/s over the cross section of the column. In addition, a pilot-scale adsorption unit (cross section 0.50 m sq., packed with 30 kg granular activated carbon) was installed for the adsorption test. A gas flow drawn from a vent of a restaurant kitchen cooking Chinese-type food was introduced into the pilot adsorber. A flow rate of 12.6 m3/min was used and the superficial gas velocity was 0.84 m/s.
Results indicate that THC and odor (sensory test) removals of 15-35 and 35-65% were obtained, respectively, form the scrubbing test. There was no significant difference in the performance by using one of water or the two aqueous chemical solutions as the scrubbing liquor. Most of the characteristic food-grilling and flavoring smells were removed by the scrubber and some bitter smells like burnt carbon were found in the scrubbed gas.
High moisture contents (around 95% in relative humidity) of the vent gas from the sausage-toasting oven resulted in a significant reduction in the activated carbon adsorption capacity for THCs from the tested gas. From results of the pilot-scale adsorption test, THC removals of 60-80% form the vent gas (around 50-60% in relative humidity) of the Chinese-type kitchen were found during the initial adsorption time of 0-50 hr. A long time (200 hr) operation resulted in a decrease in the THC removal efficiency. However, the adsorber exhibited as an odor equalization unit by reducing peaks of the odor emissions from the kitchen. Characteristic odors from various food cooking operations were reduced by the adsorber.
It was estimated that a total of around NT$ 57 is required for the full-scale scrubber for treating the gas flow of 102 m3/min for an operation time of 7 hr per day, and the cost is equivalent to NT$ 1.33/(1,000 m3 gas). The cost for the activated carbon adsorption unit of 13 m3/min was estimated to be NT$ 134 for 8 hr per streaming day. The unit cost is NT$ 22.1/(1,000 m3 gas).
|
134 |
Mathematical Modeling Of Adsorption/desorption Systems For Chemical Heat PumpsYurtsever, Ahmet Onur 01 January 2011 (has links) (PDF)
Despite their limited commercial applications, chemical heat pumps (CHP)
have been considered as an important alternative to conventional heating
and cooling technologies. In this study, the adsorption-desorption of
ethanol over activated carbon was applied on the CHP reactor. The
ethanol vapor - activated carbon adsorption rate was determined at 30,
60, 90 and 120° / experimentally by using Intelligent Gravimetric Analyzer
C(IGA). The experimental adsorption data were used on the transient
modeling of reactor by assuming single component gas phase. Then,
spatial and temporal temperature, rate of heat transfer, and total amount
of heat transferred for a given period were determined. Finally, the
calculated adsorption and temperature profiles were integrated over
volume to predict performance of heat pump for different reactor
geometries. The results showed that, with proper modeling satisfactory
performance values can be attained using these systems.
|
135 |
A Study on the Measurement and Analysis of Mercury in Flue Gas Emitted from Municipal Waste Incinerator and the Adsorption of Gaseous Mercury Chloride by Powder Activated Carbon Derived from the Pyrolysis of Waste TiresWu, Chun-Hsin 01 August 2000 (has links)
The objective of this study was to remove mercury vapor from municipal waste incinerator (MWI) by the adsorption of powder activated carbon (PAC) prepared from the pyrolysis of waste tire. The study focused on the measurement of mercury concentration in flue gas emitted from municipal waste incinerator, the preparation of PAC from the pyrolysis of the waste tire and impregnated with sulfur, and the adsorption capacity of mercury by the self-made PAC.
The measurement of heavy metals in flue gas emitted from four typical MWIs was conducted in this study. Experimental results obtained from the measurement of mercury from flue gas indicated that the removal efficiency of mercury ranged from 83.71%~96.22%for the tested MWIs. This study revealed that the injection of PAC in flue gas would enhance the removal efficiency of mercury. Besides, oxided mercury (Hg2+) can be removed much more easily than elemental mercury (Hg0).
Experimental results obtained from the pyrolysis of waste tires indicated that the pyrolysis temperature of waste tire was approximately 400~500¢J, and the percentage of carbon residue is 35~37%. With higher temperature and water feed rate and longer activation time, the specific surface area and total pore volume of PAC increased while the average pore radius decreased. The highest specific surface area of PAC obtained in this study was 996 m2/g. In addition, experimental results obtained from sulfur impregnation process indicated that the specific surface area of PAC decreased dramatically as sulfur was added to PAC.
Experiment results obtained from the adsorption capacity of HgCl2 on PAC by column test indicated that PAC with higher specific surface area could adsorb more HgCl2 at room temperature (25¢J). The adsorption capacity of sulfur impregnated PAC decreased at 25¢J was due to the decrease of specific surface area of PAC. However, results from the comparison of two PAC with similar specific surface area indicated that the PAC with higher sulfur content had higher adsorption capacity. It suggested that the addition of sulfur to PAC could enhance the adsorption of HgCl2 at 25¢J. Experimental results obtained from column tests at 150¢J showed that the adsorption capacity of PAC increased as sulfur content of PAC increased. These results suggested that the adsorption mechanism of HgCl2 by PAC was mainly physical adsorption at lower temperature and it was chemisorption at higher temperature. Besides, the self-made PAC demonstrated the similar adsorption capacity of HgCl2 with commercial PAC used in MWIs.
|
136 |
Study on the Treatment Efficiency of ATP and Application of Powdered Acti vated Carbon and Membrane Bioreactor to Remove Organic Compounds in Drinking WaterHuang, Chine-er 24 July 2009 (has links)
To improve water quality of drinking water, the Taiwan Water Supply Corp (TWSC) upgraded three water treatment plants (WTP), changing traditional treatment processes into two advanced membrane processes and one advanced ozonation processes in recent years. Membrane water treatment units of the water treatment plant comprise ultrafiltration (UF) and reverse osmosis (RO). And the advanced ozonation water treatment units comprise pellet softening, post-ozonation and biological activated carbon (BAC) adsorption. This study investigated the formation of disinfection byproducts (DBPs), dissolved organic carbon (DOC) and assimilable organic carbon (AOC) at two advanced water treatment plants (ATP) in Kaohsiung City, Taiwan, by implementing a sampling program. The purposes of this study include¡G(1) The evaluation of treatment efficiency of advanced water treatment plants. (2) Application of powdered activated carbon and membrane bioreactor in removing organic compounds in drinking water.
TCM was by far the predominant species in the finished water, the average concentration of DPBs in this study at both plants were 13.97¡Ó4.18£gg/L and 21.49¡Ó10.59£gg/L of THMs for plant A and plant B, respectively. However, levels for DPBs compound are low in both plants and lower than the current national drinking water quality standards 80 £gg / L. But for anther typical DPBs (HAAs compounds), the average concentrations were 17.67¡Ó14.50£gg/L and 33.03¡Ó16.24£gg/L of HAA5 for plant A and plant B, respectively. DCAA and TCAA were the two major species of HAAs found in the two water samples under study. The sums of the two species represented in finished water were about 67% and 83% of HAA5 in A and plant B, respectively. The results showed that HAA5 concentration of all samples could meet current USEPA standards for drinking water quality.
Importantly, our work show the advanced treatment processes have good removal on DPBs of treated water. In organic compounds removal, there is high efficiency by using post-ozonation combined with BAC, but low efficiency for membrane process due to the inhibition of electrical charge happened on surface of membrane. This inhibition is caused probably by high hardness and high ion strength in water. We found by combining BAC with membrane filtration process will effectively remove the organic compounds and lower the concentration of AOC for passing the limit value suggested in related researches of the world.
|
137 |
Pharmaceutical compounds; a new challenge for wastewater treatment plantsDlugolecka, Maja January 2007 (has links)
<p>Analytical analyses conducted at the Himmerfjärden WWTP (285.000 PE connected) identified 70 pharmaceutical compounds belonging to different therapeutic classes. Such organic micropollutants at low detected concentration range of µg - ng l<sup>-1</sup> did not affect the treatment processes at WWTP. Results from analytical studies indicated continuous discharge of organic micropollutants to the surface water with a calculated load amounting to 1.51 kg day-1. Metoprolol, carbamazepine and naproxen were chosen for testing different removal methods. Oxygen Uptake Rate (OUR) tests were conducted to assess the bacterial activity of an activated sludge taken from a full scale aeration plant with the presence of selected target compounds.</p><p>A semi-technical scale membrane bioreactor ZeeWeed10™, treating final effluent from the Himmerfjärden WWTP (Sweden) was seeded with activated sludge from full scale biological stage. The membrane bioreactor (MBR) system placed after the final treatment appeared to be an insufficient technology for removal of residual amounts of organic micropollutants from WWTP effluents. Batch test studies with activated sludge taken from the membrane bioreactor and with application of granular activated carbon (GAC) filtration resulted in giving an overall assessment of removal efficiency. Metoprolol and carbamazepine tend to be resistant to the biodegradation process and in the dosed high concentration lead to bacterial cell decomposition in the activated sludge. Apparently, removal efficiency for naproxen exceeded the value of 46% with the spiked initial amount of 3.3 mg NAP g<sup>-1 </sup>MLSS. Application of the GAC filtration proved to be an efficient technique for removal of pharmaceutical compounds from treated wastewater.</p><p>Application of the statistical programme Modde7 was a time saving tool in studies of fouling occurrence. The effect of fouling phenomenon, which is a highly limiting factor for MBR performance, was minimised by adjusting the operational parameters as predicted by the Modde7 programme.</p>
|
138 |
Evaluation of the Removal Efficiency of Perfluoroalkyl Substances in Drinking WaterEnglund, Sophie January 2015 (has links)
Per- and polyfluoroalkyl substances (PFASs) are chemicals that have been used for over 50 years. They are both hydrophobic and hydrophilic, which make them useful in a wide range of products, both in the domestic and industrial market. Recently, the global attention on PFASs has increased due to their possible harmful health effects on humans. Furthermore, PFASs have been detected in drinking water sources all over the world. Conventional treatment processes in drinking water treatment plants (DWTPs) are not able to remove PFASs. Therefore, more research is required to find efficient removal techniques for these compounds. The aim of this study was to investigate the removal efficiency of PFASs using two different adsorption techniques, anion exchange (AE) with the resin Purolite A-600, and granular activated carbon (GAC) of type Filtrasorb®400. The experiments were performed in laboratory batch-scale, at Swedish University of Agriculture (SLU), and column tests in pilot-scale, at Bäcklösa DWTP in Uppsala. The PFASs showed a high sorption potential to AE and GAC. However, the removal efficiency differed depending on the perfluorocarbon chain length, functional group, and concentration level. For the AE, in average 92 % of the PFASs were removed in the end of the batch experiments while the average removal efficiency in the column experiment was 86 %. In the batch experiments treated with GAC on average 55 % of the PFASs were removed in the end of the experiments while the column experiment had the average removal efficiency of 86 %. There was an increase in the removal efficiency with increasing perfluorocarbon chain length in the column experiments. However, in the batch experiments, the adsorption of PFASs decreased with an increasing chain length, except for the highest PFAS concentration level (5000 ng L-1) treated with AE and the lowest PFAS concentration level (200 ng L-1) treated with GAC. In the column experiments, the perfluoroalkane sulfonates (PFSAs) were slightly better removed than perfluoroalkyl carboxylates (PFCAs) with an average removal efficiency of 97 % for AE and 91 % for GAC compared to 67 % and 82 % for AE and GAC, respectively. In the batch experiments, there was no clear trend between the removal efficiency and functional group. Overall, the pilot-scale experiments removed the PFASs relatively well even after 42 days (on average, 86 % for both AE and GAC). The lowest removal capacity in the column experiments was seen for the shorter chained PFSAs (in average 46 % for ≤C6 PFCAs using AE and 75 % for ≤C7 PFCAs using GAC). More efficient treatment techniques are needed to minimise the PFAS concentrations in drinking water and the potential human. / Per- och polyfluorerade alkylsubstanser (PFASs) är kemikalier som har används globalt under de senaste 50 åren. Tack vare att de är uppbygda av både en hydrofob och en hydrofil del är de ytaktiva (s.k. surfaktanter) och har ett brett användningsområde, både för industri- och hushållsprodukter. På senare år har dessa ämnen fått uppmärksamhet på grund av att exponering för PFASs har visats kunna medföra hälsorisker. PFASs har upptäckts i dricksvatten på många håll i världen, men flera av de konventionella reningsmetoderna för dricksvatten är inte effektiva för PFASs och därför finns ett behov av mer forskning och kunskap inom vattenberedningsområdet. I denna studie undersöktes reningseffektiviteten för PFASs hos två adsorptionstekniker; i) anjonbyte (AE) med Purolite A-600 och ii) granulerat aktivt kol (GAC) med Filtrasorb®400. Studien utformades så att inverkan av kolkedjans längd, molekylens funktionella grupp samt koncentrationsnivån av PFASs kunde utvärderas. Experimenten utfördes både i liten skala genom försök i bägare på Sveriges lantbruksuniversitet (SLU) och i något större skala i en pilotanläggning med kolonnexperiment på Bäcklösa dricksvattenverk i Uppsala. Båda reningsmetoderna visade god effekvititet för avlägsnandet av PFASs i dricksvatten. I slutet av bägarexperimenten var i medeltal 92 % och 55 % av PFASs eliminerade för de prover behandlade med AE respektive GAC. Reningseffektivititen för kolonnexperimenten var i medeltal 86 % för båda metoderna. Reningsgraden var beroende av längden på den perfluorerade kolkedjan. I kolonnexperimenten visades att ökad kedjelängd ledde till ökad reningseffektivitet, medan bägarexperimenten visade på motsatt trend, med undantag för prover behandlades med AE och PFAS-koncentration 5000 ng L-1 samt prover behandlade med GAC och PFAS-koncentration 200 ng L-1. Reningseffektiviteten varierade också beroende på funktionell grupp, d.v.s. beroende på om det var en sulfonat eller en karboxylat. I kolonnexperimenten avlägsnades de perfluorerade alkylsulfonaterna (PFSAs) i något högre grad (97 % och 91 %; AE och GAC) än karboxylaterna (PFCAs; 67 % och 82 %; AE och GAC). För bägarexperimenten hittades dock inget tydligt motsvarande samband. Sammanfattningsvis renades PFASs från dricksvattnet i kolonnexperimenten relativt väl även i slutet av experimentent (efter 42 dagar). De sämst renade PFAS ämnena var de med kortare kolkedja. Efter 42 dagar hade PFCAs med kolkedjelängd ≤C6 renats bort med 46 % (AE) och på PFCAs med kolkedjelängd ≤C7 med 75 % (GAC). Behovet av bättre reningsmetoder för dessa PFASs är därför stort.
|
139 |
Advanced Carbon Materials for Environmental and Energy ApplicationsDua, Rubal 05 1900 (has links)
Carbon based materials, including porous carbons and carbon layer composites, are finding increased usage in latest environmental and energy related research. Among porous carbon materials, hierarchical porous carbons with multi-modal porosity are proving out to be an effective solution for applications where the traditional activated carbons fail. Thus, there has been a lot of recent interest in developing low-cost, facile, easy to scale-up, synthesis techniques for producing such multi-modal porous carbons. This dissertation offers two novel synthesis techniques: (i) ice templating integrated with hard templating, and (ii) salt templating coupled with hard templating, for producing such hierarchically porous carbons. The techniques offer tight control and tunability of porosity (macro- meso- and microscale) in terms of both size and extent. The synthesized multi-modal porous carbons are shown to be an effective solution for three important environment related applications – (i) Carbon dioxide capture using amine supported hierarchical porous carbons, (ii) Reduction in irreversible fouling of membranes used for wastewater reuse through a deposition of a layer of hierarchical porous carbons on the membrane surface, (iii) Electrode materials for electrosorptive applications. Finally, because of their tunability, the synthesized multi-modal porous carbons serve as excellent model systems for understanding the effect of different types of porosity on the performance of porous carbons for these applications. Also, recently, there has been a lot of interest in developing protective layer coatings for preventing photo-corrosion of semiconductor structures (in particular Cu2O) used for photoelectrochemical water splitting. Most of the developed protective strategies to date involve the use of metals or co-catalyst in the protective layer. Thus there is a big need for developing low-cost, facile and easy to scale protective coating strategies. Based on the expertise gained in synthesizing porous carbon materials, and owing to our group’s interest in developing suitable photoelectrode materials, this dissertation also proposes a novel carbon-Cu2O composite comprising of a carbon layer coated Cu2O nanowire array structure as a high performance and stable photoelectrode material for photoelectrochemical water splitting.
|
140 |
Attenuation Of Trace Organic Compounds By Advanced Treatment Technologies In Water ReuseAnumol, Tarun January 2014 (has links)
The ubiquity of pharmaceuticals and personal care products in water systems is well known. With the increasing implementation of water reuse schemes in the US, concern about potential health effects of these compounds in humans has risen. While potential synergistic effects of chronic low doses exposure to a cocktail of these compounds is still being studied, it is prudent to monitor and attenuate these trace organic compounds (TOrCs) from our water sources. This research initially focused on identifying suitable `indicator' TOrCs based on theoretical physico-chemical parameters and actual experimental data. It was concluded that an indicator list will be specific to the goal targeted with dependence on treatment process, occurrence and analytical ease. Quantification of these TOrCs are part per trillion levels in water requires accurate, precise and robust analytical techniques. The next part of this research was spent on developing three different analytical methods with LC-MS/MS for the sensitive detection of TOrCs in several different water matrices including raw sewage and final drinking water. The treatment efficacy of granular activated carbon for attenuation of TOrCs is studied in detail with emphasis on developing correlations between TOrC removal and bulk organic parameters of water like UV absorbance and fluorescence by using rapid small-scale column testing. The results indicate a correlation between removal of TOrCs and bulk organic parameters that is independent of water quality. The effectiveness of commercially available activated carbon based point-of-use (POU) devices for removal of a set of TOrCs from water was evaluated. The data indicated that POUs are a viable option for treatment of TOrCs but specific removal depends on type of device, water quality and amount of water treated. Finally, further research was targeted at identifying transformation products as a result of oxidation of polyfluorinated precursor materials in reclaimed waters. The results illustrated that toxic perfluorocarboxylic acids can be formed on oxidation of fluorotelomer unsaturated carboxylic acids that are known to be present in water.
|
Page generated in 0.0639 seconds