scholarly journals Adsorption capacity of GAC pilot filter-adsorber and postfilter- adsorber for individual THMs from drinking water, Athens

2013 ◽  
Vol 13 (1) ◽  
pp. 50-58
Keyword(s):  
Drinking Water ◽  
Adsorption Capacity ◽  
Operation Time ◽  
Freundlich Isotherm ◽  
Physicochemical Characteristics ◽  
Mean Value ◽  
Laboratory Animals ◽  
Residual Chlorine ◽  
Uniformity Coefficient ◽  
Regular Sampling

Trihalomethanes are a major class of chlorination by-products in drinking water. They are formed when chlorine reacts with bromide (Br-) and natural organic matter (NOM) in source waters. Toxicology studies have shown all THMs to be carcinogenic or to cause adverse reproductive or developmental effects in laboratory animals. THMs are small volatile molecules, which are hydrophobic, non biodegradable and adsorbable on granular activated carbon (GAC). The objective of this pilot study is to evaluate the adsorption capacity for individual THMs of a GAC filter-adsorber (A) and a GAC postfilter-adsorber (B), both fed with chlorinated natural water. For this purpose, a GAC pilot plant was operated as a filter-adsorber and a postfilter-adsorber in Galatsi WTP, Athens (GTP) until the removal of individual THMs by GAC was eliminated (breakthrough). Regular sampling was performed during operation and the parameters measured were: THMs, DOC, free residual chlorine, bromide, turbidity, pH and temperature. From the experimental data, GAC bed life, GAC usage rate, GAC loading and operation time to breakthrough were calculated for most THMs. TBM was almost not detected. Some desorption of THMs, especially TCM and BDCM, was noticed during the operation of both adsorbers. Near breakthrough for THMs, equilibrium between adsorbed and dissolved THMs was considered to have been established. The GAC equilibrium loading of individual THMs was assumed to depend on the mean value of their influent concentration, which was not constant. By correlating the equilibrium data by linear regression to conform to the Freundlich isotherm, the Freundlich constants 1/n and k were determined for each of THMs. They are related to the physicochemical characteristics and background organics of water and the specific GAC used. The strength of the adsorption bond and the GAC capacity was higher for DBCM, lower for BDCM and even lower for TCM for both adsorbers. In addition, the GAC(B) capacity for BDCM and DBCM was higher than that of GAC(A), probably due to larger surface area and surface chemistry of GAC(B). Also, the lower particle size and the higher uniformity coefficient of GAC(B), along with the lower flow rate may have attributed to that by enhancing GAC equilibration. However, TCM was less adsorbed by GAC(B), probably due to the stronger competition effect by BDCM and DBCM, being in much higher mean influent concentration. The DOC content of influent water seems also to reduce significantly the adsorption of THMs (especially of TCM), as the comparison of our results with the isotherm results with distilleddeionized water by other researchers showed.

scholarly journals Biochar from Agricultural by-Products for the Removal of Lead and Cadmium from Drinking Water

Water ◽  
2020 ◽  
Vol 12 (10) ◽  
pp. 2933
Author(s):  
Edgar Pineda Puglla ◽  
Diana Guaya ◽  
Cristhian Tituana ◽  
Francisco Osorio ◽  
María J. García-Ruiz
Keyword(s):  
Drinking Water ◽  
Adsorption Capacity ◽  
Freundlich Isotherm ◽  
Maximum Adsorption Capacity ◽  
Peanut Shell ◽  
Experimental Conditions ◽  
Lower Efficiency ◽  
Lead And Cadmium ◽  
Removal Capacity ◽  
Removal Of Heavy Metals

This study reports the adsorption capacity of lead Pb2+ and cadmium Cd2+ of biochar obtained from: peanut shell (BCM), “chonta” pulp (BCH) and corn cob (BZM) calcined at 500, 600 and 700 °C, respectively. The optimal adsorbent dose, pH, maximum adsorption capacity and adsorption kinetics were evaluated. The biochar with the highest Pb2+ and Cd2+ removal capacity is obtained from the peanut shell (BCM) calcined at 565 °C in 45 min. The optimal experimental conditions were: 14 g L−1 (dose of sorbent) and pH between 5 and 7. The sorption experimental data were best fitted to the Freundlich isotherm model. High removal rates were obtained: 95.96% for Pb2+ and 99.05. for Cd2+. The BCH and BZM revealed lower efficiency of Pb2+ and Cd2+ removal than BCM biochar. The results suggest that biochar may be useful for the removal of heavy metals (Pb2+ and Cd2+) from drinking water.

Adsorption of 2-Methylisoborneol in Drinking Water by Different Granular Carbons

2011 ◽  
Vol 255-260 ◽  
pp. 2981-2986
Author(s):  
Xiao Yan Ma ◽  
Nai Yun Gao ◽  
Jun Li ◽  
Chen Chen
Keyword(s):  
Drinking Water ◽  
Adsorption Capacity ◽  
Pure Water ◽  
Freundlich Isotherm ◽  
Coconut Shell ◽  
Raw Water ◽  
Equilibrium Isotherm ◽  
Simulation Results

Three kinds of granular carbon made from different materials of coal, coconut shell and jujube seed were evaluated for adsorption of 2-methylisoborneol in drinking water by equilibrium isotherm simulation. Results showed that Freundlich isotherm can more suitable to describe the adsorption of these three kinds of carbon. For coal-based, coconut shell and jujube seed carbon, the largest adsorption capacity of 2-MIB were 2225.0，3152.8 and 1E-07（ng/g）(L/ng)n respectively in pure water, and in raw water they were 559.6，612.5 and 6E-28（ng/g）(L/ng)n respectively, about one-fifth of those in pure water. Among the selected carbons, coconut shell carbon had the largest adsorption capacity, followed by coal-based and jujube seed carbon which can hardly absorb 2-MIB.

scholarly journals Removal of Specific DBP by GAC in Galatsi (Athens) WTP

2013 ◽  
Vol 11 (3) ◽  
pp. 349-356
Keyword(s):  
Drinking Water ◽  
Activated Carbon ◽  
Operation Time ◽  
Freundlich Isotherm ◽  
Haloacetic Acids ◽  
Feed Water ◽  
Sudden Drop ◽  
Influent Concentration ◽  
Operation Conditions ◽  
By Products

The objective of this pilot-study is to evaluate the Granular Activated Carbon (GAC) performance for the removal of specific disinfection by-products (DBPs), trihalomethanes (THMs) and haloacetic acids (HAAs), from Athens drinking water. For this purpose, a GAC pilot filter-adsorber was operated in Galatsi WTP, Athens, for 235 days, until the GAC removal efficiency for individual THMs, HAAs and DOC was almost eliminated (breakthrough). From the experimental results, GAC bed life, GAC loading, carbon usage rate, and operation time to breakthrough for most THMs and HAAs were calculated. The average influent concentrations of the more chlorinated THMs and HAAs were higher than those of less chlorinated and more brominated species and their mass adsorbed on the GAC column was also higher, as expected according to Freundlich isotherm. TCA, TCM and DCA had the highest influent concentrations and they seemed to be better adsorbed than the rest. TBM, TBA and DBCA were almost not detected in feed water. Comparison of the GAC loading at breakthough for pairs of compounds with similar average influent concentration showed that TCA is better adsorbed than TCM and that BDCA is better adsorbed than MCA, BDCM and DBCM. Desorption phenomena of some THMs and HAAs, probably caused by a sudden drop in influent concentration, were also noticed. The above findings represent real operation conditions for Athens drinking water. Further research is recommended on methods to reduce desorption from carbon beds.

A Residual Chlorine Removal Method to Allow Drinking Water Monitoring by Biological Early Warning Systems

2005 ◽  
Author(s):  
Willian H. VAN DER Schalie ◽  
David E. Trader ◽  
Mark W. Widder ◽  
Tommy R. Shedd ◽  
Linda M. Brennan
Keyword(s):  
Drinking Water ◽  
Early Warning ◽  
Early Warning Systems ◽  
Water Monitoring ◽  
Residual Chlorine ◽  
Warning Systems ◽  
Removal Method ◽  
Chlorine Removal

The Relationship between Concentration and Sensory Properties of 2-Methylisoborneol and Geosmin in Drinking Water

1988 ◽  
Vol 20 (8-9) ◽  
pp. 11-17 ◽  
Author(s):  
T. Ito ◽  
T. Okumura ◽  
M. Yamamoto
Keyword(s):  
Drinking Water ◽  
Water Temperature ◽  
Forced Choice ◽  
Residual Chlorine ◽  
Mixing Ratio ◽  
Consumer Panel ◽  
Triangle Method ◽  
Musty Odor ◽  
The Relationship ◽  
Mixed Samples

The study of the relations between the senses of smell and taste and odorant concentration is important for the solution of odor problems. The threshold concentrations of odor and taste (TOC, TTC) of 2-methylisoborneol (MIB) and geosmin were measured by the non-forced choice triangle method using 12-20 panelists. Both TOC and TTC were found to be functions of water temperature and the concentration of residual chlorine. The TOC and TTC of mixed samples were rather lower than the concentrations calculated from the mixing ratio. The sensitivities of the consumer panel and the number of musty odor complaints from consumers are related to MIB or geosmin concentration. The ratio of the number of complaints to MIB (or geosmin) concentration decreased after maximum complaint, but the sensitivity of the consumer panel remained the same.

PTSA (pressure and thermal swing adsorption) method to remove trihalomethanes from drinking water

1997 ◽  
Vol 35 (7) ◽  
pp. 243-250 ◽  
Author(s):  
Shigekazu Nakano ◽  
Tomoko Fukuhara ◽  
Masami Hiasa
Keyword(s):  
Drinking Water ◽  
Residual Chlorine ◽  
Remarkable Difference ◽  
Adsorption Method ◽  
Heating And Cooling ◽  
Point Of Use ◽  
Thermal Swing Adsorption ◽  
Long Time ◽  
Musty Odor ◽  
Vacuum Heating

It has been widely recognized that trihalomethanes (THMs) in drinking water pose a risk to human health. THMs can be removed to a certain extent by the conventional point-of-use (POU) unit which is composed of activated carbon (AC) and microfilter. But it's life on THMs is relatively shorter than on residual chlorine or musty odor. To extent the life of AC adsorber, pressure and thermal swing adsorption (PTSA) was applied by preferential regeneration of chloroform. PTSA was effective to remove THMs, especially chloroform. Adsorption isotherms of chloroform at 25 and 70°C showed a remarkable difference so that thermal swing was considered effective. Chloroform was also desorbed by reducing pressure. By vacuum heating at 70°C, chloroform was almost desorbed from AC and reversible adsorption was considered possible. A prototype of POU unit with PTSA was proposed. Regeneration mode would consist of dewatering, vacuum heating and cooling (backwashing). The unit was maintained in bacteriostatic condition and could be used for a long time without changing an AC cartridge.

scholarly journals Preliminary Research on a Comparison and Evaluation of FY-4A LMI and ADTD Data through a Moving Amplification Matching Algorithm

2020 ◽  
Vol 13 (1) ◽  
pp. 11
Author(s):  
Pengfei Li ◽  
Guofu Zhai ◽  
Wenjing Pang ◽  
Wen Hui ◽  
Wenjuan Zhang ◽  
...  
Keyword(s):  
Detection Efficiency ◽  
Spherical Surface ◽  
Operation Time ◽  
Mean Value ◽  
China Meteorological Administration ◽  
Matching Algorithm ◽  
Lightning Detection ◽  
Spatial Differences ◽  
System Data ◽  
Spatial Threshold

In this study, a new moving amplification matching algorithm was proposed, and then the temporal and spatial differences and correlation were analysed and evaluated by comparing the FengYun-4A Lightning Mapping Imager (FY-4A LMI) data and the China Meteorological Administration Lightning Detection Network Advanced TOA and Direction (CMA-LDN ADTD) system data of southwest China in July 2018. The results are as follows. Firstly, the new moving amplification matching algorithm could effectively reduce the number of invalid operations and save the operation time in comparison to the conventional ergodic algorithms. Secondly, LMI has less detection efficiency during the daytime, using ADTD as a reference. The lightning number detected by ADTD increased from 5:00 AM UTC (13:00 PM BJT, Beijing Time) and almost lasted for a whole day. Thirdly, the trends of lightning data change of LMI and ADTD were the same as the whole. The average daily lightning matching rate of the LMI in July was 63.23%. The average hourly lightning matching rate of the LMI in July was 75.08%. Lastly, the mean value of the spherical surface distance in the matched array was 35.49 km, and roughly 80% of the matched distance was within 57 km, indicating that the spatial threshold limit was relatively stable. The correlation between LMI lightning radiation intensity and ADTD lighting current intensity was low.

Fluorescence moieties as a surrogate for residual chlorine in three drinking water networks

2021 ◽  
Vol 411 ◽  
pp. 128519
Author(s):  
Tahir Maqbool ◽  
Jiaxing Zhang ◽  
Yanling Qin ◽  
Muhammad Bilal Asif ◽  
Quang Viet Ly ◽  
...  
Keyword(s):  
Drinking Water ◽  
Residual Chlorine ◽  
Water Networks

scholarly journals Preparation and Characterization of Cationized Cellulose for the Removal of Anionic Dyes

2001 ◽  
Vol 19 (3) ◽  
pp. 197-210 ◽  
Author(s):  
A. Hashem ◽  
Reda M. El-Shishtawy
Keyword(s):  
Adsorption Capacity ◽  
Freundlich Isotherm ◽  
Structural Features ◽  
Isotherm Models ◽  
Acid Orange 7 ◽  
Anionic Dyes ◽  
Adsorption Parameters ◽  
Direct Blue ◽  
Equilibrium Data

The factors influencing the cationization of microcrystalline cellulose with 3-chloro-2-hydroxypropyl triethylammonium chloride in the presence of NaOH were investigated. The course of the reaction was followed by estimating the nitrogen content of the cationized product while its structural features were confirmed by IR analysis. The ability of cationized cellulose to adsorb anionic dyes, viz. Acid Orange 7, Direct Blue 75 and Direct Violet 31, was investigated at 25°C and 50°C. The equilibrium data obtained were fitted by the Langmuir and Freundlich isotherm models, allowing the corresponding adsorption parameters to be determined. The results showed that the adsorption capacity was dependent on the adsorbent, temperature, the nature of the dye and (to some extent) on van der Waals and hydrogen bonding. Cationized cellulose exhibited a much better adsorption capacity towards anionic dyes than cellulose.

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