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.

scholarly journals Pilot Study on the Combination of Different Pre-Treatments with Nanofiltration for Efficiently Restraining Membrane Fouling While Providing High-Quality Drinking Water

Membranes ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 380
Author(s):  
Yan Chen ◽  
Huiping Li ◽  
Weihai Pang ◽  
Baiqin Zhou ◽  
Tian Li ◽  
...  
Keyword(s):  
Drinking Water ◽  
Activated Carbon ◽  
Membrane Fouling ◽  
Membrane Surface ◽  
Post Treatment ◽  
Size Exclusion ◽  
Transmembrane Pressure ◽  
Feed Water ◽  
High Quality ◽  
Treated Water

Nanofiltration (NF) is a promising post-treatment technology for providing high-quality drinking water. However, membrane fouling remains a challenge to long-term NF in providing high-quality drinking water. Herein, we found that coupling pre-treatments (sand filtration (SF) and ozone–biological activated carbon (O3-BAC)) and NF is a potent tactic against membrane fouling while achieving high-quality drinking water. The pilot results showed that using SF+O3-BAC pre-treated water as the feed water resulted in a lower but a slowly rising transmembrane pressure (TMP) in NF post-treatment, whereas an opposite observation was found when using SF pre-treated water as the feed water. High-performance size-exclusion chromatography (HPSEC) and three-dimensional excitation–emission matrix (3D-EEM) fluorescence spectroscopy determined that the O3-BAC process changed the characteristic of dissolved organic matter (DOM), probably by removing the DOM of lower apparent molecular weight (LMW) and decreasing the biodegradability of water. Moreover, amino acids and tyrosine-like substances which were significantly related to medium and small molecule organics were found as the key foulants to membrane fouling. In addition, the accumulation of powdered activated carbon in O3-BAC pre-treated water on the membrane surface could be the key reason protecting the NF membrane from fouling.

scholarly journals Formation of DBPs in the drinking eater of Athens, Greece: a Ten-Year study

2013 ◽  
Vol 7 (1) ◽  
pp. 106-118
Keyword(s):  
European Union ◽  
Drinking Water ◽  
Water Treatment ◽  
Chloral Hydrate ◽  
Haloacetic Acids ◽  
The European Union ◽  
Water Treatment Plants ◽  
Naturally Occurring ◽  
By Products ◽  
The Eu

The formation of Disinfection By-Products (DBPs) in drinking water results from the reaction of chlorine or other disinfectants added to the water with naturally occurring organic materials, and has raised concerns during the last decades because these compounds are harmful for human health. During the present work, the formation of different categories of DBPs was investigated in four water treatment plants (WTP) using chlorine as disinfectant, and in selected points of the distribution network of Athens, Greece, which is supplied from these four WTP, during a period of ten years. The concentrations of DBPs were generally low and the annual mean concentrations always well below the regulatory limit of the European Union (EU) for the total trihalomethanes (TTHMs). The haloacetic acids (HAAs) have not been regulated in the EU, but during this investigation they often occurred in significant levels, sometimes exceeding the levels of TTHMs, which highlights the importance of their monitoring in drinking water. Apart from THMs and HAAs, several other DBPs species were detected at much lower concentrations in the chlorinated waters: chloral hydrate, haloketones and, in a limited number of cases, haloacetonitriles.

scholarly journals Biodegradation of six haloacetic acids in drinking water

2007 ◽  
Vol 6 (1) ◽  
pp. 15-22 ◽  
Author(s):  
Walt Bayless ◽  
Robert C. Andrews
Keyword(s):  
Drinking Water ◽  
Trichloroacetic Acid ◽  
Distribution Systems ◽  
Water Distribution ◽  
Haloacetic Acids ◽  
Health Concern ◽  
Drinking Water Distribution Systems ◽  
Drinking Water Distribution ◽  
Monobromoacetic Acid ◽  
By Products

Haloacetic acids (HAAs) are produced by the reaction of chlorine with natural organic matter and are regulated disinfection by-products of health concern. Biofilms in drinking water distribution systems and in filter beds have been associated with the removal of some HAAs, however the removal of all six routinely monitored species (HAA6) has not been previously reported. In this study, bench-scale glass bead columns were used to investigate the ability of a drinking water biofilm to degrade HAA6. Monochloroacetic acid (MCAA) and monobromoacetic acid (MBAA) were the most readily degraded of the halogenated acetic acids. Trichloroacetic acid (TCAA) was not removed biologically when examined at a 90% confidence level. In general, di-halogenated species were removed to a lesser extent than the mono-halogenated compounds. The order of biodegradability by the biofilm was found to be monobromo > monochloro > bromochloro > dichloro > dibromo > trichloroacetic acid.

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.

High removal of haloacetic acids from treated drinking water using bio-activated carbon method

2016 ◽  
Vol 57 (53) ◽  
pp. 25627-25638 ◽  
Author(s):  
Jie-Chung Lou ◽  
Hung-Yi Chan ◽  
Jia-Yun Han ◽  
Chih-Yuan Yang
Keyword(s):  
Drinking Water ◽  
Activated Carbon ◽  
Haloacetic Acids ◽  
Treated Drinking Water

Humic Substances as Precursors for Potentially Harmful Disinfection By-Products

1999 ◽  
Vol 40 (9) ◽  
pp. 25-30 ◽  
Author(s):  
P.C. Singer
Keyword(s):  
Drinking Water ◽  
Carbon Content ◽  
Human Health ◽  
Humic Substances ◽  
Organic Material ◽  
Haloacetic Acids ◽  
Aromatic Carbon ◽  
Ultraviolet Absorbance ◽  
Natural Organic Material ◽  
By Products

During the chlorination of drinking water, chlorine reacts with natural organic material to produce disinfection by-products, such as trihalomethanes and haloacetic acids, which are believed to be harmful to human health. The formation of these by-products is related to the aromatic carbon content of the water, for which specific ultraviolet absorbance serves as a useful surrogate. Because humic substances in water tend to have a higher aromatic carbon content and a higher specific ultraviolet absorbance than non-humic substances, they produce greater levels of disinfection by-products.

scholarly journals The microbial colonization of activated carbon block point-of-use (PoU) filters with and without chlorinated phenol disinfection by-products

2017 ◽  
Vol 3 (5) ◽  
pp. 830-843 ◽  
Author(s):  
Chia-Chen Wu ◽  
Sudeshna Ghosh ◽  
Kelly J. Martin ◽  
Ameet J. Pinto ◽  
Vincent J. Denef ◽  
...  
Keyword(s):  
Drinking Water ◽  
Activated Carbon ◽  
Bacterial Community Structure ◽  
Microbial Colonization ◽  
Opportunistic Pathogens ◽  
Absolute Abundance ◽  
Carbon Block ◽  
Point Of Use ◽  
Water Filters ◽  
By Products

Activated carbon based point-of-use drinking water filters change the bacterial community structure and increase the absolute abundance of genera, including those associated with opportunistic pathogens.

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