Controlling Adsorbable Organic Halogens (AOX) and Trihalomethanes (THM) Formation by Ozonation and Two-Step Granule Activated Carbon (GAC) Filtration

1999 ◽  
Vol 40 (9) ◽  
pp. 249-256 ◽  
Author(s):  
R. Vahala ◽  
V.-A. Långvik ◽  
R. Laukkanen
Keyword(s):  
Activated Carbon ◽  
Distribution System ◽  
Minor Importance ◽  
Chlorine Disinfection ◽  
Simulated Distribution ◽  
Organic Halogens ◽  
A Minor ◽  
Parallel Filter ◽  
Filter Bed ◽  
Adsorbable Organic Halogens

A pilot plant study in four parallel filter runs was performed in order to determine the effect of ozonation and two-step granular activated carbon (GAC) filtration on the removal of disinfection by-product (DBP) precursors. The results showed that ozonation significantly decreased the adsorbable organic halogens (AOX) (35%), simulated distribution system (SDS) AOX (37%) and SDS trihalomethanes (THM) (76%) from chemically treated and sand-filtered lake water, but did not decrease either short-term or the long-term chlorine demand. Biofiltration with exhausted GAC had a minor importance in the precursor removal (0-20%). The performance of adsorptive GAC filtration was strongly dependent on the age of the GAC filter bed, which was also seen as a strong correlation between the natural organic matter (NOM) measurements and DBP formation potential. Disinfection with chloramine produced lower THM, AOX, mutagenicity and MX (Z-3-chloro-4-(dichloromethyl)-5-hydroxy-2(5H)-furanone) levels compared to chlorine disinfection.

scholarly journals Adsorptive removal of adsorbable organic halogens by activated carbon

2018 ◽  
Vol 5 (12) ◽  
pp. 181507 ◽  
Author(s):  
Chengrong Qin ◽  
Baojie Liu ◽  
Lingzhi Huang ◽  
Chen Liang ◽  
Cong Gao ◽  
...  
Keyword(s):  
Activated Carbon ◽  
Theoretical Basis ◽  
Chemical Process ◽  
Chemical Compositions ◽  
Optimum Conditions ◽  
Adsorptive Removal ◽  
Organic Halogen ◽  
Organic Halogens ◽  
Aox Removal ◽  
Adsorbable Organic Halogens

Current research mainly focuses on the reduction of adsorbable organic halogen (AOX) sources, while studies on AOX monitoring and management in the environment are scarce. Organic pollutants in water are mainly fixed by sediments. Thus, in this paper, activated carbon was used to simulate the adsorption of AOX by sediments. AOX volatilization and degradation were also studied to exclude their effect on adsorption. Micromolecule chlorides were more easily volatilized and degraded than chlorobenzene and chlorophenol. The adsorption of activated carbon to AOX in bleaching wastewater was also studied and the optimum conditions for AOX removal were elucidated (particle size, 62 µm; time, 120 min; pH, 2.5; temperature, 40°C; and activated carbon dosage, 1.75 g l −1 ). AOX adsorption by activated carbon is a chemical process. Hence, the chemical compositions of the bleaching effluent with and without adsorption were analysed by GC-MS. The results revealed that activated carbon exhibits a good AOX removal effect, thereby providing a theoretical basis for monitoring the AOX distribution in the environment.

How can drinking water treatments influence chlorine dioxide consumption and by-product formation in final disinfection?

2015 ◽  
Vol 16 (2) ◽  
pp. 333-346 ◽  
Author(s):  
Sabrina Sorlini ◽  
Michela Biasibetti ◽  
Francesca Gialdini ◽  
Maria Cristina Collivignarelli
Keyword(s):  
Activated Carbon ◽  
Lake Water ◽  
Water Source ◽  
Product Formation ◽  
Activated Carbon Adsorption ◽  
Artificial Lake ◽  
Carbon Adsorption ◽  
Subalpine Lake ◽  
Organic Halogens ◽  
Adsorbable Organic Halogens

In this study water samples of different origins (subalpine lake, artificial lake and river) were treated by pre-oxidation, coagulation/flocculation, adsorption on granular activated carbon and disinfection. Different laboratory-scale tests were carried out to evaluate the treatment impact on ClO2 consumption in disinfection and on the formation of disinfection by-products (trihalomethanes, adsorbable organic halogen, chlorite and chlorate). The results showed that coagulation/flocculation and activated carbon adsorption have the most significant impact on reducing disinfectant consumption. Pre-oxidation of artificial lake water with KMnO4 and NaClO determines the highest ClO2 consumption. Regardless of the water source, the amount of chlorite produced after disinfection with ClO2 is 40–60% lower using NaClO as the pre-oxidant rather than KMnO4 or ClO2. Otherwise, NaClO leads to a high formation of adsorbable organic halogens and trihalomethanes in artificial lake water (up to 60 μg/L and 20 μg/L respectively), while in the case of ClO2 oxidation, trihalomethane formation is 98% less compared to NaClO. Further, adding ferrous ion in coagulation/flocculation improves the removal of chlorite produced during pre-oxidation, with a 90% removal, mainly due to the reduction of chlorite to chloride. Finally, activated carbon adsorption after pre-oxidation and coagulation/flocculation removes adsorbable organic halogens and trihalomethanes respectively by 50–60% and 30–98%, and completes the chlorite and chlorate removal.

CHEMICAL PULPING. Oxidative degradation of AOX in softwood-based kraft mill effluents from E C F bleachin g

2012 ◽  
Vol 27 (4) ◽  
pp. 707-713 ◽  
Author(s):  
Jukka Pekka lsoaho ◽  
Suvi Tarkkanen ◽  
Raimo Alen ◽  
Juha Fiskari
Keyword(s):  
Reaction Time ◽  
Oxidative Degradation ◽  
Cost Effective ◽  
Process Conditions ◽  
Main Process ◽  
Chemical Pulping ◽  
Kraft Mill ◽  
Organic Halogens ◽  
Aox Removal ◽  
Adsorbable Organic Halogens

Abstract Softwood-based kraft mill bleaching effluents from the initial bleaching stages D0 and E1 (the bleaching sequence being D0E 1D 1 E2D2) were treated by the oxidative Fenton method (H20rFeS04) to decompose organic pollutants contammg adsorbable organic halogens (AOX). Experiments designed using the Taguchi method were applied to predict the process conditions that would result in a cost-effective and adequate removal of AOX. In addition to the composition and concentration of the reagents (H202 and Fe2+), the main process parameters selected were temperature and reaction time, while pH was adj usted to an approximate value of 4 (the volumetric ratio of the mixed effluents D0:E 1 was 3 :2). The results indicated that an AOX removal of about 70% for this mixture ( corresponding to about 50% for the mill) was achieved when the eftluent samples were treated for 60 min at 70°C with H202 and Fe2+ at a concentration of 1 600 mg/1 and 28 mg/1, respectively.

Dynamics of oxytocin, estrogen and progestin receptors in the bovine endometrium during the estrous cycle

1988 ◽  
Vol 118 (1) ◽  
pp. 96-104 ◽  
Author(s):  
H. H. D. Meyer ◽  
Th. Mittermeier ◽  
D. Schams
Keyword(s):  
Estrous Cycle ◽  
Luteal Phase ◽  
Oxytocin Receptor ◽  
Minor Importance ◽  
Progestin Receptors ◽  
Progestin Receptor ◽  
Nuclear Estrogen Receptor ◽  
Low Sensitivity ◽  
A Minor ◽  
Estradiol Levels

Abstract. The levels of oxytocin receptor (OTR), cytosolic progestin receptor (cPR), cytosolic and nuclear estrogen receptor (cER, nER) were measured in the endometrium of 28 heifers that had been slaughtered on a defined day of the estrous cycle, In an additional, trial endometrial tissue obtained from 78 heifers or cows at the abattoir was analyed for OTR. OTR was absent during the luteal phase (after day 6), but a minor elevation was observed after day 15. OTR increased rapidly after luteolysis on days 17–18 reaching a maximum during estrous on day 21, and decreased again during days 1–6. cER and cPR were different to OTR but followed a similar pattern with maximal levels during days 1–8 of the estrous cycle. At day 12 both receptors were minimal and increased again towards day 21. nER was maximal at day 19–21 coinciding with maximal estradiol levels and estrous. Our data indicate that owing to an increasing sensitivity of the endometrium to progesterone and estradiol after day 12, these steroids may be mainly responsible for the initiation of first PGF2α surges and luteolysis. Oxytocin seems to be of minor importance at this stage owing to low sensitivity of the endometrium for oxytocin.

scholarly journals Biofilm forming ability of Sphingomonas paucimobilis isolated from community drinking water systems on plumbing materials used in water distribution

2017 ◽  
Vol 15 (6) ◽  
pp. 942-954 ◽  
Author(s):  
Parul Gulati ◽  
Moushumi Ghosh
Keyword(s):  
Drinking Water ◽  
Distribution System ◽  
Biofilm Formation ◽  
Water Distribution ◽  
Sem Analysis ◽  
Sphingomonas Paucimobilis ◽  
Simulated Distribution ◽  
Flow Through ◽  
Materials Used ◽  
Biofilm Development

Sphingomonas paucimobilis, an oligotroph, is well recognized for its potential for biofilm formation. The present study explored the biofilm forming ability of a strain isolated from municipal drinking water on plumbing materials. The intensity of biofilm formation of this strain on different plumbing materials was examined by using 1 × 1 cm2 pieces of six different pipe materials, i.e. polyvinyl chloride (PVC), polypropylene (PP), polyethylene (PE), aluminium (Al), copper (Cu) and rubber (R) and observing by staining with the chemical chromophore, Calcofluor. To understand whether biofilm formation occurs under flow through conditions, a laboratory-scale simulated distribution system, comprised of the above materials was fabricated. Biofilm samples were collected from the designed system at different biofilm ages (10, 40 and 90 hours old) and enumerated. The results indicated that the biofilm formation occurred on all plumbing materials with Cu and R as exceptions. The intensity of biofilm formation was found to be maximum on PVC followed by PP and PE. We also demonstrated the chemical chromophore (Calcofluor) successfully for rapid and easy visual detection of biofilms, validated by scanning electron microscope (SEM) analysis of the plumbing materials. Chlorination has little effect in preventing biofilm development.

Adsorbable Organic Halogens Generation and Reduction During Degradation of Phenol by UV Radiation/Sodium Hypochlorite

2009 ◽  
Vol 81 (2) ◽  
pp. 178-183 ◽  
Author(s):  
Qing-fu Zeng ◽  
Jie Fu ◽  
Yin-tao Shi ◽  
Dong-sheng Xia ◽  
Hai-liang Zhu
Keyword(s):  
Uv Radiation ◽  
Sodium Hypochlorite ◽  
Organic Halogens ◽  
Adsorbable Organic Halogens

Presence and formation of disinfection by-products in Cairo residential water supply

2009 ◽  
Vol 9 (2) ◽  
pp. 113-120 ◽  
Author(s):  
E. H. Smith ◽  
K. E. El-Deen
Keyword(s):  
Natural Organic Matter ◽  
Distribution System ◽  
Tap Water ◽  
Residential Community ◽  
Chlorine Disinfection ◽  
Sampling Program ◽  
The Impact ◽  
By Products ◽  
The U.S ◽  
Residential Water

A sampling program was conducted in a residential community in Cairo, Egypt in order to determine the presence of chlorine disinfection by-products (DBPs) in treated water and to observe the impact of the distribution system on DBP levels. Five campaigns were conducted over a 15-month period during 2005–2006. Trihalomethanes (THMs) and haloacetic acids (HAAs) exceeded local and international limits depending upon the season. Tap water concentrations of THMs were considerably higher in summer than during the rest of the year. In the Summer 2005 event, the average for the 20 tap water locations was 158 μg/l Total-THMs, well in excess of the U.S. EPA limit of 80 μg/L and the current Egyptian standard of 100 μg/l; all 20 locations exceeded the 100 μg/l limit. For the following event in late Fall 2005, the average dropped to 84 μg/l with 11 and 6 sites exceeding the U.S. EPA and Egyptian limits, respectively. HAA levels tended to be complementary to Total-THM values in that they were lower in summer but higher during fall and spring. The U.S. EPA limit on a select set of 5 HAAs (HAA5) is 60 μg/l (Egypt does not currently regulate HAAs). The average for HAA5 in the Summer 2005 event was 52 μg/l with 8 of the 20 tap samples equalling or exceeding the 60 μg/l standard. By contrast, in Fall 2005, the HAA5 average increased to 89 μg/l, with 15 of 20 sites exceeding the limit. THM and HAA concentrations generally increased with distance from the WTP along a targeted distribution main, while chlorine and natural organic matter tended to decrease.

scholarly journals The ADAMTS13 metalloprotease domain: roles of subsites in enzyme activity and specificity

Blood ◽  
2010 ◽  
Vol 116 (16) ◽  
pp. 3064-3072 ◽  
Author(s):  
Rens de Groot ◽  
David A. Lane ◽  
James T. B. Crawley
Keyword(s):  
Single Point ◽  
Minor Importance ◽  
Variable Regions ◽  
Cleavage Efficiency ◽  
Scissile Bond ◽  
A Minor ◽  
Von Willebrand ◽  
A2 Domain ◽  
Willebrand Factor

Abstract ADAMTS13 modulates von Willebrand factor (VWF) platelet-tethering function by proteolysis of the Tyr1605-Met1606 bond in the VWF A2 domain. To examine the role of the metalloprotease domain of ADAMTS13 in scissile bond specificity, we identified 3 variable regions (VR1, -2, and -3) in the ADAMTS family metalloprotease domain that flank the active site, which might be important for specificity. Eight composite sequence swaps (to residues in ADAMTS1 or ADAMTS2) and 18 single-point mutants were generated in these VRs and expressed. Swapping VR1 (E184-R193) of ADAMTS13 with that of ADAMTS1 or ADAMTS2 abolished/severely impaired ADAMTS13 function. Kinetic analysis of VR1 point mutants using VWF115 as a short substrate revealed reduced proteolytic function (kcat/Km reduced by 2- to 10-fold) as a result of D187A, R190A, and R193A substitutions. Analysis of VR2 (F216-V220) revealed a minor importance of this region. Mutants of VR3 (G236-A261) proteolysed wild-type VWF115 normally. However, using either short or full-length VWF substrates containing the P1′ M1606A mutation, we identified residues within VR3 (D252-P256) that influence P1′ amino acid specificity, we hypothesize, by shaping the S1′ pocket. It is concluded that 2 subsites, D187-R193 and D252-P256, in the metalloprotease domain play an important role in cleavage efficiency and site specificity.

Comparative study of degradation of 4-chlorophenol by ultraviolet irradiation/sodium hypochlorite and ultraviolet irradiation/ozonation

2009 ◽  
Vol 9 (5) ◽  
pp. 601-609 ◽  
Author(s):  
J. Fu ◽  
J. Huang ◽  
Z. Liu ◽  
Q. F. Zeng ◽  
S. Q. An ◽  
...  
Keyword(s):  
Sodium Hypochlorite ◽  
Ultraviolet Irradiation ◽  
Pilot Scale ◽  
Economic Advantage ◽  
Photochemical Oxidation ◽  
Small Scale ◽  
Final Solution ◽  
Ph Values ◽  
Organic Halogens ◽  
Adsorbable Organic Halogens

The photochemical oxidation of 4-chlorophenol solutions by ultraviolet irradiation/sodium hypochlorite (UV/NaClO) and ultraviolet irradiation/ozonation (UV/O3) respectively was studied in a pilot scale photochemical reactor. The degradation efficiency of UV/NaClO was lower than that of UV/O3. The final UV absorption removals of the two processes were approximately 80% and approximately 90% respectively. During the two processes, dihydroxylated chlorophenols were the main intermediates. And pH values decreased with the oxidation being carried on. However, the UV/NaClO process was incomplete and some adsorbable organic halogens, such as ethyl 2-chloroacetate, 3,4-dichlorobut-3-en-2-one, ethyl 2,2-dichloroacetate, 2-chloro-1,1-diethoxyethane, ethyl 2,2,2-trichloroacetate and 2,4,6-trichlorophenol, still existed in the final solution. The costs of the two processes were also estimated. On a small scale, UV/NaClO process had significant economic advantage.

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