Chlorinous Odor Research Articles

Determination of an acceptable assimilable organic carbon (AOC) level for biological stability in water distribution systems with minimized chlorine residual

There is considerable interest in minimizing the chlorine residual in Japan because of increasing complaints about a chlorinous odor in drinking water. However, minimizing the chlorine residual causes the microbiological water quality to deteriorate, and stricter control of biodegradable organics in finished water is thus needed to maintain biological stability during water distribution. In this investigation, an acceptable level of assimilable organic carbon (AOC) for biologically stable water with minimized chlorine residual was determined based on the relationship between AOC, the chlorine residual, and bacterial regrowth. In order to prepare water samples containing lower AOC, the fractions of AOC and biodegradable organic matter (BOM) in tap water samples were reduced by converting into biomass after thermal hydrolysis of BOM at alkaline conditions. The batch-mode incubations at different conditions of AOC and chlorine residual were carried out at 20 °C, and the presence or absence of bacterial regrowth was determined. The determined curve for biologically stable water indicated that the acceptable AOC was 10.9 μg C/L at a minimized chlorine residual (0.05 mg Cl(2)/L). This result indicated that AOC removal during current water treatment processes in Japan should be significantly enhanced prior to minimization of the chlorine residual in water distribution.

浄水酸化処理過程におけるアミノ酸の挙動：カルキ臭に及ぼす影響

浄水酸化処理過程におけるアミノ酸の挙動：カルキ臭に及ぼす影響

A survey on levels and seasonal changes of assimilable organic carbon (AOC) and its precursors in drinking water

In Japan, customers’ concerns about chlorinous odour in drinking water have been increasing. One promising approach for reducing chlorinous odour is the minimization of residual chlorine in water distribution, which requires stricter control of organics to maintain biological stability in water supply systems. In this investigation, the levels and seasonal changes of assimilable organic carbon (AOC) and its precursors in drinking water were surveyed to accumulate information on organics in terms of biological stability. In tap water samples purified through rapid sand filtration processes, the average AOC concentration was 174 µgC/L in winter and 60 µgC/L in summer. This difference seemed to reflect the seasonal changes of AOC in the natural aquatic environment. On the other hand, very little or no AOC could be removed after use of an ozonation–biological activated carbon (BAC) process. Especially in winter, waterworks should pay attention to BAC operating conditions to improve AOC removal. The storage of BAC effluent with residual chlorine at 0.05–0.15 mgCl2/L increased AOC drastically. This result indicated the possibility that abundant AOC precursors remaining in the finished water could contribute to newly AOC formation during water distribution with minimized residual chlorine. Combined amino acids, which remained at roughly equivalent to AOC in finished water, were identified as major AOC precursors. Prior to minimization of residual chlorine, enhancement of the removal abilities for both AOC and its precursors would be necessary.

Simultaneous Control of Bromate Ion and Chlorinous Odor in Drinking Water Using an Advanced Oxidation Process (O3/H2O2)

Simultaneous control of chlorinous odor and bromate ion formation was attempted by using an advanced oxidation process (AOP, O3/H2O2). Also, the relationship between trichloramine (NCl3, a suspected odor compound in drinking water) and chlorinous odor in drinking water was studied through a headspace GC-MS analysis and the triangle sensory test. Odor strength after chlorination decreased by more than 50% for the samples pretreated with conventional ozonation and AOP. The change of hydroxyl radical exposure (•OH-ct) when AOP was applied did not show the clear difference in terms of the removal of chlorinous odor compared with conventional ozonation, but AOP was better for the control of bromate ion. Trichloramine seemed not to be a major odor compound in the chlorinated water of this experiment. The change of ammonium ion, bromide ion, and ozone dose did not clearly affect the efficiency of odor removal.

Determination of trichloramine in drinking water using headspace gas chromatography/mass spectrometry

Trichloramine (NCl3) is one of the major causes of the chlorine odor in drinking water. In the present study, a method was developed for analysis of NCl3 concentration in water using headspace gas chromatography/mass spectrometry (HS–GC/MS). For quantification of NCl3, m/z of 51 was selected because other major m/z of NCl3 were also observed as fragments of trichloromethane (CHCl3) and the peaks of NCl3 and CHCl3 overlapped on the chromatogram. The limit of quantification for NCl3 was set to 15 μg-Cl2/L. The calibration curve of NCl3 was expressed as a quadratic curve because of the partial NCl3 decomposition. NCl3 concentrations in chlorinated ammonium solution were determined by HS–GC/MS and titration using N,N-diethyl-p-phenylenediamine and ferrous ammonium sulfate (DPD/FAS), and the results using the two methods were similar at pH 6 and 7. However, at pH 8, NCl3 was detected using HS–GC/MS, but not using DPD/FAS titration. NCl3 concentrations in nine tap water samples were determined using HS–GC/MS and ranged from < 15 to 46 μg-Cl2/L. The results of the present study indicated that HS–GC/MS is applicable to determination of NCl3 in drinking water.

Determination of odour threshold concentration ranges for some disinfectants and disinfection by-products for an Australian panel

Taste-and-odour complaints are a leading cause of consumer dissatisfaction with drinking water. The aim of this study was to determine odour threshold concentration ranges and descriptors, using a Western Australian odour panel, for chlorine, bromine, chlorine added to bromide ions, the four major regulated trihalomethanes (THMs), and combined THMs. An odour panel was established and trained to determine odour threshold concentration ranges for odorous compounds typically found in drinking water at 25 degrees C, using modified flavour profile analysis (FPA) techniques. Bromine and chlorine had the same odour threshold concentration ranges and were both described as having a chlorinous odour by a majority of panellists, but the odour threshold concentration range of bromine expressed in free chlorine equivalents was lower that that of chlorine. It is likely that the free chlorine equivalent residuals measured in many parts of distribution systems in Western Australia are comprised of some portion of bromine and that bromine has the potential to cause chlorinous odours at a lower free chlorine equivalent concentration than chlorine itself. In fact, bromine is the likely cause of any chlorinous odours in Western Australian distributed waters when the free chlorine equivalent concentration is between 0.04 and 0.1 mg L(-1). Odour threshold concentrations for the four individual THMs ranged from 0.06-0.16 mg L(-1), and the odour threshold concentration range was 0.10 + or - 0.09 mg L(-1) when the four THMs were combined (in equal mass concentrations). These concentrations are below the maximum guideline value for total THM concentration in Australia so odours from these compounds may possibly be observed in distributed waters. However, while the presence of THMs may contribute to any sweet/fragrant/floral and chemical/hydrocarbon odours in local drinking waters, the THMs are unlikely to contribute to chlorinous odours.

Submicron-sized activated carbon particles for the rapid removal of chlorinous and earthy-musty compounds

Research Article| December 01 2008 Submicron-sized activated carbon particles for the rapid removal of chlorinous and earthy-musty compounds Yoshihiko Matsui; Yoshihiko Matsui 1Division of Built Environment, Graduate School of Engineering, Hokkaido University, N13W8, Sapporo, 060-8628, Japan Tel.: & Fax: +81-11-706-7280; E-mail: matsui@eng.hokudai.ac.jp Search for other works by this author on: This Site PubMed Google Scholar Kenji Murai; Kenji Murai 1Division of Built Environment, Graduate School of Engineering, Hokkaido University, N13W8, Sapporo, 060-8628, Japan Search for other works by this author on: This Site PubMed Google Scholar Hiroshi Sasaki; Hiroshi Sasaki 1Division of Built Environment, Graduate School of Engineering, Hokkaido University, N13W8, Sapporo, 060-8628, Japan Search for other works by this author on: This Site PubMed Google Scholar Koichi Ohno; Koichi Ohno 1Division of Built Environment, Graduate School of Engineering, Hokkaido University, N13W8, Sapporo, 060-8628, Japan Search for other works by this author on: This Site PubMed Google Scholar Taku Matsushita Taku Matsushita 1Division of Built Environment, Graduate School of Engineering, Hokkaido University, N13W8, Sapporo, 060-8628, Japan Search for other works by this author on: This Site PubMed Google Scholar Journal of Water Supply: Research and Technology-Aqua (2008) 57 (8): 577–583. https://doi.org/10.2166/aqua.2008.070 Article history Received: August 06 2007 Accepted: December 25 2007 Views Icon Views Article contents Figures & tables Video Audio Supplementary Data Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Cite Icon Cite Permissions Search Site Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentAll JournalsThis Journal Search Advanced Search Citation Yoshihiko Matsui, Kenji Murai, Hiroshi Sasaki, Koichi Ohno, Taku Matsushita; Submicron-sized activated carbon particles for the rapid removal of chlorinous and earthy-musty compounds. Journal of Water Supply: Research and Technology-Aqua 1 December 2008; 57 (8): 577–583. doi: https://doi.org/10.2166/aqua.2008.070 Download citation file: Ris (Zotero) Reference Manager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex Submicron-sized powdered activated carbon (PAC) was produced from a commercially available normal PAC by a bead mill. The submicron PAC decomposed dichloramine and nitrogen trichloride, impairing aesthetic quality with chlorinous odor, at a much faster rate than did normal PAC. Moreover, decomposition rates were faster for dichloramine and nitrogen trichloride than for monochloramine and free chlorine. Selective removal of chlorinous odors among chlorine compounds in a short time was thereby possible. The earthy–musty compound geosmin was also much more rapidly removed by adsorption on submicron PAC than on normal PAC. The increased removal rate was partly due to the adsorption capacity increase owing to the particle size reduction of PAC to submicron range, which accounted for 40% of the improvement of geosmin removal at a PAC contact time of 10 min. adsorption, drinking water, flavor, particles This content is only available as a PDF. © IWA Publishing 2008 You do not currently have access to this content.

Effective Use of Bleach as an Antiseptic and Disinfectant

Cecil H. and Michele H. Fox point out the disinfecting properties of inexpensive and universally available diluted bleach (5% sodium hypochlorite) as an important germicide to help control the spread of influenza (or any other communicable virus, bacteria, or fungus) (Microbe, April 2006, p. 159). A few more details might help for the effective use of diluted bleach as an antiseptic and disinfectant. Bleach is sold as a stable alkaline solution with a pH value of about 11 or 12. At this alkaline pH value, virtually all of the bleach is in the form of the chlorite ion (OCl−). At an acidic pH value of about 6.0 to 6.8, 90% of the bleach is in the form of hypochlorous acid (HOCl). Hypochlorous acid is 80 to 200 times more antimicrobial than the chlorite ion. Thus a simple formula to prepare an effective antimicrobial dilution of bleach is to add 2.0 oz of concentrated bleach to one gallon of tap water, and then add 2.0 oz of 5% distilled white cooking vinegar, also inexpensive and commonly available, to lower the pH of bleach to about 6.0. This will yield about 800 ppm free available chlorine from hypochlorous acid. Use this acidified bleach in well-ventilated areas as there will be a mild odor of chlorine. The acidified bleach must be prepared fresh daily. Protect eyes and mucous membranes. Never add ammonia to bleach. Follow the safety directions as found on the bleach label.

Dechlorination techniques to improve sensory odor testing of geosmin and 2‐MIB

Chlorine in finished water can mask the more subtle odors of geosmin and 2‐methylisoborneol (2‐MIB), two chemicals that often trigger consumer complaints when present at even nanogram‐per‐litre concentrations. These are two of the odors that are revealed as chlorine dissipates in the distribution system, which is typically at the consumer's end. As a result, odor monitoring at the treatment plant may not identify unpleasant smells because chlorine levels at the plant are typically high and mask the other odors. Proper sensory evaluation of these odor‐causing substances requires that the chlorine odor first be reduced or eliminated so that the secondary odor can be identified. In this study, ascorbic acid, hydrogen peroxide, oxalic acid, sodium thiosulfate, and ultraviolet (UV) irradiation were evaluated for their effectiveness in reducing chlorine solutions and for their subsequent usefulness in sensory analysis. Oxalic acid and UV irradiation were inefficient dechlorinators, and sodium thiosulfate produced a rotten‐egg odor under the study conditions. Triangle testing and flavor profile analysis showed that ascorbic acid and hydrogen peroxide were effective in reducing chlorinous odors without producing new odors, and they did not alter the testers' sensory perceptions of geosmin and 2‐MIB.

Study of the Possible Origins of Chlorinous Taste and Odour Episodes in a Distribution Network

Occasionally in winter some inhabitants of the city of Paris complain of a bad chlorinous odour when the chlorine residual in the water distribution network is 0.1 mg/l. Several hypotheses have been made. Many taste and odour profiles have been made on one plant and aminoacids and aldehydes have been analysed. Chlorination of urea has not led to the chlorinous taste. We think that these odours are due to trichloramine, which is produced by chlorination of some organo nitrogen compounds with a slow kinetics of formation during winter. Results show that the combined chlorine level is constant with time and we have reproduced this offensive odour but the origin does not seem to be aldehydes.

Odors Arising from Ammonia and Amino Acids with Chlorine During Water Treatment

Odor produced by breakpoint chlorination in a drinking water purification process was researched. Ammonia and six amino acids (glycine, alanine, valine, leucine, arginine, proline) were chlorinated and production of odor and its change were investigated. An intense odor which was different to the odor of residual free chlorine was detected after the chlorination of ammonia. The production of the odor was affected by pH and chlorine dose rate. While the intense odor was not produced in the breakpoint chlorination at pH 8.3, a weak odor before the breakpoint and the intense odor after the breakpoint were produced at pH 6.5. At pH 3.0, the intense odor was detected even in a sample of low chlorine dose rate. An identification of the intense odor substance was done using a gas chromatograph-mass spectrometer and trichloramine or a dimer of dichloramine was suspected as the odor causing substance. In chlorination of the six amino acids, the intense odor and its change were different according to each amino acid. Production of chlorinated intermediate and final products which had a different odor were suspected as one of the reasons.

The Drinking Water Taste and Odor Wheel for the Millennium: Beyond Geosmin and 2-Methylisoborneol

The “Taste and Odor Wheel” developed over the last 15 years has been updated to include new compounds identified in the eight classes of odorants, four tastes, and one mouth feel/nose feel category. Over the last 10 years, other types of odors have been identified, in addition to chlorinous and ozonous odors of disinfectants, the earthy compound geosmin, and the musty compound 2-methylisoborneol (2-MIB). Sophisticated instrumental analysis, e.g., gas chromatography/mass spectrometry (GC/MS), and sensory analysis, e.g., flavor-profile analysis (FPA), have been successfully combined with sensory GC to identify various odorants.

Advances in Treatment Processes to Solve Off-Flavor Problems in Drinking Water

There have been significant advances in the development and application of treatment processes to control off-flavor problems in drinking water in the past few years. This paper updates two major treatment process summaries that appeared in 1988 and 1995. The paper also puts the efficiencies of the treatment processes in perspective by using the drinking water flavor wheel as a reference point. Removal or control of classes of off-flavor problems are described in relation to the categories on the wheel. Specifically, processes such as oxidation, adsorption, biological treatment and membranes are described. The recent literature is reviewed and advances in treatment are identified. A new treatment process for controlling nitrification in distribution systems is introduced which has the potential to dramatically reduce the problems of chlorinous odor complaints from customers.

Study of the possible origins of chlorinous taste and odour episodes in a distribution network

Occasionally in winter some inhabitants of the city of Paris complain of a bad chlorinous odour when the chlorine residual in the water distribution network is 0.1 mg/l. Several hypotheses have been made. Many taste and odour profiles have been made on one plant and aminoacids and aldehydes have been analysed. Chlorination of urea has not led to the chlorinous taste. We think that these odours are due to trichloramine, which is produced by chlorination of some organo nitrogen compounds with a slow kinetics of formation during winter. Results show that the combined chlorine level is constant with time and we have reproduced this offensive odour but the origin does not seem to be aldehydes.

Advances in treatment processes to solve off-flavor problems in drinking water

There have been significant advances in the development and application of treatment processes to control off-flavor problems in drinking water in the past few years. This paper updates two major treatment process summaries that appeared in 1988 and 1995. The paper also puts the efficiencies of the treatment processes in perspective by using the drinking water flavor wheel as a reference point. Removal or control of classes of off-flavor problems are described in relation to the categories on the wheel. Specifically, processes such as oxidation, adsorption, biological treatment and membranes are described. The recent literature is reviewed and advances in treatment are identified. A new treatment process for controlling nitrification in distribution systems is introduced which has the potential to dramatically reduce the problems of chlorinous odor complaints from customers.

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

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.

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

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 that on residual chlorine or musty odor. To extend 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.

Question of the Month

This month's question concerns a strong chlorine taste and odor in the water, eventhough the chlorine feed was lowered. The answer states that this phenomenon is associated with a chlorine dosage that is too low rather than too high. The article provides a brief discussion of breakpoint chlorination, the point at which the chlorine dosage has satisfied the chlorine demand, and includes a table to illustrate chlorine breakpoint.

Influence of the Chlorination of Natural Nitrogenous Organic Compounds on Tastes and Odors in Finished Drinking Waters

The objective of the study was to determine the influence of chlorination by-products of naturally occuring nitrogenous organic compounds on tastes and odors in drinking waters. Amino acids, peptides and amino sugars have been chlorinated under various chlorine/nitrogen ratios. Six natural amino acids were shown to induce tastes and odors at concentrations in the range 10-20 µg/l after chlorination. A multicomponent mixture containing 2.5 µg/l each of these 6 amino acids consistently induced detectable odors after a contact time with chlorine of 2 hours. Investigation of the by-products indicated that the odors generated were systematically linked to the aliphatic aldehydes formed. The peptides investigated revealed varying degrees of odor formation potential, while the amino sugars did not impart any odor. Chlorinous odors occasionally detected during these experiments were thought to arise from the organic chloramines or other oxidation by-products.

Household Odors Associated With the Use of Chlorine Dioxide

In recent years, reports have indicated that the use of chlorine dioxide (ClO2) instead of chlorine as a preoxidant during water treatment is somehow related to the production of offensive odors at customers' homes and businesses. These odors were described by terms such as “kerosenelike,” “cat‐urine‐like,” and “strong chlorinous.” Attempts to isolate and identify the odor‐causing compounds in water samples taken from treatment plants and homes were unsuccessful. Suggestions from others that the offensive odors were in some way related to the presence of new carpeting in homes and businesses provided the basis for additional experiments. The principal conclusions derived from the study are that the strong chlorinous odors are caused by ClO2 itself, whereas the kerosenelike and cat‐urine‐like odors are products of gas‐phase reactions between ClO2 liberated from the water and organic substances in the air inside the customer's residence.