Chlorinous Odor Research Articles

Optimization of Secondary Chlorination in Water Distribution Systems for Enhanced Disinfection and Reduced Chlorine Odor Using Deep Belief Network and NSGA-II

This research explores the strategic optimization of secondary chlorination in water distribution systems (WDSs), in order to enhance the efficiency of disinfection while mitigating odor and operational costs and promoting sustainability in water quality management. The methodology integrates EPANET simulations for water hydraulic and quality modeling with a deep belief network (DBN) within the deep learning framework for accurate chloric odor prediction. Utilizing the non-dominated sorting genetic algorithm-II (NSGA-II), this methodology systematically balances the objectives of chloride dosage and chloramine formation. It combines a chloric odor intensity assessment, a multi-component kinetic model, and dual-objective optimization to conduct a comparative analysis of case studies on secondary chlorination strategies. The optimal configuration with five secondary chlorination stations reduced chloric odor intensity to 1.20 at a cost of USD 40,020.77 per year in Network A while, with eight stations, chloric odor intensity was reduced to 0.88 at a cost of USD 71,405.38 per year in Network B. The results demonstrate a balanced trade-off between odor intensity and operational cost on one hand and sustainability on the other hand, highlighting the importance of precise chlorine management to improve both the sensory and safety qualities of drinking water while ensuring the sustainable use and management of water resources.

Risk Analysis of Otitis Externa (Swimmer’s Ear) in Children Pool Swimmers: A Case Study from Greece

Otitis is an ear inflammation characterized by an accumulation of polluted fluids in the ear, inflating the drum, causing ear pain, and draining the mucous membrane (pus) into the ear canal if the drum is perforated. Swimmer’s otitis, also known as acute external otitis, is a medical condition that frequently affects competitive swimmers. The risk factor analysis study was based on data obtained between May 2018 and May 2019 from four public swimming pools in Patras, Achaia. A checklist was created to evaluate the pools’ operational conditions, and it included information on the pools’ sanitation as well as swimming pool hygiene guidelines. In addition, a questionnaire was devised to collect data on pool swimmers’ use of the pools. Microbiological testing of the pool water was done ahead of time, and data on external otitis cases from hospitals was gathered. Based on this information, a risk factor analysis was conducted. Gender, weight, and age do not appear to have an impact on the number of otitis media cases that occur because of swimming in the pools. There is also no statistically significant link between episodes and the frequency of otitis events in locker rooms, restrooms, or swimming pools. The frequency with which swimmers utilize the pool, rather than the pool’s microbial burden, is the most significant determinant in otitis episodes. Furthermore, there is no statistically significant link between chlorine odor and otitis episodes. Additionally, several abnormalities in the ear or the child’s history do not appear to affect otitis episodes. More research is needed to determine whether infections are linked to microbial load or if other factors are responsible for the emergence of waterborne infections.

Interlaboratory comparison of the intensity of drinking water odor and taste by two-way ordinal analysis of variation without replication.

A case study of ordinal data from human organoleptic examination (sensory analysis) of drinking water obtained in an interlaboratory comparison of 49 ecological laboratories is described. The recently developed two-way ordinal analysis of variation (ORDANOVA) is applied for the first time for the treatment of responses on the intensity of chlorine and sulfurous odor of water at 20 and 60 °C, which is classified into the six categories from 'imperceptible' to 'very strong'. The one-way ORDANOVA is used for the analysis of the 'salty taste' intensity of the water. A decomposition of the total variation of the ordinal data and simulation of the multinomial distribution of the data-relative frequencies in different categories allowed the determination of the statistical significance of the difference between laboratories in classifying chlorine or sulfurous odor intensity by categories, while the effect of temperature was not significant. No statistical difference was found between laboratories on salty taste intensity. The capabilities of experts to identify different categories of the intensity of the odor and taste are also evaluated. A comparison of the results obtained with ORDANOVA and ANOVA showed that ORDANOVA is a more useful and reliable tool for understanding categorical data such as the intensity of drinking water odor and taste.

Joint majorization of waterworks and secondary chlorination points considering the chloric odor and economic investment in the DWDS using machine learning and optimization algorithms

The traditional methods of increasing the chlorine disinfectant dosage in the drinking water distribution system (DWDS) to control microorganisms and improve the safety of drinking water quality are subjected to several challenges. One noticeable problem is the unpleasant odor generated by chlorine and chloramines. However, the generally proposed chlorine dosage optimization model ignores the chloric odor distribution in the DWDS. This study proposes a comprehensive multi-parameter water quality model and aims to balance the trade-offs between: (i) minimize the flavor profile analysis (FPA) degree of the chloric odor produced by chlorine and chloramines in the DWDS, and (ii) minimize the economic investment (chlorine dosage and operation cost). EPANET and back propagation (BP) network integrated with the Borg algorithm were employed as innovative approaches to simulate the chlorine, chloramines, and chloric odor intensity in the DWDS. Moreover, the application of the multi-parameter model was demonstrated in a real-world DWDS case study. 0.5 mg-Cl2/L (mg/L) chlorine at 8 secondary chlorination points was added to the DWDS as an optimized chlorine dosing scheme considering the olfactory and financial objective functions simultaneously. When switching to a superior water source, the FPA of the chloric odor in DWDS increased by a maximum of 1.4 at most if the initial chlorine dosage remained as before. To avoid the occurrence of chloric odor and also control the residual free chlorine (residual chlorine) at a suitable value, the initial and secondary chlorine dosages were optimized to 0.4 mg/L and 0.3 mg/L, respectively. Under this condition, the initial chlorine dosage was reduced by 50% compared to the original operation scheme in City J, China, the qualification rate of the residual chlorine reached 97.2%, basically consistent with that before water source switching, and the chloric odor intensity of the DWDS was controlled below FPA 3.4.

Effect of phytic acid as an endodontic chelator on resin adhesion to sodium hypochlorite-treated dentin.

ObjectivesPhytic acid (IP6), a naturally occurring agent, has been previously reported as a potential alternative to ethylenediaminetetraacetic acid (EDTA). However, its effect on adhesion to sodium hypochlorite (NaOCl)-treated dentin and its interactions with NaOCl have not been previously reported. Thus, in this study, the effects of IP6 on resin adhesion to NaOCl-treated dentin and the failure mode were investigated and the interactions between the used agents were analyzed.Materials and MethodsMicro-tensile bond strength (µTBS) testing was performed until failure on dentin treated with either distilled water (control), 5% NaOCl, or 5% NaOCl followed with chelators: 17% EDTA for 1 minute or 1% IP6 for 30 seconds or 1 minute. The failed specimens were assessed under a scanning electron microscope. The reaction of NaOCl with EDTA or IP6 was analyzed in terms of temperature, pH, effervescence, and chlorine odor, and the effects of the resulting mixtures on the color of a stained paper were recorded.ResultsThe µTBS values of the control and NaOCl with chelator groups were not significantly different, but were all significantly higher than that of the group treated with NaOCl only. In the failure analysis, a distinctive feature was the presence of resin tags in samples conditioned with IP6 after treatment with NaOCl. The reaction of 1% IP6 with 5% NaOCl was less aggressive than the reaction of the latter with 17% EDTA.ConclusionsIP6 reversed the adverse effects of NaOCl on resin-dentin adhesion without the chlorine-depleting effect of EDTA.

Investigating the Taste, Odor and Appearance of Selected Bottled and Sachet Sold Drinking Water in Burkina Faso

Background: Drinking water should be harmless to its consumers and aspects such as appearance, taste and/or odor should be acceptable. In Burkina Faso, the sold bottled and sachet drinking waters are not always respecting the quality in terms of potability. Method: In this study we investigated the appearance, taste and/or odor of eleven (11) selected bottled and sachet waters sold in Burkina Faso through a set of five (05) water treatment professionals with ten (10) organoleptic parameters been considered (Organic Solvent, Metallic, Chlorine, Fishy, Sulfur, Earthy, Bitter, Fruity, Spoiled, and Sour). Results: The study showed that all the investigated waters have unpleasant taste and/or odor, with the worst cases in all five (05) brands sachet waters. The bad quality of the sachet waters is generally due to the conditioning (sun, dust, rain). Ouagadougou tap water showed unpleasant chlorine odor mainly caused by the “remanent” chlorine. However, that chlorine ensure the water safety to its consumers. Conclusion: This study showed that the best way to drink safe water in Burkina Faso is to supply a good quality tap water to its population, and to improve the taste and/or odor. Since the sold bottled and sachet waters are not yet well regulated in terms of their quality, the country should be aware of the current study in order to improve the sold drinking water quality.

Barriers and Facilitators to Chlorine Tablet Distribution and Use in Emergencies: A Qualitative Assessment

Chlorine tablets are commonly distributed for household water treatment in emergencies. However, confirmed use after distribution ranges widely (from 7–87%), which raises concerns about chlorine tablet effectiveness, as measured by acceptance and appropriate use. To investigate chlorine tablet effectiveness, we conducted nine key informant interviews (KIIs) on tablet distribution in emergencies in general, five KIIs on chlorine taste and odor acceptance and rejection specifically, and a literature review on chlorine taste and odor concerns. We found: (1) chlorine tablets are regarded as one of the most effective water treatment methods and are often considered appropriate in emergency response, (2) dosing confusion and taste and odor rejection are perceived as the main problems limiting effectiveness, and (3) the primary solutions suggested for these problems were social and behavioral. We recommend that social and behavioral scientists are routinely integrated into chlorine tablet programming to improve user feedback and behavioral interventions for chlorine tablet promotion in emergencies. We also suggest that more research is conducted on chlorine taste and odor rejection in vulnerable populations, and that improved guidance is developed to facilitate intra-agency coordination and select, promote, and monitor tablets appropriate for each context.

Measurement of Odour on Source of Drinking Water Using Threshold Odour Number and Modified Olfactometry

Concerns on odour of water have increased rapidly. However, odour measurement in water for drinking sources has yet to be established in Malaysia. More study is needed for an approach to quantify the odour incidences in water supply, one that is effective and applicable as a guideline towards the early identification of contamination occurrences. Thus, the objective of this study was to identify correlation (if any) between Threshold Odour Number (TON) test with a portable olfactometry plus odour wheel (POPOW) combination method for assessing odour in drinking water. Water samples collected from a drinking water supply system was tested for odour concentration as well as its character based on an odour wheel. Results from the Pearson correlation showed that the TON and POPOW gave the r-value of 0.833 which indicates that both method highly correlate with a level of confidence of 99 percent. Sample water that was taken near the main source of drinking water was given off as earthy smell, indicating geosmin as a likely contaminant. On the other hand, treated water samples taken directly at the treatment plant had a distinctive, chlorinous odour, which was expected from it use of chlorine as a disinfectant. This study has demonstrated the effectiveness of the portable olfactometer and odour wheel combination method for detecting odour in drinking water supply with at par results to the standard TON. More importantly, POPOW would enable the assessment of odour at site and at a shorter test preparation time, traits which are important especially for remotely located sites.

Factors affecting the water odor caused by chloramines during drinking water disinfection

Chloramine disinfection is one of the most common disinfection methods in drinking water treatment. In this study, the temporal variability of water odors during monochloramine auto-decomposition was investigated to elucidate the characteristics of odor problems caused by adopting chloramine disinfection in tap water. Odor intensities and dominant odorant contributions were determined using the flavor profile analysis (FPA) and odor active value (OAV), respectively. During auto-decomposition of monochloramine, Cl2/N molar ratio, pH, temperature, and the presence of NOM all affected odor intensity and odor temporal variation in drinking water. In general, decreasing pH from 8.5 to 6.0 led to increasing perceived odor intensity due to the formation of dichloramine. The major odorants responsible for chlorinous odor under acidic and non-acidic conditions were dichloramine and monochloramine, respectively. Chloraminated water with a Cl2/N molar ratio of 0.6 or NOM concentration <2 mg-C L−1 inhibited odor intensity. Furthermore, the influence of rechlorination on chlorinous odor intensity for chloraminated water should not be neglected. The results of this study will be beneficial for the control of chlorinous odors caused by chloramine disinfection in drinking water.

Evaluating the efficiency of chlorine removal from potable tap water using off-gassing, boiling, and filtration treatment methods

&#x0D; Background: One of the most frequent complaints to water distribution systems is the taste and odor of chlorine in consumer tap water. Chlorine is a common disinfectant used to inactivate and breakdown microbes and other contaminants. However, excess chlorine can result in an unpalatable chlorinous taste and odor. When water taste becomes too objectionable, consumers may search for alternative water sources, such as raw, untreated water that does not contain chemical additives. Raw, untreated water contains various contaminants, including disease-causing pathogens. To encourage consumers to drink treated tap water, and prevent disease, this study evaluated and compared the effectiveness of off-gassing, boiling and filtration as dechlorination methods for consumers to perform on their tap water. Method: Hach Method 8021 was performed to collect and analyse water samples following treatment with Off-gassing, Boiling and Filtration. Water samples were collected from BCIT SW1-1230. The Hach Pocket Colorimeter ™ II determined the free chlorine concentration of the water samples, and compared to a sample of untreated chlorinated tap water to see which method reduced chlorine concentrations the most. Results: Mean concentration of chlorine following off-gassing was determined to be 0.51 ppm, 0.24 ppm following boiling, and 0.55 ppm following filtration. It was determined that the boiling method was statistically significantly different from the mean values of chlorine concentration from the other two methods, as shown by the Kruskal-wallis test (P=0.000), and therefore was the most effective in dechlorinating tap water samples. This was further confirmed by the Scheffe’s Mutliple-Comparison Test and eyeball test. Conclusion: Based on the results, boiling water is the most effective method to dechlorinate potable tap water for consumer acceptability. The free chlorine levels found post-boiling were also found to be below the WHO’s threshold for tasting and smelling chlorine in drinking water (0.3 ppm), and above WHO’s minimum required 0.2 ppm chlorine residual. Therefore, drinking water following boiling will be safe for consumption, as well as free of chlorinous taste and smell. Public Health professionals can safely advise consumers of an effective method to encourage treated tap water consumption, and to discourage finding alternative water sources.&#x0D;

Effect of Residual Chlorine Concentration on Water Pipe Corrosion

1. Introduction Water pipe corrosion corrodes the iron by the oxidation reduction reaction, and the corrosion rate is accelerated by the oxidizing agent used as disinfectant in the tap water. The major oxidizing agent in tap water are ozone and chlorine. pH, alkalinity and residual chlorine concentration are factors of internal corrosion. We are replacing the ductile cast iron pipe with inner coating and stainless steel pipe. However, it is still used in many cases, such as gray cast iron pipes and galvanized steel pipes without internal coatings in Korea. Chlorine is a very strong oxidant for all metals and organics, and the reaction between chlorine and iron is as follows. HOCl + 2Fe2+ + 5H2O → 2Fe(OH)3↓ + Cl- + 5H+ Recently, as the problem with sinkholes has arisen on the a buried road as water pipes, sewage pipes, etc, interest in corrosion has been growing. The purpose of this study is to evaluate the effect of residual chlorine on the corrosion factor by analyzing the water quality and to evaluate the necessity of the proper residual chlorine on in the water purification plant. 2. Experimental Method In order to evaluate the corrosion of residual chlorine concentration of tap water, we were carried out Tafel experiment and water quality analysis. The corrosion rate was measured by a Tafel experiment using an electrochemical corrosion measurement system (PAR VMP-3). For tap water in Seoul, corrosion evaluation was performed according to alkalinity and hardness, residual chlorine concentraion. 3. Summary of results The tap water quality of Seoul was as follows that residual chlorine is 0.4 mg/L, and alkalinity is 50 mg/L as CaCO3, with a pH of 7.3. The results of experiments on the rate of corrosion of Carbon Steel specimens to residual chlorine in seoul tap water, can be seen in Fig. 1. As a result of the Tafel experiment according to the initial residual chlorine concentration under the same conditions (same LI index), The corrosion rate was 0.01 mmpy at 0 mg/L of residual chlorine and 0.074mmpy at 0.8mg/L of residual chlorine, corrosion rate for residual chlorine in carbon steel specimens was more than 7 times. It was confirmed that the higher the concentration of residual chlorine, the faster the corrosion rate was increased. The corrosivity of tap water in Korea is evaluated by the LI index, but residual chlorine has a large effect on corrosion, so it is required to add residual chlorine for the tap water corrosion evaluation. It is reducing the concentration of residual chlorine for reduce the chlorine odor of tap water in the distribution water system in Korea. But, residual chlorine guideline for corrosion reduction is necessary in Korea. Figure 1

Hypochlorite solution for root canal irrigation that lacks a chlorinated odor.

Objectives:This is an in vitro study to develop a formulation of a hypochlorite solution for root canal irrigation that lacks a chlorinated odor. The antibacterial effect, tissue dissolution efficacy, and the cytotoxicity of the solution were assessed in cell culture and were compared with those of commercial sodium hypochlorite (NaOCl) solutions.Materials and Methods:Trichloroisocyanuric acid (TCA) was used as the source of hypochlorite ions in solution. All required properties of the NaOCl irrigant were evaluated and compared with those of original 2.5% NaOCl solutions currently in use.Results:Our results revealed that a TCA 3.5% + 1/6 Buffer-1 solution passed the short-term stability test. Moreover, no odor of chlorine gas was detected by three independent observers. The hypochlorite ion content and pH were stable over an incubation period of 4 weeks. The new solution did not differ from commercial products in terms of the dissolution property on bovine pulpal tissue (P > 0.05). Moreover, the antibacterial effect of this solution on Enterococcus faecalis did not differ from that of the commercial products (P > 0.05). In addition, our biocompatibility analysis demonstrated no difference among the tested solutions (P > 0.05).Conclusions:According to the results of all properties tested, TCA 3.5% + 1/6 Buffer-1 could be considered an option for NaOCl irrigation with the benefit of no detectable chlorine odor.

Characterization of organic precursors for chlorinous odor before and after ozonation by a fractionation technique

To identify the primary fraction of dissolved organic matter (DOM) responsible for chlorinous odor, waters treated by the conventional treatment (i.e., coagulation, flocculation, sedimentation and rapid sand filtration (RSF)) and ozonation were characterized by a fractionation technique prior to chlorination. Furthermore, chlorinous odor strengths originated from organic fractions were compared with that resulted from trichloramine (NCl3). Odor strengths and trichloramine concentrations were determined by the triangle sensory test and head space-GC/MS, respectively. The major DOM fraction for outlet water of RSF was hydrophobic acid (HoA), whereas the hydrophilic acid (HiA) fraction was dominant in the ozonated water. For a fixed DOC level (1 mgC/L), the base (Bas) or hydrophilic base (HiB) fraction was found to be the major organic precursor of chlorinous odor for the effluent of RSF. Even the mass percentages of DOM fractions in RSF water were considered, Bas was the major DOM fractions responsible for chlorinous odor. For ozonated water, two major precursors of chlorinous odor were HiA and hydrophilic neutral (HiN) fractions. Furthermore, the influence of trichloramine on chlorinous odor intensity for ozonated water should not be negligible. Under variation of seasonal organic contents, changes in precursors of chlorinous odor were observed.

Abundance and diversity of ammonia-oxidizing archaea and bacteria on granular activated carbon and their fates during drinking water purification process.

Ammonia is a precursor to trichloramine, which causes an undesirable chlorinous odor. Granular activated carbon (GAC) filtration is used to biologically oxidize ammonia during drinking water purification; however, little information is available regarding the abundance and diversity of ammonia-oxidizing archaea (AOA) and bacteria (AOB) associated with GAC. In addition, their sources and fates in water purification process remain unknown. In this study, six GAC samples were collected from five full-scale drinking water purification plants in Tokyo during summer and winter, and the abundance and community structure of AOA and AOB associated with GAC were studied in these two seasons. In summer, archaeal and bacterial amoA genes on GACs were present at 3.7 × 10(5)-3.9 × 10(8) gene copies/g-dry and 4.5 × 10(6)-4.2 × 10(8) gene copies/g-dry, respectively. In winter, archaeal amoA genes remained at the same level, while bacterial amoA genes decreased significantly for all GACs. No differences were observed in the community diversity of AOA and AOB from summer to winter. Phylogenetic analysis revealed high AOA diversity in group I.1a and group I.1b in raw water. Terminal-restriction fragment length polymorphism analysis of processed water samples revealed that AOA diversity decreased dramatically to only two OTUs in group I.1a after ozonation, which were identical to those detected on GAC. It suggests that ozonation plays an important role in determining AOA diversity on GAC. Further study on the cell-specific activity of AOA and AOB is necessary to understand their contributions to in situ nitrification performance.

Mechanisms of trichloramine removal with activated carbon: Stoichiometric analysis with isotopically labeled trichloramine and theoretical analysis with a diffusion-reaction model

This study investigated the mechanism by which activated carbon removes trichloramine, a byproduct of water treatment that has a strongly offensive chlorinous odor. A stoichiometrical mass balance for 15N before and after activated carbon treatment of laboratory-prepared 15N-labeled trichloramine solutions clearly revealed that the mechanism of trichloramine removal with activated carbon was not adsorption but rather reductive decomposition to nitrogen gas. There was a weak positive correlation between the surface decomposition rate constant of trichloramine and the concentration of basic functional groups on the surface of the carbon particles, the suggestion being that the trichloramine may have been reduced by sulfhydryl groups (–SH) on the activated carbon surface. Efficient decomposition of trichloramine was achieved with super powdered activated carbon (SPAC), which was prepared by pulverization of commercially available PAC into very fine particles less than 1 μm in diameter. SPAC could decompose trichloramine selectively, even when trichloramine and free chlorine were present simultaneously in water, the indication being that the strong disinfection capability of residual free chlorine could be retained even after trichloramine was effectively decomposed. The residual ratio of trichloramine after carbon contact increased somewhat at low water temperatures of 1–5 °C. At these low temperatures, biological treatment, the traditional method for control of a major trichloramine precursor (ammonium nitrogen), is inefficient. Even at these low temperatures, SPAC could reduce the trichloramine concentration to an acceptable level. A theoretical analysis with a diffusion-reaction model developed in the present study revealed that the increase in the trichloramine residual with decreasing water temperature was attributable to the temperature dependence of the rate of the reductive reaction rather than to the temperature dependence of the diffusive mass transfer rate.

What Bathers Put into a Pool: A Critical Review of Body Fluids and a Body Fluid Analog

Bathers add inorganic and organic materials to pool water primarily via sweat and urine but also via sunscreens and cosmetics. The organic nitrogen (organic-N) compounds react with chlorine to form organic chloramines that have no biocidal effectiveness, volatile inorganic chloramines, and other oxidation products that create high combined chlorine measurements and chlorinous odors. Recent research on the reactions of free available chlorine (FAC) with organic-N components of body fluids and models of other organic-N compounds likely to be present in pool water is reviewed. One recipe for a body fluid analog (BFA) was found in model pool studies to reproduce a field-observed median chlorine demand of 5.5 g/standard bather and to contain a reduced nitrogen mass per average bather within the ranges of published estimates. Guidelines for the combined chlorine measurement are routinely exceeded in operating pools and in model pool studies even at modest bather loads simulated using the BFA recipe.

Control of trichloramine formation by two-step chlorination in water purification processes

Chlorinous odour in drinking water is of great concern in Japan. Some water utilities use trichloramine (NCl3) as an index of chlorinous odour and are attempting to control its levels in drinking water. In the present study, the effects of two-step chlorination, involving addition of chlorine twice, on NCl3 control were investigated. The results regarding ammonia (NH3), glycine solutions and raw waters at water purification plants (WPPs) indicated that NCl3-formation potentials (FPs) were reduced by two-step chlorination when NH3 was a primary NCl3 precursor and the 1st chlorine addition was set at an excess breakpoint (BP). However, no effect on NCl3-FP was observed when the 1st chlorine addition was set below BP. Two-step chlorination was not effective for NCl3 control regardless of the amounts of the 1st chlorine addition when organic nitrogen compounds were the primary NCl3 precursors. Moreover, the NCl3-FPs in raw water with relatively high NH3 were reduced at actual WPPs when two-step chlorination was applied.

Chlorine requirement for biologically stable drinking water after nanofiltration

There is considerable interest in minimizing the chlorine residual in Japan's tap water because of increasing consumer complaints about the chlorinous odor of drinking water. However, minimization of the chlorine residual requires stricter control of biodegradable organics in finished water to ensure biological stability during water distribution. In this context, we investigated the improvement of biological stability of drinking water by nanofiltration (NF). The removal of assimilable organic carbon (AOC) was 52% on average, but showed large seasonal variation. It was found to be difficult to maintain the acceptable AOC level for biologically stable water by NF. In addition, significant bacterial regrowth in NF permeates was still observed without chlorination, although 52% AOC was removed. Then, the chlorine concentration required to prevent bacterial regrowth during distribution of nanofiltrated water was determined using continuous-flow reactor systems. The heterotrophic plate counts (HPC) densities in biofilm were monitored at different chlorine conditions. The results indicated that the NF process could significantly reduce the chlorine requirement of the finished water. The relationship between free chlorine residual and HPC in biofilm formed from 1 μgC AOC showed that a trace level of chlorine residual, &amp;lt;0.1 mg/L, could inactivate heterotrophic bacteria and prevent biofilm formation.

Reduction of chlorinous odor by the combination of oxidation and ion-exchange treatments

Research Article| November 04 2013 Reduction of chlorinous odor by the combination of oxidation and ion-exchange treatments S. Echigo; S. Echigo 1Graduate School of Engineering, Kyoto University, C1, Nishikyo, Kyoto 615-8540, Japan E-mail: echigo@urban.env.kyoto-u.ac.jp Search for other works by this author on: This Site PubMed Google Scholar S. Itoh; S. Itoh 1Graduate School of Engineering, Kyoto University, C1, Nishikyo, Kyoto 615-8540, Japan Search for other works by this author on: This Site PubMed Google Scholar S. Ishihara; S. Ishihara 2Kobelco Eco-Solutions Co., Ltd, 1-4-78, Wakihama-cho, Chuo, Kobe 651-0072, Japan Search for other works by this author on: This Site PubMed Google Scholar Y. Aoki; Y. Aoki 3Ajinomoto Co., Inc., 1-1, Suzuki, Kawasaki, Kanagawa 210-8681, Japan Search for other works by this author on: This Site PubMed Google Scholar Y. Hisamoto Y. Hisamoto 4METAWATR Co. Ltd., 1, Fuji-cho, Hino, Tokyo 191-8502, Japan Search for other works by this author on: This Site PubMed Google Scholar Journal of Water Supply: Research and Technology-Aqua (2014) 63 (2): 106–113. https://doi.org/10.2166/aqua.2013.205 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 S. Echigo, S. Itoh, S. Ishihara, Y. Aoki, Y. Hisamoto; Reduction of chlorinous odor by the combination of oxidation and ion-exchange treatments. Journal of Water Supply: Research and Technology-Aqua 1 March 2014; 63 (2): 106–113. doi: https://doi.org/10.2166/aqua.2013.205 Download citation file: Ris (Zotero) Reference Manager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex To better control chlorinous odor in tap water, we assessed the performance of the combination of oxidation (ozonation or advanced oxidation processes, AOP) and ion-exchange treatment. In this process, the hydrophilic neutral fraction (a major dissolved organic matter (DOM) fraction) is converted to ionic species, and these ions and ammonium ion are effectively removed during ion-exchange processes. We found that each treatment process (e.g., oxidation alone or ion exchange alone) was effective for the reduction of chlorinous odor to some extent, but the chlorinous odor formation potential was lower when the oxidation process and ion exchange were applied in series. The combination of AOP (ozone/vacuum ultraviolet treatment) at a high ozone dose and ion exchange (both cation and anion) was most effective, and the chlorinous odor formation potential was reduced to approximately 30 TON (threshold odor number) from more than 100 TON. Also, dissolved organic carbon and ammonium ion were effectively removed with this process. Compared with ozonation, AOP was more effective at a higher ozone dose. The effectiveness of this process was also confirmed in continuous mode by pilot-scale experiment. advanced oxidation, ammonium ion, chlorinous odor, dissolved organic matter, ion exchange, trichloramine This content is only available as a PDF. © IWA Publishing 2014 You do not currently have access to this content.

Drinking water: the problem of chlorinous odours

Chlorinous off-flavours in drinking water are a leading cause of complaints to Australian water utilities and other utilities worldwide. The occurrence and causes of chlorinous odours in drinking water were investigated with the use of an odour panel, trained using a modified flavour profile analysis technique. A new system for classifying water types according to the causes of chlorinous odours was developed in order to enable improved management strategies for the reduction of these off-flavours. Waters of ‘Type 1’ exhibit a chlorinous odour only when the free chlorine equivalent concentration is equal to or above the odour threshold concentration (OTC) for free chlorine. Waters exhibiting a chlorinous odour both above and below the OTC of free chlorine are designated ‘Type 2’. ‘Type 3’ waters are those in which the possible presence of a chlorinous odour is masked by another odour. Although causative compounds of the chlorinous off-flavours were not determined, bromine was proposed to play an important role in distribution systems where source waters have high concentrations of bromide that may not be removed by the available treatment processes. Management strategies for improvements in aesthetic water quality for each water type are proposed.