Chlorination By-products Research Articles

Chlorination by-products of bisphenol A enhanced retinoid X receptor disrupting effects

There is increasing evidence of activities of chlorinated by-products of bisphenol A (BPA) on retinoic acid system. Their agonistic and antagonistic activities to human retinoid X receptor (RXR) were assessed by a two-hybrid yeast assay. Aqueous solutions of 1mg/L BPA were chlorinated by sodium hypochlorite (NaClO). It showed that chlorination of BPA increased RXRβ antagonistic activity, while no agonistic activity was detected, showing chlorine might act as a toxic potentiator rather than a toxic deactivator in RXRβ disrupting effects. BPA and its byproducts including 2,2′,6,6′-tetrachlorobisphenol A (TCBPA) and 2,4,6-trichlorophenol (TCP) were quantitatively determined by gas chromatography/mass spectrometry (GC/MS). BPA rapidly degraded. With the increasing of ICC and reaction time, concentration of formed TCBPA increased initially then decreased, while concentration of formed TCP increased stably. Using the toxic equivalent (TEQ) approach, the main contributors should be mono-, di- and tri- chlorobisphenol A at initial chlorine concentration (ICC) of 1mg/L. At ICC of 2 and 5mg/L, the main contributors were TCBPA and TCP, being 57.7%–70.7% and 45.3%–59.4%. Molecular docking showed BPA chlorination by-products might have the same mode of action with BPA, forming hydrogen bond and pi–pi interaction with their OH group or hydrophobic ring.

Colorectal Cancer and Long-Term Exposure to Trihalomethanes in Drinking Water: A Multicenter Case-Control Study in Spain and Italy.

Background:Evidence on the association between colorectal cancer and exposure to disinfection by-products in drinking water is inconsistent.Objectives:We assessed long-term exposure to trihalomethanes (THMs), the most prevalent group of chlorination by-products, to evaluate the association with colorectal cancer.Methods:A multicenter case–control study was conducted in Spain and Italy in 2008–2013. Hospital-based incident cases and population-based (Spain) and hospital-based (Italy) controls were interviewed to ascertain residential histories, type of water consumed in each residence, frequency and duration of showering/bathing, and major recognized risk factors for colorectal cancer. We estimated adjusted odds ratios (OR) for colorectal cancer in association with quartiles of estimated average lifetime THM concentrations in each participant’s residential tap water (micrograms/liter; from age 18 to 2 years before the interview) and estimated average lifetime THM ingestion from drinking residential tap water (micrograms/day).Results:We analyzed 2,047 cases and 3,718 controls. Median values (ranges) for average lifetime residential tap water concentrations of total THMs, chloroform, and brominated THMs were 30 (0–174), 17 (0–63), and 9 (0–145) μg/L, respectively. Total THM concentration in residential tap water was not associated with colorectal cancer (OR = 0.92, 95% CI: 0.66, 1.28 for highest vs. lowest quartile), but chloroform concentrations were inversely associated (OR = 0.31, 95% CI: 0.24, 0.41 for highest vs. lowest quartile). Brominated THM concentrations showed a positive association among men in the highest versus the lowest quartile (OR = 1.43, 95% CI: 0.83, 2.46). Patterns of association were similar for estimated average THM ingestion through residential water consumption.Conclusions:We did not find clear evidence of an association between detailed estimates of lifetime total THM exposure and colorectal cancer in our large case–control study population. Negative associations with chloroform concentrations and ingestion suggest differences among specific THMs, but these findings should be confirmed in other study populations.Citation:Villanueva CM, Gracia-Lavedan E, Bosetti C, Righi E, Molina AJ, Martín V, Boldo E, Aragonés N, Perez-Gomez B, Pollan M, Gomez Acebo I, Altzibar JM, Jiménez Zabala A, Ardanaz E, Peiró R, Tardón A, Chirlaque MD, Tavani A, Polesel J, Serraino D, Pisa F, Castaño-Vinyals G, Espinosa A, Espejo-Herrera N, Palau M, Moreno V, La Vecchia C, Aggazzotti G, Nieuwenhuijsen MJ, Kogevinas M. 2017. Colorectal cancer and long-term exposure to trihalomethanes in drinking water: a multicenter case–––control study in Spain and Italy. Environ Health Perspect 125:56–65; http://dx.doi.org/10.1289/EHP155

Transformation pathways and acute toxicity variation of 4-hydroxyl benzophenone in chlorination disinfection process

Benzophenones compounds (BPs) are widely used as UV filters, and have been frequently found in multiple environmental matrices. The residual of BPs in water would cause potential threats on ecological safety and human health. Chlorination disinfection is necessary in water treatment process, in which many chemicals remained in water would react with disinfectant chlorine and form toxic by-products. By using ultra performance liquid phase chromatography quadrupole time of flight mass spectrometer (UPLC-QTOF-MS), nuclear magnetic resonance (NMR), the transformation of 4-hydroxyl benezophenone (4HB) with free available chlorine (FAC) was characterized. Eight major products were detected and seven of them were identified. Transformation pathways of 4HB under acid, neutral, and alkaline conditions were proposed respectively. The transformation mechanisms involved electrophilic chlorine substitution of 4HB, Baeyer-Villiger oxidation of ketones, hydrolysis of esters and oxidative breakage of benzene ring. The orthogonal experiments of pH and dosages of disinfectant chlorine were conducted. The results suggested that pH conditions determined the occurrence of reaction types, and the dosages of disinfectant chlorine affected the extent of reactions. Photobacterium assay demonstrated that acute toxicity had significant increase after chlorination disinfection of 4HB. It was proved that 3,5-dichloro-4HB, one of the major transformation products, was responsible for the increasing acute toxicity after chlorination. It is notable that, 4HB at low level in real ambient water matrices could be transformed during simulated chlorination disinfection practice. Especially, two major products 3-chloro-4HB and 3,5-dichloro-4HB were detected out, implying the potential ecological risk after chlorination disinfection of 4HB.

Laboratory-scale simulations with hydrated lime and organic polymer to evaluate the effect of pre-chlorination on motile <i>Ceratium hirundinella</i> cells during conventional water treatment

Algal genera such as Carteria, Chlamydomonas, Chlorogonium, Cryptomonas, Ceratium, Peridinium and Euglena are motile and may disrupt unit processes and cause water treatment problems. Algal species belonging to these motile algal genera are known to interfere with coagulation and flocculation unit processes which are the main processes for algal removal. These cells are well adapted, by means of their motile structures, morphological shapes and storage products, to remain in the supernatant (by swimming or floating) until it is carried over to sand filters, where cells may cause filter-clogging problems. When organic material is released from algal cells as a result of physical-chemical impacts on the cells, it may result in tasteand odour-related problems or the formation of harmful organic products such as trihalomethanes (THM). The aims of this study were to: (i) determine chlorine concentrations required to immobilise C. hirundinella cells; (ii) determine the removal efficiencies of pre-chlorination; (iii) investigate the integrity of C. hirundinella cells; and (iv) identify trihalomethanes that are formed. Source water samples enriched with C. hirundinella cells were exposed to a pre-determined chlorineconcentration range (0.05–0.45 mg/L). This study found that the half-maximal inhibitory concent ration (IC50-values) for chlorine < 0.20 mg/L is sufficient to render C. hirundinella cells immobile, while cells remain intact. Pre-chlorination did not have an impact on C. hirundinella removal when hydrated lime was used as a coagulant or coagulant aid. However, when organic polymer only was used as coagulant, removal efficiencies were improved by 20%. Chlorine by-products were measured, but posed no specific health risks to drinking water consumers due to the low concentration levels measured. Algal removal challenges that occur in water treatment plants when dosing organic polymers can be resolved by implementation of effective pre-chlorination strategies. Keywords : algae, coagulation, dinoflagellate, pre-treatment, trihalomethanes (THM)

Protein-bound tyrosine oxidation, nitration and chlorination by-products assessed by ultraperformance liquid chromatography coupled to tandem mass spectrometry

BackgroundFree radicals cause alterations in cellular protein structure and function. Oxidized, nitrated, and chlorinated modifications of aromatic amino acids including phenylalanine and tyrosine are reliable biomarkers of oxidative stress and inflammation in clinical conditions. ObjectiveTo develop, validate and apply a rapid method for the quantification of known hallmarks of tyrosine oxidation, nitration and chlorination in plasma and tissue proteins providing a snapshot of the oxidative stress and inflammatory status of the organism and of target organs respectively. Material and MethodsThe extraction and clean up procedure entailed protein precipitation, followed by protein re-suspension and enzymatic digestion with pronase. An Ultra Performance Liquid Chromatography–tandem Mass Spectrometry (UPLC-MS/MS) method was developed to quantify protein released ortho-tyrosine (o-Tyr), meta-tyrosine (m-Tyr), 3-nitrotyrosine (3NO2-Tyr) and 3-chlorotyrosine (3Cl-Tyr) as well as native phenylalanine (Phe) and tyrosine (p-Tyr) in plasma and tissue from a validated hypoxic newborn piglet experimental model. ResultsIn plasma there was a significant increase in the 3NO2-Tyr/p-Tyr ratio. On the other hand m-Tyr/Phe and 3Cl-Tyr/p-Tyr ratios were significantly increased in liver of hypoxic compared with normoxic animals. Although no significant differences were found in brain tissue, a clear tendency to increased ratios was observed under hypoxic conditions. ConclusionsUPLC-MS/MS has proven suitable for the analysis of plasma and tissue samples from newborn piglets. The analysis of biomarkers of protein oxidation, nitration and chlorination will be applied in future studies aiming to provide a deeper insight into the mechanisms of oxidation-derived protein modification caused during neonatal asphyxia and resuscitation.

2,3,7,8-Tetrachlorodibenzo-p-dioxin: Genotoxicity and Oxidative Damage Potential in Human Peripheral Blood Lymphocytes

Dioxin-like compounds, e.g. 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzo-furans (PCDFs) and dioxin-like polychlorinated biphenyls (PCBs) are a widespread and diverse group of persistent, lipophilic and hazardous environmental pollutants. Additionally, because they are by-products of chlorine- containing manufacturing process and incineration, they represent a serious environmental problem. In this research study; we investigated the genotoxic and oxidative effects of TCDD using single cell gel electrophoresis/COMET assay and measuring levels of catalase, superoxide dismutase enzymes, and malondialdehyde values for lipid peroxidation in peripheral blood lymphocyte cultures at three different doses. Blood samples were taken from healthy non-smoking male subjects by venipuncture. In this study, the three doses of 2,3,7,8-tetrachlorodibenzo-p-dioxin were used as 62.5 ng/ml, 31.25 ng/ml, 15.625 ng/ml. In comet assay, two different parameters were evaluated. Damaged cell percent (DCP). Genetic damage index (GDI). Both GDI and DCP significantly increased in a dose-dependent manner at statistical level. There is no statistically significant difference the levels of catalase, superoxide dismutase enzymes, malondialdehyde values compared with negative control.

Remediation of hexachlorocyclohexanes by cobalt-mediated activation of peroxymonosulfate

Hexachlorocyclohexane isomers (HCHs) are one of the most ubiquitous and most easily detected organochlorine pesticides in environmental samples. This global distribution is enabled by HCH persistence. Moreover, HCH tends to bioaccumulate in human and animal adipose tissue. Since certain HCHs cause central nervous system, reproductive, and other endocrine damages, there is a necessity of a suitable remediation method to remove HCH from contaminated groundwater and soil. This study was conducted to evaluate the potential of peroxymonosulfate (Oxone) induced by cobalt salt (Co(NO3)2; Co(II)) to degrade HCHs. Cobalt(II) nitrate has been chosen instead of cobalt(II) chloride (which presents better activation properties for Oxone) in order to avoid an excess of chloride interference and more additional chlorination by-products. The optimal conditions (oxidant dose as well as cobalt dose) were determined for spiked water with HCH (0.85μm of summed HCH isomers). Optimal oxidant dose was established by running a test with three different Oxone concentrations (molar ratio of Oxone:Co(NO3)2—1:0.1): 0.06, 0.6, and 6 mM. Degradation curves of summed HCH isomers were fitted into the pseudo-first-order kinetic model, and reaction rates are shown to be 0.03, 0.31, and 0.55 min−1 for doses 0.06, 0.6, and 6 mM, respectively. Further experiments were carried out to determine the optimal Oxone:Co(NO3)2 molar ratio. Effectiveness of HCHs decontamination by Oxone:Co(NO3)2 in various molar ratios was in the order 1:0.1 > 1:1 > 1:0.01 > 1:0.001. It was observed that surplus of Co(NO3)2 can slow down the degradation rate constants. A reaction between sulfate radicals and Co(NO3)2 could be responsible for this phenomenon, which can lead to the formation of sulfate ions without HCHs oxidation. In addition, tests with higher HCH dose (close to the solubility limit) were carried out to determine by-products of decontamination. In these tests 2,4,6-trichlorophenol (2,4,6-TCP) was found to be the major intermediate of HCH isomers degradation. Trace levels of the trichlorobenzene (TCB), tetrachlorophenol (TeCP), and pentachlorophenol (PCP) were detected as well. The study revealed that Oxone induced by Co(II) shows a high degradation rate with HCH isomers, which can make it an attractive method for HCHs decontamination in the future.

Water supply of Zaporizhzhya Priazovye: nascent, stages of development, problems of nowadays and hygienic substantiation of ways of their solutions.

At the modern stage of development humanity is on the verge of the pandemic of non-communicable diseases. It is not an exception for the population of the Ukraine, among which more than 2/3 of the total morbidity incidences is non-communicable diseases: desieses of cardiovascular system, cancer, chronic respiratory diseases, diabetes. To the mind of experts in the field of public health and environment protection,the first place among factors affecting the level of population’s health in Ukraine is given to the water that is ahead of air and food products in this aspect. Taking into consideration the fact that after annexation of the Crimea by the Russian Federation in March of 2014and uncertainty in the military-political situation on the East of the Ukraine, Zaporizhzhya Priazovye is becoming a recreational zone, and with each year it will be used by more and more Ukrainian citizens.The objective of our research was to investigate nascent, stages of development and nowadays problems of region’s water supply as well as hygienic substantiation of complex ways of nowadays problem of Zaporizhzhya Priazovye water supply. As a result of conducted researches it was found that single economically feasible way of providing population of Zaporizhzhya Priazovye with water with normative total hardness and general mineralization is supply ofthe Dnipro water carried out by operation ofWestern group water conduit. To reduce the formation of chlorination by-products in the process of water purification it is necessary to use iron-containing chlorine-sulfate coagulant "Aula" of brand A according to the technical requirements TR U 24.1-33075701-002: 2011. For utilization of flush water of contact clarifiers, it is necessary to retool water purification facilities by clarifiers-recirculators with sediment recirculation in “inner contour”. It was proved that corrosive aggressiveness is an indicator of water quality which will determine further development of the group water conduits of Ukraine. At the same time it was established that stabilization and correction of water corrosive aggressiveness with chemical Sea-Quest allows to supply normative quality water through extended water supply systems to the end consumers, to significantly slow down the process of senescence, particularly in pipelines and in tanks of clean water as well.

Hybrid disinfection of sewage effluent—A comparative study of three secondary treatment plants of Jaipur, India

Chlorination is one of the most widely used methods to disinfect wastewater, despite innumerable objections raised due to the resultant by-products. Any attempt to reduce the dosage of chlorine can be very useful in lowering the concentration of the disinfection by-products, many of which have been reported to be carcinogenic. This study examines the microbiological characterization of secondary treated sewage from three different sewage treatment plants based on different unit processes, namely activated sludge process, moving bed biofilm reactor and rotating biological contractor. The study also assesses the efficacy of using chlorine on major coliform species in order to achieve the objective of bringing the effluent to the desired standard for total coliform count (TCC) of 1,000 per 100 mL. The results indicate that 5 parts per million (ppm) chlorine dose (CD) was able to attain the TCC standard, if the counts for Serratia/Hafnia species were ignored. These species offered high resistance to chlorination due to which excessive overall doses were required to confirm to TCC standard. The chlorinated samples were further subjected to ultraviolet (UV-C) disinfection, the results of which can be employed to design a hybrid disinfection strategy with chlorination at a relatively low CD as the first step for removing bulk of the coliform population, followed by another process to which Serratia/Hafnia are susceptible. This can not only reduce the CD and thereby the by-products of chlorination but also bring down the overall cost of disinfection.

Chlorination and oxidation of sulfonamides by free chlorine: Identification and behaviour of reaction products by UPLC-MS/MS

Sulfonamides (SAs) are one class of the most widely used antibiotics around the world and have been frequently detected in municipal wastewater and surface water in recent years. Their transformation in waste water treatment plants (WWTP) and in water treatment plants (WTP), as well as, their fate and transport in the aquatic environment are of concern.The reaction of six sulfonamides (sulfamethoxazole, sulfapyridine, sulfamethazine, sulfamerazine, sulfathiazole and sulfadiazine) with free chlorine was investigated at a laboratory scale in order to identify the main chlorination by-products. A previously validated method, liquid chromatography/mass spectrometry, was used to analyse SAs and their chlorination by-products. At room temperature, pH 6–7, reaction times of up to 2 h and an initial concentration of 2 mg/L of free chlorine, the majority of SAs suffered degradation of around 65%, with the exception of sulfamethoxazole and sulfathiazole (20%). The main reaction of SAs with free chlorine occurred in the first minute.

Chlorination by-product concentration levels in seawater and fish of an industrialised bay (Gulf of Fos, France) exposed to multiple chlorinated effluents

Chlorination is one of the most widely used techniques for biofouling control in large industrial units, leading to the formation of halogenated chlorination by-products (CBPs). This study was carried out to evaluate the distribution and the dispersion of these compounds within an industrialised bay hosting multiple chlorination discharges issued from various industrial processes. The water column was sampled at the surface and at 7m depth (or bottom) in 24 stations for the analysis of CBPs, and muscle samples from 15 conger eel (Conger conger) were also investigated. Temperature and salinity profiles supported the identification of the chlorination releases, with potentially complex patterns. Chemical analyses showed that bromoform was the most abundant CBP, ranging from 0.5 to 2.2μgL−1 away from outlets (up to 10km distance), and up to 18.6μgL−1 in a liquefied natural gas (LNG) regasification plume. However, CBP distributions were not homogeneous, halophenols being prominent in a power station outlet and dibromoacetonitrile in more remote stations. A seasonal effect was identified as fewer stations revealed CBPs in summer, probably due to the air and water temperatures increases favouring volatilisation and reactivity. A simple risk assessment of the 11 identified CBPs showed that 7 compounds concentrations were above the potential risk levels to the local marine environment. Finally, conger eel muscles presented relatively high levels of 2,4,6-tribromophenol, traducing a generalised impregnation of the Gulf of Fos to CBPs and a global bioconcentration factor of 25 was determined for this compound.

Fate of natural organic matter at a full-scale Drinking Water Treatment Plant in Greece.

The aim of this study was to investigate the fate of natural organic matter (NOM) and subsequent changes during the various treatment processes at a full-scale Drinking Water Treatment Plant (DWTP). Monthly sampling campaigns were conducted for 1 year at six sites along DWTP of Thessaloniki, Northern Greece including raw water from the Aliakmonas River that supplies DWTP and samples from various treatment processes (pre-ozonation, coagulation, sand filtration, ozonation, and granular activated carbon (GAC) filtration). The concentration of NOM and its characteristics as well as the removal efficiency of various treatment processes on the basis of dissolved organic carbon, UV absorbance, specific ultra-violet absorbance, fluorescence intensity, hydrophobicity, biodegradable dissolved organic carbon, and formation potential of chlorination by-products trihalomethanes (THMs) and haloacetic acids (HAAs) were studied. The concentration of dissolved organic carbon (DOC) in reservoir of the Aliakmonas River ranged from 1.46 to 1.84 mg/L, exhibiting variations regarding UV, fluorescence, and hydrophobic character through the year. Along DWTP, a significant reduction of aromatic, fluorophoric, and hydrophobic character of NOM was observed resulting in significant elimination of THM (63%) and HAAs (75%) precursors.

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

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.

Enhancement effects of ultrasound on secondary wastewater effluent disinfection by sodium hypochlorite and disinfection by-products analysis

Since fecal coliforms was introduced as a standard indicator of pollutants in effluents of municipal wastewater treatment plants in China in 2003, chlorine had been widely used in many wastewater treatment plants. However, concerns about the disinfection by-products (DBPs) of chlorine have been increasing. One of the effective way to reduce the production of DBPs is to reduce the effective chlorine dosage by improving the utilization rate of disinfectant. Ultrasound (US) is proved to be effective in wastewater treatment for its multiple chemical and physical effects produced by cavitation, which could favor the disinfection process accordingly. For the purpose of improving disinfection efficiency with the help of US, following points are addressed in the current study: (1) investigate the enhancement effects of US on the disinfection efficiency of sodium hypochlorite (NaClO) for real secondary effluents of municipal wastewater treatment plants; (2) evaluate the possibility of using US specific energy consumption (kJ/L) as an parameter for disinfection efficiency evaluation; and (3) quantify the reduction in chlorine-DBPs through US application. Results demonstrated that sonication could reduce two-thirds (US pretreatment) or one-third (simultaneous US and NaClO disinfection) of the required concentrations of NaClO (available chlorine) for 4 log reduction of fecal coliforms, which could meet the Class 1A (fecal coliforms less than 1000CFU/L) discharge standard of China. In addition, US pretreatment with NaClO disinfection performed better enhancement in disinfection efficiency compared with simultaneous US and NaClO disinfection. Furthermore, analysis on DBPs showed that US application as pretreatment could obviously reduce the contents of trichloromethane (TCM) and trichloroacetic acid (TCAA) by more than 85% and 50%, respectively, compared with NaClO disinfection alone for the same disinfection efficiency. Meanwhile, the experimental results also showed that the disinfection efficiency and DBPs concentration were only slightly affected under a constant US specific energy consumption, although input power density and irradiation time changed, indicating that specific energy consumption (kJ/L) could be considered as a better control parameter for disinfection efficiency evaluation.

Formation of Chlorination Byproducts and Their Emission Pathways in Chlorine Mediated Electro-Oxidation of Urine on Active and Nonactive Type Anodes.

Chlorination byproducts (CBPs) are harmful to human health and the environment. Their formation in chlorine mediated electro-oxidation is a concern for electrochemical urine treatment. We investigated the formation of chlorate, perchlorate, and organic chlorination byproducts (OCBPs) during galvanostatic (10, 15, 20 mA · cm(-2)) electro-oxidation of urine on boron-doped diamond (BDD) and thermally decomposed iridium oxide film (TDIROF) anodes. In the beginning of the batch experiments, the production of perchlorate was prevented by competing active chlorine and chlorate formation as well as by direct oxidation of organic substances. Perchlorate was only formed at higher specific charges (>17 Ah · L(-1) on BDD and >29 Ah · L(-1) on TDIROF) resulting in chlorate and perchlorate being the dominant CBPs (>90% of initial chloride). BDD produced mainly short chained OCBPs (dichloromethane, trichloromethane, and tetrachloromethane), whereas longer chained OCBPs (1,2-dichloropropane and 1,2-dichloroethane) were more frequently found on TDIROF. The OCBPs were primarily eliminated by electrochemical stripping: On BDD, this pathway accounted for 40% (dichloromethane) to 100% (tetrachloromethane) and on TDIROF for 90% (1,2-dichloroethane) to 100% (trichloromethane) of what was produced. A post-treatment of the liquid as well as the gas phase should be foreseen if CBP formation cannot be prevented by eliminating chloride or organic substances in a pretreatment.

Development of a Site-Specific Kinetic Model for Chlorine Decay and the Formation of Chlorination By-Products in Seawater

Chlorine is used commonly to prevent biofouling in cooling water systems. The addition of chlorine poses environmental risks in natural systems due to its tendency to form chlorination by-products (CBPs) when exposed to naturally-occurring organic matter (NOM). Some of these CBPs can pose toxic risks to aquatic and benthic species in the receiving waters. It is, therefore, important to study the fate of residual chlorine and CBPs to fully understand the potential impacts of chlorination to the environment. The goal of this study was to develop improved predictions of how chlorine and CBP concentrations in seawater vary with time, chlorine dose and temperature. In the present study, chlorination of once-through cooling water at Ras Laffan Industrial City (RLIC), Qatar, was studied by collecting unchlorinated seawater from the RLIC cooling water system intake, treating it with chlorine and measuring time series of chlorine and CBP concentrations. Multiple-rate exponential curves were used to represent fast and slow chlorine decay and CBP formation, and site-specific chlorine kinetic relationships were developed. Through extensive analysis of laboratory measurements, it was found that only some of the control parameters identified in the literature were important for predicting residual chlorine and CBP concentrations for this specific location. The new kinetic relationships were able to significantly improve the predictability and validity of Generalized Environmental Modeling System for Surfacewaters (GEMSS)-chlorine kinetics module (CKM), a three-dimensional hydrodynamic and chlorine kinetics and transport model when applied for RLIC outfall studies using actual field measurements.

Removal of trihalomethane from chlorinated seawater using gamma radiation.

Chlorine addition as a biocide in seawater results in the formation of chlorination by-products such as trihalomethanes (THMs). Removal of THMs is of importance as they are potential mutagenic and carcinogenic agents. In this context, a study was conducted that used ionizing radiation to remove THMs from chlorinated (1, 3, and 5 mg/L) seawater by applying various dosages (0.4-5.0 kGy) of gamma radiation. Bromoform (BF) showed a faster rate of degradation as compared to other halocarbons such as bromodichloromethane (BDCM) and dibromochloromethane (DBCM). In chlorine-dosed seawater, total irradiation dose of 0.4 to 5 kGy caused percentage reduction in the range of 6.9 to 76.7%, 2.3 to 99.6%, and 45.7 to 98.3% for BDCM, DBCM, and BF, respectively. During the irradiation process, pH of the chlorinated seawater decreased with increase in the absorbed dose; however, no change in total organic carbon (TOC) was observed. The results show that gamma dose of 2.5 kGy was adequate for maximum degradation of THM; but for complete mineralization, higher dose would be required.

Formation of trichloromethane in chlorinated water and fresh-cut produce and as a result of reaction with citric acid

Chlorine (sodium hypochlorite) is commonly used by the fresh produce industry in the U.S. to sanitize wash water, fresh and fresh-cut fruits and vegetables. However, possible formation of harmful chlorine by-products is a concern. The objectives of this study were to compare chlorine and chlorine dioxide in trichloromethane formation, determine trichloromethane levels in chlorinated wash water, cut-lettuce and diced onions, and evaluate the reaction of chlorine with citric acid, a chemical often used to adjust pH of chlorine solution. Results showed that little trichloromethane (≤3μgL−1) was produced from chlorine dioxide solution even at concentrations up to 200mgL−1 compared with the trichloromethane level (∼40μgL−1) in solutions of chlorine mixed with lettuce extract. The formation of trichloromethane in 1L of 100mgL−1 chlorine wash water increased from 155 to 284μgL−1 after repeated use of the wash water to wash six batches of 100g cut lettuce. Levels of trichloromethane in the washed cut lettuce were in the range of 14–22μgkg−1, and were reduced to less than 8μgkg−1 after being rinsed with water. Chlorine solution used to wash diced onions produced much less trichloromethane (32μgL−1) compared with that for washing cut lettuce despite higher chemical oxygen demand and turbidity in the wash water. Citric acid reacted with chlorine and produced trichloromethane. Over 1000μgL−1 trichloromethane was produced after 30min reaction with chlorine at 22°C, while less than 35μgL−1 trichloromethane was produced when Na-phosphate was used to adjust pH of chlorine. The amount of trichloromethane increased with reaction time and concentration of citrate. Our results demonstrated that formation of trichloromethane in wash water depended on type of cut-vegetables, and citric acid contributed to a significant amount of trichloromethane formation.

Can electrochemical oxidation techniques really decontaminate saline dyes wastewater?

Formation of toxic chlorinated organic byproducts is of great concern when selecting electrochemical oxidation (EO) as decontamination technology for saline dye wastewater, but still not verified. To test the applicability of EO, methyl orange (MO) was used as a model dye for anodic contact glow discharge electrolysis (CGDE) and conventional electrolysis (CE) in the presence of chloride. The degradation kinetics and organic intermediates were analyzed. In the presence of chloride, the rates of dye degradation were significantly increased as CGDE and CE were applied. CE resulted in higher mineralization efficiency than CGDE which needs much energy input. Several refractory chlorinated aromatic and even aliphatic compounds were identified during MO degradation, as well as the other anthraquinone dye, alizarin red S (AR). Therefore, the issues of toxic chlorinated byproducts and energy cost should be preferentially evaluated prior to the selection of EO technologies.

Ubiquitous occurrence of chlorinated byproducts of bisphenol A and nonylphenol in bleached food contacting papers and their implications for human exposure.

The occurrence of bisphenol A (BPA), nonylphenol (NP), and their six chlorinated byproducts were investigated in 74 food contacting papers (FCPs) from China, the U.S.A., Japan, and Europe using a sensitive dansylation LC-MS/MS method. BPA (<LOQ-83 ng/g) and NP (<LOQ-5.4 ng/g) were widely detected in FCPs, while the six chlorinated byproducts were detected in less than half of the samples. The concentrations of chlorinated BPAs and chlorinated NPs in FCPs were significantly correlated with the concentrations of BPA and NP, respectively, and their concentrations mainly depended on bleaching processes in paper production. The mean concentrations of monochloro-BPA (MCBPA), dichloro-BPA (DCBPA), trichloro-BPA (TCBPA), tetrachloro-BPA (TeCBPA), monochloro-NP (MCNP), and dichloro-NP (DCNP) in bleached FCPs were 0.019 ± 0.025, 0.0033 ± 0.0059, 0.0030 ± 0.0045, 0.0081 ± 0.019, 0.23 ± 0.46, and 0.066 ± 0.11 ng/g, respectively, much higher than those (0.0021 ± 0.0020 ng/g for MCBPA, 0.00068 ± 0.00076 ng/g for DCBPA, <LOQ for TCBPA and TeCBPA, 0.006 ± 0.003 ng/g for MCNP, and <LOQ for DCNP) in unbleached FCPs. Furthermore, it was shown that BPA, NP, and some of their chlorinated byproducts could migrate from coffee filters into coffee solution with migration rates of 71 ± 10% for BPA, 2.4 ± 0.33% for NP, 47 ± 1.4% for MCBPA, and 0.35 ± 0.11% for MCNP. This is the first report on the occurrence of chlorinated derivatives of BPA and NP in FCPs and their migration, which provides important information to comprehensively understand human exposure to BPA, NP, and their chlorinated derivatives.