Formation Of Chlorinated Byproducts Research Articles

Reactive species conversion into 1O2 promotes substantial inhibition of chlorinated byproduct formation during electrooxidation of phenols in Cl−-laden wastewater

The generation of chlorinated byproducts during the electrochemical oxidation (EO) of Cl−-laden wastewater is a significant concern. We aim to propose a concept of converting reactive species (e.g., reactive chlorines and HO• resulting from electrolysis) into 1O2 via the addition of H2O2, which substantially alleviates chlorinated organic formation. When phenol was used as a model organic compound, the results showed that the H2O2-involving EO system outperformed the H2O2-absent system in terms of higher rate constants (5.95 × 10−2 min−1vs. 2.97 × 10−2 min−1) and a much lower accumulation of total organic chlorinated products (1.42 mg L−1vs. 8.18 mg L−1) during a 60 min operation. The rate constants of disappearance of a variety of phenolic compounds were positively correlated with the Hammett constants (σ), suggesting that the reactive species preferred oxidizing phenols with electron-rich groups. After the identification of 1O2 that was abundant in the bulk solution with the use of electron paramagnetic resonance and computational kinetic simulation, the routes of 1O2 generation were revealed. Despite the consensus as to the contribution of reaction between H2O2 and ClO− to 1O2 formation, we conclude that the predominant pathway is through H2O2 reaction with electrogenerated HO• or chlorine radicals (Cl• and Cl2•−) to produce O2•−, followed by self-combination. Density functional theory calculations theoretically showed the difficulty in forming chlorinated byproducts for the 1O2-initiated phenol oxidation in the presence of Cl−, which, by contrast, easily occurred for the Cl•-or HO•-initiated phenol reaction. The experiments run with real coking wastewater containing high-concentration phenols further demonstrated the superiority of the H2O2-involving EO system. The findings imply that this unique method for treating Cl−-laden organic wastewater is expected to be widely adopted for generalizing EO technology for environmental applications.

Revealing the mechanism of formation and transformation of chlorinated by‐products during electrolyzing synthetic urine using Ti/RuOx‐IrOx and BDD electrodes

AbstractIn this study, the mechanism of chlorinated by‐products (CBPs) formation and transformation during urine electrolysis was comparatively investigated with active and nonactive electrodes. It was found that nutrients removal and CBPs formation was dominated by the chlorine evolution on the active Ti/RuOx‐IrOx electrodes. CBPs formation was inhibited by the ammonia and urea chlorination and kept at a relatively low level before chlorination breakpoint. After the concentration of organic CBPs (OCBPs) increasingly reaching the maximum as a result of the peak concentration of free chlorine, most free chlorine transformed into inorganic chlorination by‐products (ICBPs) with the chlorate as the main species. In contrast, the formation of CBPs on boron‐doped diamond (BDD) electrodes was jointly dominated by the direct oxidation and chlorine mediated oxidation, which resulted in the complete degradation of OCBPs and the accumulation of ICBPs throughout the electrolysis. The organics with high molecular weight readily formed CBPs. Moreover, higher current density would accelerate the production of ICBPs on both electrodes, although it could mitigate OCBPs production at chlorination breakpoint for Ti/RuOx‐IrOx anodes. Separation of chloride ions and organics with high molecular weight from urine using nanofiltration was proposed to mitigate the production of CBPs.

Chlorination by-products formation in a drinking water distribution system treated by ultrafiltration associated with pre-ozonation or coagulation/flocculation

One of the main drawbacks of ultrafiltration (UF) membranes is their limited capacity to remove organic matter, which can favour the biofilm development in drinking water distribution systems (DWDS) and the deterioration of water quality, mainly due to the formation of disinfection by-products. This was conducted to assess the evolution of the water quality in an experimental DWDS fed with water treated by spiral-wound-polyvinylidene-fluoride UF membranes. Two different systems were compared: a coagulation-flocculation-UF and an ozonation-UF. Comparison was made with respect to the occurrence of trihalomethanes (THMs) and haloacetic acids (HAAs) as well as biofilm development in the DWDS, along with the evolution of pH, DOC, UV254, turbidity and total aerobic bacteria. During both stages, the surface of the DWDS was colonized by bacteria, and water quality deteriorated, although to a lesser degree when the coagulation-flocculation-UF was applied. The use of ozone caused a higher increase in the formation of both THMs and HAAs than coagulation-flocculation, with chloroform as the only THM detected and dichloroacetic acid as the main HAA (90%) for both stages. Mean THM concentrations of 177.7 μg L−1 and 85.0 μg L−1 of HAAs were registered working with the ozonation-UF, which throws considerable doubt on the potability of the water in DWDS. In addition to the treatment, water temperature was the most influential variable on the formation of HAAs and THMs, whereas DOC, UV254 or specific UV absorbance proved not to be useful parameters for assessing the possible formation of THMs or HAAS in DWDS.

Health effects of exposure to chlorination by-products in swimming pools.

Concerns have been raised regarding the potential negative effects on human health of water disinfectants used in swimming pools. Among the disinfection options, the approaches using chlorine-based products have been typically preferred. Chlorine readily reacts with natural organic matter that are introduced in the water mainly through the bathers, leading to the formation of potentially harmful chlorination by-products (CBPs). The formation of CBPs is of particular concern since some have been epidemiologically associated with the development of various clinical manifestations. The higher the concentration of volatile CBPs in the water, the higher their concentration in the air above the pool, and different routes of exposure to chemicals in swimming pools (water ingestion, skin absorption, and inhalation) contribute to the individual exposome. Some CBPs may affect the respiratory and skin health of those who stay indoor for long periods, such as swimming instructors, pool staff, and competitive swimmers. Whether those who use chlorinated pools as customers, particularly children, may also be affected has been a matter of debate. In this article, we discuss the current evidence regarding the health effects of both acute and chronic exposures in different populations (work-related exposures, intensive sports, and recreational attendance) and identify the main recommendations and unmet needs for research in this area.

Chlorinated Byproduct Formation during the Electrochemical Advanced Oxidation Process at Magnéli Phase Ti4O7 Electrodes.

This research investigated chlorinated byproduct formation at Ti4O7 anodes. Resorcinol was used as a model organic compound representative of reactive phenolic groups in natural organic matter and industrial phenolic contaminants and was oxidized in the presence of NaCl (0-5 mM). Resorcinol mineralization was >68% in the presence and absence of NaCl at 3.1 V/SHE (residence time = 13 s). Results indicated that ∼4.3% of the initial chloride was converted to inorganic byproducts (free Cl2, ClO2-, ClO3-) in the absence of resorcinol, and this value decreased to <0.8% in the presence of resorcinol. Perchlorate formation rates from chlorate oxidation were 115-371 mol m-2 h-1, approximately two orders of magnitude lower than reported values for boron-doped diamond anodes. Liquid chromatography-mass spectroscopy detected two chlorinated organic products. Multichlorinated alcohol compounds (C3H2Cl4O and C3H4Cl4O) at 2.5 V/SHE and a monochlorinated phenolic compound (C8H7O4Cl) at 3.1 V/SHE were proposed as possible structures. Density functional theory calculations estimated that the proposed alcohol products were resistant to direct oxidation at 2.5 V/SHE, and the C8H7O4Cl compound was likely a transient intermediate. Chlorinated byproducts should be carefully monitored during electrochemical advanced oxidation processes, and multibarrier treatment approaches are likely necessary to prevent halogenated byproducts in the treated water.

Comparison of the Fe2+/H2O2 and Fe2+/PMS systems in simulated sludge: Removal of PAHs, migration of elements and formation of chlorination by-products

In this study, polycyclic aromatic hydrocarbons (PAHs) at practical concentrations in the simulated sludge treated by the Fe2+/H2O2 and Fe2+/peroxymonosulfate (PMS) systems were evaluated in terms of the PAHs (phenanthrene, anthracene, fluoranthene) removal, element migration, Cl− effect, and chlorination by-product formation. The results indicated that according to the removal rate of PAHs, the optimal dosage of the Fe2+/PMS system (∑PAHs removal rate was 64.66 ± 2.82 %) was 1/30 of that for the Fe2+/H2O2 system (∑PAHs removal rate was 78.63 ± 0.38 %). The elemental contents in the simulated sludge were mainly affected by the extent of advanced oxidation and the amount of generated iron flocs. By studying the PAHs removal, free chlorine formation, total organochlorine content, and PAHs products in Fe2+/H2O2/Cl- and Fe2+/PMS/Cl- systems, it was found that chlorine radicals (·Cl) had high reactivity with phenanthrene and fluoranthene, whereas dichloride anion radicals (Cl2·-) exhibited the opposite behavior. Furthermore, PAHs were oxidized by ·Cl and hydroxyl radical in the Fe2+/H2O2/Cl- system, whereas PAHs and their products were chlorinated by free chlorine and ·Cl in the Fe2+/PMS/Cl- system to six chlorinated by-products such as Cl-PAHs (9-Cl-phenanthrene, 2-Cl-anthracene, 9,10-Cl2-anthracene, 3-Cl-fluoranthene). These results provide some useful suggestions for the safe advanced oxidation process treatment of textile dyeing sludge.

Formation of chlorination by-products in drinking water treatment plants using breakpoint chlorination

In drinking water treatment plants generally chlorination is applied for disinfection using Cl2, ClO2, or NaOCl reagents. In Hungary due to the relatively high ammonium ion concentration of source water originating from deep aquifiers, not only the disinfection but simultaneously the ammonium ion removal is also a crucial task to prevent the nitrite formation. For this purposes the breakpoint chlorination is used which needs approximately 10 times more chlorine than the disinfection resulting in enhanced formation of organic and inorganic by-products. Chlorination by-product formation was investigated in twelve drinking water treatment plants applying breakpoint chlorination. Trihalomethanes were detected in the highest concentration (14.7 μg/L to 143 μg/L), followed by haloacetic acids and haloacetonitriles. In 50% of the investigated water treatment plants, the concentration of trihalomethanes in finished water exceeded the Hungarian parametric value, but it was the same range as in water supplies using chlorine for disinfection. The concentration of trihalomethanes, haloacetic acids, haloacetonitriles and adsorbable organic halides in finished water was found to correlate with residual free chlorine (r > 0.5) and raw water temperature (r > 0.48). At high bromide concentration (cBr- > 0.2 mg/L) of the raw water the proportion of brominated by-products (trihalomethanes and haloacetic acids) increased up to 50%. Chlorate concentration was particularly high at drinking water treatment plants using hypochlorite (0.66–2.0 mg/L).By-products are mostly generated at breakpoint chlorination, but their additional formation within the water distribution system is also significant, especially where the concentration of free chlorine is high and the residence time is long. Elimination (potentially biodegradation) of haloacetic acids and haloacetonitriles was observed at several sampling sites. The efficiency of the granulated activated carbon filters in removing adsorbable organic halides, trihalomethanes and haloacetic acids amounted generally under 25%.

Impact of UV disinfection on potential of personal care products components on chlorination by-products formation in swimming pool water

Impact of UV disinfection on potential of personal care products components on chlorination by-products formation in swimming pool water

Investigation on decolorization of biologically pretreated cellulosic ethanol wastewater by electrochemical method

The biologically pretreated cellulosic ethanol wastewater poses a serious environmental concern because of its refractory and color compounds. The decolorization of electrochemical oxidation using Sb doped Ti/SnO2 electrode for advanced treatment of cellulosic ethanol wastewater under different current density (5–30mA·cm−2), initial pH (3–8.9) and supporting electrolyte (0–0.25M NaCl) was investigated in this study. Complete decolorization, 8.5% chemical oxygen demand (COD) and 69.1% dissolved organic carbon removal efficiencies were achieved under the optimal conditions (20mA·cm−2, pH 5 and supporting electrolyte of 0.1M NaCl) after 150min. The energy consumption required to meet National Discharge Standard (GB 27631-2011) is 93.8kWhkg COD−1. Further investigation revealed that hydroxyl radicals played a primary role in the degradation of organic contaminants, while active chlorine formed from chloride oxidation played a less important role. Direct anodic oxidation and indirect reaction via peroxodisulfate generated from sulfate oxidation could be negligible. The formation of chlorination by-products appeared to be low since the final total Trihalomethanes concentration detected was 263µgL−1, with the detection of chloroform as the main Trihalomethanes.

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.

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.

Impact of groundwater surface storage on chlorination and disinfection by-product formation

The change in water quality arising from the open storage of groundwater (GW) and its impact on chlorination and chlorination by-product formation were investigated. Water quality descriptors, such as temperature, pH, chlorophyll, and dissolved oxygen contents of GW undergo substantial alteration when stored in a reservoir. Dissolved organic content (DOC) measured in the two water sources studied, i.e., GW and open reservoir water (RW), varied from 0.41 mg/L to 0.95 mg/L and 0.93 mg/L to 2.53 mg/L, respectively. Although DOC demonstrated wide variation, UV absorbance at 254 nm (UVA254) values for GW (0.022-0.067) and RW (0.037-0.077) did not display reciprocal variations. The chlorine demand (CD) of RW was always higher than that of GW for the corresponding sampling period. Average trihalomethane (THM) formation for RW was 50-80% higher compared to GW and thus poses an enhanced health risk. Appreciable amounts of bromide present in these water sources (0.15-0.26 mg/L in GW and 0.17-0.65 mg/L in RW) have resulted in the non-selective distribution of the four THM species. The formation of more toxic brominated THM due to chlorination of these near-coast drinking water sources must be regarded as a decisive factor for the choice of water disinfection regime.

Determination, Interpretation and Modeling of Chlorination by-Products Concentrations in Surface Waters

The formation of chlorination by-products (CBPs) was investigated by bench-scale chlorination experiments&#x0D; with surface waters from different sources in Lesvos island, Greece. The main factors studied were&#x0D; organic matter content of water (expressed as UV-272 absorbance), time and chlorine dose. The CBPs,&#x0D; determined by gas chromatographic techniques, belong to the categories of trihalomethanes (THMs),&#x0D; haloacetic acids (HAAs), haloacetonitriles, chloral hydrate and chloropicrin. HAAs and THMs were the&#x0D; most abundant CBPs detected in the chlorinated samples, while haloketones, haloacetonitriles and chloral&#x0D; hydrate occurred at much lower concentrations. Statistical analysis of the results with multifactor&#x0D; analysis of variance revealed the influence of the parameters studied on the formation of individual compounds.&#x0D; Application of principal component analysis (PCA) provided a clear picture of the differentiations&#x0D; between varying water sources and chlorination conditions. Multiple regression was used for development&#x0D; of predictive models for CBPs formation. The proposed models are considered satisfactory for&#x0D; predicting CBPs concentrations for water sources and chlorination conditions similar to those examined.

Oxidation of Microcystis aeruginosa and Anabaena flos-aquae by ozone: Impacts on cell integrity and chlorination by-product formation

Pre-ozonation of cyanobacterial (CB) cells in raw water and inter-ozonation of settled water can cause CB cell damage. However, there is limited information about the level of lysis or changes in cell properties after ozonation, release of intracellular compounds and their contribution to the formation of disinfection by-products (DBPs). This study aims to: (1) assess the extent of the pre-ozonation effects on CB cell properties; (2) determine the CT (ozone concentration × detention time) values required for complete loss of cell viability; and (3) study the DBPs formation associated with the pre-ozonation of cyanobacterial cells in laboratorial suspensions. To these ends, both Microcystis aeruginosa and Anabaena flos-aquae suspensions were prepared at concentrations of 250,000 cells mL−1 and 1,500,000 cells mL−1 and were subjected to ozone dosages of 0.5, 2.0 and 4.0 mg L−1 at pH 6 and pH 8. A quick and complete loss of viability was achieved for both CB species after exposure (CT) to ozone of <0.2 mg min L−1, although no significant decrease in total cell numbers was observed. Maximum dissolved organic carbon (DOC) releases of 0.96 mg L−1 and 1.63 mg L−1 were measured after ozonation of 250,000 cells mL−1 of M. aeruginosa and A. flos-aquae, respectively. DOC release was found to be pH and ozone dose dependent. Ozonation of CB cells increased formation of trihalomethanes (THM) and haloacetic acids (HAA), mainly for suspensions of A. flos-aquae at pH 8 (by 174% and 65% for THM and HAA respectively). Utilities considering using ozone for oxidising CB cells should weigh out the benefit of CB control with the potential increased formation of chlorinated DBPs.

Characteristics of natural organic matter and formation of chlorination by-products at Masaka waterworks

Research Article| December 01 2011 Characteristics of natural organic matter and formation of chlorination by-products at Masaka waterworks H. M. Kalibbala; H. M. Kalibbala 1Department of Civil & Environmental Engineering, College of Engineering, Design, Art & Technology, Makerere University, P.O. Box 7062, Kampala, Uganda E-mail: hkalibbala@tech.mak.ac.ug Search for other works by this author on: This Site PubMed Google Scholar Rose Kaggwa; Rose Kaggwa 2External Services, National Water & Sewerage Corporation, P.O. Box 7053, Kampala, Uganda Search for other works by this author on: This Site PubMed Google Scholar O. Wahlberg; O. Wahlberg 3Department of Inorganic Chemistry, Royal Institute of Technology (KTH), Teknikringen 30, SE-100 44 Stockholm, Sweden Search for other works by this author on: This Site PubMed Google Scholar E. Plaza E. Plaza 4Department of Land & Water Resources Engineering, Royal Institute of Technology (KTH), Teknikringen 30, SE-100 44 Stockholm, Sweden Search for other works by this author on: This Site PubMed Google Scholar Journal of Water Supply: Research and Technology-Aqua (2011) 60 (8): 511–519. https://doi.org/10.2166/aqua.2011.076 Article history Received: November 01 2010 Accepted: September 28 2011 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 H. M. Kalibbala, Rose Kaggwa, O. Wahlberg, E. Plaza; Characteristics of natural organic matter and formation of chlorination by-products at Masaka waterworks. Journal of Water Supply: Research and Technology-Aqua 1 December 2011; 60 (8): 511–519. doi: https://doi.org/10.2166/aqua.2011.076 Download citation file: Ris (Zotero) Reference Manager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex To minimise the formation of chlorination by-products (CBPs) it is imperative that attention is directed towards the structure and occurrence of natural organic matter (NOM) in raw water sources, and its flow and fate during water treatment processes. In this study, an assessment of the characteristics and flow of NOM along the treatment train at the full scale treatment plant at Masaka, Uganda, was made. Results indicated that 79% of the NOM, determined as total organic carbon, was in the dissolved form (DOC) with 83% of the DOC being hydrophilic in character. The insignificant amount of hydrophobic fraction in the raw water implies that the contributing fraction to THMs formation was mainly the hydrophilic component which subsequently was poorly removed along all units except clarification. The treated water from all unit processes provided specific ultraviolet absorbance values greater than 2 L/mg-m at 254 nm wavelength, indicating that it still had a high potential of reacting with chlorine to form CBPs. This renders water from Nabajjuzi River as unsuitable for chlorination in early stages of treatment and necessitating modification of the processes to reduce or avoid formation of unwanted by-products. chlorination by-products, drinking water, natural organic matter This content is only available as a PDF. © IWA Publishing 2011 You do not currently have access to this content.

Electrochemical oxidation of landfill leachates at pilot scale: evaluation of energy needs

Two of the main drawbacks to be overcome before full scale implementation of boron-doped diamond electro-oxidation were addressed in this work; its energy consumption and hazard of formation of chlorinated organics. This was framed within a study in which the technical and economic feasibility of BDD electro-oxidation of landfill leachate was evaluated at pilot scale. On one hand, its technical feasibility was assessed based on COD and NH(4)(+) removal, allowing the selection of the operation conditions that provide optimal energy efficiency, and special attention was paid to the risk of formation of undesired by-products such as nitrite, nitrate ions and trihalomethanes. On the other hand, treatment costs were estimated based on energy consumption required to reach the disposal limits to natural watercourses established by legislation. The results were compared with those of other commonly used AOPs. Under the operating conditions studied, the concentration of COD decreased below the disposal limit (160 mg L(-1)) and ammonia concentration reached values as low as 30 mg L(-1). The energy consumption needed was estimated at 54 kWh/m(3) and the formation of chlorination by-products appeared to be low as the maximum total trihalomethane concentration detected was 432 microg/L.

Electrochemical disinfection of simulated ballast water using Artemia salina as indicator

This work examined the potential of electrochemical disinfection to treat simulated ballast water with Artemia salina ( A. salina) as an indicator organism. The effect of contact time (residence time in the electrolytic cell) and current density were investigated. Furthermore, the formation of disinfection by-products (trihalomethanes) was also examined. Under conditions of single pass through the electrolytic cell, a current density of 135 mA/cm 2 and a residence time of around 1 min were required for 100% mortality of A. salina. Dissolved organic carbon due to cell lysis increased by 1–2 mg/L, while the formation of chlorination by-products, expressed as trihalomethanes was very small (less than 10 μg/L at 135 mA/cm 2).

Parallel Factor Analysis of Excitation–Emission Matrices to Assess Drinking Water Disinfection Byproduct Formation During a Peak Formation Period

Parallel factor (PARAFAC) analysis was applied to the fluorescence excitation–emission matrices (EEM) of a water treatment plant's source and coagulated water during a peak chlorinated byproduct formation period. Water plant operations included the use of surface water only and surface/ground water mixtures. Three statistically significant components were obtained through PARAFAC analysis and were correlated to dissolved organic carbon (DOC), chlorine consumption, and individual disinfection byproduct (DBP) formation potential. Multifactor linear regression of select component scores showed linear relationships to individual chloro-DBP compounds providing insight to possible precursor locations within the EEM and organic matter, as well as, organic compound characteristics responsible for chloro-DBP formation. Likewise, linear relationships were also observed between component scores and empirically estimated precursor concentration methods reported in the literature. These results suggest PARAFAC analysis of EEM may be an effective tool for monitoring source water, measuring treatment process effectiveness (removal of specific DBP precursor), and estimating DBP precursor concentrations and individual DBP compound formation potential.

Formation of Chlorination By-Products in Sanitary Hot Water Networks Treated by Continuous Chlorination

Formation of Chlorination By-Products in Sanitary Hot Water Networks Treated by Continuous Chlorination