DBPs Formation Research Articles

Disinfection By-Products Formation Potential Along the Melendiz River, Turkey; Associated Water Quality Parameters and Non-Linear Prediction Model

Organic matters in raw water have a potential to generate harmful disinfection byproducts such as trihalomethanes (THMs) and haloacetic acid (HAA) during the chlorination process. The aim of this study was to investigate the trihalomethane formation potential (THMFP) and haloacetic acid formation potential (HAAFP) in Melendiz River and to determine the effect of several factors including water quality parameters, distance, and seasonal variation. Water samples (n = 93) were collected at Melendiz River during December 2015–November 2016. The range of THMFP and HAAFP was 47.28–3348.73 μg/L and 41.42–4952.68 μg/L, respectively. ANOVA analysis was performed to understand the impact of the seasonal and/or distance changes on DBPs formation. It was found that the seasonal variations (sig. ≤ 0.01) are more effective than distance variations (sig. > 0.80) at Melendiz River. Finally, a non-linear statistical model was developed based on Multiple Stepwise Regression Analysis using highly correlated water quality parameters with TTHM and THAA5 in Pearson Correlation Analysis. According to the results, among all factors, flow, dissolved organic carbon (DOC), UV254, UV272, bromide, temperature, and additional chlorine dose have a remarkable effect on THMFP and HAAFP. Especially, the Pearson correlation (P) values for the DOC and the Chlorine dosages are 0.583, 0.786 and 0.994 and 0.865 for THMFP and HAAFP models, respectively. In addition to this, the high R2 (0.95) values were obtained when compared to other predictive models. The local model development should be utilized because each water source has different organic characterization. For this reason, the development of local models for each water source is important for achieving more consistent results.

Use of fluorescence excitation–emission matrices coupled with parallel factor analysis to monitor C- and N-DBPs formation in drinking water recovered from cyanobacteria-laden sludge dewatering

This is the first time that correlations between the spectroscopic properties of algal organic matter (AOM) and cyanobacteria-related C- and N-disinfection byproduct (DBP) formation have been presented. Three types of coagulants, aluminium chloride (AC), chitosan (CTS) and a composite chitosan-aluminium chloride (CTSAC), were selected to assess and compare the performance of coagulation to control DBPs formation in dewatering water (DW). Fluorescence excitation–emission matrices (EEMs) coupled with parallel factor analysis (PARAFAC) indicated that four components dominated the EEM of the DW samples. Examination of C-, N-DPBs formation and attendant changes in the AOM parameters allows the establishment of strong linear relationships between yields of the trihalomethanes, haloacetonitriles and trichloronitromethane and the relative changes in the fluorescence compounds. Stronger linear correlations were found between trihalomethanes and tryptophan-like substance C1 (r = 0.918), between haloacetonitriles and C1 (r = 0.934), and between trichloronitromethane and amino acid-like substance C2 (r = 0.915) than other AOM parameters, suggesting that tryptophan-like substance and amino acid-like substance in AOM play major roles in generating cyanobacteria-related DBPs upon chlorination. Furthermore, because the CTSAC composite was effective in removing fluorophores and caused little cell lysis during the first 4 days of sludge storage, the production of C-, N-DBPs in the DW was lower than those in the AC or CTS systems for the same storage period. This indicates the feasibility of surrogate monitoring of the production of cyanobacteria-related C-, N-DBPs via online measurements of water EEM fluorescence. CTSAC composite coagulant is thus recommended, and the sludge should be disposed of within 4 days to obtain DW with lower DBPs formation potentials.

Development of a Chlorine Dosing Strategy for Fresh Produce Washing Process to Maintain Microbial Food Safety and Minimize Residual Chlorine.

The chlorine dosing strategy can be used for fresh produce washing process to enhance the microbial food safety and minimize the DBPs formation potential.

Formation and speciation of disinfection byproducts in desalinated seawater blended with treated drinking water during chlorination

Desalinated seawater containing bromide ion (Br−) blended with drinking water may produce brominated disinfection byproducts (Br-DBPs) during chlorination, which would pose a potential threat to human health when incorporated into the municipal water supply system. This study investigated the formation and speciation of twenty-one DBPs during chlorination in two desalinated seawater blends, i.e., treated drinking water blended with reverse osmosis (RO) permeate and post-treatment (PT) product water. After chlorination, the number and concentrations of DBPs formed in the desalinated seawater obviously enhanced, with chlorinated DBPs (Cl-DBPs) dominating. Sixteen DBPs were found in both RO and PT blends samples during chlorination, in which haloacetic acids (HAAs) had the highest concentration, followed by trihalomethanes (THMs) and halogen acetonitriles (HANs). When the volume of desalinated seawater in the blends was increased, the transformation from Cl-DBPs to Br-DBPs was observed for THMs and HANs, indicating that Br− was more easily incorporated into THMs and HANs than HAAs. Additionally, more Br− participated in the DBPs formation per unit dissolved organic carbon and Br-DBPs/DBPs increased, when the blended ratio of the desalinated seawater increased. The DBP-associated toxicity in the blends was estimated based on the toxicity-weighted concentration with Br-HANs as the predominant contributor, followed by Cl-HAAs.

Reducing DBPs formation in chlorination of Br-containing Diclofenac via Fe-Cu-MCM-41/O3 peroxidation: Efficiency, characterization DBPs precursors and mechanism

Abstract Fe-Cu-MCM-41/O3 was first used as an alternative to O3 to control disinfection by-products generation from chlorinated-disinfection of Br-containing Diclofenac. Accompanying with decrease of TOC, THMs and HAAs had an initial increase, reaching the highest at 30 min, then gradually decreased. Coupling Fe-Cu-MCM-41 with O3 successfully enhanced TOC removal and inhibited bromate, THMs and HAAs formation in post-chlorination when compared with those in ozonation. Four kinds of THMs and six kinds of HAAs were detected. CHCl3 was main Cl-THMs and CHBrCl2 was main Br-THMs. CHCl2COOH was the dominant Cl-HAAs and CHClBrCOOH was main Br-HAAs. A converse Br-THMs order was observed in O3 and Fe-Cu-MCM-41/O3 pre-treatment. Fe-Cu-MCM-41 decreased ozone exposure, reducing the direct reaction of O3 with Br− to form bromate. More DBPs precursors in Fe-Cu-MCM-41/O3 were removed by ·OH. H2O2, which generated during pre-treatment process, reduced HBrO/BrO−to Br−, inhibiting both its reaction with Br-DBPs precursors and bromate formation. The pre-treatment process changed intermediates’ properties and hydrophilic DOM was the dominant component. Hydrophobic acids and transphilic DOM were the main chlorine consuming intermediates and had major contribution to DBPs formation. Fulvic-like intermediates was suggested as precursors of Br-DBPs. Fe-Cu-MCM-41/O3 were suggested as a good alternative to O3 pretreatment.

Nitrogen Transformation and Microbial Spatial Distribution in Drinking Water Biofilter

Well understanding the rule of nitrogen mutual transformation in biofilters is important for controlling the DBPs formation in the subsequent disinfection process. Ammonia nitrogen removal effect and nitrogen transformation approach in biofilter of drinking water was researched in the study. The biofilter removed ammonia of 48.5% and total phosphorus of 72.3%. And the removal rate of TN, NO3--N, DON were 37.1%, 33.1%, 46.9%, respectively. Biomass and bioactivity of different depth of the biofilter were determined, too. The overall distribution of biomass showed a decreasing trend from top to bottom. The bioactivity in lower layer gradually increased. Especially the bioactivity of heterotrophic microorganisms showed a gradual increase trend. The amount of the nitrogen loss was 3.06mg/L. Non-nitrification pathway of “nitrogen loss” phenomenon in biofilter might exist assimilation, nitrification and denitrification in autotrophic.

Effect of coagulation and adsorption on DON removal and DBPs formation potential in municipal wastewater effluent

Effect of coagulation and adsorption on DON removal and DBPs formation potential in municipal wastewater effluent

Field data analysis of active chlorine-containing stormwater samples

Many municipalities in Canada and all over the world use chloramination for drinking water secondary disinfection to avoid DBPs formation from conventional chlorination. However, the long-lasting monochloramine (NH2Cl) disinfectant can pose a significant risk to aquatic life through its introduction into municipal storm sewer systems and thus fresh water sources by residential, commercial, and industrial water uses. To establish general total active chlorine (TAC) concentrations in discharges from storm sewers, the TAC concentration was measured in stormwater samples in Edmonton, Alberta, Canada, during the summers of 2015 and 2016 under both dry and wet weather conditions. The field-sampling results showed TAC concentration variations from 0.02 to 0.77 mg/L in summer 2015, which exceeds the discharge effluent limit of 0.02 mg/L. As compared to 2015, the TAC concentrations were significantly lower during the summer 2016 (0–0.24 mg/L), for which it is believed that the higher precipitation during summer 2016 reduced outdoor tap water uses. Since many other cities also use chloramines as disinfectants for drinking water disinfection, the TAC analysis from Edmonton may prove useful for other regions as well. Other physicochemical and biological characteristics of stormwater and storm sewer biofilm samples were also analyzed, and no significant difference was found during these two years. Higher density of AOB and NOB detected in the storm sewer biofilm of residential areas – as compared with other areas – generally correlated to high concentrations of ammonium and nitrite in this region in both of the two years, and they may have contributed to the TAC decay in the storm sewers. The NH2Cl decay laboratory experiments illustrate that dissolved organic carbon (DOC) concentration is the dominant factor in determining the NH2Cl decay rate in stormwater samples. The high DOC concentrations detected from a downstream industrial sampling location may contribute to a high stormwater NH2Cl decay rate in this area.

XANTHAN GUM AS A NOVEL FLOCCULANT AID EMPLOYED IN DRINKING WATER TREATMENT

Aluminum salts used for drinking water treatment are strongly related to environmental implications and health hazards. In order to reduce aluminum concentration in water and enhance the quality of the flocs formed, flocculant additives are employed. This paper evaluated polyaluminum chloride as coagulant in combination with xanthan gum as a novel flocculant to improve drinking water quality. Optimum results for color removal of 97.4 %, were observed with 5.0 ppm of polyaluminum chloride combined with 0.6 ppm of xanthan gum, prepared at 65 oC. Turbidity removal was complete with 5.0 ppm of polyaluminum chloride combined with xanthan gum solution, prepared at 65 oC in all evaluated concentrations. Moreover, PACl combined with xanthan gum at 0.6 ppm, prepared at 65 oC, enhanced the removal of other contaminants, which could improve posterior stages of water treatment, as filtration and disinfection, resulting in greater control of organic load and DBPs formation.

Impact of anionic ion exchange resins on NOM fractions: Effect on N-DBPs and C-DBPs precursors

The formation potential of carbonaceous and nitrogenous disinfection by-products (C-DBPs, N-DBPs) after ion exchange treatment (IEX) of three different water types in multiple consecutive loading cycles was investigated. Liquid chromatography with organic carbon detector (LC-OCD) was employed to gauge the impact of IEX on different natural organic matter (NOM) fractions and data obtained were used to correlate these changes to DBPs Formation Potential (FP) under chlorination. Humic (-like) substances fractions of NOM were mainly targeted by ion exchange resins (40-67% removal), whereas hydrophilic, non-ionic fractions such as neutrals and building blocks were poorly removed during the treatment (12-33% removal). Application of ion exchange resins removed 13-20% of total carbonaceous DBPs FP and 3-50% of total nitrogenous DBPs FP. Effect of the inorganic nitrogen (i.e., Nitrate) presence on N-DBPs FP was insignificant while the presence of dissolved organic nitrogen (DON) was found to be a key parameter affecting the formation of N-DBPs. DON especially the portion affiliated with humic substances fraction, was reduced effectively (∼77%) as a result of IEX treatment.

Characteristics of C-, N-DBPs formation from algal organic matter: Role of molecular weight fractions and impacts of pre-ozonation

Extracellular organic matter (EOM) and intracellular organic matter (IOM) of Microcystis aeruginosa have been reported to contribute to the formation of carbonaceous disinfection by-products (C-DBPs) and nitrogenous disinfection by-products (N-DBPs). Little is known about DBPs formation from different molecular weight (MW) fractions, especially for N-nitrosodimethylamine (NDMA). This study fractionated EOM and IOM into several MW fractions using a series of ultrafiltration membranes and is the first to report on the C-DBPs and N-DBPs formation from chlorination and chloramination of different MW fractions. Results showed that EOM and IOM were mainly distributed in low-MW (<1 KDa) and high-MW (>100 KDa) fractions. Additionally, the low-MW and high-MW fractions of EOM and IOM generally took an important part in forming C-DBPs and N-DBPs, either in chlorination or in chloramination. Furthermore, the effects of pre-ozonation on the formation of DBPs in subsequent chlorination and chloramination were also investigated. It was found that ozone shifted the high-MW fractions of EOM and IOM into lower MW fractions and increased the C-DBPs and N-DBPs yields to different degrees. As low-MW fractions are more difficult to remove than high-MW fractions by conventional treatment processes, therefore, activated carbon adsorption, nanofiltration (NF) and biological treatment processes can be ideal to remove the low-MW fractions and minimize the formation potential of C-DBPs and N-DBPs. Moreover, the use of ozone should be carefully considered in the treatment of algal-rich water.

하수처리장 방류수의 UV 처리시 유기물질, 잔류염소 및 소독부산물 생성 거동

Study on effluent organic matter (EfOM) characteristic and removal efficiency is required, because EfOM is impor­tant in regard to the stability of effluents reuse, quality issues of artificial recharge and water conservation of aqueous system. UV technology is widely used in wastewater treatment. Many reports have been conducted on microbial disinfection and micro pollutant reduction with UV treatment. However, the study on EfOM with UV has limited because low/medium pressure UV lamp is not sufficient to affect refractory organics. The high intensity of pulsed UV would mineralize EfOM itself as well as change the characteristics of EfOM. Chlorine demand and DBPs formation is affected on the changed amounts and properties of EfOM. The objective of this study is to investigate the effect on EfOM, chlorine residual, and chlorinated DBPs formation with low pressure and pulsed UV treatment. The removal of organic matter through low pressure UV treatment is insignificant effect. Pulsed UV treatment effectively removes/transforms EfOM. As a result, the chlorine consumption is changed and chlorine DBPs formation is decreased. However, excessive UV treatment caused problems of increasing chlorine consumption and generating unknown by-products.

Factors affecting THMs, HAAs and HNMs formation of Jin Lan Reservoir water exposed to chlorine and monochloramine

The formations of THMs, HAAs, and HNMs from chlorination and chloramination of water from Jinlan Reservoir were investigated in this study. Results showed that monochloramine rather than chlorine generally resulted in lower concentration of DBPs, and the DBPs formation varied greatly as the treatment conditions changed. Specifically, the yields of THMs, HAAs and HNMs all increased with the high bromide level and high disinfectant dose both during chlorination and chloramination. The longer reaction time had a positive effect on the formation of THMs, HAAs and HNMs during chlorination and HNMs during chloramination. However, no time effect was observed on the formation of THMs and HAAs during chloramination. An increase in pH enhanced the levels of THMs and HNMs upon chlorination but reduced levels of HNMs upon chloramination. As for the THMs in chloramination and HAAs in chlorination and chloramination, no obvious pH effect was observed. The elevated temperature significantly increased the yields of THMs during chlorination and HNMs during chloramination, but has no effect on THMs and HAAs yields during chloramination. In the same temperature range, the formation of HAAs and HNMs in chlorination showed a first increasing and then a decreasing trend. In chloramination study, addition of nitrite markedly increased the formation of HNMs but had little impact on the formation of THMs and HAAs. While in chlorination study, the presence of high nitrite levels significantly reduced the yields of THMs, HAAs and HNMs. Range analysis revealed that the bromide and disinfectant levels were the major factors affecting THMs, HAAs and HNMs formation, in both chlorination and chloramination. Finally, comparisons of the speciation of mono-halogenated, di-halogenated, tri-halogenated HAAs and HNMs between chlorination and monochloramination were also conducted, and factors influencing the speciation pattern were identified.

Pulsed UV 처리수에서의 자연유기물질, 잔류염소 및 소독부산물 생성 거동

UV technology is widely used in water and wastewater treatment. Many researches have been conducted on microbial disinfection and micro pollutant reduction with UV treatment. However, the study on NOM with UV has limited because low/medium pressure UV lamp is not sufficient to affect refractory organics such as NOM. Pulsed UV treatment using UV flash lamp can be operated in the pulsed mode with much greater peak intensity. The pulse duration is typically in microseconds, whereas the interval between pulses is in the order of milliseconds. The high intensity of pulsed UV would mineralize NOM itself as well as change the characteristics of NOM. Chlorine demand and DBPs formation is affected on the changed amounts and properties of NOM. The objective of this study is to investigate the effect on NOM, chlorine residual, and chlorinated DBPs formation with pulsed UV treatment.

Characteristics of Disinfection By-Products Formation in Chlorination of Principal Raw Waters for Drinking Water of Jeju Island, Korea

Abstract This study was carried out to investigate the characteristics of disinfection by-products (DBPs-trihalomethanes (THMs), haloacetic acids (HAAs) and haloacetonitriles (HANs) formation in chlorination of principal raw waters used for drinking water on Jeju Island, Korea. The domestic water supply of other area and humic acid solution (HA) were used as a reference point. The effects of chlorine contact time, solution temperature and pH on DBPs formation potential (DBPFP) were investigated for raw waters. In addition, the effect of Br - was studied for HA. The DBPFP (THMFP, HAAFP and HANFP) were increased with increasing chlorine contact time. Comparing the individual DBPFPs for raw waters, they decreased in the order of HAAFP > THMFP ≥ HANFP. As the solution temperature was increased, the THMFP, HAAFP and HANFP increased. With increasing the solution pH, the THMFP was increased, but HAAFP and HANFP were decreased. With the addition of 0.3 mg/L Br - for HA, the DBPFP was increased and the major chemical species changed: from trichloromethane to dibromochloromethane and tribromomethane for THMs; from dichloroacetic acid and trichloroacetic acid to tribromoacetic acid for HAAs; and from dichloroacetonitrile to dibromoacetonitrile for HANs.

Evaluation of DBPs Formation Potential during Chlorination of Dissolved Organic Matter Fractions Isolated from Eutrophic Water

Dissolved organic matter (DOM) in water from eutrophic water source was isolated into four classes as hydrophilic substances (HIS), hydrophobic acids (HOA), hydrophobic neutrals (HON), and hydrophobic bases (HOB). The formation of Trihalomethanes (THMs) and Haloacetic acids (HAAs) in chlorination of different DOM fractions was evaluated. The dominate species of THMs and HAAs were chloroform (CF) and trichloroacetic acid (TCAA) in the chlorination of raw water. There were close linear relationship between THMs/HAAs yields and SUVA254 values. Increasing of contact time and chlorine dosage enhanced the formation of THMs/HAAs yields from different DOM fractions. The increase of pH leads to more formation of THMs, and the highest production of HAAs was observed at pH 7.

Effects of UV/H 2O 2 on NOM fractionation and corresponding DBPs formation

In this study, UV/H 2O 2 treatment was used to evaluate its efficacy for control of natural organic matter (NOM) in different water sources in Taiwan and the results were compared with the conventional water treatment process. The NOM fractions analysis showed that compositions of NOM could be very different between the various water sources, and the raw water quality in Kin-Men (an off shore island of Taiwan) was characteristic when compared to other water sources. Raw water taken from Kin-Men generally had high dissolved organic carbon (DOC) concentrations and ~ 50% of the NOM in the raw water was hydrophilic. After UV/H 2O 2 treatment, a portion of the hydrophobic fractions of NOM in raw waters were transformed into hydrophilic ones. In conventional water treatment process, coagulation and slow filtration treatments have better efficiency to reduce the NOM in water especially for the hydrophobic portion. However, the pre-chlorination treatment for raw water increased the DOC concentration due to the lysis of algae cells. This study concluded that hydrophobic acids portion is the most sensitive portion of NOM to UV/H 2O 2 and conventional treatment processes. Trihalomethanes formation potential (THMFP) tests showed that hydrophobic acids portion is also the main contributor to THMs formation after chlorination process.

The effects of UV disinfection on drinking water quality in distribution systems

UV treatment is a cost-effective disinfection process for drinking water, but concerned to have negative effects on water quality in distribution system by changed DOM structure. In the study, the authors evaluated the effects of UV disinfection on the water quality in the distribution system by investigating structure of DOM, concentration of AOC, chlorine demand and DBP formation before and after UV disinfection process. Although UV treatment did not affect concentration of AOC and characteristics of DOM (e.g., DOC, UV254, SUVA254, the ratio of hydrophilic/hydrophobic fractions, and distribution of molecular weight) significantly, the increase of low molecular fraction was observed after UV treatment, in dry season. Chlorine demand and THMFP are also increased with chlorination of UV treated water. This implies that UV irradiation can cleave DOM, but molecular weights of broken DOM are not low enough to be used directly by microorganisms in distribution system. Nonetheless, modification of DOM structure can affect water quality of distribution system as it can increase chlorine demands and DBPs formation by post-chlorination.

Chemical fractions of natural organic matter in two water treatment plants of Tehran and DBPS formation potential

Chemical fractions of natural organic matter in two water treatment plants of Tehran and DBPS formation potential

Differential vs. absolute UV absorbance approaches in studying NOM reactivity in DBPs formation: Comparison and applicability

Differential absorbance at wavelengths near 272 nm (−ΔA 272) has been used to track the halogenation of NOM, but its performance for different drinking water sources before and after water treatment processes has not been thoroughly ascertained. In this study, the behavior of −ΔA 272 during the halogenation process was determined to be strongly correlated with DBPs' concentrations regardless of the NOM properties. However, chlorination of different NOM samples resulted in different patterns when DBP concentrations were plotted vs. −ΔA 272. In order to quantify the reactivity of NOM in DBPs formation an alternative index, denoted as −ΔA 272( t = 2 h), that is the differential absorbance at 272 nm obtained at 2 h of reaction time and pH 7.0, was proposed. This parameter was strongly correlated with DBPs' concentrations regardless of the major chlorination conditions (chlorine dose, water temperature) and NOM properties (raw, treated and fractionated samples). Its performance was found better than that of other widely used surrogate parameters (i.e. DOC, SUVA 254, A 254, A 272) and it presents several options for field applications.