Trihalomethanes (THMs) are prevalent disinfection by-products. High THM formation is usually associated with natural organic matter with high molecular weight and aromatic characteristics, which is ...efficiently removed by nanofiltration (NF). In the Sea of Galilee and the Israeli National Water Carrier (NWC), water shows high THM formation potential, although it mainly contains low molecular weight and hydrophilic organic matter with low aromaticity. In the present study, NF removal abilities were tested on treated NWC water using three different spiral wound membranes (NF90, NF270, and DL). Rejections and fluxes were tested as a function of pressure, water recovery, and membrane type. Feed and permeate dissolved organic carbon (DOC), UVA254, total THM formation (THMF), and total THM formation potential (THMFP), as well as alkalinity, conductivity, hardness, Ca2+, Mg2+, and Cl− were measured to evaluate rejection and THM formation reduction. The results demonstrated that NF can efficiently remove natural organic matter (NOM) and reduce THM formation, even in this challenging type of water. At low water recovery, membranes showed average rejection of about 70–85% for THMFP and THM. Upon elevating recovery, average THM and THMFP rejection decreased to 55–70%, with THM content still well below regulation limits. Of the membranes tested, the higher permeability of NF270 appears to make it economically favorable for the applications tested in this work.
Abstract
Currently, there is contradictory evidence for the risk of adverse pregnancy outcomes associated with maternal exposure to disinfection byproducts (DBPs). We examine the association between ...maternal exposure to trihalomethanes (THMs) in drinking water and adverse pregnancy outcomes, including premature birth, low birth weight (LBW) and small for gestational age (SGA). In total, 1,167 women older than 18 years were enrolled at public antenatal venues in two geographical districts. For each district, we measured the levels of residential drinking water DBPs (measured in THMs) through regulatory data and routine water sampling. We estimated the individual uptake of water of each woman by combining individual water use and uptake factors. Increased daily internal dose of total THMs during the third trimester of pregnancy significantly increased the risk of delivering premature infants (AOR 3.13, 95% CI 1.36–7.17). The risk of premature birth was also positiviely associated with exposure to total THMs during the whole pregnancy (AOR 2.89, 95% CI 1.25–6.68). The risk of delivering an SGA and LBW infant was not associated with maternal exposure to THMs. Our findings suggest that exposure to THMs is associated with certain negative pregnancy outcomes. The levels of THMs in water should be routinely monitored.
Recent epidemiological studies reported that brominated DBPs may be more carcinogenic than their chlorinated analogs. Thus, this research was designed to investigate the role of bromide ion in the ...formation and speciation of disinfection by-products (DBPs) during chlorination of Buyukcekmece Lake Water (BLW) in Istanbul. Chlorination of BLW samples was carried out at pH 7.0 with 5 and 12
mg/l chlorine dosages. For each chlorine dosage, six bromide concentrations ranging from 0.05 to 4.0
mg/l were added to form a 2
×
6 experimental matrix. In general, increasing bromide concentration gradually shifted trihalomethanes (THMs) and haloacetic acids (HAAs) speciation from chlorinated species to the mixed bromochloro species during chlorination. The halogen substitution ability of HOBr and HOCl during the formation of THMs and HAAs can be estimated through the use of probability theory. It was concluded that, in both halogen substitution for THM and dihalogenated HAA formation, HOBr was found to be 20 times more reactive than HOCl.
Pre-ozonation in combination with enhanced coagulation was used to remove NOM from lake water as to control the formation of disinfection by-products, DBPs. The effect of the ...hydrophobicity/hydrophilicity nature of NOM on the performance of the combined pre-ozonation and coagulation process was studied. The hydrophilicity/hydrophobicity property of NOM was characterized in terms of mass distribution of the phydrophilic and the hydrophobilic fractions of NOM. The optimal condition for the combined pre-ozonation–coagulation was established: pH
=
ca. 9.0 and ozone dose
=
0.45
mg-O
3/mg-DOC. Under the optimal condition, it was able to achieve ∼
60% of THMFP removal. In terms of THMPF, results also indicated that the distribution between the hydrophilic and the hydrophobic fractions of NOM was 57.3 and 98.7
µg-THMFP/mg-DOC, respectively. Ozonation alters the structures and characteristics of NOM thereby affecting the coagulation effectiveness. Pre-ozonation was effective in removing the hydrophobic NOM, with a decrease of THMFP by ∼
20% versus ∼
10% for the hydrophilic fraction. The dosage of coagulant also governed DOC removal. The removal of hydrophobic and hydrophilic NOM were in the range of 27–41 and 2.5–22.7%, respectively at alum dosage of 0.41–1.65 (in Al/DOC) and 0.41–1.65 (in Al/DOC) and ozone dose of 0.58–2.93, mg/mg respectively. The adsorption characteristics of the hydrophilic and the hydrophobic fractions of NOM on aluminum hydroxide (from coagulant alum) were studied. Results indicated that the modified Langmuir isotherm of competitive adsorption was able to describe the adsorption of NOM onto hydrous aluminum hydroxide formed during alum coagulation of the lake waters.
In this study, the concentrations of disinfection byproducts (DBPs), including trihalomethanes (THMs; chloroform, bromodichloromethane, dibromochloromethane, and bromoform), haloacetic acids (HAAs; ...dichloroacetic acid and trichloroacetic acid), haloacetonitriles (HANs; dichloroacetonitrile, trichloroacetonitrile, bromochloroacetonitrile, and dibromoacetonitrile), and chloral hydrate (CH) were measured in 86 indoor swimming pools in Seoul, Korea, treated using different disinfection methods, such as chlorine, ozone and chlorine, and a technique that uses electrochemically generated mixed oxidants (EGMOs). The correlations between DBPs and other environmental factors such as with total organic carbon (TOC), KMnO
4 consumption, free residual chlorine, pH, and nitrate (NO
3
−) in the pools were examined. The geometric mean concentrations of total DBPs in swimming pool waters were 183.1
±
2.5
μg/L, 32.6
±
2.1
μg/L, and 139.9
±
2.4
μg/L in pools disinfected with chlorine, ozone/chlorine, and EGMO, respectively. The mean concentrations of total THMs (TTHMs), total HAAs (THAAs), total HANs (THANs), and CH differed significantly depending on the disinfection method used (
P
<
0.01). Interestingly, THAAs concentrations were the highest, followed by TTHMs, CH, and THANs in all swimming pools regardless of disinfection method. TOC showed a good correlation with the concentrations of DBPs in all swimming pools (chlorine;
r
=
0.82,
P
<
0.01; ozone/chlorine;
r
=
0.52,
P
<
0.01, EGMO;
r
=
0.39,
P
<
0.05). In addition, nitrate was positively correlated with the concentrations of total DBPs in swimming pools disinfected with chlorine and ozone/chlorine (chlorine;
r
=
0.58; ozone/chlorine;
r
=
0.60,
P
<
0.01), whereas was negative correlated with the concentrations of total DBPs (
r
=
−0.53,
P
<
0.01) in the EGMO-treated pools.
The purpose of this study was to develop the multiple regression models to evaluate the formation of trihalomethanes (THMs) and haloacetonitriles (HANs) during chlorination of source water with low ...specific ultraviolet absorbance (SUVA) in Yangtze River Delta, China. The results showed that the regression models of THMs exhibited good accuracy and precision, and 86–97 % of the calculated values fell within ±25 % of the measured values. While the HANs models showed relatively weak evaluation ability, as only 75–83 % of the calculated values were within ±25 % of the measured values. The organic matter dissolved organic carbon (DOC) or UV absorbance at 254 nm and bromide exerted the most important influence on the formation of HANs. While for THMs, besides the organic matter and bromide, reaction time was also a key factor. Comparing the models for total THMs (T-THMs) in this study with others revealed that the regression models from the low SUVA waters may have low DOC coefficients, but high bromide coefficients as compared with those from the high SUVA waters.
In this study, municipal wastewater was treated by a SMBR system and further disinfected with chlorine to produce reclaimed water. The primary objective was to examine the water quality with a focus ...on trihalomethanes (THMs). As disinfection conditions are important aspects in controlling the formation of THMs, influences of chlorine dose and contact time on THM formation and speciation were also investigated. High quality reclaimed water was generated though the SMBR system with regard to five-day biological oxygen demand (BOD5), suspend solid (SS) and turbidity. However the concentration of total trihalomethanes (TTHM) in the chlorinated SMBR effluent was up to 160μg/L, demonstrating that the SMBR was insufficient in the removal of THM precursors. TTHM levels increased with chlorine dose and contact time. As chlorine dose increased, the yields of trichloromethane (CHCl3) and bromodichloromethane (CHBrCl2) increased, whereas both tribromomethane (CHBr3) and dibromochloromethane (CHBr2Cl) decreased due to the rise of Cl2/Br− ratio. In order to reduce health risks of reclaimed water, efficient removal of disinfection by-product precursor and opportune chlorine disinfection conditions are recommended.
► SMBR with post-chlorination was used for municipal wastewater reuse. ► Evaluation of the reused water quality was focused on trihalomethanes (THMs) level. ► Single SMBR process was proved insufficient in THM precursor removal. ► Higher chlorine dose and contact time were found to create more THMs formation
The formation of trihalomethanes (THMs) and haloacetic acids (HAAs), two major disinfection by-products (DBPs), from the breakpoint chlorination of three diluted yet buffered (pH 7.0) wastewater ...effluents was studied. The concentrations and distributions of THMs and HAAs species varied among different effluents at different zones of the breakpoint curves. Nevertheless, some common trends were observed. The formation of chloro-only THMs and HAAs, after normalization with the carbon contents of the effluents, increased with increasing the specific UV absorbance (SUVA) of the effluents but the dependency is not valid for bromo- or bromochloro-DBPs. The formation of THMs and HAAs showed no significant inclination with increasing chlorine dosages up to the breakpoint, but increased sharply beyond the breakpoint dosing level. Bromine incorporations into THMs and HAAs increased with an increasing bromide to DOC molar ratio. In addition, the bromine incorporation was also found to be highly dependent on the chlorine dosage and the bromide to ammonia ratio. A longer reaction time increased the yields of THMs and HAAs and was found to favor the formation of dihalogenated HAAs. A two-stage correlation between the total THMs and the total HAAs was found for each wastewater effluent.
Membrane filtration is commonly applied to reduce dissolved organic carbon (DOC) to control the formation of trihalomethanes (THMs); however, high levels of DOC can cause severe fouling of reverse ...osmosis membranes. The integrated biological and reverse osmosis membrane (IBROM) process is a combination of biological filters and reverse osmosis membranes. The IBROM process claims to remove biodegradable dissolved organic carbon (BDOC), which apparently should result in reduced membrane fouling. The goal of this research was to conduct a preliminary investigation into the claims of the IBROM system, using water collected from the Herbert water treatment plant (Saskatchewan). The plant is utilizing the IBROM for the treatment of a dugout and groundwater blend (DOC of 17.5–22.7 mg/L). The results demonstrated that BDOC concentrations did not change significantly throughout the plant. Optimized laboratory-scale coagulation with polyaluminium chlorohydrate achieved 58% removal of BDOC. Oxidation with permanganate increased the concentration of BDOC (from 5.7 to 8.8 mg/L). Overall, BDOC was effectively removed by optimized coagulation rather than the IBROM system. Moreover, the results show an inverse relationship between BDOC and THMs formation potential (THMFP) in both coagulated and oxidized water. For all concentrations, more biodegradable DOC had less tendency to form THMs based on the lower THMFP.
The concentrations of trihalomethanes (THMs), including chloroform, bromodichloromethane, dibromochloromethane, and bromoform, and haloacetic acids (HAAs; monochloroacetic acid, monobromoacetic acid, ...dibromoacetic acid, dichloroacetic acid, and trichloroacetic acid) were measured in tap waters passing through water distribution systems of six water treatment plants in Seoul, Korea, and their associated health risks from exposure to THMs through ingestion, dermal contact, and inhalation were estimated using a probabilistic approach. The concentration ranges for total THMs and HAA
5
were 3.9–53.5 and <LOD–49.5 μg/L, respectively. Among DBPs, chloroform, bromodichloromethane, dichloroacetic acid, and trichloroacetic acid were the most frequently detected. Spatial and seasonal variations in concentrations of THMs and HAAs in the six water distribution systems were significant (
P
< 0.001).The mean lifetime cancer risks through ingestion, dermal contact, and inhalation during showering ranged as 7.23–10.06 × 10
−6
, 2.19–3.63 × 10
−6
, and 5.22–7.35 × 10
−5
, respectively. The major exposure route to THMs was inhalation during showering. Sensitivity analysis showed that shower time and shower frequency had a great impact on the lifetime cancer risk by the exposure to THMs in tap water.
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