Trihalomethane hydrolysis in drinking water at elevated temperatures

a b s t r a c t Hydrolysis could contribute to the loss of trihalomethanes (THMs) in the drinking water at elevated temperatures. This study was aimed at investigating THM hydrolysis pertaining to the storage of hot boiled water in enclosed containers. The water pH value was in the range of 6.1e8.2 and the water temperature was varied from 65 to 95 C. The effects of halide ions, natural organic matter, and drinking water matrix were investigated. Results showed that the hydrolysis rates declined in the order following CHBrCl 2 > CHBr 2 Cl > CHBr 3 > CHCl 3 . THM hydrolysis was primarily through the alkaline pathway, except for CHCl 3 in water at relatively low pH value. The activation energies for the alkaline hydrolysis of CHCl 3 , CHBrCl 2 , CHBr 2 Cl and CHBr 3 were 109, 113, 115 and 116 kJ/mol, respectively. No hydrolysis intermediates could accumulate in the water. The natural organic matter, and probably other constituents, in drinking water could substantially decrease THM hydrolysis rates by more than 50%. When a drinking water was at 90 C or above, the first order rate constants for THM hydrolysis were in the magnitude of 10 À2 -10 À1 1/h. When the boiled real tap water was stored in an enclosed container, THMs continued increasing during the first few hours and then kept decreasing later on due to the competition between hydrolysis and further formation. The removal of THMs, especially brominated THMs, by hydrolysis would greatly reduce one's exposure to disinfection by-products by consuming the boiled water stored in enclosed containers. © 2015 Published by Elsevier Ltd. Introduction Chemical disinfection acts as the cornerstone unit operation of water treatment processes that secure drinking water safety w a t e r r e s e a r c h 7 8 ( 2 0 1 5 ) 1 8 e2 7 http://d

Finishing the euchromatic sequence of the human genome

The sequence of the human genome encodes the genetic instructions for human physiology, as well as rich information about human evolution. In 2001, the International Human Genome Sequencing Consortium reported a draft sequence of the euchromatic portion of the human genome. Since then, the international collaboration has worked to convert this draft into a genome sequence with high accuracy and nearly complete coverage. Here, we report the result of this finishing process. The current genome sequence (Build 35) contains 2.85 billion nucleotides interrupted by only 341 gaps. It covers ∼99% of the euchromatic genome and is accurate to an error rate of ∼1 event per 100,000 bases. Many of the remaining euchromatic gaps are associated with segmental duplications and will require focused work with new methods. The near-complete sequence, the first for a vertebrate, greatly improves the precision of biological analyses of the human genome including studies of gene number, birth and death. Notably, the human enome seems to encode only 20,000-25,000 protein-coding genes. The genome sequence reported here should serve as a firm foundation for biomedical research in the decades ahead

Association between haloacetic acid degradation and heterotrophic bacteria in water distribution systems. Water Research,

Disinfection byproduct Distribution system Haloacetic acid Heterotrophic bacteria Chlorine residual a b s t r a c t The occurrences of trihalomethanes (THMs), haloacetic acids (HAAs) and heterotrophic bacteria were monitored in five small water systems over a nine-month period to investigate the association between HAA degradation and heterotrophic bacteria populations. The sampling sites were chosen to cover the entire distribution network for each system. An inverse association between heterotrophic bacteria and HAA concentrations was found at some locations where chlorine residuals were around or less than 0.3 mg L À1 . At other sample locations, where chlorine residuals were higher (over 0.7 mg L À1 ), no HAA reduction was observed. A high heterotrophic bacteria count accompanied with a low chlorine residual could be used as an indicator for HAA degradation in distribution systems. ª 2008 Elsevier Ltd. All rights reserved. Introduction Under , respectively. For disinfection byproduct (DBP) monitoring, peak DBP concentration locations should be selected for each system. Water systems are required to identify peak DBP concentration locations throughout the distribution system via an Initial Distribution System Evaluation (IDSE) under this USEPA Stage 2 D/DBPR. Several factors affect DBP concentrations in a distribution system. These factors include pH, water temperature, total organic carbon (TOC) concentrations, chlorine residuals, bromide concentration, and microbial activit

Rejection of nine haloacetic acids and coupled reverse draw solute permeation in forward osmosis

• Forward osmosis rejects haloacetic acids (HAAs) well. • The active-layer facing feed water (AL-FW) orientation is preferred. • The solution-diffusion model predicts HAA rejection better for AL-FW. • The solution-diffusion model accurately predicts reverse draw solution permeation. G R A P H I C A L A B S T R A C T The behaviors of haloacetic acid (HAA) rejection by forward osmosis are obtained by experiments and predicted by the solution-diffusion model combined with concentration polarization for both the AL-FW (active layer facing the feed water) and the AL-DS (active layer facing the draw solution) orientations. The rejection of haloacetic acids (HAAs) by forward osmosis (FO) and the coupled reverse draw solute permeation were experimentally determined and mathematically modeled by using the solution-diffusion model for both the AL-FW (active layer facing the feed water) and the AL-DS (active layer facing the draw solution) orientations. The rejection ratio for each HAA increased with the increase of draw solute concentration for the AL-FW orientation. In contrast, the HAA rejection ratio could reach its maximum under a medium osmotic pressure difference for the AL-DS orientation. The rejection ratios for all HAAs were higher than 94.6% for the AL-FW orientation and ranged from 73.8% to 89.1% for the AL-DS orientation under a draw solute concentration of 1 mol/L NaCl. The reverse draw solute flux for the AL-FW orientation was lower than that for the AL-DS orientation. The model-predicted HAA rejection results matched well with the experimental rejection ratios for the AL-FW orientation. However, the model over-estimated the rejection ratios for the AL-DS mode, likely due to the adoption of inaccurate mass transfer coefficient for internal concentration polarization. Regarding the reverse draw solute permeation, a general agreement between the model prediction and experimental data was observed for both orientations. a b s t r a c t a r t i c l e i n f

Pathway fraction of bromate formation during O 3 and O 3 /H 2 O 2 processes in drinking water treatment

h i g h l i g h t s • A method was developed to calculate the pathway fraction of bromate formation. • 68.9% of bromate was formed through direct-indirect pathway during surface water ozonation. b s t r a c t Ozone process has been widely used for drinking water treatment recently. In the oxidation process, bromate is formed by three pathways, i.e., the direct pathway, the direct-indirect pathway and the indirectdirect pathway. This study developed a method to calculate the percentage of these three pathways for bromate formation during O 3 process and O 3 /H 2 O 2 process. Two kinds of water, distilled water containing bromide (DW) and surface water from the Yellow River (SW) were selected as raw rater. The result showed that in natural water systems, the direct-indirect pathway was dominant for bromate formation during the oxidation process. When 3 mg L −1 O 3 was used as the only oxidant, nearly 26% of bromide ion was transferred into bromate in two kinds of water after 80 min. The dominant pathway in DW was the direct pathway (48.5%) and the direct-indirect pathway (46.5%), while that was the direct-indirect pathway (68.9%) in SW. When O 3 /H 2 O 2 were used as oxidants, as the H 2 O 2 dosage increased, the fractions of bromate formation by direct pathway and direct-indirect pathway decreased, while that by indirectdirect pathway increased. The conversion ratio from bromide to bromate first kept stable or increased, then decreased and reached its minimum when [H 2 O 2 ]/[O 3 ] ratio was 1.0 in DW and 1.5 in SW. Under this condition the indirect-direct pathway took the largest fraction of 70.7% in DW and 64.0% in SW, respectively

Electric field-based ionic control of selective separation layers

status: publishe

JMJD3 activated hyaluronan synthesis drives muscle regeneration in an inflammatory environment

International audienceMuscle stem cells (MuSCs) reside in a specialized niche that ensures their regenerative capacity. Although we know that innate immune cells infiltrate the niche in response to injury, it remains unclear how MuSCs adapt to this altered environment for initiating repair. Here, we demonstrate that inflammatory cytokine signaling from the regenerative niche impairs the ability of quiescent MuSCs to reenter the cell cycle. The histone H3 lysine 27 (H3K27) demethylase JMJD3, but not UTX, allowed MuSCs to overcome inhibitory inflammation signaling by removing trimethylated H3K27 (H3K27me3) marks at the Has2 locus to initiate production of hyaluronic acid, which in turn established an extracellular matrix competent for integrating signals that direct MuSCs to exit quiescence. Thus, JMJD3-driven hyaluronic acid synthesis plays a proregenerative role that allows MuSC adaptation to inflammation and the initiation of muscle repair