Enhanced iodinated disinfection byproducts formation in iodide/iodate-containing water undergoing UV-chloramine sequential disinfection: Machine learning-aided identification of reaction mechanisms.

Restricted to the complex nature of dissolved organic matter (DOM) in various aquatic environments, the mechanisms of enhanced iodinated disinfection byproducts (I-DBPs) formation in water containing both I and IO (designated as I/IO in this study) during the ultraviolet (UV)-chloramine sequential disinfection process remains unclear. In this study, four machine learning (ML) models were established to predict I-DBP formation by using DOM and disinfection features as input variables. Extreme gradient boosting (XGB) algorithm outperformed the others in model development using synthetic waters and in cross-dataset generalization of surface waters.

Far-UVC direct photolysis of iohexol and acetochlor: an experimental and mechanism study.

Recently, the emission of 222 nm Far-UVC krypton chloride (KrCl*) excimer lamps, has gained widespread attention in the field of water treatment. This study compared the degradation kinetics of IOX and ACE under UV and UV irradiation. The results demonstrated that UV irradiation exhibited higher efficiency, increasing the removal rates of IOX and ACE from 72.

Mixed chlorine/chloramines in disinfected water and drinking water distribution systems (DWDSs): A critical review.

Mixed chlorine/chloramines are commonly occurring in real drinking water distribution systems (DWDSs) but often overlooked. This review provides a comprehensive overview of the occurrences, characteristics, analysis methods, and control strategies of mixed chlorine/chloramines in DWDSs. The characteristics of mixed chlorine/chloramine species are summarized for treated water in drinking water treatment plants (DWTPs), secondary disinfection facilities, and DWDSs where different disinfectants could be blended.

Enhanced degradation of emerging contaminants by Far-UVC photolysis of peracetic acid: Synergistic effect and mechanisms.

Krypton chloride (KrCl*) excimer lamps (222 nm) are used as a promising irradiation source to drive ultraviolet-based advanced oxidation processes (UV-AOPs) in water treatment. In this study, the UV/peracetic acid (PAA) process is implemented as a novel UV-AOPs for the degradation of emerging contaminants (ECs) in water. The results demonstrate that UV/PAA process exhibits excellent degradation performance for carbamazepine (CBZ), with a removal rate of 90.

Sequential combination of pre-chlorination and powdered activated carbon adsorption on iodine removal and I-THMs control in drinking water.

Combining pre-oxidation with activated carbon adsorption was explored as an ideal approach for removing iodine from water source to eliminate the formation of Iodinated trihalomethanes (I-THMs). Compared with permanganate and monochloramine, chlorine is more suitable as pre-oxidant to obtain higher active iodine species (HOI/I). Active iodine species adsorption using both powdered activated carbon (PAC) and granular activated carbon (GAC) can be well fitted the pseudo-second-order kinetic model indicating that chemical adsorption was the dominant mechanism for HOI/I adsorption.

Insight into the formation of iodinated trihalomethanes during chlorination, monochloramination, and dichloramination of iodide-containing water.

In this study, the formation of iodinated trihalomethanes (I-THMs) was systematically evaluated and compared for three treatment processes - (i) chlorination, (ii) monochloramine, and (iii) dichloramination - under different pH conditions. The results demonstrated that I-THM formation decreased in the order of monochloramination > dichloramination > chlorination in acidic and neutral pH. However, the generation of I-THMs increased in the dichloramination < chlorination < monochloramination order in alkaline condition.

Micropollutant removal and disinfection byproduct control by sequential peroxymonosulfate-UV treatment in water: A case study with sulfamethoxazole.

UV/peroxymonosulfate (UV/PMS) advanced oxidation process has attracted significant attention for removal of micropollutants in water. However, during practical water treatment applications, the PMS treatment must be performed before the UV treatment to achieve full contact. In this study, sulfamethoxazole (SMX) was selected as the target micropollutant.

Enhanced degradation of emerging contaminants by permanganate/quinone process: Case study with bisphenol A.

Permanganate (Mn(VII)) is widely used as a mild oxidant in water treatment. However, the reaction rates of some emerging contaminants with Mn(VII) are extremely low. In this study, benzoquinone (BQ), a redox mediator with the important component in dissolved organic matter (DOM), enhanced the oxidation of bisphenol A (BPA) by Mn(VII) in a wide pH range of 4.

The formation, analysis, and control of chlor(am)ination-derived odor problems: A review.

Odors and tastes have become universal problems related to drinking water quality. In addition to the typical odor problems caused by algae or microorganisms, the occurrence of odors derived from drinking water disinfection have attracted attention. The chlor(am)ination-derived odor substances have certain toxicity and odor-causing characteristics, and would enter the tap water through water distribution systems, directly affecting drinking water safety and customer experience.

The application of UV-C laser in persulfate activation for micropollutant removal: Case study with iodinated X-ray contrast medias.

A novel light source UV-C laser was applied in persulfate (PS) activation to effectively remove iodinated X-ray contrast medias (ICMs) including iohexol (IOX), iopamidol (IPM) and diatrizoate (DTZ) in this study. Significant ICMs degradation was observed in UV-C laser/PS systems with pseudo first-order rate constants of 0.022-0.

Iodinated trihalomethanes formation in iopamidol-contained water during ferrate/chlor(am)ination treatment.

Iopamidol is a commonly used iodinated X-ray contrast media in medical field, and its residue in water can react with disinfectants to form highly toxic iodinated disinfection by-products (I-DBPs). This study investigated the degradation of iopamidol and formation of DBPs, especially iodinated trihalomethanes (I-THMs), during ferrate (Fe(VI)) pre-oxidation and subsequent chlor(am)ination under raw water background. It was found that iopamidol degradation efficiency in raw water by Fe(VI) at pH 9 could reach about 80%, which was much higher than that at pH 5 and pH 7 (both about 25%).

Formation of disinfection by-products in a UV-activated mixed chlorine/chloramine system.

In recent years, ultraviolet (UV) irradiation coupled with chlor(am)ination process is ubiquitous in secondary water supply systems in many cities of China. However, the disinfection by-products (DBPs) formation in a UV-activated mixed chlorine/chloramine system (MCCS) still remains unclear. In this study, the DBPs formation in a UV-activated MCCS was systematically investigated, considering influencing factors including the mass ratios of free chlorine to NHCl, UV irradiation, pH values, NOM types, Br concentration and toxicity of the DBPs.

[Degradation of RBK5 by High Crystallinity Mn-Fe LDH Catalyst Activating Peroxymonosulfate].

High crystallinity Mn-Fe LDH was synthesized by improved co-precipitation combined with the hydrothermal method and was utilized as a catalyst for peroxymonosulfate (PMS) activation to degrade reactive black 5. The high crystal purity and clear lamellar structure were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), energy dispersive X-ray spectrometer (EDS), Fourier transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS). The operating parameters such as Mn/Fe molar ratio, catalyst dosage, PMS concentration, and initial pH value on the absorption efficiency, catalytic degradation, and reaction kinetics of RBK5 were also investigated.

[Degradation of RBk5 with Peroxymonosulfate Efficiently Activated by N-Doped Graphene].

The large loss of catalysts and secondary pollution problems are bottlenecks for the utilization of persulfate advanced oxidation processes. Thus, a modified Hummers method combined with a hydrothermal method was used to prepare N-doped graphene as a catalyst for peroxymonosulfate (PMS) activation. The produced sulfate radical (SO·) and hydroxyl radical (·OH) were able to degrade RBk5.

Comparative genomic analysis of gene variations of two Chinese Yersinia pestis isolates from vaccine strain EV76.

Objective: To investigate genomic variations of two Chinese Yersinia pestis isolates that were isolated from different plague foci obtained from vaccine strain EV76 from the Yunnan province of China.

Methods: A microarray containing 12 000 probes covering the entire genome of seven Yersinia pestis and two Yersinia pseudotuberculosis strains, was used. PCR assays were performed to confirm microarray results.

[Study on the identification characteristics of rRNA genes on Yersinia pestis].

Objective: To study the identification characteristics of rRNA genes on Yersinia (Y.) pestis.

Methods: By means of comparative genomics, we compared the rRNA genome sequences of nine completely sequenced strains of Y.

Assessment of comparative genomic hybridization experiment by an in situ synthesized CombiMatrix microarray with Yersinia pestis vaccine strain EV76 DNA.

Objective: The quality of microarray data influences the accuracy of comparative genomic analyses to a large extent. To ensure that the results obtained by using an in situ synthesized microarray are accurate, data quality is to be assessed by evaluating the melting temperature (Tm) of probes, probability of false synthesis rates, and fragmentation of labeled targets.

Methods: DNA from the Yersinia pestis vaccine strain EV76 was used for microarray analyses.

[Clone expression of the caf1 gene of Yersinia pestis and immunological evaluation on recombinant F1 antigen].

Objective: To get recombinant F1 antigen (rF1) and to construct the detection dipstick of plague antibody.

Methods: The caf1 gene removing the signal peptide coding sequence was cloned into plasmid pET32a(+) by double-digested sites of BamHI and Not I. Recombinant plasmid caf1-pET32a(+) was transformed into BL21 (DE3) and the rF1 was expressed.

Safety and immunogenicity from a phase I trial of inactivated severe acute respiratory syndrome coronavirus vaccine.

Background: Emergence of severe acute respiratory syndrome (SARS) from the winter of 2002 to the spring of 2003 has caused a serious threat to public health.

Methods: To evaluate the safety and immunogenicity of the inactivated SARS coronavirus (SARS-CoV) vaccine, 36 subjects received two doses of 16 SARS-CoV units (SU) or 32 SU inactivated SARS-CoV vaccine, or placebo control.

Results: On day 42, the seroconversion reached 100% for both vaccine groups.

Phylogenetic analysis of Bartonella detected in rodent fleas in Yunnan, China.

Previous studies have demonstrated a diversity of Bartonella spp. in rodent populations in Yunnan Province, China. Although Bartonella spp.

[Study on the application and evaluation of methods for gene and antigen detection in plague surveillance program].

Objective: To apply and evaluate new methods regarding specific gene and antigen detection in plague surveillance program.

Methods: 1798 samples from natural foci of plague were tested, using internal quality control multiple-polymerase chain reaction, F1 antigen marked by immuno chromatographic assay and enzyme linked immunosorbent assay. Culture of Yersinia pestis and reverse indirect hemagglutination assay were used as reference diagnostic methods.

[Use of variable-number tandem repeats to examine genetic diversity of Bacillus anthracis].

Objective: To study the genotyping of Bacillus anthracis based on multiple-locus variable-number tandem repeats(VNTR) in the B. anthracis genome.

Methods: We selected 13 VNTR loci (which cited from published articles) to study 88 strains of B.