Characterization of UV/chlorine process for micropollutant abatement by probe compound-based kinetic models.

Micropollutant (MP) abatement efficiencies are critical information for optimizing water treatment process for cost-effective operations. Nevertheless, due to the vast number of MPs in real water matrices, it is infeasible to measure their abatement efficiencies individually in practical applications. In this study, a probe compound-based kinetic model was developed for generalized prediction of MP abatement in various water matrices by the ultraviolet (UV)/chlorine process. The results show that by measuring the depletion of three probe compounds (ibuprofen, primidone, and dimetridazole) spiked in the water matrix, the exposures of main reactive chlorine species (RCS including chlorine radicals (Cl•), dichloride radicals (Cl2-•) and chlorine oxide radicals (ClO•)) and hydroxyl radicals (•OH) during the UV/chlorine process could be calculated using the model. Based on the determined exposures, the abatement efficiencies of various MPs in different water matrices (e.g., surface water, groundwater, and wastewater) could generally be predicted with acceptable accuracy by the model without prior water-specific calibration. In addition, the relative contribution of UV photolysis and oxidation with active chlorine, RCS, and •OH to MP abatement could be quantitatively simulated using the model to clarify the abatement mechanism of MPs during the UV/chlorine process. The probe-based kinetic model can thus offer a useful tool to guide practical water and wastewater treatment for MP abatement and to explore the mechanism of UV/chlorine process.

Removal of antibiotic resistant bacteria and plasmid-encoded antibiotic resistance genes in water by ozonation and electro-peroxone process.

The electro-peroxone (EP) process is an electricity-based oxidation process enabled by electrochemically generating hydrogen peroxide (H2O2) from cathodic oxygen (O2) reduction during ozonation. In this study, the removal of antibiotic resistant bacteria (ARB) and plasmid-encoded antibiotic resistance genes (ARGs) during groundwater treatment by ozonation alone and the EP process was compared. Owing to the H2O2-promoted ozone (O3) conversion to hydroxyl radicals (•OH), higher •OH exposures, but lower O3 exposures were obtained during the EP process than ozonation alone. This opposite change of O3 and •OH exposures decreases the efficiency of ARB inactivation and ARG degradation moderately during the EP process compared with ozonation alone. These results suggest that regarding ARB inactivation and ARG degradation, the reduction of O3 exposures may not be fully counterbalanced by the rise of •OH exposures when changing ozonation to the EP process. However, due to the rise of •OH exposure, plasmid DNA was more effectively cleaved to shorter fragments during the EP process than ozonation alone, which may decrease the risks of natural transformation of ARGs. These findings highlight that the influence of the EP process on ARB and ARG inactivation needs to be considered when implementing this process in water treatment.

Proteotranscriptomic Analysis and Toxicity Assay Suggest the Functional Distinction between Venom Gland Chambers in Twin-Spotted Assassin Bug, Platymeris biguttatus.

Assassin bugs use their salivary venoms for various purposes, including defense, prey paralyzation, and extra-oral digestion, but the mechanisms underlying the functional complexity of the venom remain largely unclear. Since venom glands are composed of several chambers, it is suggested that individual chambers may be specialized to produce chemically distinct venoms to exert different functions. The current study assesses this hypothesis by performing toxicity assays and transcriptomic and proteomic analysis on components from three major venom gland chambers including the anterior main gland (AMG), the posterior main gland (PMG), and the accessory gland (AG) of the assassin bug Platymeris biguttatus. Proteotranscriptomic analysis reveals that AMG and PMG extracts are rich in hemolytic proteins and serine proteases, respectively, whereas transferrin and apolipophorin are dominant in the AG. Toxicity assays reveal that secretions from different gland chambers have distinct effects on the prey, with that from AG compromising prey mobility, that from PMG causing prey death and liquifying the corpse, and that from AMG showing no significant physiological effects. Our study reveals a functional cooperation among venom gland chambers of assassin bugs and provides new insights into physiological adaptations to venom-based predation and defense in venomous predatory bugs.

Removal of micropollutants by an electrochemically driven UV/chlorine process for decentralized water treatment.

The ultraviolet/chlorine (UV/Cl2) process is an emerging advanced oxidation technology for micropollutant abatement in water and wastewater treatment. However, the application of the conventional UV/Cl2 process in decentralized systems is limited by the transport and management of liquid chlorine. To overcome this limitation, this study evaluated an electrochemically driven UV/Cl2 (E-UV/Cl2) process for micropollutant abatement under conditions simulating decentralized water treatment. The E-UV/Cl2 process combines UV irradiation with in situ electrochemical Cl2 production from anodic oxidation of chloride (Cl-) in source waters. The results show that with typical Cl- concentrations present in water sources for decentralized systems (30-300 mg/L Cl-), sufficient amounts of chlorine could be quickly electrochemically produced at the anode to enable E-UV/Cl2 process for water treatment. Due to its multiple mechanisms for micropollutant abatement (direct photolysis, direct electrolysis, Cl2-mediated oxidation, as well as hydroxyl radical and reactive chlorine species oxidation), the E-UV/Cl2 process effectively eliminated all micropollutants (trimethoprim, ciprofloxacin, metoprolol, and carbamazepine) spiked in a surface water in 5 min. In contrast, at least one micropollutant with ∼20-80% residual concentrations could still be detected in the water treated by 10 min of UV irradiation, chlorination, electrolysis, and the conventional UV/Cl2 process under similar experimental conditions. The electrical energy per order (EEO) for micropollutant abatement ranged from 0.15 to 1.8 kWh/m3 for the E-UV/Cl2 process, which is generally comparable to that for the conventional UV/Cl2 process (0.14-2.7 kWh/m3). These results suggest that by in-situ generating Cl2 from anodic oxidation of Cl-, the E-UV/Cl2 process can overcome the barrier of the conventional UV/Cl2 process and thus provide a promising technology for micropollutant abatement in decentralized water treatment systems.

Kinetic study of the degradation of rhodamine B using a flow-through UV/electro-Fenton process with the presence of ethylenediaminetetraacetic acid.

An UV enhanced electro-Fenton (EF) process was conducted in a flow-through system to remove rhodamine B (RhB) in the presence of ethylenediamine tetraacetate (EDTA). The process was denoted as UV/EDTA/EF where EDTA formed complexes with iron ions, thus keeping them soluble at high pH values. The process was very efficient as it could initiate the fast reduction of FeIII to FeII and thus the decomposition of H2O2. The influence of Fe dose, the ratio of EDTA:Fe, aeration rate, flow rate, current, initial RhB concentration and pH on the RhB removal in the UV/EDTA/EF process was investigated. The best RhB removal was obtained as 89.9% at [Fe]0 = [EDTA]0 = 0.2 mM, current = 50 mA, aeration rate = 20 mL min-1, flow rate = 7 mL min-1, pH = 7 and [Na2SO4]0 = 0.05 M. The degradation of EDTA during the process was also studied. Radical scavenging experiments indicated that OH was the dominant radical for RhB removal. While, the photolysis of FeIIIEDTA was mainly responsible for EDTA degradation. RhB and EDTA removal in different systems was compared. The stability test proved that in the presence of EDTA, the UV/EF process could remove RhB with high efficiency in the first two runs. While, the efficiency dropped remarkably after EDTA's complete depletion. The mechanisms of the UV/EDTA/EF process were proposed. UV/EDTA/EF conducted in the flow-through system was able to efficiently remove RhB as well as EDTA in a wide pH range and proposed as a promising approach for wastewater treatment.

A highly efficient flow-through electro-Fenton system enhanced with nitrilotriacetic acid for phenol removal at neutral pH.

Low pH requirement is one of the biggest limitations of the application of traditional Fenton and electro-Fenton (EF) process because FeII/FeIII would precipitate at high pH. In this study, a flow-through EF system operated in batch recirculation mode was constructed. Nitrilotriacetic acid (NTA) was used as a chelating agent in the EF system (NTA/EF) to keep iron soluble at high pH values, producing OH by reaction of H2O2 generated in situ with FeIINTA that obtained by the reduction of FeIIINTA at the cathode. This flow-through NTA/EF system accelerated the mass transfer of target molecules to the electrode surface and showed high efficiency for phenol removal at pH 5-8 with rate constants (k) at around 0.26 min-1, higher than that of the batch test (k = 0.15 min-1) and EF process without NTA (k = 0.16 min-1). The influences of aeration rate, current, flow rate, Fe dose, the ratio of NTA to Fe, pH, and initial phenol concentration on the phenol removal were investigated. The system could be used for at least 3 times for phenol removal without obvious efficiency decline. The flow-through NTA/EF system is promising for the removal of organic contaminants in a wide pH range.

Three Melanin Pathway Genes, TH, yellow, and aaNAT, Regulate Pigmentation in the Twin-Spotted Assassin Bug, Platymeris biguttatus (Linnaeus).

Pigmentation plays a vital role in insect survival and reproduction. Many melanin pathway genes have been studied in holometabolous insects; however, they have only been studied in two hemimetabolous insect genera, Oncopeltus and Periplaneta. Here we analyzed three melanin pathway genes (TH, yellow, and aaNAT) using RNA interference (RNAi) in another hemimetabolous insect, namely the twin-spotted assassin bug, Platymeris biguttatus. TH was highly expressed in freshly molted nymphs and adults. TH RNAi resulted in a complete loss of black pigment, with yellow coloration maintained. Therefore, black pigment in this assassin bug is solely generated from the melanin pathway, whereas yellow pigment is generated from other unknown pigmentation pathways. yellow and aaNAT were highly expressed in the white spot of the hemelytra. Downregulation of yellow caused a brown phenotype with high mortality, indicating an important role of yellow functions in cuticle formation and in the process of converting melanin from brown to black. Interestingly, aaNAT RNAi caused not only loss of white pigment, but also loss of yellow and red pigments. This phenotype of aaNAT has not been reported in other insects. Our results provide new information for understanding the melanin pathway in which aaNAT is essential for the formation of colorless patterns.

Simultaneous sulfadiazines degradation and disinfection from municipal secondary effluent by a flow-through electro-Fenton process with graphene-modified cathode.

Conventionally the deep treatment and disinfection are fulfilled by different processes for municipal wastewater treatment, this work verified a breakthrough by one process of novel flow-through electro-Fenton (EF) with graphene-modified cathode, which is usually seemed to be ineffective. This process was firstly confirmed to be cost-effective for simultaneous sulfadiazines (SDZs) degradation and disinfection from municipal secondary effluent with a very low electrical energy consumption (EEC) of 0.21 kW h/m3, attributed to the high H2O2 production of 4.41 mg/h/cm2 on the novel graphite felt cathode modified by electrochemically exfoliated graphene (EEGr) with a low EEC of 3.08 kW h/(kg H2O2). Compared with the ineffective SDZs degradation by the conventional flow EF, this process was more cost-effective and overcame the harsh requirements on electrolyte concentration. It also showed good effectiveness in the degradation of different antibiotics, and the graphene-modified cathode still kept stable performance after eight consecutive runs. Account for the combined action of OH and active chlorine, the formation of hydroxylated and chlorine containing by-products was confirmed, and a possible degradation mechanism for SDZs was proposed. This flow-through EF process provided an alternative method for the disinfection and antibiotics degradation by one process for the treatment and reuse of municipal secondary effluent.

Simultaneous removal of tetracycline and disinfection by a flow-through electro-peroxone process for reclamation from municipal secondary effluent.

Pharmaceutical and personal care products as one of the micropollutants and bacteria in secondary effluent restrict the water reuse from municipal secondary effluent. Electro-peroxone (EP) process where H2O2 is generated in-situ by electrolysis is an emerging advanced oxidation process and an improvement of traditional peroxone method (O3/H2O2). In this work, a flow-through EP process was compared with ozonation and electrolysis for simultaneous disinfection and degradation of tetracycline (TC). The disinfection effect by EP was higher than the sum of standalone ozone and electrolysis and the coupling coefficient of ozonation and electrolysis in EP process was 1.2. The flow-through EP system presented similar efficiency for separately and simultaneously treating E. coli and TC. For the actual secondary effluent treatment, trihalomethanes, haloacetonitrile and halonitromethanes, the main disinfection by-products, were much lower than the WHO's thresholds for drinking water. TOC and COD removal was 44% and 65%, respectively, at flow rate of 35 mL/min. BOD5, bacteria, pH and other parameters in the effluent could satisfy the recreational landscape water quality standard, and the required energy consumption was 0.47 kW h/m3 at the flow rate 35 mL/min. Most of the degradation products were small-molecule organic acids, and possible degradation pathway of TC was suggested.

Temporal transcriptomic profiling of the ant-feeding assassin bug Acanthaspis cincticrus reveals a biased expression of genes associated with predation in nymphs.

Acanthaspis cincticrus (Stål) is an assassin bug with a specialized camouflaging behavior to ambush ants in the nymphal stages. In this study, we comprehensively sequenced all the life stages of A. cincticrus, including the eggs, five nymph instars, female and male adults using Illumina HiSeq technology. We obtained 176 million clean sequence reads. The assembled 84,055 unigenes were annotated and classified functionally based on protein databases. Among the unigenes, 29.03% were annotated by one or more databases, suggesting their well-conserved functions. Comparison of the gene expression profiles in the egg, nymph and adult stages revealed certain bias. Functional enrichment analysis of significantly differentially expressed genes (SDEGs) showed positive correlation with specific physiological processes within each stage, including venom, aggression, olfactory recognition as well as growth and development. Relative expression of ten SDEGs involved in predation process was validated using quantitative real-time PCR (qRT-PCR).

[Research on development and experiment of NIR wheat quality quick detection system].

In order to detect wheat quality rapidly and nondestructively, NIR wheat quality quick detection system was developed on the base of grating technology. To test accuracy, repeatability and stability of this self-made system, Bruker MPA spectroscopy was selected as target analyzer and 56 wheat samples were analyzed by building and validating PLS calibration models. In the 4 models of the self-made system, the coefficient of determination R2 is 92.38%, 93.48%, 93.16% and 94.44%; root mean square error of cross validation RMSECV = 0.405, 0.374, 0.383, 0.346; ratio of performance to standard deviate RPD = 3.62, 3.39, 3.82, 4.24, respectively. And evaluating indicators of validating results in the 4 models are as follows: R2 = 96.97%, 94.22%, 96.62% and 96.34%; Root mean square error of prediction RMSEP = 0.221, 0.305, 0.233 and 0.243 respectively. The model of MPA spectroscopy gave an R2 of 95.99%, a RMSECV of 0.293, RPD of 5 and validation results are R2 of 98.31%, RMSEP of 0.165, respectively. The results show that the models of self-made instrument have good prediction performance, stability and repeatability, and wavelength and absorbance of the obtained spectra have a good repeatability. The prediction effect of single spectrum is not ideal, but it can be improved by using average spectrum of repeated acquisition. NIR wheat quality quick detection system can detect wheat quality with good performance.