High UV Doses Research Articles

Degradation of highly chlorinated pesticide, lindane, in water using UV/persulfate: kinetics and mechanism, toxicity evaluation, and synergism by H2O2

Sulfate radical-advanced oxidation processes (SR-AOPs) are emerging technologies for decomposing organic pollutants in water. This study investigated the efficiency of UV/persulfate (UV/S2O82−) process to degrade lindane in water, showing 93.2% lindane removal ([lindane]0 = 3.43 μM, [S2O82−]0 = 100 μM) at a UV fluence of 720 mJ/cm2. The lindane degradation followed first order kinetics and mechanistic studies suggested H-abstraction by SO4•− and Cl removal via C-Cl bond cleavage by UV-C light. Toxicity assessment using ECOSAR program showed toxicity gradually decreased and eventually no significant toxicity remained when all by-products vanished at high UV dose. Removal efficiency of lindane decreased from 93.2% to 38.4, 45.5, 56.0, 84.3 and 88.6%, by adding 1.0 mg/L humic acid or 1.0 mM CO32−, HCO3−, Cl− or SO42−, respectively. Coupling of H2O2 with UV/S2O82− showed a significant synergistic effect with 99.0% lindane removal at a UV fluence of 600 mJ/cm2, using [S2O82−]0 = [H2O2]0 = 50 μM while UV/H2O2 resulted in only 36.6% lindane removal ([lindane]0 = 3.43 μM, [H2O2]0 = 100 μM) at a UV fluence of 720 mJ/cm2. The results indicate that SR-AOP has potential for consideration as a remedial technology to treat persistent chlorinated pesticides such as lindane in contaminated water.

Regulation of the abundance of Y-family polymerases in the cell cycle of budding yeast in response to DNA damage

Y-family DNA polymerases mediate DNA damage tolerance via translesion synthesis (TLS). Because of the intrinsically error-prone nature of these enzymes, their activities are regulated at several levels. Here, we demonstrate the common regulation of the cellular abundance of Y-family polymerases, polymerase eta (Pol eta), and Rev1, in response to DNA damage at various stages of the cell cycle. UV radiation influenced polymerase abundance more when cells were exposed in S-phase than in G1- or G2-phases. We noticed two opposing effects of UV radiation in S-phase. On one hand, exposure to increasing doses of UV radiation at the beginning of this phase increasingly delayed S-phase progression. As a result, the accumulation of Pol eta and Rev1, which in nonirradiated yeast is initiated at the S/G2-phase boundary, was gradually shifted into the prolonged S-phase. On the other hand, the extent of polymerase accumulation was inversely proportional to the dose of irradiation, such that the accumulation was significantly lower after exposure to 80 J/m2 in S-phase than after exposure to 50 J/m2 or 10 J/m2. The limitation of polymerase accumulation in S-phase-arrested cells in response to high UV dose was suppressed upon RAD9 (but not MRC1) deletion. Additionally, hydroxyurea, which activates mainly the Mrc1-dependent checkpoint, did not limit Pol eta or Rev1 accumulation in S-phase-arrested cells. The results show that the accumulation of Y-family TLS polymerases is limited in S-phase-arrested cells due to high levels of DNA damage and suggest a role of the Rad9 checkpoint protein in this process.

The alkaloid brachycerine contributes to protection against acute UV-B damage in Psychotria

Plants developed several strategies to cope with ultraviolet radiation (UV) exposure, including accumulation of specialized metabolites, with a recognized major role played by flavonoids. The unique alkaloid brachycerine of Psychotria brachyceras (Rubiaceae) is induced by leaf exposure to high UV intensity and is a potent antioxidant, so it is likely to participate as a protecting factor against this radiation. The capacity of brachycerine as a putative agent in acute UV protection was tested by comparison of P. brachyceras with P. carthagenensis, a closely related and co-ocurring species devoid of alkaloids, in UV-B exposure experiments. Leaves of P. brachyceras were very tolerant to high UV doses when compared with P. carthagenensis, lacking chlorophyll loss and membrane lipid peroxidation. Overall, well known leaf defenses against UV-B, such as flavonoids and cuticular waxes, were not markedly different between Psychotria species. The alkaloid was found both in the epidermis and mesophyll in leaves of P. brachyceras. Brachycerine is an effective in vitro superoxide scavenger and, when applied to the surface of P. carthagenensis leaves, significantly increased UV-B tolerance, improving chlorophyll concentration and several photosynthetic parameters under this treatment. Profiles of brachycerine extracted from alkaloid-treated P. carthagenensis leaves showed partial degradation after UV exposure, suggesting alkaloid involvement in chemical quenching of reactive oxygen species. In addition to flavonoids, the alkaloid brachycerine may improve tolerance to acute UV-B, representing a chemical tool to protect plants against this harmful condition.

Evaluating a Combined Method of UV and Washing for Sanitizing Blueberries, Tomatoes, Strawberries, Baby Spinach, and Lettuce

We assessed a fresh produce decontamination system using a combined method of UV and washing (water-assisted UV [WUV]) in different scales. The system used tap water to wash fresh produce while exposing it to UV light. First, the reduction of Salmonella in tap water under UV treatment (1 to 1,740 mJ/cm2) was determined. Increasing the UV dose significantly (P < 0.05) increased the Salmonella reduction in wash water, and UV intensity of more than 2 mW/cm2 could reduce Salmonella in tap water to below 1 CFU/mL given enough processing time (more than 1 min; UV dose of 120 mJ/cm2). Then, the decontamination effectiveness of a small WUV system was tested on blueberries (50 g). Blueberries were spot or dip inoculated with a Salmonella cocktail and treated by the small WUV system (200 mL of water). In general, WUV treatments achieved significantly better Salmonella inactivation than tap water wash; tap water wash (10 min) and 2 mW/cm2 WUV treatment (with a UV dose of 1,200 mJ/cm2) reduced populations of spot-inoculated Salmonella on blueberries by 2.44 and 5.45 log, respectively. Compared with spot-inoculated Salmonella on blueberries, dip-inoculated Salmonella was more difficult to be inactivated by WUV treatments. Then, the decontamination effectiveness of WUV treatments was tested on blueberries (170 g), tomatoes (290 g), strawberries (170 g), baby spinach (60 g), and lettuce (60 g) using a larger WUV system. In general, 10 min of 29 mW/cm2 WUV treatment (a high UV dose of 17,400 mJ/cm2) resulted in significantly better Salmonella inactivation than tap water wash (for 10 min) regardless the inoculation method, agreeing with the results of the small-scale study. For both spot- and dip-inoculated lettuce, no significant difference (P > 0.05) in Salmonella inactivation by WUV treatments was observed when the quantity of lettuce increased from 50 to 100 g.

Incubation in light versus dark affects the vitality of UV-irradiated Tetraselmis suecica differently: A flow cytometric study.

In this study, we used flow cytometry to examine how incubation in dark versus light affects the vitality and viability of UV-irradiated Tetraselmis suecica. High UV doses (300 and 400 mJ/cm2) affected the esterase activity, membrane permeability, and chlorophyll content more when the subsequent incubation took place in light. For non- or low UV dose (100 and 200 mJ/cm2)-treated cells, incubation in light resulted in cell regrowth as compared to incubation in dark. Damaged cells (enzymatically active but with permeable membranes) did not recover when incubated under light or dark conditions. Exposure to light reduces the evaluation time of any given ballast water treatment, as viable cells will be detected at an earlier stage and the vitality is more affected. When evaluating the performance of UV-based ballast water treatment systems (BWTS), these results can be useful for type approval using T. suecica as a test organism in the test regime.

Efficiency of chlorine and UV in the inactivation of Cryptosporidium and Giardia in wastewater.

Wastewater from different sources is contaminated by protozoan parasites including Cryptosporidium and Giardia. Many protozoan parasites are becoming resistant to chemical treatment. The challenge of finding alternatives is presented to researchers by exploring other methods of eliminating protozoan parasites from wastewater. The aim of this study was to assess the speciation and the viability of Cryptosporidium and Giardia in environmental samples with the specific objective of evaluating if effluent chlorination and UV affect the viability. Different doses of chlorine with different exposure times were experimented with both distilled water and waste water spiked with (oo)cysts derived from environmental samples. UV irradiation at different doses was also experimented using the same spiked samples. Two methods of quantification and detection, namely, microscopy and flow cytometry, were used in the experiment. Two vital dyes, Syto-9+PI and DAPI+PI, were the used for staining the collected wastewater samples. It was found that the (oo)cysts responded to chlorination and UV treatments with Giardia responding better than Cryptosporidium. Giardia responded very well to UV irradiations with almost 0 percent remaining viable after a low dose of UV. Cryptosporidium was found to be resistant to chlorination even at high doses but responded well to high UV doses. DAPI+PI dye gave a lower mean percentage viability values than Syto-9+PI. Flow cytometry gave higher mean percentage than microscopy from the results. It is concluded that UV is a promising alternative to Chlorine in removing Cryptosporidium and Giardia from waste water. Appropriate treatment method for wastewater is necessary to minimize water resources pollution when wastewater is released into water systems.

Adult UVR exposure changes with life stage - a 14-year follow-up study using personal electronic UVR dosimeters.

Over a period spanning 14 years (1999-2001, 2006 and 2012), 31 volunteers participated in sun behaviour studies with the same protocol wearing a personal, electronic wrist-borne UVR dosimeter and completed sun exposure diaries resulting in a total of 15 946 measurements days (126 days per person per year). The participants individually maintained their UVR dose level and behaviour over the years. No statistically significant differences were seen from year to year in the "estimated annual UVR dose", the "mean UVR dose per day", the "mean percentage of ambient UVR", "days sunbathing to get a tan", "days with intermittent exposure" or in "sunburn episodes". The 20 participants still active in the labour market used sunscreen on more days in 2012 than in 1999 (p = 0.019) and with a significantly higher SPF (sun protecting factor (p < 0.001)) resulting in significantly fewer days with risk behaviour without sunscreen applied in 2012 than in 2006 (p < 0.001) and 1999 (p < 0.003). This was in contrast to the 11 participants who retired during the study period. The retired group received a non-significant 45% higher UV dose in 2012 than in 1999 (p = 0.054). In an additional study, nine 30-year-old indoor workers (high school students in the 1999 study) had changed their sun exposure pattern and had fewer days sunbathing (p = 0.008) and fewer risk behaviour days without sunscreen applied in 2012 than in 1999 (p = 0.002). Conclusion: The participants still active in the labour market maintained their sun exposure behaviour over a 14-year period. The retirees had a higher UVR dose and riskier exposure behaviour after retirement, while the high school students had changed to less risky sun behaviour on becoming indoor workers.

Synthesis of New Binder Polymers for Photolithographic Patterning of Black Pixel Define Layers of Organic Light Emitting Diode

The fabrication of black pixel define layer (PDL) on the organic light emitting diode (OLED) panel has been developed actively by using negative-tone black photoresist which contain photoinitiator, photosensitizer, binder polymer, multifunctional monomer and black mill base in order to improve the outdoor visibility of OLEDs. Cardo type binder polymer containing bulky and rigid fluorene group has been widely used in the black photoresist formulation. However, the commercial cardo binder polymer has high cost and requires high UV dose for the fine patterning of PDL in the photolithographic process. In this study we designed and synthesized various non-cardo type binder polymers and evaluated the new binder polymers in comparison with the cardo binder polymer for the improved patterning of PDL on the OLED panel.

Inactivation of biofilm-bound Pseudomonas aeruginosa bacteria using UVC light emitting diodes (UVC LEDs)

Ultraviolet light emitting diodes (UV LEDs) are a promising technology for the disinfection of water and wetted surfaces, but research into these applications remains limited. In the drinking water field, UV LEDs emitting at wavelengths ranging from 254 nm to 285 nm (UVC LEDs) have been shown to be effective for the inactivation of numerous pathogens and pathogen surrogate organisms at UV doses comparable to conventional germicidal UV lamps. Surface disinfection with UV light, from UVC LEDs or from conventional UV lamps, is not as well understood. As the technology underlying the design and construction of UV LEDs matures and their energy efficiency improves, it is likely that they will become ubiquitous in small scale water treatment applications and surface disinfection in various industries, including the medical and dental fields. A simple, easily replicated methodology was developed and optimized to grow, irradiate, and recover biofilms from coupons. It was hypothesized that higher UV doses would be required to inactivate biofilm-bound bacteria than planktonic (free-floating) bacteria because the biofilm would provide some degree of protection from the effects of UVC irradiation. Indeed, UV LED irradiation at 265 nm achieved 1.3 ± 0.2 log inactivation of biofilm-bound Pseudomonas aeruginosa at a UV dose of 8 mJ/cm2. This inactivation level is lower than those that have been reported by researchers using UVC LEDs to inactivate planktonic P. aeruginosa, a finding that can be explained by the higher resistance of biofilm-bound bacteria to UV inactivation. A dose-response curve was developed and fitted to three disinfection models: the Chick-Watson model, the multi-target model, and the Geeraerd model. This last, which posits a subpopulation of organisms that are resistant to treatment, was a good fit to the dose-response data. ATP results obtained using the biomass recovery ATP method (ATPBR), a method that includes a 4 h incubation period after treatment, was well correlated to the results of conventional plate counts.

Inactivation of airborne bacteria using different UV sources: Performance modeling, energy utilization, and endotoxin degradation

Airborne bacteria-containing bioaerosols have attracted increased research attention on account of their adverse effects on human health. Ultraviolet germicidal irradiation (UVGI) is an effective method to inactivate airborne microorganisms. The present study models and compares the inactivation performance of three UV sources in the UVGI for aerosolized Escherichia coli. Inactivation efficiency of 0.5, 2.2 and 3.1 logarithmic order was obtained at an exposure UV dose of 370 J/m3 under UVA (365 nm), UVC (254 nm) and UVD (185 nm) sources, respectively. A Beer–Lambert law-based model was developed and validated to compare the inactivation performances of the UV sources, and modeling enabled prediction of inactivation efficiency and analysis of the sensitivity of several parameters. Low influent E. coli concentrations and high UV doses resulted in high energy consumption (EC). The change in airborne endotoxin concentration during UV inactivation was analyzed, and UVC and UVA irradiation showed no marked effect on endotoxin degradation. By contrast, both free and bound endotoxins could be removed by UVD treatment, which is attributed to the ozone generated by the UVD source. The results of this study can provide a better understanding of the air disinfection and airborne endotoxin removal processes.

Effectiveness of zinc oxide-assisted photocatalysis for concerned constituents in reclaimed wastewater: 1,4-Dioxane, trihalomethanes, antibiotics, antibiotic resistant bacteria (ARB), and antibiotic resistance genes (ARGs)

Microbial and emerging chemical contaminants are unwanted constituents in reclaimed wastewater, due to the health concerns of using the water for agricultural irrigation, aquifer recharges, and potable water. Removal of these contaminants is required but it is currently challenging, given that there is no simple treatment technology to effectively remove the mixture of these contaminants. This study examined the effectiveness of ZnO-assisted photocatalytic degradation of several constituents, including 1,4-dioxane, trihalomethanes (THMs), triclosan (TCS), triclocarban (TCC), antibiotic resistant bacteria (ARB) and antibiotic resistant genes (ARGs), under low intensity of UV exposure. E. coli with an ARGs-carrying circular plasmid (pUC19) was used as a model antibiotic resistant bacterium. Our results show that commercial zinc oxide (C-ZnO) assisted photodegradation of 1,4-dioxane, and dehalogenation of THMs, TCS, and TCC, while tetrapodal zinc oxide (T-ZnO) enhanced the dehalogenation of TCS and TCC. Additionally, T-ZnO assisted the photocatalytic inactivation of the E. coli within 6 h and caused structural changes in the plasmid DNA (pUC19) with additional UV exposure, resulting in non-functional AGR-containing plasmids. These results also suggest that higher UV dose is required not only to inactivate ARB but also to damage ARGs in the ARB in order to decrease risks in promoting ARB population in the environment. Overall, our results implicated that, under low UV intensity, ZnO-assisted photocatalysis is a promising alternative to simultaneously remove biological and emerging chemical contaminants in treated wastewater for safe reuse.

Deletion of the DEF1 gene does not confer UV-immutability but frequently leads to self-diploidization in yeast Saccharomyces cerevisiae

In yeast Saccharomyces cerevisiae, the DEF1 gene is responsible for regulation of many cellular processes including ubiquitin-dependent degradation of DNA metabolism proteins. Recently it has been proposed that Def1 promotes degradation of the catalytic subunit of DNA polymerase δ at sites of DNA damage and regulates a switch to specialized polymerases and, as a consequence, DNA-damage induced mutagenesis. The idea was based substantially on the severe defects in induced mutagenesis observed in the def1 mutants. We describe that UV mutability of def1Δ strains is actually only moderately affected, while the virtual absence of UV mutagenesis in many def1Δ clones is caused by a novel phenotype of the def1 mutants, proneness to self-diploidization. Diploids are extremely frequent (90%) after transformation of wild-type haploids with def1::kanMX disruption cassette and are frequent (2.3%) in vegetative haploid def1 cultures. Such diploids look “UV immutable” when assayed for recessive forward mutations but have normal UV mutability when assayed for dominant reverse mutations. The propensity for frequent self-diploidization in def1Δ mutants should be taken into account in studies of the def1Δ effect on mutagenesis. The true haploids with def1Δ mutation are moderately UV sensitive but retain substantial UV mutagenesis for forward mutations: they are fully proficient at lower doses and only partially defective at higher doses of UV. We conclude that Def1 does not play a critical role in damage-induced mutagenesis.

Ultraviolet radiation modulates C:N stoichiometry and biomass allocation in Fagus sylvatica saplings cultivated under elevated CO2 concentration

Under the conditions of ongoing climate change, terrestrial ecosystems will be simultaneously exposed to a permanent rise in atmospheric CO2 concentration and increasing variability of such environmental factors as temperature, precipitation, and UV radiation. This will result in numerous interactions. The interactive effects caused by exposure to such multiple environmental factors are not yet well understood. We tested the hypotheses that enhanced UV radiation reduces the stimulatory effect of elevated CO2 concentration on plant biomass production and that it alters biomass allocation in broadleaved European beech (Fagus sylvatica L.) saplings. Our results after 2 years of exposure confirmed interactive effects of CO2 concentration and UV radiation on biomass production, and particularly on biomass allocation to roots and aboveground biomass. The strongest stimulatory effect of elevated CO2 on aboveground biomass and roots was found under ambient UV radiation, while both low and high UV doses reduced this stimulation. Nitrogen content in the roots and the distribution of nitrogen among leaves and roots were also significantly affected by interaction of CO2 concentration and UV radiation. The observed changes in leaf and root C:N stoichiometry were associated with altered morphological traits, and particularly with a change in the proportion of fine roots. As the biomass allocation and especially the proportion of fine roots can play an important role in effective water and nutrient use and acclimation to future climates, it is essential to obtain a deeper understanding of the links between C:N stoichiometry and biomass accumulation.

Daily very low UV dose exposure enhances adaptive immunity, compared with a single high-dose exposure. Consequences for the control of a skin infection.

Ultraviolet radiation (UVr) promotes several well-known molecular changes, which may ultimately impact on health. Some of these effects are detrimental, like inflammation, carcinogenesis and immunosuppression. On the other hand, UVr also promotes vitamin D synthesis and other beneficial effects. We recently demonstrated that exposure to very low doses of UVr on four consecutive days [repetitive low UVd (rlUVd)] does not promote an inflammatory state, nor the recruitment of neutrophils or lymphocytes, as the exposure to a single high UV dose (shUVd) does. Moreover, rlUVd reinforce the epithelium by increasing antimicrobial peptides transcription and epidermal thickness. The aim of this study was to evaluate the adaptive immune response after shUVd and rlUVd, determining T-cell and B-cell responses. Finally, we challenged animals exposed to both irradiation procedures with Staphylococcus aureus to study the overall effects of both innate and adaptive immunity during a cutaneous infection. We observed, as expected, a marked suppression of T-cell and B-cell responses after exposure to an shUVd but a novel and significant increase in both specific responses after exposure to rlUVd. However, the control of the cutaneous S. aureus infection was defective in this last group, suggesting that responses against pathogens cannot be ruled out from isolated stimuli.

Optimum Chip-Tape Adhesion for Reliable Pickup Process

An efficient UV-irradiation process plays an important role for a successful pickup of very thin ( $ ) Si chips, such as for integrated circuits, power semiconductors, or microelectromechanical systems devices. Before the UV-irradiation process, a dicing tape is laminated on the back of the wafer to hold it tightly (high adhesion strength), which enables rapid and smooth dicing of the wafer into separate Si chips. In the second stage, the adhesive layer is irradiated with UV light through the front side of the backing substrate, which decreases the adhesion strength to the level where the diced chips are picked up easily for further die-bonding processes. However, various malfunctions during the UV-irradiation process can lead to a different and occasionally insufficient UV dose. Consequently, the adhesion is not sufficiently reduced, which could later lead to pickup problems at the die-attach equipment during assembly. In this paper, we present the consequences of an insufficient UV dose on adhesion behavior and pickup efficiency. Using calculated adhesive energy, pickup simulation was done, and accumulated stress in the chips was evaluated at different UV doses. At lower UV doses, the adhesive energy showed rate-dependent behavior, while at higher UV doses, such a behavior was not shown. The accumulated stress within chips showed a linear correlation to adhesive energy, where at lower UV doses, the strength of the silicon chip was exceeded. In the practical process, with an increased pickup rate, higher energy is needed to delaminate the chip. With higher energy needed, accumulated stress in the chip is increased and could lead to the breaking of the chip.

UV adaptation: Pigmentation and protection against overexposure.

The skin is known to adapt to UV exposures, that is become less sensitive to sunburn. Reported decreases in sensitivity vary widely from well over 10-fold down to a negligible 10%. This appears to depend importantly on the UV irradiation spectrum to which the skin adapts and on the UV irradiation spectrum that is used to test the sensitivity. The sensitivity is conventionally and generally assessed by the reciprocal of the minimal erythema dose (MED): the UV dose causing a just perceptible reddening of the skin after 8-24hours. However, MED is much too subtle for everyday life: people will not notice a minimal reddening and commonly consider themselves sunburnt at considerably higher UV doses causing an intense reddening. Levels of adaptation of a well-tanned skin may be substantially higher at these more intense levels of reddening than MED levels. This expectation is based on the fact that people with a constitutively coloured skin may show moderate differences in MED compared with fair-skinned people but far less steep increases in reddening with overexposures to solar-simulated radiation (SSR). UVA exposure is known to enhance pigmentation and may thus be important in protection against overexposure to SSR.

Comparison of the Conventional Dresden Protocol and Accelerated Protocol With Higher Ultraviolet Intensity in Corneal Collagen Cross-Linking for Keratoconus.

To compare the accelerated corneal cross-linking (CXL) protocol and the conventional Dresden protocol in patients with keratoconus in terms of visual acuity, keratometric values, and topographic parameters. Twenty-eight eyes of 25 patients with primary keratoconus were divided into 2 groups; 15 eyes in group 1 received CXL under the standard Dresden protocol (3 mW/cm for 30 min, dose 5.4 J/cm) and 13 eyes in group 2 were treated with the accelerated protocol (30 mW/cm for 3 min 40 s, dose 6.6 J/cm). Visual acuity, refractive error, keratometry values obtained by both Pentacam and Auto Kerato-Refractometer, corneal thickness, and topometric indexes were compared 6 months postoperatively. The visual acuity improved significantly from 0.17 ± 0.16 to 0.08 ± 0.09 logarithm of the minimum angle of resolution in group 1 (P = 0.009). The cylindrical refractive error improved in both groups (P = 0.05 in group 1 and P = 0.011 in group 2), and the spherical equivalent increased in group 1 (P = 0.021). In group 1, the maximum keratometry value decreased by 0.55 ± 0.89 diopters (P = 0.03), and the mean keratometry value decreased by 0.44 ± 0.63 diopters (P = 0.017), whereas the changes in visual acuity, spherical and spherical equivalent refractive errors, and keratometric values in group 2 were not statistically significant. The corneal thickness at the apex decreased significantly in group 1 (P = 0.001), but the change was not significant in group 2. Despite a higher UV dose (6.6 J/cm), accelerated CXL with higher UV intensity and reduced irradiation time showed a smaller topographic flattening effect than did the conventional Dresden protocol in primary keratoconus with documented progression.

Advanced oxidative processes and membrane separation for micropollutant removal from biotreated domestic wastewater.

The presence of micropollutants in sewage is already widely known, as well as the effects caused by natural and synthetic hormones. Thus, it is necessary to apply treatments to remove them from water systems, such as advanced oxidation processes (AOPs) and membrane separation processes, which can oxidize and remove high concentrations of organic compounds. This work investigated the removal of 17β-estradiol (E2), 17α-ethinylestradiol (EE2), and estriol (E3) from biotreated sewage. Reverse osmosis processes were conducted at three recoveries (50, 60, and 70%). For E2 and EE2, the removals were affected by the recovery. The best results for RO were as follows: the E2 compound removal was 89% for 60% recovery and the EE2 compound removal was 57% for 50% recovery. The RO recovery did not impact the E3 removal. It was concluded that the interaction between the evaluated estrogens, and the membrane was the major factor for the hormone separation. The AOP treatment using H2O2/UV was carried out in two sampling campaigns. First, we evaluated the variation of UV doses (24.48, 73.44, 122.4, and 244.8kJm-2) with 18.8mgL-1 of H2O2 in the reaction. EE2 showed considerable removals (around 70%). In order to optimize the results, an experimental design was applied. The best result was obtained with higher UV dose (122.4kJm-2) and lower H2O2 concentration (4mgL-1), achieving removal of 91% for E3 and 100% for E2 and EE2.

Detection, fate and inactivation of pathogenic norovirus employing settlement and UV treatment in wastewater treatment facilities

It is accepted that discharged wastewaters can be a significant source of pathogenic viruses in receiving water bodies contributing to pollution and may in turn enter the human food chain and pose a risk to human health, thus norovirus (NoV) is often a predominant cause of gastroenteritis globally. Working with NoV poses particular challenges as it cannot be readily identified and detection by molecular methods does not assess infectivity. It has been proposed that the infectivity of NoV may be modelled through the use of an alternative virus; F-specific RNA (FRNA) bacteriophages; GA genotype and other FRNA bacteriophages have been used as a surrogate in studies of NoV inactivation.This study investigated the efficiency of novel pulsed ultraviolet irradiation and low pressure ultraviolet irradiation as a potential pathogen inactivation system for NoV and FRNA bacteriophage (GA) in secondary treated wastewaters. The role of UV dose and the impact of suspended solids concentration on removal efficiency were also examined. The study also investigated the role of settlement processes in wastewater treatment plants in removing NoV. While NoV inactivation could not be determined it was found that at a maximum UV dose of 6.9J/cm2 (6900mJ/cm2) an average 2.4 log removal of FRNA bacteriophage (GA) was observed; indicating the potential need for high UV doses to remove NoV if FRNA bacteriophage prove a suitable indicator for NoV. The study found that increasing concentrations of suspended solids impacted on PUV efficiency however, it appears the extent of the impact may be site specific. Furthermore, the study found that settlement processes can play a significant role in the removal of FRNA bacteriophage, thus potentially NoV.

Transformation of Phenylphenol Isomers by UVC Irradiation in Aqueous Solution

AbstractThe objective of this work was to study the photochemical behavior of ortho-phenylphenol (o-PP), metaphenylphenol (m-PP) and para-phenylphenol (p-PP) aqueous solutions exposed to 254 nm radiation. The influence of various reaction parameters on degradation rate was examined. Moreover, degradation products and toxicity of the reaction solutions were studied. It was observed that photolysis of phenylphenols was dependent on oxygen concentration in the reaction solution. The presence of radical and singlet oxygen scavengers in the reaction solution did not affect the photolytic degradation of the studied compounds. The values of apparent quantum yields of o-PP, m-PP and p-PP photolysis at pH 7 were equal to 0.019±0.00043, 0.023±0.00038 and 0.014±0.00083, respectively. The main intermediates of phenylphenols phototransformation were isomers of dihydroxybiphenyl. The degradation of phenylphenols during photolysis by 254 nm radiation ran quite fast. However, for the total mineralization of these compounds in water several times higher UV doses than those usually applied during UV disinfection process were required.