108 results found
Sfynia C, Bond T, Kanda R, et al., 2020, The formation of disinfection by-products from the chlorination and chloramination of amides, Chemosphere, Vol: 248:125940, ISSN: 0045-6535
This study examined the potential of six aliphatic and aromatic amides, commonly found in natural waters or used as chemical aids in water treatment, to act as organic precursors for nine haloacetamides (HAcAms), five haloacetonitriles (HANs), regulated trihalomethanes (THMs) and haloacetic acids (HAAs) upon chlorination and chloramination. The impact of key experimental conditions, representative of drinking water, including pH (7 & 8), retention time (4 & 24 h) and bromide levels (0 & 100 μg/L), on the generation of the target DBPs was investigated. The highest aggregate DBP yields upon chlor(am)ination were reported for the aromatic and hydrophobic hydroxybenzamide; 2.7% ± 0.1% M/M (chlorination) and 1.7% M/M (chloramination). Increased reactivity was observed in aliphatic and hydrophilic compounds, acrylamide (2.5 ± 0.2% M/M) and acetamide (1.3 ± 0.2% M/M), in chlorination and chloramination, respectively. The addition of bromide increased average DBP yields by 50–70%. Relative to chlorination, the application of chloramines reduced DBP formation by 66.5% (without Br−) and by 46.4% (with Br−). However, bromine incorporation in HAAs and HAcAms was enhanced following chloramination, of concern due to the higher toxicological potency of brominated compounds.
Braun L, Hazell L, Webb AJ, et al., 2020, Determining the viability of Schistosoma mansoni cercariae using fluorescence assays: an application for water treatment, PLOS Neglected Tropical Diseases, Vol: in press, ISSN: 1935-2727
Krueger BC, Fowler GD, Templeton MR, et al., 2020, Resource recovery and biochar characteristics from full-scale faecal sludge treatment and co-treatment with agricultural waste, Water Research, Vol: 169:115253, ISSN: 0043-1354
Unsafe disposal of faecal sludge from onsite sanitation in low-income countries has detrimental effects on public health and the environment. The production of biochar from faecal sludge offers complete destruction of pathogens and a value-added treatment product. To date, research has been limited to the laboratory. This study evaluates the biochars produced from the co-treatment of faecal sludge from septic tanks and agricultural waste at two full-scale treatment plants in India by determining their physical and chemical properties to establish their potential applications. The process yielded macroporous, powdery biochars that can be utilised for soil amendment or energy recovery. Average calorific values reaching 14.9 MJ/kg suggest use as solid fuel, but are limited by a high ash content. Phosphorus and potassium are enriched in the biochar but their concentrations are restricted by the nutrient-depleted nature of septic tank faecal sludge. High concentrations of calcium and magnesium led to a liming potential of up to 20.1% calcium carbonate equivalents, indicating suitability for use on acidic soils. Heavy metals present in faecal sludge were concentrated in the biochar and compliance for soil application will depend on local regulations. Nevertheless, heavy metal mobility was considerably reduced, especially for Cu and Zn, by 51.2–65.2% and 48.6–59.6% respectively. Co-treatment of faecal sludge with other carbon-rich waste streams can be used to influence desired biochar properties. In this case, the addition of agricultural waste increased nutrient and fixed carbon concentrations, as well as providing an additional source of energy. This study is a proof of concept for biochar production achieving full-scale faecal sludge treatment. The findings will help inform appropriate use of the treatment products as this technology becomes more commonly applied.
Mayor-Smith I, Templeton MR, 2019, Development of a mercury free ultraviolet high pressure plasma discharge for disinfection, Water and Environment Journal, Vol: in press, ISSN: 1747-6585
Ultraviolet (UV) disinfection is a critical and growing application for the disinfection of water. Current UV systems for disinfection applications are designed around the use of Low Pressure (LP) and High Pressure (HP) mercury based lamps. Increasing demand to reduce and ideally remove the use of mercury requires innovative adaptations and novel approaches to current technology. A potential alternative technology could be Light Emitting Diodes (LEDs) however with current low efficiencies, high costs and low operating powers a development gap for a high power mercury source has been identified. A mercury free tellurium based high pressure plasma was developed and assessed. Although relatively low efficiencies were measured compared to current mercury based technology rapid improvements are likely obtainable. Such an approach enables a novel adaptation to current technology utilising established; manufacturing facilities, approaches of UV system design and validation protocols. As a consequence it offers the potential for a rapid low cost transition to mercury free UV disinfection where no alternative is currently available.
Templeton MR, 2019, Achieving real-world impact, Environmental Science: Water Research and Technology, Vol: 5, Pages: 2070-2071, ISSN: 2053-1400
Hazell L, Braun L, Templeton MR, 2019, Ultraviolet sensitivity of WASH (water, sanitation, and hygiene) related helminths: a systematic review, PLOS Neglected Tropical Diseases, Vol: 13:e0007777
Dewhurst RN, Furlong C, Tripathi S, et al., 2019, Evaluating the viability of establishing container-based sanitation in low-income settlements, Waterlines, Vol: 38, Pages: 154-169, ISSN: 1756-3488
Container-based sanitation (CBS) services operate in a number of low-income urban settlements across the globe, providing sanitation services where other on-site and off-site sanitation systems face logistical and environmental restrictions. The viability of each CBS service is influenced by a number of location-specific factors. Drawing on an initial review of existing CBS services, this paper identifies and evaluates these factors in relation to establishing CBS in a new service location. By applying a weighted scoring matrix to these factors, the potential viability of CBS services has been assessed for urban informal settlements in Kathmandu Valley, Nepal. The viability of CBS services in these settlements was found to be most influenced by the current availability of basic sanitation facilities, the unfamiliarity with paying for sanitation services, and the universally adopted practice of anal cleansing with water. The process and scoring matrix developed and subsequently applied in Nepal are recommended as part of the pre-feasibility stage assessment where a CBS service is being considered as a sanitation option in new locations.
Charani E, Cunnington AJ, Yousif AHA, et al., 2019, In transition: current health challenges and priorities in Sudan, BMJ Global Health, Vol: 4:e001723, ISSN: 2059-7908
A recent symposium and workshop in Khartoum, the capital of the Republic of Sudan, brought together broad expertise from three universities to address the current burden of communicable and non-communicable diseases facing the Sudanese healthcare system. These meetings identified common challenges that impact the burden of diseases in the country, most notably gaps in data and infrastructure which are essential to inform and deliver effective interventions. Non-communicable diseases, including obesity, type 2 diabetes, renal disease and cancer are increasing dramatically, contributing to multimorbidity. At the same time, progress against communicable diseases has been slow, and the burden of chronic and endemic infections remains considerable, with parasitic diseases (such as malaria, leishmaniasis and schistosomiasis) causing substantial morbidity and mortality. Antimicrobial resistance has become a major threat throughout the healthcare system, with an emerging impact on maternal, neonatal, and paediatric populations. Meanwhile, malnutrition, micronutrient deficiency, and poor perinatal outcomes remain common and contribute to a lifelong burden of disease. These challenges echo the UN sustainable development goals and concentrating on them in a unified strategy will be necessary to address the national burden of disease. At a time when the country is going through societal and political transition, we draw focus on the country and the need for resolution of its healthcare needs.
Destiani R, Templeton MR, 2019, Chlorination and ultraviolet disinfection of antibiotic-resistant bacteria and antibiotic resistance genes in drinking water, AIMS Environmental Science, Vol: 6, Pages: 222-241, ISSN: 2372-0352
Ritson JP, Croft JK, Clark JM, et al., 2019, Sources of dissolved organic carbon (DOC) in a mixed land use catchment (Exe, UK), Science of the Total Environment, Vol: 666, Pages: 165-175, ISSN: 0048-9697
Many catchment management schemes in the UK have focussed on peatland restoration to improve ecosystem services such as carbon sequestration, water quality and biodiversity. The effect of these schemes on dissolved organic carbon (DOC) flux is critical in understanding peatland carbon budgets as well as the implications for drinking water treatment. In many catchments, however, peatland areas are not the only source of DOC, meaning that their significance at the full catchment scale is unclear. In this paper we have evaluated the importance of different land uses as sources of DOC by combining three datasets obtained from the Exe catchment, UK. The first dataset comprises a weekly monitoring record at three sites for six years, the second, a monthly monitoring record of 25 sites in the same catchment for one year, and the third, an assessment of DOC export from litter and soil carbon stocks. Our results suggest that DOC concentration significantly increased from the peaty headwaters to the mixed land-use areas (ANOVA F = 12.52, p < 0.001, df = 2), leading to higher flux estimates at the downstream sites. We present evidence for three possible explanations: firstly, that poor sampling of high flows may lead to underestimation of DOC flux, second, that there are significant sources of DOC besides the peatland headwaters, and finally, that biological- and photo-degradation decreases the influence of upstream DOC sources. Our results provide evidence both for the targeting of catchment management in peatland areas as well as the need to consider DOC from agricultural and forested areas of the catchment.
Auwerter LCC, Templeton MR, van Reeuwijk M, et al., 2019, Development of porous glass surfaces with recoverable hydrophobicity, Materials Letters: X, Vol: 1, ISSN: 2590-1508
Porous glass tiles have been reacted with a low-surface energy coating to produce hydrophobic surfaces. Washing the surface with surfactant reduces hydrophobicity and the wetting state changes from Cassie-Baxter to Wenzel. Passing air through the porous glass when it is immersed in water causes a solid-gas-liquid interface to form and this is associated with recovery of hydrophobicity. The processing and microstructural characteristics of the porous glass that show this effect are reported. Potential applications include low-friction pipes, where maintaining the Cassie-Baxter state at the water-pipe interface would significantly reduce the energy required to transport water.
Destiani R, Templeton MR, 2018, The antibiotic resistance of heterotrophic bacteria in tap waters in London, Water Science and Technology: Water Supply, Vol: 19, Pages: 179-190, ISSN: 1606-9749
This study assessed the occurrence and prevalence of antibiotic-resistant bacteria (ARBs) and antibiotic resistance genes (ARGs) in tap water sampled across London, United Kingdom. Sampling was conducted seasonally from nine locations spread geographically across the city. ARBs and ARGs (tet(A), dfrA7, and sul1) were detected in all sampling locations in all sampling rounds. Resistance to trimethoprim was the highest among the tested antibiotics and sul1 gene was the most abundant resistance gene detected. Several opportunistic pathogens were identified amongst the ARBs in the water samples, including Pseudomonas aeruginosa and Stenotrophomonas maltophilia.
Semitsoglou-Tsiapou S, Templeton MR, Graham NJD, et al., 2018, Potential formation of mutagenicity by low pressure-UV/H2O2 during the treatment of nitrate-rich source waters, Environmental Science: Water Research and Technology, Vol: 4, Pages: 1252-1261, ISSN: 2053-1400
Mutagenicity formation by low pressure (LP)-UV/H2O2 treatment of nitrate-rich water containing natural organic matter (NOM) was investigated. Laboratory-grade water samples spiked with either Pony Lake NOM or Suwannee River NOM (4 mg L−1 in both cases) and nitrate (50 mg L−1) were irradiated with UV fluences of 0, 1500 and 2000 mJ cm−2 and a H2O2 dose of 15 mg L−1 and tested for mutagenicity with the Ames II assay. LP-UV photolysis of nitrate in the presence of Pony Lake NOM caused a significant increase in the Ames II assay response and low concentrations of nitrite (0.08–0.09 mg NO2− L−1) and nitrophenols (0.014–0.046 μg L−1) were detected. Suwannee River NOM produced the same nitrite levels but no significant responses in the Ames II assay were observed. Additionally, samples collected from a drinking water treatment plant in the UK using LP-UV/H2O2 treatment were analysed with the Ames II assay. LC-OCD fractionation and SUVA measurements were performed to observe any changes in the properties of NOM. Significant differences in the mutagenicity response were observed between the treatment steps as well as between the two sampling periods. However, with respect to standard thresholds, none of the samples were found to be mutagenic towards the Salmonella typhimurium strain TA98 used.
Khan SJ, Gagnon GA, Templeton MR, et al., 2018, The rapidly growing role of UV-AOPs in the production of safe drinking water, Environmental Science: Water Research and Technology, Vol: 4, Pages: 1211-1212, ISSN: 2053-1400
Angoua ELE, Dongo K, Templeton MR, et al., 2018, Barriers to access improved water and sanitation in poor peri-urban settlements of Abidjan, Cote d'Ivoire, PLOS One, Vol: 13(8):e0202928, ISSN: 1932-6203
Bell MC, Ritson JP, Verhoef A, et al., 2018, Sensitivity of peatland litter decomposition to changes in temperature and rainfall, Geoderma, Vol: 331, Pages: 29-37, ISSN: 0016-7061
Changes to climate are projected over the next 50 years for many peatland areas. As decomposition of peat-forming vegetation is likely to be intrinsically linked to these changes in climate, a clear understanding of climate-peat dynamics is required. There is concern that increased temperature and decreased precipitation could increase the rate of decomposition and put the carbon sink status of many peatlands at risk, yet few studies have examined the impact of both climatic factors together. To better understand the sensitivity of peatland decomposition to changes in both temperature and precipitation and their interaction, we conducted a short-term laboratory experiment in which plant litters and peat soil were incubated, in isolation, in a factorial design. Treatments simulated baseline and projected climate averages derived from the latest UK climate change projections (UKCP09) for Exmoor, a climatically marginal peatland in SW England. Regular carbon dioxide flux measurements were made throughout the simulation, as well as total mass loss and total dissolved organic carbon (DOC) leached. The largest effect on carbon loss in this multifactor experiment was from substrate, with Sphagnum/peat releasing significantly less C in total during the experiment than dwarf shrubs/graminoids. Climate effects were substrate specific, with the drier rainfall treatment increasing the DOC leaching from Calluna, but decreasing it from Sphagnum. Partitioning between CO2 and DOC was also affected by climate, but only for the peat and Sphagnum samples, where the future climate scenarios (warmer and drier) resulted in a greater proportion of C lost in gaseous form. These results suggest that indirect effects of climate through changes in species composition in peatlands could ultimately turn out to be more important for litter decomposition than direct effects of climate change from increased temperatures and decreased rainfall.
Destiani R, Templeton MR, Kowalski W, 2018, Relative ultraviolet sensitivity of selected antibiotic resistance genes in waterborne bacteria, Environmental Engineering Science, Vol: 35, Pages: 770-774, ISSN: 1092-8758
This study investigated the ability of monochromatic ultraviolet (UV) light at 254 nm applied at typical drinking water disinfection doses to damage the antibiotic-resistant genes mph(A), sul1, tet-A, and bla-Tem1 in waterborne bacteria. UV sensitivity rank was bla-TEM1 > tet-A > sul1 > mph(A), which is consistent with predictions of a previously presented genomic-based UV sensitivity model. It is the first time that predictions of the relative UV sensitivity of antibiotic resistance genes have been validated with experimental data and suggest that such modeling is useful for determining the UV sensitivity of other genes in waterborne microorganisms.
Hammoud AS, Leung J, Tripathi S, et al., 2018, The impact of latrine contents and emptying practices on nitrogen contamination of well water in Kathmandu Valley, Nepal, AIMS Environmental Science, Vol: 5, Pages: 143-153, ISSN: 2372-0352
Leaching of nitrogen-containing compounds (e.g., ammonia, nitrate) from pit latrines and seepage tanks into groundwater may pose health risks, given that groundwater is a significant source for drinking water in many low-income countries. In this study, three communities within Kathmandu, Nepal (Manohara, Kupondole, and Lokanthali) were visited to investigate the impact of pit latrines on groundwater quality, with a focus on understanding the fate of nitrogen-containing compounds specifically. Well water samples were analyzed over two seasons (wet and dry) for their nitrogen content, dissolved oxygen (DO), chemical oxidation demand (COD), and oxidation-reduction potential (ORP), and samples collected from within the nearby pits were also analyzed to determine nitrogen content and COD. Hand dug wells were found to be more likely receptors of contamination than tube wells, as expected, with inter-well variations related to the relative redox conditions in the wells. Increased pit-emptying frequency was related to lower levels of nitrogen in the latrines and in the nearest wells, suggesting this may be an effective strategy for reducing the risks of groundwater contamination in such settings, all else being equal.
Braun L, Grimes JET, Templeton MR, 2018, The effectiveness of water treatment processes against schistosome cercariae: a systematic review, PLOS Neglected Tropical Diseases, Vol: 12:e0006364
Bond T, Tse Q, Chambon C, et al., 2018, The feasibility of char and bio-oil production from pyrolysis of pit latrine sludge, Environmental Science: Water Research and Technology, Vol: 4, Pages: 253-264, ISSN: 2053-1400
Sustainable methods are required in developing regions to treat and recover value from pit latrine sludge. One strategy is to pyrolyse pit latrine contents and generate char and bio-oil, which can then be used as a soil enhancer and fuel, respectively. Despite the many benefits associated with the process, there is very limited relevant literature available. This study examines its feasibility. Initially, the energy balance for the pyrolysis of sewage sludge was calculated using data from 14 literature studies. The average net energy recovery from pyrolysis of dewatered and dried sewage sludge followed by use of bio-oil as fuel was calculated as 4.95 ± 0.61 MJ kg−1. For dewatered sewage sludge, an average net energy input of 2.23 ± 0.31 MJ kg−1 was required. Parallel calculations were undertaken where pit latrine sludge with 0–100% water content was the hypothetical feedstock. On average, net energy recovery from produced bio-oil was achievable when pit latrine sludge with a water content of ≤∼55% was the feedstock. When both bio-oil and char were utilised, net energy recovery was feasible at a water content value of ≤∼65%. Char production is more favourable from stabilised pit latrine sludge with lower moisture and volatile solids content. Barriers to the pyrolysis of pit latrine sludge include its heterogeneous composition and the difficulty of collecting high-viscosity sludge. Overall, this study demonstrates the potential of pyrolysis as a disposal and value addition method for pit latrine sludge. Innovative methods for sludge drying and pit emptying will expedite the process becoming a reality.
Todman LC, Chhang A, Riordan HJ, et al., 2018, Soil osmotic potential and its effect on vapor flow from a pervaporative irrigation membrane, Journal of Environmental Engineering, Vol: 144:04018048, ISSN: 0733-9372
Grimes JET, Tadesse G, Gardiner IA, et al., 2017, Sanitation, hookworm, anemia, stunting, and wasting in primary school children in southern Ethiopia: baseline results from a study in 30 schools, PLOS Neglected Tropical Diseases, Vol: 11:e0005948, ISSN: 1935-2727
BackgroundInadequate nutrition; neglected topical diseases; and insufficient water, sanitation, and hygiene (WASH) are interrelated problems in schools in low-income countries, but are not routinely tackled together. A recent three-year longitudinal study investigated integrated school health and nutrition approaches in 30 government primary schools in southern Ethiopia. Here, we report on baseline associations between sanitation, hookworm infection, anemia, stunting, and wasting.MethodsIn each school, the Schistosoma mansoni, S. haematobium, and soil-transmitted helminth infection intensities; blood hemoglobin concentrations; heights; and weights of approximately 125 students were assessed. Of these 125 students, approximately 20 were randomly selected for student WASH surveys. Of these 20, approximately 15 were randomly selected for household sanitation observations. School WASH was also assessed through a combination of observations and questions to the headteacher. Mixed-effects logistic regression was used to compare household sanitation with hookworm infection (the other parasites being much less prevalent); and hookworm infection with anemia, stunting, and wasting.FindingsBlood, stool, and urine samples were provided by 3,729 children, and student WASH and household WASH surveys were conducted with 596 and 448 of these students, respectively.Hookworm, Ascaris lumbricoides, Trichuris trichiura, and S. mansoni infections had prevalences of 18%, 4.8%, 0.6%, and 0.3%, respectively, and no S. haematobium infections were found. Anemia, stunting, and wasting had prevalences of 23%, 28%, and 14%, respectively.No statistically significant associations were found between latrine absence or evidence of open defecation at home, and hookworm infection (adjusted odds ratio, OR = 1.28, 95% confidence interval, CI: 0.476–3.44; and adjusted OR = 1.21, 95% CI: 0.468–3.12; respectively); or between hookworm infection and anemia, stunting, or wasting (adjusted OR = 1
Sfynia C, Bond T, Kanda R, et al., 2017, Predicting the formation of haloacetonitriles and haloacetamides by simulated distribution systems tests, Water Distribution Systems Analysis (WDSA) Conference, Cartagena, Colombia
Ritson JP, Brazier RE, Graham NJD, et al., 2017, The effect of drought on dissolved organic carbon (DOC) release from peatland soil and vegetation sources, Biogeosciences, Vol: 14, Pages: 2891-2902, ISSN: 1726-4189
Drought conditions are expected to increase in frequency and severity as the climate changes, representing a threat to carbon sequestered in peat soils. Downstream water treatment works are also at risk of regulatory compliance failures and higher treatment costs due to the increase in riverine dissolved organic carbon (DOC) often observed after droughts. More frequent droughts may also shift dominant vegetation in peatlands from Sphagnum moss to more drought-tolerant species. This paper examines the impact of drought on the production and treatability of DOC from four vegetation litters (Calluna vulgaris, Juncus effusus, Molinia caerulea and Sphagnum spp.) and a peat soil. We found that mild droughts caused a 39.6 % increase in DOC production from peat and that peat DOC that had been exposed to oxygen was harder to remove by conventional water treatment processes (coagulation/flocculation). Drought had no effect on the amount of DOC production from vegetation litters; however large variation was observed between typical peatland species (Sphagnum and Calluna) and drought-tolerant grassland species (Juncus and Molinia), with the latter producing more DOC per unit weight. This would therefore suggest the increase in riverine DOC often observed post-drought is due entirely to soil microbial processes and DOC solubility rather than litter layer effects. Long-term shifts in species diversity may, therefore, be the most important impact of drought on litter layer DOC flux, whereas pulses related to drought may be observed in peat soils and are likely to become more common in the future. These results provide evidence in support of catchment management which increases the resilience of peat soils to drought, such as ditch blocking to raise water tables.
Bond T, Simperler A, Graham N, et al., 2017, Defining the molecular properties of N-nitrosodimethylamine (NDMA) precursors using computational chemistry, Environmental Science: Water Research and Technology, Vol: 3, Pages: 502-512, ISSN: 2053-1400
N-Nitrosodimethylamine (NDMA) is a potent carcinogen and can be produced during chloramination of drinking water and wastewater. Computational chemistry methods were used for the first time to calculate molecular descriptors for 64 NDMA precursors containing a dimethylamine (DMA) moiety. Descriptors were partial charge, bond length and pKa of the DMA nitrogen and planarity of the DMA group. Precursors classified on the basis of chemical functionality showed distinct relationships between partial charge and NDMA formation. Quaternary amines and tertiary amines with the DMA bonded to -COR and -CSR groups had a combination of low NDMA formation and high partial charge. The most potent NDMA precursors are tertiary amines with an acidic hydrogen and electron-donating group α and β to the DMA respectively. They also have comparable molecular descriptors: relatively negative partial charges, low planarity values, high bond lengths and pKa values from ∼8.3–10.1. A literature search identified 233 potential NDMA precursors that have never been tested experimentally. Of these chemicals 60% are therapeutics, 13% veterinary therapeutics and 10% natural products. Analysis combining qualitative assessment of chemical functionality and computational calculation of molecular descriptors successfully identified rivastigmine, a therapeutic, and conessine, a naturally occurring species, whose NDMA yields were determined experimentally to be 83.3 ± 0.5% and 42.3 ± 1.8% mol mol−1, respectively. This study defines the molecular properties associated with reactive NDMA precursors and the origin and identity of those amines which contribute to NDMA formation in drinking water.
Ritson JP, Bell M, Brazier RE, et al., 2016, Managing peatland vegetation for drinking water treatment, Scientific Reports, Vol: 6, ISSN: 2045-2322
Peatland ecosystem servicesinclude drinking water provision, flood mitigation, habitat provision and carbon sequestration. Dissolved organic carbon (DOC) removal is a key treatment process for the supply of potablewaterdownstream frompeat-dominated catchments. A transition from peat-forming Sphagnummoss to vascular plants has been observed in peatlands degraded by (a) land management, (b) atmospheric deposition and (c) climate change. Herewithinwe show that the presence of vascular plants with higherannual above-ground biomass productionleads to a seasonaladdition of labileplantmaterialinto the peatland ecosystemaslitter recalcitranceis lower. The net effect willbe asmaller litter carbon pool dueto higher rates of decomposition, and a greater seasonal pattern of DOC flux. Conventional water treatment involving coagulation-flocculation-sedimentation may be impeded byvascularplant-derivedDOC. It has been shown thatvascularplant-derived DOC is more difficult to remove via these methodsthan DOC derived from Sphagnum, whilst also being less susceptible to microbial mineralisation before reaching the treatment works. These results provide evidence that practices aimed at re-establishing Sphagnummoss on degraded peatlands could reduce costs and improve efficacy at water treatment works, offering an alternative to ‘end-of-pipe’ solutionsthrough management of ecosystem service provision.
Semitsoglou-Tsiapou S, Mous A, Templeton MR, et al., 2016, The role of natural organic matter in nitrite formation by LP-UV/H2O2 treatment of nitrate-rich water, Water Research, Vol: 106, Pages: 312-319, ISSN: 1879-2448
The role of natural organic matter (NOM) on nitrite formation from nitrate photolysis by low pressure ultraviolet lamp (LP-UV) photolysis and LP-UV/H2O2 treatment was investigated. Nitrate levels up to the WHO guideline maximum of 50 mg NO3−/L were used in tests. The presence of 4 mg/L Suwannee River natural organic matter (NOM) led to increased nitrite yields compared to NOM-free controls. This was caused partly by NOM scavenging of radical dotOH radicals, preserving the produced NO2− as well as the ONOO− that leads to NO2− formation, but also via the production of radical species (1O2, O2radical dot− and radical dotOH) by the photolysis of NOM. In addition, solvated electrons formed by NOM photolysis may reduce nitrate directly to nitrite. For comparison, Nordic Lake NOM, representative of aquatic NOM, as well as Pony Lake NOM, which had a greater nitrogen content (6.51% w/w) than the other two types of NOM, were investigated, yielding similar nitrite levels as Suwannee River NOM. The results suggest that neither the type nor the nitrogen content of the NOM have an effect on the nitrite yields obtained over the range of UV/H2O2 doses applied (UV fluences of 500–2100 mJ/cm2 and hydrogen peroxide doses of 10, 25, and 50 mg/L). The findings indicate that for UV fluences above 1500 mJ/cm2 the resulting nitrite concentration can exceed the 0.1 mg/L EU regulatory limit for nitrite, suggesting that nitrite formation by LP-UV advanced oxidation of nitrate-rich waters is important to consider.
Grimes JET, Templeton MR, 2016, School water, sanitation, and hygiene to reduce the transmission of schistosomes and soil-transmitted helminths, Trends in Parasitology, Vol: 32, Pages: 661-664, ISSN: 1471-5007
Grimes JET, Tadesse G, Mekete K, et al., 2016, School water, sanitation, and hygiene, soil-transmitted helminths, and schistosomes: national mapping in Ethiopia, PLOS Neglected Tropical Diseases, Vol: 10:e0004515, ISSN: 1935-2735
Semitsoglou-Tsiapou S, Templeton MR, Graham NJD, et al., 2016, Low pressure UV/H2O2 treatment for the degradation of the pesticides metaldehyde, clopyralid and mecoprop – kinetics and reaction product formation, Water Research, Vol: 91, Pages: 285-294, ISSN: 1879-2448
The degradation kinetics of three pesticides – metaldehyde, clopyralid and mecoprop – by ultraviolet photolysis and hydroxyl radical oxidation by low pressure ultraviolet hydrogen peroxide (LP-UV/H2O2) advanced oxidation was determined. Mecoprop was susceptible to both LP-UV photolysis and hydroxyl radical oxidation, and exhibited the fastest degradation kinetics, achieving 99.6% (2.4-log) degradation with a UV fluence of 800 mJ/cm2 and 5 mg/L hydrogen peroxide. Metaldehyde was poorly degraded by LP-UV photolysis while 97.7% (1.6-log) degradation was achieved with LP-UV/H2O2 treatment at the maximum tested UV fluence of 1000 mJ/cm2 and 15 mg/L hydrogen peroxide. Clopyralid was hardly susceptible to LP-UV photolysis and exhibited the lowest degradation by LP-UV/H2O2 among the three pesticides. The second-order reaction rate constants for the reactions between the pesticides and OH-radicals were calculated applying a kinetic model for LP-UV/H2O2 treatment to be 3.6 × 108, 2.0 × 108 and 1.1 × 109 M−1 s−1 for metaldehyde, clopyralid and mecoprop, respectively. The main LP-UV photolysis reaction product from mecoprop was 2-(4-hydroxy-2-methylphenoxy) propanoic acid, while photo-oxidation by LP-UV/H2O2 treatment formed several oxidation products. The photo-oxidation of clopyralid involved either hydroxylation or dechlorination of the ring, while metaldehyde underwent hydroxylation and produced acetic acid as a major end product. Based on the findings, degradation pathways for the three pesticides by LP-UV/H2O2 treatment were proposed.
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