School of Water, Energy and Environment (SWEE)
Permanent URI for this community
Browse
Browsing School of Water, Energy and Environment (SWEE) by Course name "MSc by Research in Water"
Now showing 1 - 9 of 9
Results Per Page
Sort Options
Item Open Access Comparison of advanced oxidation processes for metaldehyde removal and downstream disinfection by-product formation(Cranfield University, 2017-09) Diana, Marine; Jarvis, Peter; Hassard, FrancisMetaldehyde is the pesticide that has been found to exceed the maximum regulatory concentration of 0.1 µg/L in drinking water the most in the UK in recent years. As a result of the pesticide not being removed by conventional water treatment processes, there has been an interest in alternative treatments including advanced oxidation processes (AOPs). The latter have been reported as promising technologies for the removal of recalcitrant micropollutants. A large scale pilot study was carried out to compare the performance of two different AOPs for removing metaldehyde from sources used to produce drinking water: the UV/H₂O₂ AOP and O₃/H₂O₂ followed by UV/H₂O₂ AOP. Since AOPs can increase the formation of disinfection by-products (DBP) under certain oxidation conditions, it is important to assess their impact on DBP precursors. For this purpose, the trihalomethane formation potential (THM FP) and the haloacetic acid formation potential (HAA FP) were measured upon chlorination of samples collected at different stages of the treatment. Both AOPs were shown to remove metaldehyde efficiently achieving removals of up to 98%. They were able to reduce metaldehyde concentration below the regulatory level with UV doses lower than 1 kWh/m³ for initial metaldehyde concentrations of up to 2.10 µg/L. Concentrations as high as this value can be found in sources used to produce drinking water. The O₃/H₂O₂ - UV/H₂O₂ AOP was up to 33% more efficient than the UV/H₂O₂ AOP when applied at UV doses lower than 0.60 kWh/m3. In this work, the electrical energy applied to the system was expressed in kWh/m³ to enable the comparison of both AOPs at similar operating conditions. Both AOPs either increased or decreased the THM FP and the HAA FP between -85% and +155% with respect to the inlet. However, the quality of the inlet water better explained these changes rather than the UV and oxidant doses applied.Item Open Access Dual model sensors for viral RNA and protein detection for SARS- CoV-2 in saliva(Cranfield University, 2023-10) Ma Xuanye; Yang, Zhugen; Chiarelli, IvaThe coronavirus disease 2019 (Covid-19) pandemic emerged as an infection by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) over the past 3 years, causing enormous threats to humans and economic loss. It was reported that currently, nearly 68% of the population shows a degree of immunity to the disease. Though vaccine has played a critical role to protect the population, people are at risk of second or third infections with fading antibody titers against the virus. The detection of the viral load was crucial for monitoring the spread of this disease, and the detection of the antibody concentration to the virus was significant as well to understand the neutralization activity and vaccine response. This thesis reports the development of a rapid paper-based platform, which provides nucleic acid detection and immunoassay to test both active infections and body immunity. The project focused on a non-invasive sample, human saliva, as an alternative to nasopharyngeal swabs for diagnosis. The nucleic acid test, employing reverse transcription loop-mediated isothermal mediated amplification (RT-LAMP), was further integrated into a novel paper microfluidic platform, where the result could be reported within 30 mins. Under the optimized conditions, RT- LAMP assay correctly detects above 135 copies µL⁻¹ of synthetic SARS-CoV-2 sequence. Moreover, a paper-based immunoassay was devised and constructed, following meticulous refinement of detection parameters and comparative analysis against a conventional 96-well plate assay for the identification of immunoglobulin G (IgG) targeting the SARS-CoV-2 spike protein. For the paper- based immunoassay, the dynamic range of the IgG was 0.5 μg mL⁻¹ to 50 μg mL⁻¹ , which was sensitive enough compared to clinical values. It should be noted that only commercially available artificial saliva was utilized to test the analytical performance of the developed assay. In conclusion, these results demonstrated a rapid and easy-to-use paper microfluidics platform with the potential to be further implemented as a comprehensive detection tool for monitoring both pathogenetic infection and immune levels.Item Open Access Effectiveness of H₂O₂/UV and O₃/H₂O₂/UV for metaldehyde removal in drinking water and full-scale costing analysis(Cranfield University, 2017-09) Fernandez Lopez-Rey; Hassard, Francis; Jefferson, BruceMetaldehyde is a widely used pesticide in the UK and has been reported to produce drinking water quality failures across the national water utilities. Advanced Oxidation Processes (AOPs) are effective in the removal of recalcitrant organic constituents but pose (i) high energy and chemical costs and (ii) by- products formation upon disinfection stage. In this context, UV/H₂O₂ and O₃/H₂O₂ + H₂O₂/UV were tested at pilot-scale concurrently at Draycote water treatment work (WTW) (UK) for metaldehyde degradation and disinfection by products formation potential (DBPFP) at different energy demands (Eᴅ), H₂O₂ and O₃ doses; and pesticide concentrations. Whole-life costing analysis (WLCA) was undertaken to assess which AOP was most economic for metaldehyde removal at a Draycote sized WTW. Sensitivity analysis considered potential costs of each AOP. Metaldehyde was removed up to 98% (UV/H2O2) and 97% (O₃/H₂O₂ + H₂O₂/UV) successfully fulfilling European Directive 98/83/EC below both 1.0 kWh m⁻³ and 2.14 µg L⁻¹ pesticide inlet water level. Net DBPFP contribution ranged -283 µg L⁻¹ to +255 µg L⁻¹ for trihalomethanes formation potential (THMFP), which are UK regulated. DBPFP was related to organic background characteristics rather than the operating conditions tested in both AOPs. Cost estimating the AOPs for a 0.72-log metaldehyde removal enabled the total expenditures to be determined indicating that energy consumption accounted for 50% (UV/H₂O₂), 49 % (O₃/H₂O₂+ H₂O₂/UV) and 31% (O₃/H₂O₂) of their operating costs. Similar £14.7 million capital costs were appraised for O₃/H₂O₂ and UV/H₂O₂. Overall, O₃/H₂O₂ sub process outperformed the rest of AOPs when considering both metaldehyde degradation (≤96%) and net DBPFP contribution (≤51 µg L⁻¹ THMFP) at the most economically operating costs for 5-month yearly treatment (£0.07 m⁻³). Sensitivity analysis showed the O₃/H₂O₂ more efficient process requiring less inputs than UV/H₂O₂ for the same metaldehyde removal. However, the O₃/H₂O₂ was cost effective at an ideal stoichiometric mass ratio of 0.7 H₂O₂:O₃. Therefore, this would require validation at full-scale. The AOPs were robust for metaldehyde degradation with reasonable costs.Item Open Access Evolution of hybrid systems for treatment of effluents from the pesticide production industry.(2017-05) Goodwin, Lindsey Marie; Soares, Ana; Carra ruiz, IreneThe pesticide production industry generates a high strength wastewater containing a range of toxic pollutants (2,4-dichlorphenoxy acetic acid: 2,4-D; 4-(2,4-dichlorphenox) propionic acid: 2,4-DP; 4-(2,4-dichlorophenox) butyric acid: 2,4-DB; 2,4-dichlorophenol: 2,4-DCP; 2,4,6-trichlorophenol: 2,4,6-TCP; 4-chlororthocresol: PCOC; 4-chloro-2-methyl phenoxyacetic acid: MCPA, 4-(4-chloro-2-methylphenoxy) butyric acid: MCPB and 2-(4-chloro-2-methylphenoxy) propionic acid: MCPP). These pesticides can enter the natural environment and water sources if not removed in a wastewater treatment plant. Treated effluents are regulated by legislation such as the Water Framework Directive (WFD). The organic matter and pesticides concentrations in the wastewater were highly variable across the 12 sampling campaign carried out. These results were expected, as the pesticide production facility manufactures different formulations at different intervals of time. The biochemical oxygen demand (BOD) and chemical oxygen demand (COD) concentrations ranged from 5101-18000 mg/L and 18675-47763 mg/L, respectively. The pesticides average concentrations for 2,4-DCP were high at 58.96 mg/L, followed by MCPA at 32.45 mg/L, PCOC with 21.91 mg/L, 2,4-D at 13,94 mg/L and MCPP at 7.58 mg/L. On the other side the average concentrations for 2,4-DB and 2,4,6-TCP were >5 mg/L and the average concentrations for 2,4-DP and MCPB were <1 mg/L. When evaluating different treatment options to design a hybrid system to treat the pesticide production industry wastewater it was clear that a biological treatment process should be considered due to the high BOD and COD. Anaerobic treatability tests indicated that the wastewater was toxic to organism present in anaerobic digested sludge, as no methane production was observed at dilutions >1%. Aerobic respirometry tests showed this wastewater was toxic to activated sludge microorganisms at dilutions >25%. Nevertheless, when testing the wastewater diluted to 25%, it was observed that the addition of nutrients (1.7 g/L NH4 and 0.23 g/L PO4) and alkalinity (and 0.1 g/L) enhanced the biological degradation, with pesticide removals of 63% for phenoxy acids (MCPB, MCPA, PCOC, MCPP), 34% for 2,4,6-TCP and 17% for dichloro acids (2,4-D, 2,4-DP, 2,4-DB, 2,4DCP).. Acclimatisation studies were inconclusive. The physical/chemical characterization of the key pollutants present in the pesticide production wastewater indicates their likelihood to be adsorbed (molecular weight >170 mg/L and Log Kₒw >2.5). Tests completed with granular activated carbon (GAC) indicated high adsorption capacity for these pollutants as 1 g/L GAC removed 100% of the phenoxy acids, 2,4,6-TCP and dichloro acids within 24h. Lab-scale column tests were completed with pesticides breaking through between 599-1374 bed volumes (BV) when using 3-30 minutes EBCT. Advanced oxidation processes (AOPs) showed no removal of pesticides when treating the wastewater with Fenton process even at high doses of H₂O₂ (12500 mg/L) and Fe²⁺(20 mg/L) Other tests were completed with UV/H₂O₂ using a dose of 1250 mg/L H₂O₂ and a UV intensity of 3 mW/cm² but low 30% total pesticides removal was also observed. On the other side, UV photolysis was a shown to be efficient at removing the pesticides without the presence of H₂O₂. The GAC-biological hybrid system showed that after GAC treatment the pesticide production wastewater was not toxic to the aerobic microorganisms at 75% wastewater dilution. After 552 BV GAC and biological treatment, removal efficiencies were significant with overall pesticide removals of 86% (phenoxy acids), 98% (dichloro acids) and 83% (2,4,6-TCP). Nevertheless, the effluent quality produced by this process would not bet high enough to achieve the limits described in the WFD and the GAC would need frequent regeneration, leading to high operational costs. A number of hybrid systems (granular activated carbon, membrane bioreactor and ultraviolet photolysis) were also investigated. The MBR-GAC pilot-plant showed very effective especially after dosing with additional nutrients and alkalinity. After diluting the wastewater to 25%, to prevent toxicity to the MBR process, and GAC, the removals reached 88% for COD, 72% for BOD and 86-99% for pesticides. Photolysis with UV showed promising results to replace the GAC, as the MBR-UV system achieved a total pesticides removal of 99-100%. The MBR-UV hybrid system generated an effluent with 5 μg/L MCPA, 1 μg/L MCPB, 7 μg/L MCPP, 22 μg/L PCOC, 39 μg/L 2,4-D, 0.75 μg/L 2,4-DP, 0.37 μg/L 2,4-DB, 5 μg/L 2,4-DCP and 5 μg/L 2,4,6-TCP. Nevertheless, even with high effectiveness of the MBR and UV system the effluent did not reach the discharge limits to meet WFD annual average environmental quality standards (EQS) for 2,4-D (0.3 μg/L) and MCPA (2 μg/L), just the EQS for 2,4-DCP (20μg/L) and MCPP (18 μg/L) would be met. The EQS are set for environmental water quality and could be met if the treated wastewater is discharged to a water body that ensures 1:150 dilution, assuming that no 2,4-D is present in receiving water body.Item Open Access Investigating the hydraulic performance of fullscale treatment wetlands using electrical resistivity tomography(Cranfield University, 2024-01) Hassan, Syed Shuja Ul; Bajón-Fernández, Yadira; Lyu, TaoHorizontal subsurface flow constructed wetlands (HSFCWs) have been widely used for tertiary treatment of wastewater in the United Kingdom (UK). One of the main objectives for UK’s water industry is achieving a reduction in maintenance costs of HSFCWs by reducing frequency and cost of clogging remedial measures. However, inability of conventional clogging assessment methods to provide reliable subsurface visualisation of the HSFCWs limits understanding of clogging profiles across treatment units, hindering proactive maintenance and remedial interventions. Without trustworthy information about subsurface conditions of HSFCWs, clogging remedial measures cannot be optimised to provide targeted, proactive, and cost-effective maintenance. In this study, electric resistivity tomography (ERT) has been applied to identify its effectiveness to provide reliable visualisation of the subsurface conditions of HSFCWs. On this project, two HSFCWs with different clogging levels were tested using ERT. Anomalies in subsurface distribution of water and profiles of clog matter accumulation across the HSFCWs were identified by changes in electric resistance of the media. The output was in form of cross sections showing variation in resistance across the media with different colours. The visual representation of subsurface conditions covered the full depth as well as the length of HSFCWs. The subsurface conditions identified in ERT results were in line with those observed by conventional clogging measurement methods, including substrate permeability measurement and tracer test, which provides preliminary validation of the ERT methodology. A recently refurbished HSFCW was found to have negligible level of clogging and subsurface visualisation was depicted by consistent shades showing uniform electric resistivity values (between 20 to 300 ohm.m) across the HSFCW. Contrarily, a mature HSFCW with many years of operation and no recent remedial interventions resulted in significant colour variation across the sections, indicating uneven electric resistance across the HSFCW (between 20 to 4000 ohm.m) and the ability of the ERT methodology to infer clogging levels. Considerably higher resistivity values and their chaotic variations across the subsurface indicated the distribution of wastewater and clog matter. To Identify the effectiveness of ERT to visualise subsurface of wetland systems, two different ERT arrays (electrode configurations) were used: Dipole-Dipole characterised by better horizontal resolution and effective depth coverage at the ends of ERT line and Wenner Array characterised by better vertical resolution and less susceptibility to noise. Both arrays were successful in identifying variations in local clogging levels in the HSFCWs, with the Dipole-Dipole array results found to be more relatable with actual site conditions. This work has evidenced the potential of ERT to profile clogging in HSFCWs, providing a tool for implementing targeted asset maintenance and reduced operational costs. Further improvement in the ERT methodology is recommended by testing the impact of smaller probe spacing, controlled water levels in HSFCWs, and increased observations of the same systems at different operation ages.Item Open Access Metaldehyde treatability by dissolved air flotation combined with powdered activated carbon adsorption(Cranfield University, 2017-12) Sanchez Lopez, Sara; Jarvis, Peter; MacAdam, JitkaThe removal of metaldehyde to meet pesticide compliance limits in drinking water remains a challenge for water companies. A combined treatment of dissolved air flotation (DAF) and powdered activated carbon (PAC) was investigated as a treatment process for metaldehyde removal. Four different water sources were spiked with metaldehyde and treated using PAC. A PAC dose of 100 mg/L using a contact time of 20 minutes was required in order to effectively remove metaldehyde to the compliance concentrations for all of the water sources. The water quality was shown to affect the removal of metaldehyde through competition with NOM. Moreover, the PAC dosing position relative to the coagulant was studied regarding its impact on the removal of NOM and metaldehyde, the floc formation and the clarification efficiency. The simultaneous addition of coagulant and PAC resulted in the lowest removal of metaldehyde. The best removal was seen for dosing sequences of PAC/Coagulant and Coagulant/PAC. However, there were no significant differences between these two approaches. The sequence of addition of PAC/Coagulant was selected due to its better clarification results.Item Open Access New insights into drinking water treatment, storage and distribution systems using Flow Cytometry.(Cranfield University, 2022-09) Palazzo, Francesca; Hassard, Francis; Jarvis, PeterExcessive microbial regrowth in drinking water distribution systems (DWDS) signifies compromised biostability. In chlorinated DWDS, diminished chlorine residual and substantially elevated water age or transit times can pose risks to water safety. This study delves into microbial community dynamics within DWDS by analysing samples from 119 service reservoirs and 41 water towers across various water sources for six months (March-September 2021). Using Flow Cytometry (FCM) to directly measure microbial populations, surface water exhibited 4-10 times higher microbial loading compared to groundwater and mixed sources. Among these sites, two distinct microbial water quality compliance events (detection of culturable coliform bacteria) were identified through FCM data, each presenting different microbial trends. Factors influencing regrowth in DWDS, notably water age and free chlorine, were scrutinized. Elevated intact cell counts were noted with chlorine levels <0.50 mg/L and water ages surpassing 4 days. Multiple linear regression highlighted temperature as the prime factor affecting cell counts variability in surface and mixed waters. For groundwaters, water age was significant, likely due to decreased disinfectant residuals and minimal treatment of these sources. The Bray-Curtis similarity index, derived from FCM fingerprints, emerged as a potential metric for detecting biological instability in drinking water microbiomes. The findings underscore the necessity of optimally managed DWDS and emphasize the significance of maintaining chlorine levels, especially at higher water ages and temperatures – particularly relevant considering climate change. Through FCM and its fingerprint analysis, a more detailed view of DWDS dynamics is attainable, promoting possibility for enhanced system control. The implications of this research offering potential for safeguarding public health, ensuring consistent water quality, and pathways for more resilient and sustainable water distribution practices. As a prospective direction for future research, machine learning models could be developed to predict and classify microbial community dynamics in DWDS using the rich dataset provided by FCM fingerprints.Item Open Access A pcr-based method for SARS-COV-2 variant detection in wastewater.(Cranfield University, 2022-06) Caetano Souza, Karina; Yang, Zhugen; McAdam, EwanThe COVID-19 outbreak, caused by the SARS-CoV-2 virus, rapidly evolved into a worldwide pandemic, as declared by World Health Organization on 11th March 2020. The continued spread since early 2020 has resulted in many variants of this virus. Most mutations found along its genome are known as single nucleotide polymorphisms (SNPs) where only one base pair is mutated. Current real-time qualitative polymerase chain reaction (RT-qPCR) protocols, so called gold-standard method, are used to confirm if a person is positive or negative for the virus. There is a lack of available technology for rapid identification of variants. In order to identify the presence of a viral variant it is necessary to perform sequencing. Sequencing is expensive and may take hours to days to complete. Due to its cost, sequencing is widely unavailable in most countries. Even in countries where sequencing is available, like the UK, the number of samples sequenced are less than 10% of total cases due to extremely high cost. Wastewater-based epidemiology (WBE) is a novel approach that would help monitor and possibly revert the current health crisis. It has been reported the presence of SARS-CoV-2 RNA in faeces of infected individuals. This makes it possible to detect and monitor SARS-CoV-2 in wastewater samples, providing a health status report of the population within the catchment. To this context, WBE also enables to monitor the dissemination of variants for early warning of the outbreak within the defined population. In this project, a RT-qPCR method was developed targeting unique SNPs of SARS-CoV-2. This assay uses two probes, both targeting the same sequence, one with the SNP and the other non- SNP. These mutations are found in the N-gene of SARS-CoV-2 viral RNA, a conserved region that contains unique SNPs specific to each variant for differentiation. By using two probes, binding competition occurs, and the differentiation is done by observing an earlier detection with the SNP probe (~6 cycles). In addition to this, this method can be coupled with a melt curve analysis for further confirmation. Currently, there is a lack of available technology for rapid identification of variants of concern within the community. This assay can be implemented for routine WBE. By developing a SNP-PCR assay to detect specific variants of concern using WBE, it would be possible to accurately detect variants. This information provides a comprehensive health report on the population that could possibly help revert the current health crisis.Item Open Access Removal of micropollutants from wastewater combining adsorption and electrochemical regeneration(Cranfield University, 2017-05) Pizzagalli, Giulia; Campo Moreno, Pablo; Soares, AnaIncreasingly stringent legislations, such as the Water Framework Directive (WFD) and its daughter Directive on Environmental Quality Standards (EQS), have carried important implications for European policy on pollution control for water resources. EQS have been set or proposed for substances which hitherto had not been subjected to monitoring, calling for compliance assessments and new control measures. To address this challenge, the UK Water Industry Research (UKWIR) financed a Chemicals Investigation Programme (CIP), assessing the source, occurrence and removal of emerging pollutants in the final effluents of wastewater treatment works (WwTWs). A second phase of work, CIP2, now aims to create a justifiable base for future regulatory measures needed to achieve good status (i.e. compliance limits for specific substances), together with a data set on micropollutants’ concentrations from trials conducted at pilot and full scale all over the UK. As part of CIP2, the Arvia ODC (Organic Destruction Cell), a novel technology combining adsorption and electrochemical oxidation, has been investigated at pilot scale. Its overall performance was assessed by evaluating the removal of 68 emerging pollutants and priority substances (pharmaceuticals, steroids, industrial chemicals and heavy metals), by appraising its economic and environmental costs and by weighting its reliability, easiness of maintenance and operation. Overall, the unit was able to target pharmaceuticals better than any other class of substances, with removals consistently over 50% for the majority of them, being especially effective towards macrolide antibiotics (~ 60-70%) and statins (~70-80%). The majority of determinands (72%) were found to be at concentrations below the set EQS at discharge. However, despite some evidence of promising performance, the ODC appeared to promote the accumulation of metals (i.e. zinc, nickel) in the final effluent and overall showed quite a weak performance in relation to sanitary determinands. A multi criteria analysis was performed to compare the ODC to alternative tertiary treatments. Although considerably lower than alternative treatment technologies (i.e. GAC or ozonation), energy consumption, normalised at 0.14 kWh/treated m³, represented the major contributing factor to estimated OPEX (1.1 pence/kWh), steadily increasing with population served. The ODC does not require chemical dosing, thus lessening the sludge production and potentially offering lower operational carbon usage than other advanced oxidation processes. Further testing of the technology was carried on at bench scale, in order to assess the unit’s performance in more controlled circumstances (spiked tap water). The trial allowed to single out the main parameters (mainly current density and effluent flow) responsible for the ODC performance and to evaluate to what extent their variation contributed to the removal of carbamazepine, a pharmaceutical compound whose persistence and toxicity in the aquatic environment determined its inclusion in the list of substances investigated in CIP2. The best removal performance (78%) was achieved at intermediate values for the ranges of flow and current density explored (5 L/h, 4 mA/cm²), seemingly allowing a synergic contribution of both adsorption and electrochemical oxidation. Although the technology has been proved to perform satisfactorily towards specific micropollutants in both trials, it is not applicable with the same degree of success to the removal of the wide range of chemicals investigated in CIP2. Moreover, due to its relative novelty and hitherto lack of full scale applications, the technology still requires stages of development, especially in terms of hydraulics within the unit (i.e. backwash system) and upstream solids capture.