Browsing by Author "MacAdam, Jitka"
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Item Open Access Assessing the potential of enhanced primary clarification to manage fats, oils and grease (FOG) at wastewater treatment works(Elsevier, 2020-04-20) Collin, Thomas Denis; Cunningham, Rachel; Asghar, Mohammed Qasim; Villa, Raffaella; MacAdam, Jitka; Jefferson, BruceDaily, sewage treatment works (STWs) receive large volumes of fats, oils and greases (FOG), by-products of food preparation. To increase FOG removal at STW, conventional primary sedimentation tanks (PSTs) can be enhanced using chemical coagulant or through dissolved air flotation (DAF) techniques. This work aimed to assess the potential benefits of enhanced primary treatment for FOG removal through an energy and costs analysis. To achieve this, a five-year sampling programme was conducted monthly at 15 STWs measuring FOG concentrations in crude and settled sewage (i.e. after primary treatment). In addition, two DAF pilot systems were trialled for four months and their performance, in terms of FOG removal, was assessed and compared to that of a control primary clarifier. Across the 15 STWs, influent FOG concentrations were found at 57 ± 11 mg.L−1. Chemical coagulants dosed prior to PSTs increased FOG removal rates on average to 71% whilst traditional sedimentation only achieved 50% removal. Effluent FOG concentrations were found between 12–22 mg.L−1 and 19–36 mg.L−1 respectively. By contrast, DAF achieved FOG effluent concentrations on average at 10 ± 4 mg.L−1 corresponding to 74% removal from a relatively low influent concentration of 40 ± 30 mg.L−1. Thus, enhanced primary treatments have the potential to reduce organic load to secondary treatment and increase energy generation through anaerobic digestion. The overall net energy balance was estimated at 2269 MWh.year−1 for the DAF compared to 3445 MWh.year−1 for the chemically-enhanced PST making it a less financially attractive alternative. Yet, in the case where the works require upgrading to accommodate flow or load increases, DAF appeared as a sensible option over sedimentation offering significantly lower capital costs and footprint. In relation to FOG management, upgrading all STWs is not realistic and will require understanding where the benefits would be the highest.Item Open Access carbonate scale formation and control(Cranfield University, 2005-03) MacAdam, Jitka; Parsons, SimonScale formation in domestic appliances is a widespread problem in the UK. This project has focussed on calcium carbonate scale formation in electric showers. A literature survey identified that CaCO; deposition on heated surfaces could be controlled by chemical or non chemical methods, each with various degrees of effectiveness. One of the most effective control methods was the addition of chemicals, although this may not be the most suitable option for the domestic environment. So here the chemical inhibitors tested were used for a benchmark for all the other studies. Two laboratory tests were involved t allow u to study CaCO; precipitation and scale formation. The effect of chemical additives on CaCO; precipitation was investigated using a jar tester. The longest delay to precipitation was obtained by polyacrylic acid dosing, closely followed by zinc. To study CaCO; formation on a heated surface, a rapid scaling test was developed. This test was conducted at 42°C and 70°C to examine and compare a range of treatment options, including chemical dosing, electrolytic, magnetic and electronic water conditioning and low fouling surfaces. From the options examined, the most successful was electrolytic dosing of zinc/copper media with over 95% reduction in scaling at both temperatures. Further, the use of low fouling surfaces, such as Diamond - like carbon coating could also potentially be used in electric showers. Reduction in scaling achieved on this surface was on average 68%. Surface properties of the materials were analysed using an atomic force microscope and their relationship with the scaling behaviour of the surfaces examined. The scaling rates at both temperatures typically increased with increasing adhesion force but no clear relationship was found between the roughness of the surfaces and their scaling behaviour. The relationship between CaCO3 precipitation and scale formation in synthetic solution and natural hard water was also explored here. The induction period in natural hard water was 55 minutes longer and the scaling rate 40% lower than i synthetic hard solution of similar composition. In addition, two shower test rigs, one based at Cranfield University and the other in Attleborough were used in this study. These were used primarily to enable the compilation of background data on scale formation in electric showers, where it was found that the design of the unit has a significant influence on the scale formation. The test rig was also used t test the strategies identified during the laboratory phase of the work. It was found that electrolytic zinc dosing reduced scaling by up to 54%, depending on the shower unit design.Item Open Access Data subset for Chapter 3: Particle degradation data(Cranfield University, 2022-12-13 12:34) Brown, Gareth; Jefferson, Bruce; MacAdam, JitkaThe particle degradation dataset for all conditions which represent data supporting 'Impact of low tmperatures on anerobic hydrolysis in passive treatment systems such as septic tanks'.Item Open Access Data subset for Chapter 3: Particle sizing data(Cranfield University, 2022-12-13 12:33) Brown, Gareth; Jefferson, Bruce; Dotro, Gabriela; MacAdam, JitkaThe particle sizing dataset as underlying the data presenting in the study 'Impact of low temperatures on anaerobic hydrolysis in passive treatment systems such as septic tanks' measured on a Malvern mastersizer, for the batch tests run a 5, 15 37 degrees celcuis and a sample prior to digestion.Item Open Access Data Supporting Chapter 3: Extracellular Enzyme Activity(Cranfield University, 2022-12-13 12:34) Brown, Gareth; Jefferson, Bruce; MacAdam, Jitka; Dotro, GabrielaThe raw and processed data of thhe extracellular lipase activity supporting the study 'Impact of low temperatures on anaerobic hydrolysis in passive treatment systems such as septic tanks'Item Open Access Data Supporting: A whole life cost and carbon perspective of alternatives to septic tanks utilising nature based solutions(Cranfield University, 2022-12-13 12:33) Brown, Gareth; Jefferson, Bruce; MacAdam, Jitka; Dotro, GabrielaThe data summary alongside the costing calculation and lifecycle inventory for the study 'A whole life cost and carbon perspective of alternatives to septic tanks utilising nature based solutions'Item Open Access Data Supporting: Constructed Wetlands for the Polishing of Enhanced Septic Tank Effluent: An Operational Case Study(Cranfield University, 2022-12-16 14:14) Brown, Gareth; Jefferson, Bruce; MacAdam, JitkaOperational data of the constructed wetlands and grant test of mediaItem Open Access Data Supporting: Onsite Anaerobic Reactor Design and Complexity, the Impact on Treatment and Hydrolysis in Temperate Conditions: A Systematic Review(Cranfield University, 2022-12-16 14:23) Brown, Gareth; Jefferson, Bruce; MacAdam, JitkaData supporting Onsite Anaerobic Reactor Design and Complexity, the Impact on Treatment and Hydrolysis in Temperate Conditions: A Systematic Review. Consisting of the data extracted from literature studies and the studies from the systematic review.Item Open Access Developing the next generation of treatment flowsheets for rural wastewater(Cranfield University, 2022-12) Brown, Gareth; Jefferson, Bruce; MacAdam, Jitka; Dotro, GabrielaSeptic tank systems (STS) are one of the most common wastewater treatment systems in the world however these systems are becoming antiquated, struggling to meet tighter consent, needing frequent desludging and venting greenhouse gases to the environment. A flowsheet to tackle these issues was proposed consisting of an enhanced septic tank (EST) and a constructed wetland (CW). The proposed flowsheet was assessed by examining the underlying mechanisms, testing the flowsheet at pilot scale and assessing the cost and carbon implications of the flowsheet. A key aim of the thesis is to decrease the maintenance of the flowsheet to once every 5 to 7 years. The maintenance of septic tank is due to desludging, as the tank needs to be emptied when the sludge bed reaches a certain height. The desludging of a septic tank is dependent on the hydrolysis rate within the reactor. Batch studies into anaerobic digestion found that low operating temperatures in septic tanks impact the hydrolysis rate. However, temperature is not the dominant factor of hydrolysis and optimisation of mass transfer between hydrolytic microorganisms and degradable particulates can increase the hydrolysis rate by 200%. A pilot scale study investigated using baffles to promote hydraulic mixing within a septic tank. The presence of hydraulic mixing due to the baffles increased the hydrolysis rate constant of a septic tank from 0.0089 d⁻¹ to 0.035d⁻¹, extending the time between desludging from 4.9 to 6.7 years. The proposed flowsheet is a lower cost treatment system than a conventional package treatment system (e.g. submerged aerated filter) over a 30 year life time and leads to a significant reduction in lifetime carbon emissions compared to a STS. The cost and carbon reduction of the flowsheet make the flowsheet a viable abatement technique.Item Open Access Effect of elevated UV dose and alkalinity on metaldehyde removal and THM formation with UV/TiO2 and UV/H2O2(Elsevier, 2015-11-26) Jefferson, Bruce; Jarvis, Peter; Bhagianathan, Govind Kannoly; Smith, Heather M.; Autin, Olivier; Goslan, Emma Harriet; MacAdam, Jitka; Carra, IreneDrinking water production needs to increasingly consider removal of background organic matter and trace micropollutants without increasing disinfection-by-product (DBP) formation potential. The presented data demonstrates the efficacy of both UV/H2O2 and UV/TiO2 in removing the pesticide metaldehyde to below drinking water compliance levels in both real and synthetic waters. This pesticide has proven to be unaffected by conventional water treatment processes such as granular activated carbon and is responsible for many of the water company compliance failures in the UK. The potential of UV/H2O2 is further demonstrated to offer an alternative approach for the removal of recalcitrant organic matter to ensure DBP compliance as long as extended UV doses of over 10,000 mJ cm−2 are applied at the optimum peroxide dose of 8 mM. Alkalinity and UV dose have an impact on DBP formation: at low UV fluences, increased alkalinity reduced the DBP formation. The UV/TiO2 process was observed to be inhibited in the presence of alkalinity. Aggregation studies and comparison of the catalyst fractal dimension showed that the process inhibition is mainly due to aggregation. This restricts the surface area available for reactions, rather than changes in the catalyst properties or carbonate radical scavenging, which is often the reasoning attributed to photocatalysis inhibition. Hence, the presented results indicate that decreasing the catalyst aggregation is the key to apply photocatalysis as drinking water treatment.Item Open Access Energy potential of household fats, oils and grease (FOG) waste(Wiley, 2021-07-01) Collin, Thomas; Cunningham, Rachel; Deb, Melani; Villa, Raffaella; MacAdam, JitkaIn comparison to fats, oils and grease (FOG) found in commercial and industrial effluents, very little is known about FOG discharged at household level. To address this shortcoming, household FOG production was calculated following a year-long monthly collection at 2.3 kg/year per household, equivalent to 0.8 kg/year per capita. In the United Kingdom, these numbers translate in an annual estimated FOG production of 62 380 tonnes. Physico-chemical characterization of household FOG showed promising results for biodiesel production. Biomethane yield was measured at 875 mL CH4/g VSadded, twice as much that of sewage sludge, making it a desirable substrate for anaerobic digestion. It was thus estimated that energy recovery from household FOG through anaerobic co-digestion or biodiesel production could generate about 490 GWh/year in the United Kingdom. However, insights from participants revealed that most of this waste is currently not recovered, requiring the development of schemes fitting with households' routine to maximize collection rates.Item Open Access EST_CFD_outputs.csv(Cranfield University, 2022-10-28 15:49) Brown, Gareth; Jefferson, Bruce; MacAdam, JitkaOutputs of CFD model of EST systems for dead space, HRT and Peclet numberItem Open Access EST_HydrolysisCalculation(Cranfield University, 2022-10-28 15:47) Brown, Gareth; Jefferson, Bruce; MacAdam, JitkaCalculation of kh from sludge dataItem Open Access EST_HydrolysisRate_versus_Desludge.csv(Cranfield University, 2022-10-28 15:43) Brown, Gareth; Jefferson, Bruce; MacAdam, JitkaData outputs from matlab mass balance model for calculation of hydrolysis rate constant against desludging frequencyItem Open Access EST_OperationalData.csv(Cranfield University, 2022-10-28 15:45) Brown, Gareth; Jefferson, Bruce; MacAdam, JitkaOperational data of pilot plantsItem Open Access EST_SludgeData.csv(Cranfield University, 2022-10-28 15:46) Brown, Gareth; Jefferson, Bruce; MacAdam, JitkaDataset for the sludge within EST study pilot systemsItem Open Access Evaluating the potential of domestic fats, oils and greases (FOG) for energy recovery(Cranfield University, 2020-01-22 15:40) Collin, Thomas; Cunningham, Rachel; Villa, Raffaella; MacAdam, Jitka; Jefferson, BruceExperimental data collected for the paper titled "Evaluating the potential of domestic fats, oils and greases (FOG) for energy recovery".Item Open Access The impact of dosing sequence on the removal of the persistent pesticide metaldehyde using powdered activated carbon with coagulation and clarification(Elsevier, 2020-11-14) López, Sara Sánchez; MacAdam, Jitka; Biddle, Mark; Jarvis, PeterRemoval of pesticides from drinking water remains a challenge for water treatment suppliers throughout the world. A combined treatment of dissolved air flotation (DAF) and powdered activated carbon (PAC) was investigated as a treatment process for removal of the recalcitrant pesticide metaldehyde. The PAC dosing position relative to the coagulant was studied regarding its impact on the removal of NOM and pesticide, floc formation and the clarification efficiency. Four different water sources were spiked with the pesticide and treated using PAC. A PAC dose of 100 mg/L using a contact time of 20 min was required in order to effectively remove pesticide to the compliance concentrations for all of the water sources. The pesticide adsorption rate (kmet) decreased as the source water DOC increased, moving from 79.5–21.0 mg/μg/min with an increase in DOC from 2.6 to 6.5 mg/L. When combined with coagulation, the sequence of addition of PAC followed by coagulant was most effective due to increased incorporation of PAC into the floc, large floc size (median floc size 800 μm) and a high level of pesticide removal, reducing the metaldehyde concentration to 0.18 μg/L. Limited incorporation of PAC into flocs was observed when the adsorbent was added after the coagulant. The results provide a rational basis for selection of process conditions for pesticide removal using PAC and clarification.Item Open Access Incorporating biodegradation and advanced oxidation processes in the treatment of spent metalworking fluids(Taylor & Francis, 2012-04-27T00:00:00Z) MacAdam, Jitka; Ozgencil, Haci; Autin, Olivier; Pidou, Marc; Temple, Clive; Parsons, Simon A.; Jefferson, BruceThe treatment of spent metalworking fluids (MWFs) is difficult due to their complex and variable composition. Small businesses often struggle to meet increasingly stringent legislation and rising costs as they need to treat this wastewater on site annually over a short period. Larger businesses that treat their wastewater continuously can benefit from the use of biological processes, although new MWFs designed to resist biological activity represent a challenge. A three-stage treatment is generally applied, with the oil phase being removed first, followed by a reduction in COD loading and then polishing of the effluent's quality in the final stage. The performance of advanced oxidation processes (AOPs), which could be of benefit to both types of businesses was studied. After assessing the biodegradability of spent MFW, different AOPs were used (UV/H2O2, photo-Fenton and UV/TiO2) to establish the treatability of this wastewater by hydroxyl radicals (•OH). The interactions of both the chemical and biological treatments were also investigated. The wastewater was found to be readily biodegradable in the Zahn–Wellens test with 69% COD and 74% DOC removal. The UV/TiO2 reactor was found to be the cheapest option achieving a very good COD removal (82% at 20min retention time and 10Lmin−1 aeration rate). The photo-Fenton process was found to be efficient in terms of degradation rate, achieving 84% COD removal (1M Fe2+, 40M H2O2, 20.7Jcm−2, pH 3) and also improving the wastewater's biodegradability. The UV/H2O2 process was the most effective in removing recalcitrant COD in the post-biological treatment stage.Item Open Access Intake of lead (Pb) from tap water of homes with leaded and low lead plumbing systems(Elsevier, 2018-07-13) Jarvis, Peter; Quy, Katie; MacAdam, Jitka; Edwards, Marc; Smith, MarjorieMethods of quantifying consumer exposure to lead in drinking water are increasingly of interest worldwide, especially those that account for consumer drinking habits and the semi-random nature of water lead release from plumbing systems. A duplicate intake protocol was developed in which individuals took a sub-sample from each measured drink they consumed in the home over three days in both winter and summer. The protocol was applied in two different water company regional areas (WC1 and WC2), selected to represent high risk situations in England, with the presence or absence of lead service pipes or phosphate corrosion control. Consumer exposure to lead was highest in properties with lead service pipes, served by water without P dosing. The protocol indicated that a small number of individuals in the study, all from homes with lead service pipes, consumed lead at levels that exceeded current guidance from the European Food Standards Agency. Children's potential blood lead levels (BLLs) were estimated using the Internal Exposure Uptake Biokinetic model (IEUBK). The IEUBK model predicted that up to 46% of children aged 0–7 years old may have elevated BLLs (>5 μg/dL) when consuming the worst case drinking water quality (>99%ile). Estimating blood lead levels using the IEUBK model for more typical lead concentrations in drinking water identified in this study (between 0.1 and 7.1 μg/L), predicts that elevated BLLs may affect a small proportion of children between 0 and 7 years old.