Faculty of Engineering and the Environment

Mobile phones have relatively short lifecycles and are rapidly seen as obsolete by many users within little over a year. However, the reusability of these devices as well as their material composition means that in terms of mass and volume, mobile phones represent the most valuable electronic products that are currently found in large numbers in waste streams. End-of-life mobile phones are a high value (from a reuse and resource perspective), high volume (quantity), low cost (residual monetary value) and transient (short lifecycle) electronic product. There are very large numbers of higher education (mainly university) students in the world – there are >2.4 million in the UK alone, 19 million in Europe and 18.2 million in the USA – and they often replace their mobile phones several times before graduation. Thus, because of the potentially significant environmental and economic impacts, a large scale survey of students at 5 UK universities was conducted to assess the behaviour of students with regard to their use and disposal of mobile phones. Additionally, a small scale trial mobile phone takeback service at one of the universities was carried out. The findings indicate that many students replace their phones at least once a year; replacing broken phones, getting upgrades from network operators, remaining “fashionable” and a desire to have a handset with a longer battery life are the main reasons for such rapid replacement. Almost 60% of replaced phones are not sent to reuse or recycling operations but are stockpiled by students mainly as spare/backup phones. Approximately 61% of students own an extra mobile phone with male students replacing their phones more often than females. In particular, the results highlight the potentially huge stockpile of mobile phones – and consequently valuable supplies of rare metals – being held by the public; we estimate that there are 3.7 million phones stockpiled by students in UK higher education alone (29.3 and 28.1 million stockpiled, respectively, for Europe and USA). Although many students are aware of UK mobile phone takeback services, only a moderate number have previously used the services. Students’ recycling of other waste materials such as paper and glass did not have a significant impact on their disposal actions for their unwanted mobile phones, although students who often recycled these waste materials were also the most willing to participate in mobile phone takeback services. Monetary incentives such as cash payments and vouchers have the greatest influence over students’ willingness to utilise takeback services, followed by convenience and ease of use of the services. The paper discusses these findings as well as the outcome of the trial mobile phone takeback. It is suggested that universities should partner with established takeback operators to conduct event-based mobile phone takeback services primarily targeting students. Lessons from mobile phone takeback applicable to takeback services for end-of-life gadgets similar to mobile phones are also discussed.

Mobile phones are the most ubiquitous electronic product on the globe. They have relatively short lifecycles and because of their (perceived) in-built obsolescence, discarded mobile phones represent a significant and growing problem with respect to waste electrical and electronic equipment (WEEE). An emerging and increasingly important issue for industry is the shortage of key metals, especially the types of metals found in mobile phones, and hence the primary aim of this timely study was to assess and evaluate the voluntary mobile phone takeback network in the UK. The study has characterised the information, product and incentives flows in the voluntary UK mobile phone takeback network and reviewed the merits and demerits of the incentives offered. A survey of the activities of the voluntary mobile phone takeback schemes was undertaken in 2008 to: identify and evaluate the takeback schemes operating in the UK; determine the target groups from whom handsets are collected; and assess the collection, promotion and advertising methods used by the schemes. In addition, the survey sought to identify and critically evaluate the incentives offered by the takeback schemes, evaluate their ease and convenience of use; and determine the types, qualities and quantities of mobile phones they collect. The study has established that the UK voluntary mobile phone takeback network can be characterised as three distinctive flows: information flow; product flow (handsets and related accessories); and incentives flow. Over 100 voluntary schemes offering online takeback of mobile phone handsets were identified. The schemes are operated by manufacturers, retailers, mobile phone network service operators, charities and by mobile phone reuse, recycling and refurbishing companies. The latter two scheme categories offer the highest level of convenience and ease of use to their customers. Approximately 83% of the schemes are either for-profit/commercial-oriented and/or operate to raise funds for charities. The voluntary schemes use various methods to collect mobile phones from consumers, including postal services, courier and in-store. The majority of schemes utilise and finance pre-paid postage to collect handsets. Incentives offered by the takeback schemes include monetary payments, donation to charity and entry into prize draws. Consumers from whom handsets and related equipment are collected include individuals, businesses, schools, colleges, universities, charities and clubs with some schemes specialising on collecting handsets from one target group. The majority (84.3%) of voluntary schemes did not provide information on their websites about the quantities of mobile phones they collect. The operations of UK takeback schemes are decentralised in nature. Comparisons are made between the UK’s decentralised collection system versus Australia’s centralised network for collection of mobile phones. The significant principal conclusions from the study are: there has been a significant rise in the number of takeback schemes operating in the UK since the initial scheme was launched in 1997; the majority of returned handsets seem to be of low quality; and there is very little available information on the quantities of mobile phones collected by the various schemes. Irrespective of their financial motives, UK takeback schemes increasingly play an important role in sustainable waste management by diverting EoL mobile phones from landfills and encouraging reuse and recycling. Recommendations for future actions to improve the management of end-of-life mobile phone handsets and related accessories are made.

The estimated impacts of the digital switchover on Hampshire’s and UK’s Household Waste Recycling Centres have been evaluated and discussed in this paper. It has been established that the majority of televisions (TVs) in the UK are digital ready. Awareness levels about the switchover are high though awareness levels about the dates of the event are still modest. About half of UK households are not aware that TV recording devices will be affected by the switchover. The most important finding of the study is that the UK Government may have underestimated the quantities of TV and related devices that will be disposed during the switchover. The paper concludes by making recommendations to address identified issues.

Using Hampshire County Council (HCC) as a case study, this paper evaluates and discusses the estimated impacts of the so-called digital switchover (DSO) (scheduled for 2012 in Hampshire) on Household Waste Recycling Centres (HWRCs) in England and the UK. Two public surveys of Hampshire residents were used to collect data on their preparedness for and awareness of the switchover and its implications. The survey also sought to establish the quantities of televisions (TVs) and TV related devices that are ready for the DSO. The quantities of TV and related devices that are likely to be disposed via HCC’s collection network have been established and compared to the County’s current handling capacities for waste electronic and electrical equipment (WEEE). Best and worst case potential net disposal scenarios have been established and the latter compared to Government projections. In addition, the potential environmental, logistical, financial and legal impacts of the WEEE arising as a consequence of the switchover have been identified and discussed. The results indicate that the majority of TVs both in Hampshire and the UK are digital ready and that awareness of the switchover is high. In contrast, most recording devices in Hampshire are not ready for the DSO. Awareness of the timeframe of the event remains modest however and about half of Hampshire households were not aware that TV recording devices will be affected by the switchover. A significant proportion of waste TVs and related equipment would be taken to HWRCs in contrast to smaller items such as remote controls that would more likely be disposed with normal household waste. Projected figures for the DSO year show that if Hampshire maintained its current collection capacity for WEEE it would experience a handling shortfall of around ∼100 K for TVs and recording devices, respectively. The most important finding of the study is that the UK Government may have substantially underestimated the quantities of TV and related devices that will be disposed during the switchover. The potential impacts for local and national WEEE management have been discussed. The paper concludes by making recommendations to address identified issues.

Electrical and electronic equipment (EEE) that has come to its end-of-life (EoL) either by ceasing to function or ceasing to be of any value to its owners is commonly referred to as e-waste. In the European Union (EU), these wastes are referred to as waste electrical and electronic equipment (WEEE). This chapter discusses two key themes critical to understanding and tackling the challenge posed by WEEE, namely: (i) four key issues that make WEEE a priority waste stream; and (ii) WEEE management practices in various countries and regions. Drawing on a comprehensive literature review and four case studies, this chapter critically analyses and discusses the factors that influence the generation, collection and disposal of WEEE, specifically addressing the spatial and temporal interactions of these factors before an alternative approach to conceptualising and managing WEEE is proposed.

A GIS-based approach has been used to assess existing and potential near-future coastal habitats under different sea-level rise and management scenarios. For six local case studies on the south coast of the UK, difficulties in meeting the requirements of the EC Habitats Directive within individual case study areas were found. The most significant issues were related to intertidal saltmarsh and mudflat areas, which decline under all the sea-level rise scenarios considered. Compensation for these losses in some localities could be achieved through the creation of replacement habitat by the managed realignment of sea defences, often in conjunction with engineered sediment supply to raise intertidal surfaces to levels conducive to vegetation establishment. However, historic land use decisions will restrict this approach in many areas. In particular, managed realignment will lead to a decline in coastal grazing marsh, also a designated habitat under the Directive. However, at wider scales potential exists to compensate for lost coastal grazing marsh with fluvial grazing marsh in adjoining river catchments. Spatial planning offers the potential for future landbanking of these areas, but its implementation may require a reinterpretation of the application of the Habitats Directive.

Estuaries are among the most biologically productive ecosystems on the planet, per unit area, with intertidal habitats and particularly saltmarshes providing a variety or ecosystem services and supporting large numbers of both primary and secondary producers. These habitats are globally important and are found throughout tropical to temperate climates. Micro-tidal estuaries are found throughout the world and particularly sensitive to sea-level rise, as they are limited in their ability to adjust and are considered vulnerable to future changes .Hence, at a broad scale, understanding the drivers and mechanisms of saltmarsh change in micro-tidal systems is crucial in aiding decision making in future coastal management. This thesis explores the drivers and mechanisms of saltmarsh change through the development of a conceptual model, which is then tested using Poole Harbour, UK as a case study site. The potential drivers of saltmarsh change were investigated using a multidisciplinary app...

Saltmarshes are important habitats and have historically declined in the south of the UK and as sea-level rise is predicted to accelerate these losses are expected to increase. In order to explore estuary morphodynamics with relation to accretional and erosional trends at an estuary and sub-estuary scale, historic aerial photography were analysed with saltmarsh changes from 1947 and 2005 quantified. Using the Telemac model developed by HR Wallingford, tidal asymmetry of peak tides and slack duration was mapped and correlations between tidal asymmetry and saltmarsh change examined. Results indicate that there is a significant relationship between areas of flood dominance and the historic accretion of saltmarsh. However, there is no statistical correlation between areas that had experienced erosion and ebb dominance, indicating other dominant drivers of erosion processes. Results using hypsometric calculations suggest that the whole harbour behaves as an ebb dominant system and therefore tends towards erosion. However, when split into a sub-estuary scale, different creek systems show varying morphology and the hypsometry changes. This may have serious management implications where estuaries are manipulated through dredging and development, leading to significant effects on the surrounding intertidal habitats. However, managed realignment planning could also exploit the potential for enhancing flood dominance and hence accretion wherever possible.

A high rate anaerobic treatment of palm oil mill effluent (POME) was achieved in a two-stage up-flow anaerobic sludge blanket (UASB) reactor. The acidogenic reactor acclimated rapidly to the wastewater and was tolerant to a suspended solids (SS) concentration of 5.4 g l−1 in the influent wastewater. Loading was gradually increased over a period of 100 days resulting in a satisfactory hydrolysis and acidification giving a maximum rate of acid production of 4.1 g l−1 d−1 acetic acid at a loading rate of 16.6 g l−1 d−1 COD at a hydraulic retention time of 0.9 days. An increase in alkalinity throughout the acclimatization maintained the effluent from the reactor at around pH 5.8. The methanogenic reactor was initially fed on dilutions of the effluent from the first stage reactor after pH adjustment. The loading was gradually increased, and then stepwise, to 60 g l−1 d−1 COD at which point COD removal efficiency had declined significantly and an accumulation of long-chain volatile fatty acids was observed. It was concluded that the reactor could work efficiently up to loadings of 30 g 1−1 d−1 COD, whilst producing a good methane yield and a COD reduction of greater than 90%. Effluent recirculation alleviated the need for alkali additions to the feed of the methanogenic reactor and a direct coupling of the two reactors was achieved towards the end of the experimental run of 175 days. Both reactors showed granule formation with distinct morphological characteristics; these were observed to be formed after 80 days in the acidogenic reactor and after 110 days in the methanogenic reactor.

A laboratory-scale anaerobic reactor, in which the bottom two-thirds were occupied by a sludge blanket and the upper one-third by submerged small cubes of polyurethane foam, was evaluated for the anaerobic treatment of slaughterhouse wastewater. The reactor was operated at 35°C during the two experimental studies. In the first study, the chemical oxygen demand (COD) concentration of the wastewater was increased from 3·74 to 10·41 g l−1 whilst maintaining a constant hydraulic retention time (HRT) of 1·5 days. In the second, the HRT was decreased from 1·35 to 0·50 days, whilst maintaining a constant influent COD concentration of 10·41 g l−1. The results showed that this type of reactor was suitable for the anaerobic treatment of this wastewater and demonstrated a high COD removal of between 90·2 and 93·4% at organic loading rates between 2·49 and 20·82 g COD l−1 day−1. At an HRT of 0·5 days, the reactor achieved a methane yield of 0·345 l CH4 STP per gram of COD removed. This yield is higher than the values reported in previous studies.

An anaerobic fluidized bed reactor, operating at 35° C, was used to treat ice-cream wastewater with an influent chemical oxygen demand (COD) of 5.2 g l−1. Start-up of the reactor was achieved within 30 days by use of a regime that included stepped increases in influent COD and methanol substitution of the substrate. A steady state was achieved with 94.4% COD reduction at an organic COD loading rate of 15.6 g l−1 d−1 (HRT 8 h). This rate is somewhat faster than those achieved in previously reported studies. The reactor was subjected to transient changes in temperature, pH, influent flow-rate and COD for 6 and 12 h periods. The quality of the effluent deteriorated under these shock load conditions but returned to steady-state values within 6–16 h upon restoring normal conditions. The stability of the reactor under unfavourable process conditions is discussed.

COD removed efficiencies in the range 75·0NDASH;98·9% were achieved in an anaerobic fluidised-bed reactor treating slaughterhouse wastewater, when evaluated at organic loading rates (OLR) of between 2·9 and 54·0 g COD/l.d, hydraulic retention times (HRT) of between 0·5 and 8 h and feed COD concentrations of between 250 and 4500 mg/l. More than 94% of feed COD could be removed up to OLR of about 27 g COD/l.d. Up to 0·320 litres of methane were produced per gram of COD removed and this methane production rate was independent of the OLR applied in this investigation. Volatile fatty acid (VFA) concentration in the reactor increased sharply at an OLR of about 30 g COD/l.d and, therefore, sufficient alkalinity should be provided to prevent pH from dropping to an undesirable level. The anaerobic fluidised-bed system can be operated at a significantly higher liquid throughput than other previously reported systems while maintaining its excellent efficiency.

In the past half century, race car teams have evolved from the iconic garagistes era, where
intrepid drivers and mechanics competed with their insightful designs for glory and for sheer speed,
for a complex multi-billion dollar innovation industry with hundreds of employees and engineers
trying to optimize a car design making use of the latest technological and scientic advances, with
aerodynamics playing a leading role in reducing lap times and CFD becoming a standard tool in F1
car development in the last 15 years.
With the ever increasing computing power and the evolution of
ow modelling and computer
algorithms, teams not only started to use CFD as tool to better understand the
ow over the car,
but also as an important development tool, that reduces costs and lead time of model making for
wind tunnel testing and allow them to test thousands of concepts per week.
An example of such a design methodology for aerodynamic optimisation using CFD tools will
be shown, with an overview of a project for developing an ecient aero-design for a single seater
open-wheel hill-climb racing car. The investigation of the
ow eld of the vehicle and the design
methodology which included optimisation algorithms and management techniques that resulted in
the test of 42 dierent full car congurations will be presented.

This paper describes a method for the production of alginate microfibres using glass-based microfluidic chips fabricated by a photolithography-wet etching procedure. The main focus of the work is the fabrication of a cell containing multifunctional microfibres which have great potential for applications in drug release formulations and tissue engineering scaffolds (to guide the regeneration of tissues in predefined sizes and shapes) providing cell structural support and immunoisolation. The key parameters, which critically influence the formation of microfibres and their geometries, were identified by a classical intuitive approach COST (Changing One Separate factor a Time). In particular, their effects on the microfibre diameter were investigated, which are directly associated with their functionalities relating to the implantation site, the nutrient availability and diffusion/transport of oxygen, essential nutrients, growth factors, metabolic waste and secretory products. The interplay between the alginate solution concentration, pumping rate and gelling bath concentration in controlling the diameter of the produced microfibres was investigated with a statistical approach by means of a ''design of the experiments'' (DoEs) optimization and screening. Finally, the processing impacts on cell viability, the cellular effect of wall thickness consistency and the spatial distribution of cells within the alginate microfibre were examined. We provide an approach for the production of alginate microfibres with controlled shape and content, which could be further developed for scaling up and working towards FDA approval.

Sonoporation is a useful biophysical mechanism for facilitating the transmembrane delivery of therapeutic agents from the extracellular to the intracellular milieu. Conventionally, sonoporation is carried out in the presence of ultrasound contrast agents, which are known to greatly enhance transient poration of biological cell membranes. However, in vivo contrast agents have been observed to induce capillary rupture and haemorrhage due to endothelial cell damage and to greatly increase the potential for cell lysis in vitro. Here, we demonstrate sonoporation of cardiac myoblasts in the absence of contrast agent (CA-free sonoporation) using a low-cost ultrasound-microfluidic device. Within this device an ultrasonic standing wave was generated, allowing control over the position of the cells and the strength of the acoustic radiation forces. Real-time single-cell analysis and retrospective post-sonication analysis of insonated cardiac myoblasts showed that CA-free sonoporation induced transmembrane transfer of fluorescent probes (CMFDA and FITC-dextran) and that different mechanisms potentially contribute to membrane poration in the presence of an ultrasonic wave. Additionally, to the best of our knowledge, we have shown for the first time that sonoporation induces increased cell cytotoxicity as a consequence of CA-free ultrasound-facilitated uptake of pharmaceutical agents (doxorubicin, luteolin, and apigenin). The US-microfluidic device designed here provides an in vitro alternative to expensive and controversial in vivo models used for early stage drug discovery, and drug delivery programs and toxicity measurements.

Microreactors have been shown to be a powerful tool for the production of nanoparticles (NPs); however, there is still a lack of understanding of the role that the microfluidic environment plays in directing the nanoprecipitation process. Here we investigate the mechanism of nanoprecipitation of block copolymer stabilized organic NPs using a microfluidic-based reactor in combination with computational fluid dynamics (CFD) modelling of the microfluidic implementation. The latter also accounts for the complex interplay between molecular and hydrodynamic phenomena during the nanoprecipitation process, in order to understand the hydrodynamics and its influence on the NP formation process. It is demonstrated that the competitive reactions result in the formation of two types of NPs, i.e., either with or without loading organic actives. The obtained results are interpreted by taking into consideration a new parameter representing the mismatching between the aggregations of the polymers and actives, which plays a decisive role in determining the size and polydispersity of the prepared hybrid NPs. These results expand the current understanding of the co-nanoprecipitation mechanism of active and block copolymer stabilizer, and on the role exerted by the microfluidic environment, giving information that could be translated to the emerging fields of microfluidic formation of NPs and nanomedicine.

We report the development of a microfluidic-based process for the production of polymeric micelles (PMs) in continuous-flow microreactors where Pluronic® tri-block copolymer is used as model polymeric biomaterial relating to drug delivery applications. A flow focusing configuration is used enabling a controllable, and fast mixing process to assist the formation of polymeric micelles through nanoprecipitation which is triggered by a solvent exchange process when organic solutions of the polymer mixed with a non-solvent. We experientially investigate the effect of polymer concentration, flow rate ratio and microreactor dimension on the PMs size characteristics. The mixing process within the microfluidic reactors is further analyzed by computational modeling in order to understand the hydrodynamic process and its implication for the polymeric micells formation process. The results obtained show that besides the effect of the flow rate ratio, the chemical environment in which the aggregation takes place plays an important role in determining the dimensional characteristics of the produced polymeric micelles. It is demonstrated that microfluidic reactors provide a useful platform for the continuous-flow production of polymeric micelles with improved controllability, reproducibility, and homogeneity of the size characteristics.The efficient, fast and tuneable mixing provided by microfluidic reactors can be used to control the self-assembly of polymeric micelles. The fluid dynamics inside the microreactors is further analyzed by a CFD model in order to asses the implications for the mixing process and controlled self-assembly of polymeric micelles.► A continuous flow process was developed for the production of polymeric micelles. ► Smaller and homogeneous polymeric micelles can be produced by microfluidic approaches. ► Hydrodynamics within microreactors strongly affects the nanoprecipitation process. ► The process may be extended to produce other nanomaterials with controlled characteristics.