School of Applied Sciences (SAS) (2006-July 2014)

Permanent URI for this community

https://dspace.lib.cranfield.ac.uk/handle/1826/20

Browse

Browsing School of Applied Sciences (SAS) (2006-July 2014) by Publisher "Blackwell Publishing"

Now showing 1 - 2 of 2
  • Thumbnail Image
    ItemOpen Access
    Operating strategies for variable-flow sequencing batch reactors.
    (Blackwell Publishing, 2007-03) Bungay, S.; Humphries, M.; Stephenson, Tom
    Sequencing batch reactors (SBRs) are variable-volume, non-steady-state, suspended-growth biological wastewater treatment reactors. The treatment process is characterised by a repeated treatment cycle consisting of a series of sequential process phases: fill, react, settle, decant and idle. The design and operation of an SBR must take into account (1) the biological process requirement for treating influent wastewater and (2) the hydraulic requirement to enable throughput of the water through the reactor without compromising on the quality of biological treatment. During routine operation, the priority between the process and hydraulic consideration can change depending on the influent flow rate and its rate of change. The importance of the interaction between these considerations will vary depending on the fill strategy and the cycle time control strategy. Where flow-proportional cycle times are utilised to optimise the treatment process, the operating strategy must be capable of accurately adjusting the intercycle phase times to prevent loss of biological treatment or volumetric capacity. This paper considers various operating strategies and describes the specific strategy used at the SBR at Avonmouth wastewater treatment works.
  • Thumbnail Image
    ItemOpen Access
    Porous, functionally gradient pyroelectric materials
    (Blackwell Publishing, 2007-01) Shaw, Christopher P.; Whatmore, Roger W.; Alcock, Jeffrey R.
    Properties of a new type of pyroelectric ceramic structure containing a layer of known porosity laminated between two dense layers, to form a functionally gradient material (FGM), are reported. The combination of theoretical models for pyroelectric, dielectric, and thermal properties gave a model for the pyroelectric voltage figure of merit (FV) in good agreement with experiment, which had shown a 20% improvement for an introduced central layer porosity of 27%. Preliminary pyroelectric responsivity measurements on FGM infrared detectors indicated an even better improvement. It is postulated that this is due to the porous layer acting as a thermal barrier in the structure.