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Details of Grant 

EPSRC Reference: EP/H018506/1
Title: Controlling Problem Particles in Water Treatment
Principal Investigator: Jarvis, Professor P
Other Investigators:
Researcher Co-Investigators:
Project Partners:
Yorkshire Water
Department: Sch of Applied Sciences
Organisation: Cranfield University
Scheme: First Grant - Revised 2009
Starts: 10 May 2010 Ends: 09 May 2011 Value (£): 100,049
EPSRC Research Topic Classifications:
Complex fluids & soft solids Water Engineering
EPSRC Industrial Sector Classifications:
Environment Water
Related Grants:
Panel History:
Panel DatePanel NameOutcome
26 Nov 2009 Process Environment and Sustainability Panel Announced
Summary on Grant Application Form
The aim of this work is to develop a new test to monitor the formation and breakage of particles in water treatment processes. Before water reaches a customer's tap, it must pass through a train of processes to remove the impurities from the water before it is safe to drink. The bulk of the contaminants are removed from the water in the process of coagulation and flocculation. Here, a destabilising chemical, such as an iron or aluminium salt is added to the water which enables dissolved, colloidal and particulate material to aggregate into large, fragile particles called flocs. In most water treatment plants in the world, these particles are removed by a sedimentation or flotation process. Any fine residual particles remaining are then usually removed by a sand filter. Failure to remove these particles results in high turbidity in the filtered water, which can reduce the efficacy of disinfection and the particles can be a vehicle for more toxic compounds entering drinking water. For this reason, turbidity in drinking water is strictly controlled. In the UK, a target value for turbidity in drinking water is 1 nephelometric turbidity unit (NTU). Recent revision documents from the European Commission indicate that this will soon move to a mandatory value of 1 NTU, with a target value of 0.5 NTU.The properties of the floc particles that form has a strong influence on how well they are removed by the clarification and filtration processes. If the flocs are too small or break apart too easily, water quality is compromised. The composition and structure of the floc is a function of a number of factors, including the source water matrix, the coagulant and flocculation chemicals used and the mixing regime deployed. Measuring the character and the strength of the flocs can therefore provide some very useful information on how well they may be removed in water treatment systems. To date, floc strength tests have concentrated on characterisation of large scale floc breakage products. This can significantly underestimate the concentration of small particles in a heterogeneous system containing a wide range of particle sizes. However, it is the small particles (normally centred around 1 um for most filtration conditions used in practice) that can cause operational difficulties because they are least well removed in a filter. The intellectual contribution of this work is in developing an operationally applicable and relevant floc strength test that integrates particle size and particle removal in depth filtration. For the first time we will investigate floc strength in terms of the formation and concentration of small particles before and after floc breakage by measuring floc strength in terms of the small particles around 1 um. The project will therefore deliver a methodology to determine floc strength through understanding the formation of problem particles. In addition we will establish how the system water quality and coagulation conditions influence floc strength and the formation of particles that cause turbidity in drinking water. Finally we will develop coagulation control strategies to limit the formation of FBP to enable longer filter run times and more effective filtration which could be applied on full-scale water treatment systems.
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Organisation Website: http://www.cranfield.ac.uk