From source to tap: management of natural organic matter during drinking water production
Submitting InstitutionCranfield University
Unit of AssessmentAeronautical, Mechanical, Chemical and Manufacturing Engineering
Summary Impact TypeEnvironmental
Research Subject Area(s)
Chemical Sciences: Analytical Chemistry, Other Chemical Sciences
Engineering: Chemical Engineering
Summary of the impact
New characterisation tools for natural organic matter (NOM) in drinking
water are now used as standard practice within water companies such as
Severn Trent Water, United Utilities and Yorkshire Water. The tools inform
decisions, and help develop strategic plans on catchment management,
source selection, treatment optimisation, and disinfection practice. Water
companies experienced difficulties in treating high levels of NOM.
Cranfield created a novel characterisation toolkit to measure NOM for its
electrical charge and hydrophobicity. Also, new techniques for measuring
aggregate properties and emerging disinfection by-products have provided a
comprehensive analysis. Two novel treatment technologies are currently
marketed. These technologies have raised international interest, resulting
in industrial development in Australia.
UK Water companies have experienced difficulties in treating source
waters from peat moorland catchments since the 1990s. These sources
account for 30-40% of all the water used to produce drinking water in the
UK. The focus of the research has been on translating established
theoretical understanding to generate practical benefit that can be
applied in treatment works.
The initial work was the first to identify and publish seasonal changes
in the flux and character of NOM leaching into source waters [G1, P1].
Critically, the work identified that existing indicators, such as water
colour, were inadequate in defining NOM load for treatment purposes.
Further industrially funded projects led to Cranfield becoming the first
university outside North America to be funded by the American Water Works
Association Research Foundation (now called the Water Research Foundation)
[G2]. The project produce a novel diagnostic toolkit - still used by both
researchers and water company practitioners - to fully characterise both
NOM in the source water and the resultant coagulated NOM aggregates
(flocs) formed during treatment [P2]. This, for the first time, enabled
the link between source water changes and treatability to be understood
Application of the toolkit led to discoveries which changed the
understanding of NOM removal in relation to treatability and optimisation
of coagulation. Traditional approaches involved empirical batch testing to
(re)establish the optimum dosing conditions. As a result of the work, it
is now possible for operators to monitor and change the effect of surface
charge on the coagulation process. Direct measurement of the particle
charge is used to optimise coagulation irrespective of the source water,
coagulant used, or pH level, without the need for empirical testing,
through a universal range of zeta potential values [P3].
In relation to treatability, we demonstrated that characterisation of the
organic matter within untreated raw water, by non-specific ion exchange
resins, can be used to identify both the likely coagulant demand and the
achievable residual dissolved organic matter concentration for optimised
These key findings have been used for assessment and deployment of new
technologies and in adapting existing systems to cope with changing
environmental conditions. Work examined the potential of a novel ion
exchange process for NOM removal. We established the beneficial impacts
provided by ion exchange processes, such as reducing disinfection
by-product formation (DBP) and increasing floc strength, and thereby
reducing downstream processing costs [G3, P4]. This underpinned a decision
by Yorkshire Water to invest in the technology for full-scale application
at three treatment sites.
This was applied to other systems including algal laden reservoirs and
lowland water sources [G4]. Critically, and in conflict with conventional
thinking, the findings pertaining to peat based catchments were shown to
apply for all source waters. The work led to the discovery that sufficient
charge can be coated onto a bubble through surfactant and polymer
adsorption to obviate pre- coagulation of algae, a major limitation on
many operational sites, generating significant savings in energy and
operating costs (P5).
At the disinfection stage of water treatment, pioneering work in DBP
formation at Cranfield led to the first published work identifying the
risk associated with emerging DBPs such as haloacetic acids (HAA) and
nitrogen based DBPs in the UK [G5]. A critical discovery was the absence
of a link between treatability and DBP formation, meaning that targeted
removal of high DBP forming compounds in not possible [P6]. Recent work
funded by the Scottish Government identified that switching to
chloramination is insufficient to minimise the risk of non compliance and
highlighted the need for integrated solutions.
||Post details and dates involved
|Prof B Jefferson
Senior Lecturer (2006-2009)
|Coagulation and flocculation,
advanced oxidation processes,
floatation processes, algae, zeta
|Dr P Jarvis
||Senior Lecturer (2012- Present)
Academic Fellow (2007-2009)
|Coagulation and flocculation, ion
exchange processes, floc
|Dr E Goslan
||Senior Research Fellow (2013-present)
Research Fellow (2008-2013)
Research Officer (2003-2008)
|Disinfection by products, Characterisation
References to the research
Evidence of quality — peer-reviewed journal papers
P1. Goslan, E.H., Fearing, D.A., Banks, J., Wilson, D., Hills, P.,
Campbell, A.T. and Parsons, S.A., Seasonal variations in the disinfection
by-product precursor profile of a reservoir water. Journal of Water
Supply: Research and Technology - AQUA, 51(8), pp. 475-482,
P2. * Jarvis, P.R., Jefferson, B. and Parsons, S.A., Breakage, Regrowth,
and Fractal Nature of Natural Organic Matter Flocs. Environmental
Science Technology, 39, pp. 2307-2314, 2005. doi:
P3. Sharp, E.L., Parsons, S.A. and Jefferson, B., The impact of seasonal
variations in DOC arising from a moorland peat catchment on coagulation
with iron and aluminium salts. Environmental Pollution, 140,
pp. 436-443, 2006. doi: 10.1016/j.envpol.2005.08.001
P4. Jarvis, P., Mergens, M., McIntosh, B., Nguyen, H., Parsons, S.A. and
Jefferson, B., Pilot scale comparison of enhanced coagulation with
magnetic resin plus coagulation systems. Environmental Science
Technology, 42, pp. 1276-1282, 2008. doi: 10.1021/es071566r
P5. * Henderson, R. K., Parsons, S. A. and Jefferson, B. (2008)
Surfactants as bubble surface modifiers in the flotation of algae:
Dissolved air flotation that utilizes a chemically modified bubble
surface. Environmental Science Technology, 42, 4883-4888.
P6. * Bond, T., Henriet, O., Goslan, E., Parsons, S. A. and Jefferson, B.
(2009) Disinfection By- Product Formation and Fractionation Behaviour of
Natural Organic Matter Surrogates. Environ. Sci. Technol., 43,
5982-5989. doi: 10.1021/es900686p
* 3 identified references that best indicate the quality of the research
Further evidence of quality - underpinning research grants
G1. Yorkshire Water, United Utilities, Natural Organic Matter Character
and Reactivity: Assessing Seasonal Variation in a Moorland Water, £60,000,
10/1999-10/2003, PI: Parsons.
G2. WRF project number 2874, Treatment of elevated organics waters,
£284,000, 10/2002- 10/2005, PI: Parsons, CI: Jefferson.
G3. Orica Watercare, Impact of MIEX® on downstream processes,
10/2004-10/2007, £70,000, PI: Parsons, CI: Jefferson.
G4. Anglian Water Northumbrian Water, Thames Water, Yorkshire Water,
PosiDAF, 10/2004- 10/2007, £42,000, PI: Jefferson, CI: Parsons.
G5. Anglian Water, Northumbrian Water Limited, Severn Trent Water, United
Utilities, Yorkshire Water, HAA precursors and treatment, 10/2005-10/2008,
£180,000, PI: Parsons, CI: Jefferson.
Details of the impact
Our toolkit developed through this work, for characterising organic
matter and flocs, is now routinely used by a number of UK water companies,
as evidenced from testimonials from Severn Trent Water [C1], United
Utilities [C2] and Yorkshire Water [C3]. The fundamental process
understanding underpins significant operational activity related to NOM
Our work helped shape the operational policy relating to the scheduling
of the blending of water of different sources based on their
characterisation [C3]. The use of fractionation has been central to a
recent study looking at water intake contributions from different input
sources into two drinking water treatment works in the Yorkshire Water
region. The work on the role of zeta potential as a universal guide to
optimisation of coagulation now forms the basis of routine monitoring in
operating the largest drinking water works within the Severn Trent region
[C1]. The research findings have been embedded into operational practice
and have resulted in significant savings in chemicals and energy
consumption. Scottish Water recently adopted the combination of both sets
of techniques as standard tests as part of a detailed investigation
programme of its existing coagulation sites for process optimisation,
works audits and to guide investment decisions [C4]. Additionally, United
Utilities now routinely uses the tools as part of their coagulation
diagnostics in relation to problematic operational sites [C2]
The diagnostic tools have also been central to the assessment of new
technologies, such as novel magnetic ion exchange processes. This work
informed Yorkshire Water's decision in 2009 to invest £50M in the
technology at three drinking water treatment sites, including the first
example of the technology to be implemented in Europe. More recent work
has been utilised by the water companies to assess a number of other
technologies such as nanofiltration, electro coagulation and novel
adsorbents where the tools and approaches developed by Cranfield are used
to understand the potential of the technoloy and shape future
investment plans [C1, C3].
The application of the tools is being developed through industrially
funded projects related to catchment management [C5] so that the impact of
the research in terms of the drinking water treatment works can be
properly understood [C1, C3]. These projects represent some of the first
examples of such an approach: the findings of these studies are changing
the water companies' understanding of catchment management and shaping
future policy [C1].
The team's research has resulted in two novel technologies, marketed by
Water Innovate limited, part of the Bluewater Bio group [C6].
- The first is PosiDAF®, a novel adaption of the dissolved air flotation
process that utilises positively charged bubbles by coating them with
either surfactants or polymers. In Australia, there is a demonstration of
the potential for Cranfield's invention for algae removal from both
drinking water sources and final effluent lagoons for wastewater
treatment. The work has industrial support from five water companies and
the Australian Research council [C7]. Cranfield continues to collaborate
through a transfer of staff to the University of New South Wales.
- The second technology is the membrane chemical reactor (MC-RTM).
This is a photocatalytic reactor linked to a membrane to ensure the
containment and reuse of nano
particulate titanium dioxide catalyst particles. The technology, patented in
2005 [C8], is under further development as part of a programme of work
funded by Severn Trent Water for the removal of a recalcitrant pesticide
(metaldehyde) from river waters. Funding has now been secured for a
demonstration of a photocatalytic pilot plant to refine the business case a
full-scale version of the technology in the next asset investment plan [C9].
Our work has helped to shape investment programmes, and assist utilities
in meeting future risks from new legislation related DBPs that are
currently unregulated such as haloacetic acids. Work for the Scottish
Government on use of alternative disinfectants led to a report published
by the water quality regulator for Scotland that has influenced policy on
water compliance for Scotland [C10].
The work on emerging DBPs was funded by a consortium of UK water
companies to understand the risks.
Sources to corroborate the impact
C1. Contact: Senior Process Scientist, Severn Trent Water, Coventry, UK
C2. Contact: Senior Process Scientist, United Utilities, Warrington, UK
C3. Contact: Research Development and Implementation Project Manager,
Yorkshire Water, UK
C4. Contact: Process Optimisation Team Manager, Scottish Water,
C5. Goslan, E., Jarvis, P and Jefferson, B. (2011). NOM Fractionation and
DOC: the True Link. Yorkshire Water Framework Project.
[last accessed 12 March 2013]
C7. ARC Linkage LP0990189, South Australia Water and Australian Water
Quality Centre, United Water, Seqwater and Melbourne Water. Optimising
dissolved air flotation for algae removal by bubble modification in
drinking water and advanced wastewater systems. AUD$621,000.
C8. Parsons, S. A. and Jefferson, B. (2005) Membrane chemical reactor.
British Patent No.0501688.6
C9. Contact: Research and Development Manager, Severn Trent Water,
C10. Study into the formation of disinfection by-products of
chloramination, potential health implications and techniques for
minimization. Drinking Water Quality Regulator for Scotland (dwqr) website
www.dwqr.org.uk. [last accessed 12