3rd European Water and Wastewater Management Conference – 22nd – 23rd September 2009
ENERGY EFFICIENT SEWAGE TREATMENT CAN ENERGY POSITIVE SEWAGE
TREATMENT WORKS BECOME THE STANDARD DESIGN?
Caldwell, P.
Aker Solutions, Skanska Aker Solutions joint venture,@one Alliance, Anglian Water
E. [email protected]
ABSTRACT
The purpose of this paper is to discuss energy inputs and outputs in sewage treatment works, and
show that it is already possible to generate more energy in a sewage works than it requires in input
energy. Hence a sewage plant can be created that returns a net positive energy output to its
surroundings. If this is channelled correctly the sewage works becomes a green energy producer.
Practical examples of reduction in energy consumption and increase in energy are included. Some
newer processes are discussed, which, once tried, may prove to boost energy positive values even
further.
It is the author’s opinion that all sewage treatment works will eventually be able to be converted to
become energy positive and that water companies could become net green energy producers
rather than one of the largest energy users.
The author is a Chartered Chemical Engineer directly employed in the wastewater industry. Aker
Solutions is a leading global provider of engineering and construction services, technology products
and integrated solutions to the water, energy, process, metals and oil and gas fields. The company
has more than 40 years of experience working as contractors and partners with utilities companies
in the UK water industry, and large industrial companies. Aker Solutions has exclusivity
agreements and proprietary technology that aids best process choice and implementation.
KEY WORDS
Energy, energy needs reduction, energy generation, energy recovery, positive energy, aeration,
digestion, advanced digestion, sewage processes, process development, innovations.
INTRODUCTION
The history of water and wastewater process development started with traditional processes such
as lagoons, settlement tanks, filter beds, and solids separation. These work very well for works
serving small communities. As both communities and industry grew, new processes were
developed that were capable of treating higher loads and higher flows to improved quality
requirements. Plants became more sophisticated, with many process unit operations and the area
required for treatment became large.
In the era where land became more expensive and energy was relatively cheap, processes were
developed that were smaller footprint but more intensive from an energy viewpoint. Aeration plants
became a core process and sludge treatment processes such as digestion and incineration were
developed to treat the increasing volumes of waste sludge.
More recently energy prices have risen rapidly, disposal costs are increasing and legislation is
making increased quality of treatment a requirement on most sites. Environmental considerations
are also increasing in importance. Companies are now developing processes to minimise longer
term “whole life cost” and carbon footprint of new plants and refurbishments so that both the
running and capital costs are considered for best design.
The water industry is the fourth largest energy user in the UK and used approximately 7700
gigawatt hours (GWh) of energy in 2006, which is 1% of the average daily electricity consumption in
England and Wales (Parliamentary Office of Science and Technology, 2007). Minimising energy
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needs and maximising energy production in a sewage works is a logical current target. If sewage
works can be developed to generate more energy than they require to meet their energy needs,
then energy positive sewage treatment works are developed that can export heat, electricity, or
both to the local or national community. This will reduce the total energy needs of the water
companies.
Energy production on water industry sites is increasing. In 2005 – 6 the water industry generated
6.4% of its energy requirements on its own sites, mainly from digestion processes (Parliamentary
Office of Science and Technology, 2007). This level of energy production is increasing rapidly in
some water companies. Anglian Water has nearly doubled its energy generation capability over the
past year to 23GWh and plans to increase to 40GWh by next year (Anglian Water 2009). Energy
costs for treatment are 17% of the company costs.
If energy production can be achieved on enough sites then there is the possibility that water
companies could become net energy producers rather than energy users. This will be good for
balance sheets, but will also be an excellent example of converting a waste product into a valuable
source of green energy and will generate a very good environmental result.
In this paper I am not tracing all materials and chemicals back to their full carbon footprint for
extraction, manufacturing, transport, use and eventual disposal. I am carrying out a less complex
comparison on energy inputs and outputs for a sewage treatment works typically in the form of
chemical, electrical and heat energy.
I am a Chemical Engineer with over 28 years of practical experience in process development,
research and design, initially in the food industry, and for the last 3 years as a designer in the water
industry. I have practical experience in commissioning and running processes. Because of my
background outside the water industry I was asked to look into the fundamental science behind the
traditional design processes and question how they are performed.
Energy Balance - What Do I Mean By Energy Positive Sewage Treatment Works?
An energy positive sewage treatment works exists where the useful energy produced by processes
on the site is greater than the energy required to run the plant operations. With digesters to
produce gas that feeds a combined heat and power (CHP) system, if there is enough gas
produced, then enough electricity and heat can be generated to power the high energy consuming
processes such as aeration blowers.
Why am I confident that there is enough energy available in the sewage works input at some works
to achieve this? It is already being achieved. In Anglian Water some of the regional sludge centres
already convert enough energy to be able to provide for all of their internal processes and export
electrical energy to the National Grid. Kings Lynn is a good example (Anglian Water 2009). Strass
STW in Austria treats all of its incoming sewage, provides 108% of its electrical needs and exports
heat to a community heating scheme (Jonasson, M 2007).
So it is possible to achieve energy positive sewage treatment works in some cases. The next
question is: Can this be achieved in all sewage treatment works? To investigate this question we
have to look at the energy requirements and the energy production possible from a typical sewage
treatment works.
From a standard water industry text we can consider a typical energy needs breakdown for a
sewage treatment works.
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Table 1:
Typical energy requirements for a sewage treatment works (Metcalf and
rd
Eddy 3 Edition)
Stage
Inlet pumping and headworks
Primary clarifier and sludge pumps
Activated sludge aeration
Secondary clarifier and RAS
Thickener and sludge pump
Effluent filters and process water
Solids dewatering
Tertiary treatment
Heating
Lighting
Energy need (% )
4.9
10.3
55.6
3.7
1.6
4.5
7.0
3.1
7.1
2.2
Rank / Comments
2
1 Main power use
4
3
It is obvious from the table that the main energy use is for aeration, with over half of the plant
energy demand being in this one process. Also the top 4 processes use more than 80% of the
plant energy. From this it is sensible to target energy reduction in these high use areas first. Look
at the top 4 and see how energy could be reduced:Primary Clarifier and Sludge Pumps
•
•
•
•
Replace old pumps with high efficiency pumps or just new motors. Typically 5-15% energy
can be saved by changing to EFF1 motors and more can be saved if the pumps are old
and worn.
Make more consistent sludge by uprating from manual to auto-desludge or improving
control of the de-sludge through timers or improved instrumentation. The advantage here
is two-fold in that more consistent sludge will generally mean less material needs to be
pumped and this also helps to optimise the digestion processes by giving a more consistent
feed.
Use dosing systems to increase the quantity of sludge separated in the primary tanks.
Often iron compounds are used, though these can have negative effects on some of the
digester heating equipment by giving solids deposition. If an additional 5–15% solids and
BOD are removed in the primary stage, this can have a very positive effect in reducing the
load on the aeration stage. This also increases the amount of primary material in the
digester which aids good digestion, and increases the energy that can be produced. New
compounds are being suggested for this duty and organic based settlement aids are being
advertised although not yet being used in the water industry.
Use alternative clarifier processes rather than primary settlement tanks. For example
Salsnes filters are used extensively in Northern Europe. They claim better solids removal
than primary settlement tanks (in line with dosing), very small footprint and the capability to
dewater the sludge if it is to be transported off site for treatment (Salsnes Filter Process,
2009).
Activated Sludge Aeration
•
•
•
When designing a new works consider carefully if an alternative lower operating energy
system could be viable instead of activated sludge aeration. There may be alternative
process routes that could replace activated sludge. Trickling filters have fallen out of favour
due to high area requirements and are seen as less flexible, but they may be a sensible
alternative in terms of whole life cost, especially for smaller works. Modern filter media
could reduce size and capital cost.
Reduce the energy load by improved primary separation.
Increased aeration efficiency from “new” design aerators. A practical example of this is
shown later in this paper. The reason I put the “new” in exclamation marks is that this
design has been used in Europe for more than 20 years but had not been used extensively
in the UK. Some “new” design aerators are of a large plate design and give a much larger
number of smaller sized air bubbles, hence giving a high oxygen transfer area for the same
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•
•
•
•
•
volume of air. This can reduce the air volume required by over 25%. This design of
aerator can also be combined with a control system that flexes the membranes several
times a day to reduce solids deposition on the membranes, which is one reason why other
membrane designs become less efficient with time. The membranes also have a 20 year
working
life
(Ovezea, A 2009, Hydrok UK Process 2008, and Rogella, F 2008).
Combined nitrify-denitrify aeration systems are used to reduce the air required by more
than 20%. These use sophisticated control systems (Demoulin, G and Dutt, S, 2007) .
Advanced control systems can be used to optimise air flowrates depending on dissolved
oxygen content, inlet flowrate and using ammonia readings. Some of these designs stop
air flow when ammonia content is low. Others use pulsed air and mixing air flowrates if air
flow and sewage load are low.
Efficient blowers can replace old blowers. A typical energy saving is 10-20% by converting
to modern blowers. There are also blower designs which use high-speed oil-free turbo
systems to provide the air supply. These are truly oil-free systems and rely on magnetic
bearings to float the rotor inside the unit. They can be even more efficient than standard
modern blowers provided the total air supply and control system is well designed.
Some systems claim to make less sludge. There are dissolved oxygen control based
systems, nitrify-denitrify systems and chemical dosing systems that claim this advantage. If
less secondary sludge is made it is better operation of your digester and also reduces
sludge pumping requirements. However, less sludge may mean less energy recovery.
A recent potentially interesting development is to add a disc-based unit operation in front of
the aeration to preferentially grow bugs for good sewage treatment. It is claimed this
process operation can reduce air-supply needs by 50% and reduce sludge formation. Not
yet used at full scale in the UK.
Solids Dewatering
•
•
•
•
•
Reduced sludge dewatering load by making less sludge.
Improved dewatering systems by electrically-assisted belt sludge thickening claims to
increase solids content from 25% up to 45-66% (Coyle, L 2008). Reduces transport costs.
Filter presses can give significantly better water removal.
Vacuum dewatering can give high solids content. Reduces transport costs.
Combined vacuum and steam dewatering filter press is claimed to give exceptionally low
water content and increased microbiological kill in sludge which can be combined with
higher rates through the site digesters (TVD UK Process, 2008). Reduces transport costs.
Heating Requirements Reduction
•
Digester processes need heating. If this can be supplied by CHP and recirculating the
heated water, then the external heating requirement for the plant can be virtually
eliminated.
Other Potential Energy Savings (That Affect the Whole Plant)
•
•
•
Reducing the amount of secondary sludge produced can reduce costs across the plant and
reduce final waste levels to be transported. Traditional digesters operate more efficiently if
secondary sludge input is low, though ultrasound treatment can improve its digestibility
(Eberhard, F 2007). Other biological treatments are being developed that claim to reduce
sludge production. However, we need to balance reducing secondary sludge against the
potential to use it for energy production – some of the thermal hydrolysis processes now
claim to give good energy from secondary sludge.
The use of energy-efficient motors to replace existing motors can give energy savings in
the 5-15% range. If variable speed units are used to replace fixed-speed motors the
capability to run at the exact speed required can outweigh the electrical losses in the
variable speed unit. But be careful with this approach, there are occasions where fixed
speed can achieve the same, or better, energy benefits.
An increasing need is the capability to treat high-strength liquors (high ammonia) that are
generated as waste streams from digesters. This is often returned to the inlet works for
treatment by standard processes. New routes are being developed to treat these liquors
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•
more efficiently as side-streams. These are mainly proprietary technologies and the choice
of best unit operation/method depends on specific site targets and limitations.
Peak lopping or flow balancing can reduce the maximum amount of energy that a plant
needs at any one time. Generally the maximum load on a plant can coincide with high
electrical tariff points. If peak lopping is used then the maximum load is less and the
amount of load at the high tariff is less, giving a double cost benefit.
Consider by what proportion the energy needs (costs) could be reduced
Copy table 1 but show some typical achievable savings
Table 2:
Possible effects of energy reduction improvements on a typical STW
Stage
Change
Inlet pumping and
headworks
Primary clarifier
and sludge
pumps
Activated sludge
aeration
Efficient motors ( -10% )
Secondary
clarifier and RAS
Thickener and
sludge pump
Effluent filters and
process water
Solids dewatering
Tertiary treatment
Heating
Lighting
TOTAL
Original
Energy
need (%)
4.9
Improved
Energy need
4.4
Efficient motors ( -10% ),
remove more consistent
sludge ( -10% )
Efficient aerators ( -25% ),
efficient blowers ( -10% ),
make less sludge ( -15% )
Less sludge, lower power
( -10% )
Lower power ( -10% )
10.3
8.3
55.6
27.8
3.7
3.2
1.6
1.4
No change
4.5
4.5
More efficient ( -20% )
( -10% )
Recycle
( -10% )
7.0
3.1
7.1
2.2
100
5.6
2.8
0
2.0
60
From this relatively simple calculation table it can be seen that provided significant savings are
made in the high energy areas there is the possibility to reduce the energy used on a standard
aeration based plant by 40%. If some of the additional improvement methods suggested above are
added then achieving a 50% or larger reduction in energy required is possible.
PRACTICAL EXAMPLE 1 – ENERGY REDUCTION IN AERATION DURING A
REFURBISHMENT PROCESS
Basildon Sewage Treatment Works refurbishment for Anglian Water
The challenge
An Anglian Water 150,000 population works had an aeration system based on disc aerators that
needed to be refurbished. Over the previous two years the load on the works had increased rapidly
due to industrial and population growth within the catchment area. It was obviously approaching its
treatment limit as the ammonia level was starting to rise whenever full load was applied to the plant.
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The aeration plant was a very complex 14lane single pass system, with return activated
sludge (RAS) system that involved return via
mixing lanes. The civil structure could not be
extended.Another site project was due to
complete at the same time, which involved reinstatement of two refurbished digesters.
These had been taken out of service for repair
and conversion from floating to fixed roofs.
The digester liquors would increase the
ammonia loading on the plant and require an
air increase of approximately 20%. The site
electrical load was also near to its maximum
limit.
To summarise, the target was to obtain more
efficient aeration for a 20% higher load in the
same civil structure and maintain compliance
at all times throughout construction and
commissioning.
See picture 1 to the right, showing old discs.
The solution
A higher efficiency aeration system was sourced from a European manufacturer (Aquaconsult of
Austria), who had a new UK agent (Hydrok UK). These companies were new to Anglian Water.
The higher-efficiency aeration was achieved
by using a plate aerator that gave higher area
coverage of the aeration zone and created
smaller air bubbles. The small bubbles rise
more slowly and have a larger surface area
which increases oxygen transfer from a typical
5.5% per metre of water depth to more than
7.0% per metre. This reduces air requirement
to treat the same load level by approx 27%
and allows more oxygen transfer in the same
volume of mixed liquors. The aerator units are
linked to a control system that gives a selfcleaning routine to reduce solids build-up on
the membrane and maintain high oxygen
transfer efficiency over a longer working life.
See picture 2 to the right, showing new plates.
The old blowers were replaced with highefficiency oil-free turbo blowers. These use
10-20% less energy to produce the same
volume of air.
In combination with the
aerators and blowers change a new control
system was introduced that increased the
number of oxygen probes used, brought the 14 lanes into 3 control sets with two control zones in
each set, used eccentric plug control valves and added a control algorithm that helped to control
total dissolved oxygen levels to tighter levels. Air flowmeters and pressure sensors were used in
each zone to aid burst mixing at low flows.
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The RAS flows were redirected to reduce the amount of volume used for mixer lanes. We also had
to introduce a series of temporary works to allow a gradual transfer from the old aeration system to
the new aeration system as each lane was refurbished. We did not have the capability to stop
sewage flow, or redirect it to an alternative treatment route.
The result
See picture 3 to the right showing a
pattern test on 2 lanes to show
evenness of air distribution.
The aeration capital cost for this
solution was cost neutral compared
with using disc aerators. The whole
life cost will be significantly less for
this new design due to the much lower
operating costs.
The load did
increase by 20% as expected when
the digesters were brought back into
use. Despite the load increase, the
energy used by the blowers has
reduced by 20% from its average
value before the change. Effectively
this means that the air required has
reduced by 33% from where it would
have needed to be to treat the
increased load.
See picture 4 to the right which shows
a picture of the multiple lanes part of
the way through installation of the new
system.
In terms of cost Anglian Water has
seen an OPEX reduction of £38,000
in the first year of operation. The
system has now been in operation
since July 2008. The air pressure at
the end of the first year of operation
was the same as it was at
commissioning. So the self-cleaning
mechanism is working well on this
plant.
There will be a continued
OPEX saving until the plant next
requires refurbishment. If the plant
matches
the
performance
of
European plants this refurbishment
may not be required for 20 years.
The supplier has become a regular
supplier to Anglian Water and has
completed refurbishment on 2 other
sites where similar good energy
savings are being seen.
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Sources of energy in the sewage works
Energy available for the plant to convert to use arrives in the form of fat, oil, grease, carbohydrate
and protein suspended or dissolved in the inlet flow. Converted products that can be utilised on the
plant includes sludge formed from biomass growth as part of the treatment process. Any additional
imports to the site add to the energy available to convert.
The materials that arrive into the plant and sludge formed in aeration can be converted through
traditional anaerobic digesters to form gas that can be used for simple heating or for electrical and
heat generation through a CHP unit. The gas is a combination of methane (typically 60-65%) and
carbon dioxide. Anaerobic digesters typically have 15 days residence time and can create enough
gas to provide their own heating and provide heat to other parts of the plant/building through
burning of the gas in boilers.
With the advent of CHP digesters have been able to generate up to half of the electrical power
needed on site as well as generating heat.
How to boost energy generation capacity
Advanced digestion is the key route to increased energy generation and can give a series of
positive effects. The amount of sludge converted into methane gas is increased, along with the
level to which harmful bacteria are destroyed and the rate at which material can be passed through
the digester because less residence time is required for conversion. The smaller quantity of
enhanced treated sludge produced is often more concentrated so transport costs can be reduced.
The sludge has more potential uses due to its lower microbial content.
The sludge is either pre-heated, mechanically pre-treated, acid treated, microbiologically pretreated (or a combination of these) to generate more availability of easily digestible materials for the
anaerobic bugs in the digester to use. Several alternative processes are available to achieve this
material breakdown. References include: Cambi Process 2009; Ecosolids Process 2008;
Eberhard, F 2007; Evans, T 2008; Monsal Process 2009; Shea, T 2009; Veolia Biothelysis
Process 2009; and Water Environment Research Foundation 2005. Each of these processes has
its own positives and negatives; their suitability depending on the particular application and partly
on the views and previous experiences of the client.
The traditional anaerobic digester with CHP added can be boosted by advanced digestion pretreatment. In the case of best conversion the amount of methane gas produced can be doubled
from a standard digester, though 30-50% gas increase is more typical. The electricity produced in
the CHP plant can be increased to match or exceed the amount of electrical energy required to run
the sewage works. The CHP plant also produces waste heat which can be reused for digester preheating, or building heating for offices, which saves on gas and oil use.
There is a significant barrier in the way of all plants becoming energy positive. Small versions of
digesters and CHP plants would need to be economically viable to install and operate. There is an
added advantage of achieving this. The large costs of transporting sludge from small works to
central sludge centres and then distributing the dried sludge product over a large area could be
saved or substantially reduced.
PRACTICAL EXAMPLE 2 – INSTALLATION OF A NEW ADVANCED DIGESTION PROJECT
FOR NORTHUMBRIAN WATER AT BRAN SANDS
The challenge
Northumbrian Water Bran Sands site contains a large sludge tank farm and sludge treatment
facility. The existing method of treatment used electrical and natural gas power to dry 40,000
tonnes (dry solids equivalent) of sewage sludge from Bran Sands indigenous sludge and imports.
This process used a large amount of energy. An improved energy-efficient process was required to
be developed on the plant while maintaining operation of the existing plant, and retaining the
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capability to run the existing plant as a future back-up and as a future sludge treatment rate
expansion facility.
The solution
The Cambi thermal hydrolysis advanced digestion process was chosen for this application. The
o
sewage sludge will be treated with 12 bar steam at 192 C to achieve a 30 minute treatment at
o
o
165 C and 6 bar pressure. The treated, heat-hydrolysed sludge will then be flash-cooled to 102 C
3
and 1 bar pressure and fed to the digesters. Three 6700m digesters will be installed with 18 days
residence time to complete the sludge treatment.
3
The digesters will generate 1800m of methane gas per hour which will power 4 Jenbacker gas
engines and generate 4.7 megawatts of electrical power and 2.2 tonnes per hour of steam for
process use. There are also package boilers that can run from natural gas or fuel oil for start up,
and can then use spare biogas when it is available.
Table 3:
Power changes
Process
Electrical energy input
Natural gas energy input
Total energy input
Power before changes (MW)
1.96
17.47
19.43
Biogas produced and used
Engine heat recovery
Energy used in the process
Waste heat
Electricity produced and used
Electricity exported for use
elsewhere on site
Power after changes (MW)
0
1.4
1.4
0
0
13.14
4.33
11.5
2.0
As required
6.2
0
0
1.96
2.74
From table 3 the external power used will reduce from 19.43 to 1.4 MW. The new process will
supply all energy needed for the process, including the electrical energy, and will export 2.74 MW of
electrical power for use in other parts of the Bran Sands site.
The result
The plant is progressing towards completion of installation in September 2009. As this paper is
presented, the process of seeding the digesters and commissioning the plant for full operation
should be in progress. Picture 5 below shows the plant during construction.
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A more detailed paper and presentation on the design is to be presented at a biosolids conference
in November and a paper will be presented on the completion of commissioning and
commencement of operation in a suitable conference in 2010.
CONCLUSIONS
th
•
The water industry in the UK is the 4 largest industrial energy user and uses
approximately 1% of the total power generated. Water companies already generate
energy on their sites for internal use. By targeting energy saving and boosting energy
production the water industry could potentially become a net energy generator rather than a
net energy user.
•
It is possible to design energy positive sewage treatment works. They already exist.
•
Designs to improve energy efficiency of an existing works by reducing the energy used
and/or increasing the energy produced can be used to generate energy positive sewage
treatment works from existing works. This has already been done.
•
Designs for optimised low energy do not automatically use the current standard existing
processes, but may use traditional processes or newly developed processes.
•
There is a difficult balance to make between the risk of using alternative novel processes
versus the safety of tried and trusted existing designs, versus the use of traditional
technologies in a modern way. The key is having enough knowledge and understanding of
the plant targets and alternative processes to choose the most appropriate option.
•
Smaller scale energy positive sewage treatment works will gradually become possible as
the energy-generating unit operations improve in design to the point where they are
economically viable.
RECOMMENDATIONS
•
Use whole life cost analysis to determine the best long-term process investments. This will
encourage the use of higher energy efficiency, lower OPEX processes.
•
Use expertise that is available from contractors to help to advise and implement best
practice for energy efficiency improvement. I feel this is best achieved with a partnership
arrangement rather than a traditional client contractor arrangement. Working together from
the start of a project helps to define real needs more clearly and is likely to generate the
most appropriate overall solution.
•
Water companies can achieve significant improvements in their energy efficiencies. I am
confident that very large savings can be achieved. Targeting simple energy savings
improvements may achieve 10-20% energy savings. With good targeted process design
improvements much greater savings should be achieved, closer to the 50% savings level.
•
Some water companies have already set themselves harder targets than this. I believe a
reasonable target would be to achieve energy positive sewage treatment works at every
works that currently has a digester within 2 AMP periods (by 2020).
•
Continue to follow developments in processes for low energy operation – for example
anaerobic treatment of raw sewage and harvesting the full energy available from sludge are
developing areas.
•
With carefully planned development water companies should be able to become energy
positive overall, and change from being the fourth largest industrial energy user in the UK
to being green energy producers that contribute to power available to the community. This
would be a major cost benefit to the companies concerned and would also support
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government and international targets towards greater use of recyclable energy. Can one of
the water companies achieve this by the end of AMP7 (2025)?
•
Some water companies are already co-digesting their sewage with high energy imports.
There is the possibility that water companies, having expertise in anaerobic digestion, could
increase their digestion capacity further and import large quantities of high energy
biologically recyclable waste that is otherwise sent to landfill. This would then be a major
benefit to the environment. Perhaps this should be pursued more aggressively.
ACKNOWLEDGEMENTS
Anglian Water, the @one Alliance and Northumbrian Water have given permission for data,
pictures and examples of processes being developed on their behalf to be used in this paper.
I would also like to thank Aker Solutions for encouragement, providing time to attend exhibitions
about new technologies and proof reading of this document.
REFERENCES
rd
ADAS (2001) The safe sludge matrix, ADAS issue date April 2001, 3 Edition, AMPTU 1234/C/2
Anglian Water (2009) Annual report and accounts
Anglian Water (2009) Website article on Kings Lynn Sewage Treatment Works
Atana Process (2008) New environmental solutions – What’s in your sludge
http://www.atana.co.uk
Cambi Process (2009) Turbocharge your Digester, Biosolids brochure http://www.cambi.com
Coyle, L (2008) Improve your sludge management in 1 easy step – without the footprint ELODE
th
technology, Aquatret Environmental Engineering Limited, abstract from 13 European biosolids
and organic resources conference, Aqua Enviro Technology Transfer
DEFRA (2002) Sewage treatment in the UK : UK implementation of the EC Urban Waste Water
Treatment Directive
DEFRA (2007) Advanced biological treatment of municipal solid waste, http://www.defra.gov.uk
DEFRA (2007 update) Waste implementation programme : New technologies demonstrator
programme: catalogue of applications – 2007 update, http://www.defra.gov.uk
Demoulin, G and Dutt, S (2007) Aerated denitrifying SBR process to meet quality and other
rd
drivers in UK, CIWEM 3 National conference
Eberhard, F (2007) Full scale commercial operation of ultrasound disintegration plants in
Germany, http://www.iwe-tec.com
Ecosolids Process (2008) Eco-solids process, cellruptor and packaged biological wastewater,
http://www.ecosolids.com
Evans, T (2008) An independent review of sludge treatment processes and innovations,
Biosolids Speciality IV Conference, 11-12 June 2008, Adelaide, the Australian Water Association
Eisberg, N (2009) Sustainable energy in a changing world, J. Chemistry & Industry, 10 Aug
2009-08-14
www.ewwmconference.com
Organised by Aqua Enviro Technology Transfer
3rd European Water and Wastewater Management Conference – 22nd – 23rd September 2009
Hydrok UK Process (2008) Witham waste Water Treatment Works – Anglian Water project
summary sheet, http://www.hydrok.co.uk
Jonasson, M (2007) Energy benchmark for wastewater treatment processes – a comparison
between Sweden and Austria, Masters thesis Department of Industrial Electrical Engineering and
Automation, Lund University
Le, S and Carline, I (2009) Gravitox – a fundamental approach to aeration design, The Carbon
Crunch – Technology Solutions for the Water Industry Conference , March 2009.
Lunn, M (2009) Grids improve efficiency, J. Filters Screens & Filtration Systems 12 Jan 2009
rd
Metcalf and Eddy (2003) Wastewater engineering treatment and re-use, 4 edition, McGraw Hill
Monsal Process (2009) Advanced Digestion Technology - Advanced environmental technology
for biowaste, http://www.monsal.co.uk
Ovezea, A (2009) Saving Energy : Using fine bubble diffusers, J. Filtration and Separation Jan /
Feb 2009
Parliamentary office of science and technology (2007) Energy and Sewage, Postnote number
282.
Rogella, F (2008) The rise of the little bubble, J. Water & Wastewater treatment May 2008
Salsnes Filter Process (2009) The Salsnes Filter technology http://www.salsnes
Shea, T (2009) Thermal Hydrolysis and Acid Hydrolysis – Pre-Conditioning Technologies on the
Move, http://www.imakenews.com/restech/e_article001368484.cfm
TVD UK Process (2008) The revolutionary Dryvac dewatering and drying system,
http://www.tvduk.com
Veolia Biothelysis Process (2009) Reducing sludge production by up to 80%,
http://www.veoliawaterst.co.uk
Water Environment Research Foundation (2005) Wastewater sludge : A new resource for
alternative energy and resource recovery, http://www.werf.org
Whitlock, D (2009) Synopsis of “Sustainable Energy Management: Achieving Energy
Independence at Wastewater Utilities” , http://www.imakenews, CH2M HILL
www.ewwmconference.com
Organised by Aqua Enviro Technology Transfer