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The Cross Hands WwTW has recently been revamped to increase it’s capacity and to completely automate the treatment process. The upgrade will accommodate future industrial expansion and allow the site to maintain compliance with strict discharge consents enforced by the Environment Agency.
The site uses a conventional activated sludge process with diffused air to promote biological removal of ammoniacal-nitrogen. The plant design allows for the incoming flow to be split between two aeration lanes which are both individually controlled.
The selection of instrumentation is critical to the successful operation and control of the treatment process. The contractor was guided by Dwr Cymru Welsh Water who had previously installed instrumentation from PPM at the Cardigan Bay project for the measurement of Dissolved Oxygen and MLSS.
These two parameters are used to automate the biological treatment to ensure the correct concentrations of dissolved oxygen and activated sludge is maintained within the aeration basin.
Since installation during February 2006, the PPM monitors have required the absolute minimum of maintenance. The Dissolved Oxygen sensor has a porous Teflon membrane which minimises biological fouling and when installed below 0.50m depth typically does not require physical cleaning. The reference system also maintains calibration so user intervention is minimal.
Similarly the MLSS sensor is also low maintenance. The Visolid sensor uses continuous ultrasonic cleaning to keep the optics clean. The provision to calibrate the sensor at multiple points (up to seven different sludge concentrations may be entered) provides for a much more accurate determination of sludge concentration. The initial calibration is typically performed using just three points to obtain a representative calibration curve. Subsequently the measurement performance can be easily checked against a reference meter and a correction factor can be simply applied if required.
The continuous measurement of ammonium is also a critical parameter to demonstrate the treatment process is working properly. The ammolyt ammonium monitor was installed with automatic compressed air cleaning and is located on the final effluent discharge. The submersible probe provides a direct measurement of effluent quality and is completely reagentless.
Dwr Cymru have recently up graded the system to the ammolyt plus technology which is a second generation product offering many enhanced features. Once commissioned the system is extremely stable and does not require subsequent calibration thus reducing maintenance to an absolute minimum.
The measurement of sludge blanket within the two separate clarifiers has also proved successful. The ENV100 monitors use ultrasonic technology to continuously profile the depth to the sludge blanket and provide forward warning well before critical conditions are breached. Should the sludge level rise, then the clarifiers can be programmed to automatically decant preventing sludge carry over which can affect final effluent quality. The monitors are supplied with a small compressor unit which regularly is used to clean the submerged ultrasonic head and remove biological fouling.
The Cross Hands WwTW site is a good example of how on-line instrumentation can be successfully installed to provide continuous process measurement and allow proactive management of the individual treatment processes. Where the correct instrumentation is selected it can positively contribute to process optimisation and in doing so improve effluent quality and reduce operational costs.
For further information on how PPM can support your operation please contact:
Steven Tuck
Pollution and Process Monitoring Ltd
Tel: 01732 882044
Fax 01732 780190
TOC@pollution-ppm.co.uk
www.pollution-ppm.co.uk
Pollution and Process Monitoring is a leading manufacturer of water quality instrumentation but also recognises the need to deliver fully supported engineered systems.
Since the formation of the company in 1990, the supply of bespoke monitoring solutions has significantly contributed to the company’s growth. The ability to supply fully equipped walk-in analyser kiosks (or towable trailers) that are pre-wired and plumbed, complete with instrumentation, sample delivery systems, data recording and communications have proved popular. Where existing buildings can be utilised, the supply of pre-formed instrument panels has also been very successful.
The benefits of this approach cannot be overstated. Who better to complete the installation process than the manufacturer (or distributor) who will understand specific instrument requirements? Sometimes what may be perceived as only a minor consideration can have significant impact on the quality of the installation. Additionally, the ability to pre-engineer systems allows for complete testing before delivery, reduces time on site and therefore also reduces installed cost.
 Projects span a variety of end users including utility, construction and manufacturing industries. The Bran Sands effluent monitoring kiosk, was supplied to Northumbrian Water and sized to accommodate four ProAm ammonia monitors (complete with sample preparation) and to allow space for additional instruments. All of the sample distribution was preformed using stainless pipework. Fused spurs were provided to each analyser and signals were wired to a common signals enclosure. The installation has been supported by PPM service engineers attending site on a scheduled interval, to complete routine servicing.
The analyser kiosk engineered for BP at Hull, is an example of a bespoke system engineered to a very high specification including stainless steel sample pipework which provides sample distribution to the Total Organic Carbon (TOC) and pH instruments, in addition to automatic composite sample collection.
The latest analyser kiosk containing the two Protoc Spyder TOC analysers and a Web controller, was employed to continuously monitor and limit discharge from the site treatment facility. This new position is down-stream of the individual production areas that are already continuously analysed for TOC and pH.
 The surface water monitoring project completed for Redrow Homes required PPM to integrate a wide range of instrumentation into a walkin analyser kiosk equipped with sample preparation, lighting and frost protection. The analysers continually measure water quality (Turbidity, pH, Oil, Phosphate, Nitrate and TOC) and these values are communicated daily and also instantaneously on-alarm, to a third party who can take appropriate action if required. A Terminator system has been installed to capture non-compliant surface water, by automatically inflating a bladder within the drainage network to prevent accidental release. Regular site visits have been scheduled to maintain chemicals and provide preventative maintenance.
 The installation at Bray WTW for SE Water also demonstrates how PPM can work alongside other contractors to deliver a project. The pollution monitoring kiosk was engineered to an agreed specification to accommodate continuous measurements of ammonia, DO and oil, at the abstraction point on the River Thames. The need for simplified maintenance and the quality of measurement were important factors in choosing the correct instrumentation. PPM needed to coordinate the build with another contractor tasked to communicate signals into an existing telemetry and control system. A common signals box formed a simple point of demarcation between the two contractors.
 Engineered systems have also been supplied overseas. Where possible the enclosure is kept as small as possible to reduce transportation costs. Our French distributor – Proanatec secured an order to supply a compact monitoring kiosk to a fine chemical plant in the north west of France. The instrumentation comprises two “paired” Web analysers providing 100% data collection onto a Spyder controller to ensure surface water is free from hydrocarbon ingress. Alarm signals were connected to a control room and if activated can also engage an audible and visual beacon installed on the roof of the analyser kiosk.
With increased automation, the correct instrument selection and style of installation are very important considerations. Furthermore, scheduling regular chemical deliveries and tailoring service contracts to provide an adequate level of support can further simplify the ownership of these instruments. The investment can then positively impact without burdening operational staff with additional work.
For further information on how PPM can support your operation please contact:
Steven Tuck
Pollution and Process Monitoring Ltd
Tel: 01732 882044
Fax 01732 780190
TOC@pollution-ppm.co.uk
www.pollution-ppm.co.uk
Wessex Water has established a need to reliably and continuously monitor effluent ammonia concentration at a number of key wastewater sites along the south coast. These sites all have an effluent consent of 5 mg/l or less and any failure to comply with the discharge consent could lead to hefty financial penalties under the OFWAT performance assessment.
 The Poole WwTW site was initially used to evaluate the ProAm instrument over a 2 month period commencing November 2004. The trial was a great success and Wessex Water decided to make the installation permanent.
Subsequently to this, further installations have taken place at Holdenhurst WwTW to monitor both the final effluent discharge and the CSO (Combine Sewer Outfall) discharge from the storm settlement tanks. The CSO application was fitted with a special low cost ultra-filtration system with automatic air cleaning, as a precautionary measure to protect the instrument from unwanted solids.  Operations have again passed encouraging comment on the overall style, neatness and performance of the twin installation at the Holdenhurst site. After the success of the Holdenhurst and Poole installations units have been ordered for sites which include Dorchester and Palmers Ford WwTW to monitor final effluent quality.
The ProAm located at Poole has demonstrated how a simple design can indeed be very effective. The instrument is located at the inlet to the UV-disinfection plant, monitoring final effluent after the activated sludge treatment process. The instrument continuously analyses the ammoniacal-nitrogen concentration by using the integral peristaltic pump to draw sample directly from the final effluent chamber into the instrument. This style of installation has overcome the need to install an expensive sample acquisition system which also would add to the maintenance required to keep the system operational.
Mike Robinson the Divisional Scientist responsible for accessing the ProAm comments "Ion selective devices are an excellent technology for wastewater applications.  They are reliable and unaffected by influent variability. The Pro-Am ammonia analyser is compact, easy to operate and is self contained. The low cost of operation and accuracy of results has enabled us to make a number of changes to plant performance which has greatly reduced the risk of failure".
Already the instrument has proved invaluable providing the process scientists with crucial trending data identifying how upstream processes may be improved and ensuring compliance with the Environment Agency consent.
We should like to thank Mike Robinson for his contribution to this press release and should you need further information on the ProAm ammonia monitor or the application of this product please contact Steven Tuck
Steven Tuck
Pollution & Process Monitoring Ltd
Bourne Enterprise Centre
Borough Green
Sevenoaks
Kent TN15 8DG
Tel: +44 (0) 1732 882044
Fax:+44 (0) 1732 780190
E-mail:  TOC@pollution-ppm.co.uk
Sutton and East Surrey Water plc approached PPM during the summer 2003 to supply a suitable monitoring system to report turbidity at the Kenley WTW.
The Kenley works produces up to 45 Ml/day, serving a population of 75,000 and is situated to the south-east of Croydon located in Surrey. The Works abstracts water from the underlying chalk aquifer and whilst the quality of the supply is very good, it has temporary hardness.
If left unchecked, the temporary hardness can cause scaling of pipes and appliances so the Kenley Works includes water treatment processes to remove the dissolved salts.
To remove the temporary hardness, the abstracted water's pH is increased in a special reaction vessel that is “seeded” with a special fine particulate known as “silver sand particles”. These particles form a nucleus for the precipitation of the calcium carbonate producing small pellet sized tablets which are then re-utilised for various manufacturing applications.
The treatment process is monitored for pH and for turbidity. It is important to measure the turbidity after this process to make sure that the water into supply is not adversely affected in terms of its physical appearance. However since the turbidity measurement uses an optical methodology, it is imperative that chemical precipitation is not allowed to obscure the optics.
Instrumentation previously used for this application was continually affected by chemical precipitation and needed constant attention. Internal components needed to be physically and chemically cleaned using de-scaling agents typically on a daily interval, to maintain them in an operational state.
 PPM conducted a trial installation using the IQ Sensor Net System, fitted with the Visoturb sensor which reports turbidity. The sensor comprises a stainless-steel probe of 40mm diameter that uses the recognised nephlometric light scatter measurement principle. It is fitted with sapphire optical windows that are maintained by ultra-sonic cleaning, used to reject chemical precipitation. This style of cleaning certainly seemed to help but the client ultimately wanted a system which could be left unattended for weeks not days. An enhanced design was therefore considered. PPM proposed an engineered solution to the problem which had worked effectively in similar circumstances.
The proposed design comprised a small GRP cabinet containing all the instrumentation, with the turbidity sensor mounted into a PVC flow cell that was automatically chemically cleaned using a de-scaling agent. The instrument would initiate an automatic chemical cleaning cycle by freezing signals and introducing the cleaning solution at a user selectable interval which could be adjusted for site conditions. The flow-cell, Visoturb sensor and supply pipework could then be automatically chemically cleaned dissolving the lime-scale.
The system was installed in December 2003 and Steven Burgess based at Kenley WTW who has supervised the installation, has reported reliable operation and reproducible measurement since this time. In fact the Company is so impressed with the performance that it has now been decided to adopt the design for all the remaining locations. A total of eight systems have now been ordered and will be supplied to replace the remaining instrumentation at Kenley WTW and at a Leatherhead site which has also witnessed similar difficulties maintaining turbidity instrumentation on-line.
It is anticipated that the eight systems will be installed and commissioned towards the end of March 2005 reducing the maintenance burden on the site operational staff and providing reliable turbidity results.
We should like to thank Bernie Luis (ICA Manager) and Steven Burgess (Systems Technician) who have overseen this project and contributed to this application editorial.
For further information on the design of this system please contact:
Steven Tuck
Pollution and Process Monitoring Ltd
Bourne Enterprise Centre
Borough Green
Kent TN15 8DG
Tel: 01732 882044
Fax: 01732 780190
E mail: s.tuck@pollution-ppm.co.uk
 
Pollution and Process Monitoring is pleased to announce that SembCorp - the present owner of the Wilton International Site located in the UK, has committed to further investment in our Protoc TOC analysers.
SembCorp is a multi-facetted organisation with capability that spans the supply of Utilities, Environmental Engineering, Process Engineering and Logistics with a particularly strong presence in the Asia Pacific region. The SembUtilities division provides industry with a one-stop solution that encompasses the complete range of utility supply and support services, water and wastewater management as well as operation and maintenance services.
In the United Kingdom SembUtilities provides power, steam, water and other support services to major international chemical companies on the Wilton, Billingham and North Tees sites on Teesside, one of the largest petrochemical hubs in Europe and one of UK's most important chemical production facilities.
 The Wilton Site, which started producing chemicals over 50 years ago, covers an area in excess of two thousand acres and was formally owned by the ICI Group.
Pollution and Process Monitoring have supported the site's environmental monitoring program since 1992 supplying numerous Protoc TOC analysers monitoring key site drains and effluent discharge locations. In recent years much of the land has been let to other petrochemical companies which include Dupont SA, Dow Chemicals, Unicema, Huntsman, Air Products and Invista. Low strength effluents from some of these sites in addition to SembCorp's own surface and process water (which may include waste cooling water, discharges from a commercial laboratory and potentially fire fighting water) are managed by the SembUtilities division.
The necessity to monitor and therefore manage these process effluent streams is fundamentally important in maintaining a perfectly compliant record for site discharges to the River Tees.
Environmental monitoring stations are positioned at three principal drain positions, upstream of a “buffer tank” connected by means of diversion valves. This large wastewater holding facility is used to regulate the flow and the load reaching the main outfall that is also continuously monitored for TOC, pH, Turbidity, Ammonia, Temperature and Flow.
Mike Radigan who is tasked with the selection and maintenance of the monitoring stations has selected the latest TOC analyzers from PPM –the Protoc Spyder and Web system for a number of reasons.
The PPM instrumentation has performed reliably since its original installation in 1992 and past performance needs to be considered when selecting this type of device required twenty four-seven.
Additionally, the parameter has proved to be a very useful determinant, capable of detecting all forms of organic compounds contained within wastewater. The technique also provides a fast speed of response, from 3 minutes enabling the site to actively manage effluent in real-time to stay compliant with stringent environmental legislation.
The conceptual design of the Spyder and Web system is also important. Multiple analyzer sections can be connected to a single controller. In some instances, the cost of the installation may be reduced by removing unnecessary controller duplication. In other critical applications, duplicated analyzer sections are also important where 100% data collection is required. Duplex monitoring can therefore ensure that when one analyzer is calibrating or chemically cleaning, the other is monitoring a critical effluent stream so events such as spillages or unacceptable excursions “from the norm” are not be missed.
Additionally PPM has also supplied instrumentation to measure other important parameters. The new ProAm ammonia monitor is used to identify ammoniacal-nitrogen. The IQ Sensor Net configured for turbidity is used to physically characterise the discharge identifying fluctuations in suspended solids and the alkalinity/acidity is checked using an in-line pH meter.
BP Chemicals in Hull are continuing to invest in environmental monitoring equipment manufactured by Pollution and Process Monitoring (PPM) Ltd.
 The latest order worth over £60,000 is for an analyser kiosk internally engineered to a very high specification including stainless steel sample pipe work which provides sample distribution to the Total Organic Carbon (TOC) and pH instruments, in addition to automatic composite sample collection.
The site is permitted to discharge a regulated volume of final effluent to the Humber Estuary and additionally to a local waste-water treatment works managed by Yorkshire Water. It is important for the site to minimise their waste at source but also check at specific locations throughout the site, that effluent quality meets stringent guidelines.
 The latest analyser kiosk containing the two Protoc Spyder analysers and a Web controller for the determination of TOC, will be employed to continuously monitor and limit the outlet from the site treatment facility. This new position is down-stream of the individual production areas that are already continuously analysed for TOC and pH. The positions referred to as the “SITE and Yorkshire Water trade waste streams” effectively represent all of the sites surface water and combined process effluent prior to treatment. Monitoring and control at this location is indicative of the surface and final effluent quality leaving the site.
The sample is prepared by a “Paper Band Filtration System” to remove suspended solids above 20 micron size immediately before TOC analysis. This type of sample preparation combined with automatic chemical cleaning of the analyser section, has proved to be invaluable in similar applications on the site and once again has been utilised to optimise measurement reliability.
The relationship between the two companies is now very well established. The total spend at Hull with PPM since formation in 1990, is over half a million pounds sterling. The Protoc TOC analyser systems have been supplied for many past and present manufacturing processes to identify product loss and monitor waste-water quality. These processes have included the manufacture of Phthalates, Acetic Acid and derivatives such as Vinyl Acetate and Ethyl Acetate.
Whilst some of the site's former production processes such as for Phthalates are now redundant, there are still a total of nine of the Protoc analyser systems in use. These installations encompass the complete analyser development from the original Protoc CPU through to the more sophisticated Spyder and Web system (featuring touch screen controllers, data logging, multiple analyser sections capable of both single and duplex measurement).
Jaguar Cars contracted Pollution and Process Monitoring - PPM to
supply an environmental monitoring station at their Brown’s
Lane site, in Coventry. The system which was installed in April
2001 comprises several water quality monitors, ensuring that surface
water discharged from the site is not accidentally polluted.
The luxury car manufacturer takes environmental matters extremely
seriously and has gained certification to the environmental standard
ISO14001. The environmental standard requires the company to actively
demonstrate a commitment to continual environmental improvement
and where appropriate to monitor and control perceived risks.
 The
site at Browns Lane is extensive and has the capacity to generate
significant surface water runoff. A site survey was commissioned
to map the complex array of drains that transcend the site. One
principal drain was identified as being at the biggest risk of receiving
contamination through accidental spillage. The drain carries over
60% of the site storm water and receives surface water from road
and pavement areas. An interceptor had been installed close to the
drain’s discharge point, to recover any oil residue that may
have entered the system but dissolved contamination would previously
have passed through un-detected.
Whilst every effort is made to minimise the risks of chemical ingress
into the drainage system, it can never be completely ruled out.
For example, all chemical storage tanks are bunded to contain any
chemical spillage. Should accidental spillage occur outside the
bunded areas, clearly defined procedures are in place to ensure
that corrective action is immediately taken. In fact the company
prides itself in how quickly a specially equipped team can respond
to an incident anywhere on site, reputably within 3 minutes. The
team is well equipped with specialist tools to contain, absorb and
remove any potential hardzard. Even so, accidents can occur especially
on the site’s internal road system.
Consequently, Jaguar Cars approached PPM to design and install
a monitoring station to continuously analyse the surface water quality
prior to discharge. The instrumentation is connected to site telemetry
system and can generate alarm signals in real-time to identify an
incident should it occur, protecting the receiving watercourse.
 Installed
within the self contained kiosk are instruments that measure Total
Organic Carbon - TOC and pH. These parameters were chosen to detect
the presence of acids, bases and dissolved organic chemicals, in
particular solvents which are used across the site. Immiscible chemicals
such as lubricating oils are detected by a separate device, mounted
within the interceptor. If the oil recovery system was not working
efficiently or required maintenance, the instrument would detect
the oil film and raise an alarm to indicate oil break-through. This
type of detection was considered preferential to a concentration
monitor, where sub-surface sampling can often miss the floating
oil. It was also considered useful to automate sample collection
triggered by an instrument alarm, so further analysis could be performed
on a spot sample.
To ensure optimum perpnce PPM was also asked to provide an
annual service contract, to attend site at regular intervals confirming
that all the instrumentation was correctly calibrated and functioned
as intended.
Peter Phillipson who works within the company’s engineering
department, has over seen the project from day one. Peter comments
“PPM had previously supplied instrumentation for surface water
monitoring on another Jaguar site so we were confident of their
ability. The monitoring station at Browns Lane however is a little
more in depth and I am very pleased to report that the installation
is well designed and very reliable in operation. The service contract
has also reduced the amount of time that Jaguar needs to spend with
the system. The monitoring station provides the company with the
piece of mind we need. Knowing it monitors the water quality, second
by second and that it would spot an incident which if left un-detected
for extended period of time could then become serious, is very re-assuring”.
With the introduction of ever stringent legislation, such as IPPC
(Integrated Pollution, Prevention and Control), forcing companies
to install continuous monitoring and combined with the increasing
recognition that surface waters are vulnerable to pollution ingress,
then it is believed more companies will need to install similar
on-line devices. PPM has a wealth of experience delivering an engineered
solution, tailored to an individual’s needs, including automatic
containment systems which are simple to install and operate.
For more inption on any application requiring on-line measurement
please contact us
 Pollution
and Process Monitoring Limited - PPM has installed a Protoc TOC
- Total Organic Carbon Web Effluent Analyser at Kellogg’s
Manchester Plant, Trafford Park, to help Kellogg’s improve
its monitoring and analysis capabilities, as well as reduce its
effluent charges bill. Installed in February 2003, the new PPM system
gives Kellogg’s continuous monitoring, and is capable of providing
instantaneous output alarms and historical trending to various locations
and departments i.e. Facilities, Operations and Security.
The installation has come about as the result of Kellogg’s
recent major initiative to provide continuous sampling and monitoring
of its food waste effluent, resulting in a continual update of the
likely effluent charge rate to be issued by United Utilities.
The system comprises a Protoc Web TOC analyser (used to estimate
COD values in real-time), a Band Filter preparing sample by removing
unwanted suspended solids from the raw effluent prior to analysis,
and a Turbidity instrument to monitor Suspended Solids concentrations.
Additionally, pH and Temperature have also been integrated into
the system and all the signals are connected to the touch screen
Controller displaying and achieving data for subsequent retrieval.
Ancillaries include an industrial peristaltic sample pump with air
back-flushing, gas compressor and analyser wash systems. All the
instrumentation is housed in an IP65 enclosure providing additional
protection and simplified transportation around the site.
The PPM Protoc Web Effluent Analyser is housed in a semi-portable
enclosure, enabling periodic on-line analysis at three separate
on-site locations - the Alpha Screener, Loading Dock Screener and
the Trade Effluent Flume.
Kellogg’ s also intends to use the new PPM system to identify
major sources of waste through regular observations, enabling it
to react much faster to plant raw material and finished food issues
as well as secure considerable reduction in wastage with attendant
cost savings.
For further information, please contact
us
The Ulverston site has made a further capital commitment to the
environment, by installing three new interceptor pits with continuous
TOC - Total Organic Carbon monitors, costing nearly, £1 million.
The three analysers were installed in August 1999 to monitor individual
sewer discharges and minimise site spillages, as part of a comprehensive
scheme named the "Environmental Perpnce Improvement Project".
One of five Protoc® TOC analysers installed
at Glaxo Wellcome, Ulverston. |
 |
Pollution and Process Monitoring - PPM Ltd
installed the very first Protoc®tm analyser during October
1995 and a subsequent installation during (December 1998).
The latest installation comprised three Protoc®tm Spyder and
Web analysers, to monitor waste water quality and alarm solvent
spillage, should it occur. All five analysers have been installed
in separate walkin kiosks (also engineered by PPM), with results
continuously reported to a central computer, displaying and
archiving data. |
Footnote: Glaxo-Wellcome has subsequently changed their name to
GlaxoSmithkline
Matthew Clark Brands Limited has upgraded the control and monitoring facilities for the discharge of site effluent at its Shepton Mallet cider mill.
The Mill produces some of the country's best known brands of ciders and perrys, including Blackthorn Gaymer's Olde English, Diamond White, K premium cider and Babycham. It utilises a sophisticated real time on-line monitoring and control system based on Pollution & Process Monitoring Ltd's (PPM) acclaimed PROTOC® analysers.
Matthew Clark, working together with specialist engineers from PPM, has been able to further upgrade the control philosophy for the discharge of site effluent. Advanced new software has been written and installed on the computer system which receives signals from the PROTOC® Spyder and Web analysers, together with a flow monitor.
As a result, the site discharge can be controlled as a function of both concentration and flow, preventing any large fluctuations in effluent strength. Such fluctuations in effluent strength could otherwise have a detrimental effect on the biological treatment process at the local sewage works.
 Furthermore, the new software now allows for a direct correlation between the TOC values delivered by the PROTOC® analysers and the equivalent COD values. This has helped the company to better determine when to re-circulate high strength effluent back into the site's own effluent treatment plant.
Consequently, the company can maintain effluent discharge well within consent and provide the local water company with a constant effluent load.
Matthew Clark first started using PROTOC® 100 on-line TOC analysers to monitor peaks and troughs in effluent content in 1992. The real time analysis quickly enabled it to identify with a high degree of certainty which processes were responsible for the peaks, enabling the company to take swift and effective action. This in turn led to a significant saving on effluent costs and helped to identify better working processes. The PROTOC® 100 models have been subsequently upgraded to the Spyder and Web systems which automate chemical cleaning and calibration further reducing instrument maintenance.
In all, five
PPM PROTOC® Spyder analysers are now installed on site. Two units continuously monitor the main
streams into the site's pH correction facility, while a third measures the pH balancing tank. A fourth
monitors the output from the pH treatment facility into the main sewer and the fifth is located in a key site position where production is most concentrated. The system is already supported by sophisticated control and divert facilities and printers which provide a real time record of events.
PROTOC® on-line TOC analysers from Pollution and Process Monitoring
- PPM Ltd have recently been installed at Stansted Airport.
As Britain's third largest airport, Stansted handles over five
and a half million passengers a year. By the year 2000, this will
have risen to an estimated seven million. The airport sees activity
around the clock - passenger flights by day and mostly cargo flights
by night - and presently offers parking for between sixty five and
eighty aircraft with plans to increase this facility further.
Obviously, the airport can't afford to stop when temperatures drop
below zero, so glycol is used plentifully to de-ice aircraft, runways,
taxi-ways and standing areas when the weather deteriorates.
However, the use of glycol can pose a problem for those responsible
for ensuring the quality of water the airport discharges. It is
washed away by rain or snow into the main drainage system - and
contaminates it.
'Prior to installing the PPM PROTOC® units, the airport was only
monitoring the flow and temperature of the discharge explains Stansted's
Water Quality Manager Barry Carter. 'This only enabled us to make
general assumptions about the quality of storm water discharge.
For example, if we experienced poor flow, coupled with low ambient
temperature, it was assumed de-icing had taken place in the airport
and the run off was diverted for treatment.'
With increasingly strict EPA guidelines and discharge consents,
Stansted recognised that it needed a more thorough and accurate
monitoring and alarm system on site. Consultants Balfour Mausell
recommended the PROTOC® on-line analyser from PPM Ltd and it was
one of several instruments evaluated for the site. After a six month
on-site test period, PROTOC® was selected and four units purchased
to monitor critical areas around the site. All four were installed
in November 1997, providing Stansted with critical monitoring and
alarm facilities.
The airport has three catchment areas, taking storm water from
a comprehensive drainage system. The three areas are designated
'Urban', 'Runway' and 'Stands'. All three discharge in turn into
a holding area called 'Pond C'. A PROTOC® unit is situated at the
spilling chamber from each catchment area, monitoring the TOC content
of the water.
 |
|
Real time inption is then back indicated
from the PROTOC® units to the Airport Duty Engineer's Office
via a Faros radio linked telemetry system. High alarms are
set at 25ppm and, should high concentrations of Glycol or
other contaminants be present, an automatic divert comes into
effect. The storm water is diverted away into a storage pond
where it is aerated and then pumped away to the Thames Water
Utilities Plant at nearby Rye Meads for treatment. |
Uncontaminated storm water is allowed through to 'Pond C' where
rope mops and oil traps are used to tackle surface pollutants and
suspended solids.
From 'Pond C', the storm water runs through a water course to an
outlet on Pinchy Brook, which itself eventually feeds into the River
Stort. The flow from 'Pond C' is highly seasonal and can vary from
a low of 20 litres per second right up to 350 litres per second
in periods of high precipitation.
The fourth PPM PROTOC® unit is located at the outlet into Pinchy
Brook and provides a real time fail-safe check that discharge consents
are being adhered to. Inption from this unit is also sent back
via radio link telemetry to the Airport Duty Engineer's Office.
In addition to manufacturing and supplying the four PROTOC® units,
PPM Ltd are also providing a weekly on-site service, maintenance
and consultation facility.
Stansted are now consistently meeting or improving their discharge
consent levels. In the near future, they plan to further refine
their PROTOC® system by customising valve controls and infra-red
sensors.
Steven Tuck
Pollution & Process Monitoring Ltd
Bourne Enterprise Centre
Borough Green
Sevenoaks
Kent TN15 8DG
Tel: +44 (0) 1732 882044
Fax:+44 (0) 1732 780190
E-mail: TOC@pollution-ppm.co.uk |
