The Pulsar Sludge Finder is a new ultrasonic device designed to reliably and accurately detect and measure the interface between water and sludge in a variety of water industry clarifier applications.


Pulsar Process Measurement of Worcester has launched Sludge Finder, a new ultrasonic device designed to reliably and accurately overcome the tricky problem of detecting and measuring the interface between water and sludge in a variety of clarifier applications. A reliable sludge level measurement allows the correct dosing of chemicals to the process, reduces the amount of sludge pumping and can eliminate the need for manual measurements. Furthermore, by providing a reliable signal, advance warning of process upset can be generated so that remedial action can be taken.

Sludge Finder is an ultrasonic device, consisting of a control box and transducer, which is immersed in the liquid and fires a sound pulse down towards the sludge blanket.

This creates an echo returning to the transducer face, which is analysed in the control unit.

By using sophisticated echo processing algorithms, the change in density between the water and sludge is identified and signalled via an analogue output.

The transducer also features an automatic wiper that keeps the transducer face clean and makes the whole unit very low maintenance.

Up to four transducers can be connected to a single Sludge Finder control unit, at a distance of up to 500m.

The unique Rotorflush Filterpump, a submersible pump with a self cleaning intake screen, is used for extracting water from raw sewage and final effluent to provide washwater for inlet screens.

The unique Rotorflush Filterpump, a submersible pump with a self cleaning intake screen, is used for extracting water from raw sewage and final effluent to provide washwater for inlet screens at sewage works across the UK. The self cleaning intake filter on the Rotorflush Filterpump enables it to be used in sewage and final effluent without danger of the pump or upstream valves and nozzles becoming blocked. With outputs up to 2 litres/sec at 4 bar it's ideal for providing washwater for inlet screens.

The pump enables cost savings both in installation and running costs.

Being a multi stage submersible there is no need for weather or frost protection, it is self priming and only requires a minimum water level of 300mm to operate.

It can be installed into channels after the inlet screen, very close to where the washwater is required.

Running costs are reduced in two ways, the first and perhaps biggest saving is the re-use of sewage water, because the cost of using potable water for sewage screens is considerable and a wasteful use of this increasingly precious resource.

The second is the reduction in losses from having long pipe runs in conventional systems, which cause pipe friction losses and hence increased electricity consumption of the pressure sets.

There are 8 models to choose from both single and 3 phase with outputs from 80-120 litres/min and pressures from 2.5 bar to 8.4 bar.

The single phase versions are available with integral float switches.

The standard screen apertures on the self cleaning intake strainer are 315 micron which is more than enough filtration to prevent most nozzles and solenoid valves from blockage.

However where finer filtration is required screens can be specified with apertures down to 50 microns.

The self cleaning filter mechanism, which is the key feature of the Rotorflush Filterpump is extremely simple.

An additional impeller inside the filter continuously backwashes the filter screen, removing any debris that might be sucked onto the screen every half a second.

Without this feature the high pressure multistage pump would be blocked in a few hours when used in sewage.

The pump is finding many other uses, for example the provision of a filtered supply of water to online analysers, irrigation of effluent from dairy and pig farms, and supply of water to membrane systems.

Meeting the very specific and technically challenging requirements for new tank access covers at the Tonbridge Wastewater Treatment site - all in a day's work for GRP cover designers AMi Designs.

Meeting the very specific and technically challenging requirements for new tank access covers at the Tonbridge Wastewater Treatment site (WwTw), is another example of the engineering skills of Bristol based specialist GRP cover designers AMi Designs. Following the addition of the new Tonbridge inlet works AMi Designs were chosen to design, manufacture and install GRP covers for the inlet tanks and Magnaflow chamber. Tonbridge WWTW required the tank to be visually accessible by a series of hatches strategically placed across the length and breadth of the tank cover, without sacrificing aesthetics, strength or durability.

They also required the covers to be easily removable to allow full, uninterrupted access to the tank by their on-site staff, without the need for an additional installation team.

AMi proposed flush fitting hatches with the same herringbone design texture relief pattern (similar to a durbar pattern) to ensure a match with the existing tank cover.

To ensure a lightweight, yet strong and durable solution the safety hatches incorporated a stainless steel grill beneath the hatch lid.

This meant that the required structural support, loading (5.0kN/m2) and deflection criteria (1/200 of beam span), were all met, whilst enabling the removable part of the cover to be easy and light to handle.

To allow the large GRP cover to be fully removable, AMi Designs adopted a technique which did not necessitate the traditional overlapping panel design to be implemented.

This was achieved by placing the locating sockets in the secured supporting beams, making the interlocking flanges on the panels self-aligning and with the aid of simple handles, each panel remained vertically accessible and removable.

The cover panels are secured by steel quarter turn locks that fix onto locking clamps mounted on the inside wall of the tank at either end of each panel.

The complete hatch assembly is fitted with stainless steel hatch stays and a flush finger lift and pad lock security system.

AMi Director and qualified engineer Darren Bishop who lead the 3 man team for the Tonbridge project commented, 'This project was successfully completed thanks to our specialist design skills in GRP cover design, as illustrated by our innovative design solution which met the strength, durability and aesthetic requirements of the existing tanks'.

AMi Designs was established by Directors Kevin Daykin and Darren Bishop, who are both qualified structural engineers.

Thanks to a range of successfully completed projects, AMi is enhancing its reputation in the design, manufacture and installation of innovative GRP cover designs.

Southern Water wastewater treatment sites use automatic Boll filtration systems to ensure the primary screen washwater filtration, enabling compliance with stringent industry regulations.

Set deep in the heart of rolling Sussex countryside, the Southern Water Vine Cross wastewater treatment plant had a particular issue with build up of solids in the washwater system. Loss of the washwater system resulted in the crude sewage inlet screens becoming fouled. Final effluent from the humus tanks, which is used to keep the inlet screens clean as well as for general washwater, requires filtration to protect the high pressure multi-stage washwater pump from becoming blocked with particulates, such as algae and sludge particles.

However, the manual strainers, which required daily cleaning, were causing blockages in the system.

A similar problem had been solved at East Worthing WTW by the installation of an automatic Boll filtration system and, after liaising with the Southern Water process scientists, Morrison Utility Services recommended investing in a similar system at Vines Cross WTW.

The Bollfilter system is a low pressure installation comprising a Boll 6.18 automatic self-cleaning filter with independent backflush pump fitted on the water inlet to the waste water pump.

The unit, which operates at pressures of between 0.5 and 1 bar, is set up to automatically clean once an hour.

Ideal for remote water sites, Boll systems feature unique backflushing technology to ensure reliable, efficient filtration with minimal maintenance and without the need for regular cleaning.

Jon Moss, part of Morrison Utility Services, is pleased with the performance of the new system.

He commented: 'Compliance issues are always urgent and Bollfilter was able to provide a suitable system without delay.

The two operators based at Vines Cross, who are also responsible for a number of other sites, no longer have to take time every day to clean the manual strainers.'

Speed of installation and minimal disruption were the important benefits appreciated by Water Services of Ireland in a recent project by specialist GRP cover designers AMi Designs.

Speed of installation and minimal disruption were among the important benefits appreciated by Water Services of Ireland following the completion of a recent project by specialist GRP cover designers AMi Designs. Bristol based AMi Designs have installed both GRP covers and baffle walls at the WS water and waste treatment site situated in Strabane, Northern Ireland. This most recent project, completed in conjunction with the contractor EarthTech (Ireland), required the design and installation of a single GRP cover for an existing tank with an inside diameter of 8.5 metres.

The cover was for odour control purposes and was designed and installed with all connections and vents to suit the existing tank.

AMi successfully completed the project, and had the cover assembled, placed and bolted into position in a single day.

Established by Directors Kevin Daykin and Darren Bishop, AMi Designs are building a reputation for innovative GRP cover designs combined with outstanding success in fast and efficient installations across a wide range of engineering projects.

AV Technology has successfully completed a six week exercise to monitor and record in-service loadings on scraper blades operating in primary settlement tanks, a Zone 1 hazardous area.

The Structural Monitoring Division of Stockport based AV Technology (AVT) has successfully completed a six week exercise to monitor and record in-service loadings on scraper blades operating in the Primary Settlement Tanks at Davyhulme sewage treatment Works in South Manchester. Based on a six channel, hazardous area, strain gauge monitoring system, the work has been carried out for Birse Water as part of a wider odour control project at the works for United Utilities. Although Birse were able to use their in-house finite element (FE) capability to understand the stress distribution on the structure, no data existed which could quantify the actual in-service loadings on the scraper blades resulting from the different depths of settled sludge for the two operating regimes.

As a result, AVT were contracted to measure and record the actual bending forces acting on the scraper frames as they move up and down the tanks.

The project presented several practical challenges for AVT, as their special projects manager Neil Parkinson explains: 'Firstly, in order to measure the maximum bending moment forces on the frame legs the strain gauges had to operate permanently underwater at a depth of around 1.5 metres.

Secondly, because the scraper frame runs up and down rails either side of the 70 metre long tank, the monitoring system needed to be able to operate remotely under its own power.

The task of measuring the forces was further complicated by the fact that the three primary settling tanks have recently been fully enclosed to provide effective odour control for the surrounding residential area.

Due to the potential risk of explosive gases entering the sewage network, and subsequently the settling tanks, the environment inside the tanks is classified as a Zone 1 hazardous area.

To meet the ATEX requirements, we created a micro safe area around our equipment fitted on top of the scraper bridge.

This consisted of a novel dual Exd-Exi environment using two explosion proof enclosures (EExd IIC T6), one to house the Campbell Scientific CR10X Data logger, multi-plexer and zener barrier systems, the second the 7Ah battery pack.

This novel solution is virtually identical to a strain monitoring system we have installed on an offshore oil tanker to monitor the integrity of the mooring chains'.

To measure the maximum bending forces on the six vertical legs, pairs of waterproof single element gauges were spot-welded at the mid point on the front and back of each leg.

These were then wired back to the Exd enclosure using the integral leads.

To ensure gauge integrity in this particularly harsh environment, the gauges were protected with a further 3-stages of environmental coating.

Precision 120 ohm resistors were used to complete a full Wheatsone Bridge configuration in the enclosure for each leg and the input and outputs were wired through zener barriers to the data logger.

In order to comply with the ATEX requirements for simple apparatus, an insulation test was carried out on each strain gauge to ensure that the insulation between the gauge circuit and the metal supporting substrate was capable of withstanding an AC rms test voltage of 500 V.

The output strain signals from the gauges have been calibrated into bending moments (Nm) based on a site calibration procedure using a reference load cell.

This was achieved by attaching a winch to the end wall of the tank and applying a force to each leg in turn, using the reference load cell to measure the load applied.

The project was split into two three week tests.

Initially measurements were taken with the scraper carrying out a scrape approximately every eight hours.

To optimise storage capabilities the data logger was timed to log data during these three 'time windows'.

It was programmed to measure strains every 1 second and to store running maximum values per channel every 10 seconds.

With a scrape time of approximately 40 minutes, this gave the unit the capacity to store data for up to 37 days with the data from each three week test fitting on a single Excel spreadsheet.

The measurements were then taken for the second three week period with the scraper only carrying out one cycle during a 24 hour period.

The data were manually collected by AVT on a weekly basis.

As the system is self-contained within the hazardous environment a mandatory gas test was carried out to ensure a safe working environment before opening the explosion proof enclosure and downloading the data to a laptop.

Collecting data is only a small part of the work AVT carry out and as Neil Parkinson continues: 'The key to successful fatigue analysis is being able to analyse and interpret large amounts of information and then present it to the client in the optimum format.

All round good communication and the ability to work closely with other interested parties are also vital ingredients.

In projects such as this one at Davyhulme, the working environment is far from perfect and a far cry from conditions found in the laboratory.

However, we are used to working in difficult and often remote areas with limited facilities and have developed a high level of ingenuity to ensure that our equipment can operate without problems.' The Chief Mechanical Engineer at Birse Water, Ken Craven, is pleased with the overall results and as he concludes: 'We needed to establish the nature of the loading on the scrapers under the two operational regimes attributable to varying sludge depth, to assess the long term reliability implications.

We recognised that gathering real time data in such an awkward environment was not going to be very straightforward.

However from the outset AVT applied a professional and pragmatic approach to the problem and their expertise has allowed us to obtain some very useful information.

We have combined the results of their trial with data we also collected regarding the build-up of sludge within the tanks under the two operational regimes and we are now working with our client to determine the best way forward.'

The Pulsar Sludge Finder is a new ultrasonic device designed to reliably and accurately detect and measure the interface level between water and sludge blanket in a variety of clarifier applications.

Pulsar Process Measurement of Worcester has launched Sludge Finder, a new ultrasonic device designed to reliably and accurately overcome the tricky problem of detecting and measuring the interface level between water and sludge in a variety of clarifier applications. A reliable sludge level measurement allows the correct dosing of chemicals to the process, reduces the amount of sludge pumping and can eliminate manual measurement. Furthermore, by providing a reliable signal, advance warning of any process upset can be generated so that remedial action can be taken.

Sludge Finder is an ultrasonic device, consisting of a control box and transducer, which is immersed in the liquid and fires a sound pulse down towards the sludge blanket.

This creates an echo returning to the transducer face, which is analysed in the control unit.

By using sophisticated echo processing algorithms, the change in density between the water and sludge is identified and signalled via an analogue output.

The transducer also features an automatic wiper that keeps the transducer face clean and makes the whole unit very low maintenance.

Emotron variable speed drives and softstarters control pumps, blowers and mixers, and Emotron shaft power monitors protect other equipment on a new sewage works at Svenljunga.

When the sewage treatment plant in Svenljunga, a community of 10,000 inhabitants, was renovated in the summer of 2005, investments were made in order to increase operational efficiency and reliability. One measure taken was to install Emotron variable speed drives and softstarters to control pumps, blowers and mixers, and Emotron shaft power monitors to protect equipment. The result has been more reliable control, lower energy consumption and reduced wear.

The whole plant is now managed by one operator, instead of the two or three that used to be required for daily control and supervision.

The increased efficiency means, among other things, that time has been freed up for preventive measures and maintenance.

'We used to regulate most of the equipment manually, but today everything is controlled by Emotron products,' says electrician Johan Arvidsson.

In a sewage treatment plant, the objective is to keep a constant flow despite the large variation in load during the day and night.

In Svenljunga, Emotron products ensure efficient operation continuously adjusted to demand.

Variable speed drives and softstarters regulate pumps, blowers and mixers, and shaft power monitors protect screw conveyors.

'One advantage of Emotron products is that they can withstand harsh environments and be located within the plant,' says Johan Arvidsson: 'No costly cabling or cabinets are required.

We also minimise the risk of damage and downtime, since we are warned in good time of process disturbances'.

The Emotron products react immediately to deviations and send a warning or stop the process if operation is not optimal, for example if a pipe is blocked or a valve is not fully opened.

The operator can take action quickly in order to prevent damage and downtime.

Common and costly problems such as cavitation and dry-running can be avoided.

The stop sequence is a critical moment in pump operation, often causing stress on pipes, valves and other equipment.

The Emotron solution offers soft stops by gradually reducing the pump speed, thereby avoiding water hammer and other potential damage.

A total of 17 Emotron FDU variable speed drives are installed in the plant.

They control, among other things, three inlet pumps that pump in untreated sewage.

Two of the pumps are normally used to handle storm overflow water, i.e water that is allowed to pass the plant after only limited treatment, for example in the case of heavy rainfall.

The flow must not exceed 220 m3/hour in order for the particles that are to be removed to have time to settle to the bottom and not run out with the water.

If the flow is too high, the system regulates this by starting the third pump to pump water past so that the particles can settle.

The operation of the blowers supplying oxygen to the sewage water was also made more efficient by installing Emotron FDU variable speed drives.

'Until now the blowers were either running at maximum speed or standing still,' says Johan Arvidsson: 'That was wasting energy.

The Emotron FDU now continuously adjusts to demand, ensuring that the water maintains the correct oxygen content.

In this way we minimise our energy consumption and equipment wear'.

The sludge scrapers in the sedimentation basins are monitored by Emotron M20 shaft power monitors.

The monitors send a warning or stop the process if operation is not optimal, for example if a scraper is blocked, a blade is worn or a chain is broken.

Equipment wear and downtime are minimised.

The monitors are connected to the motor cable.

No sensors are required.

Emotron FDU variable speed drives control the sludge pumps that pump out surplus sludge from the basins.

The FDU units are located in cabinets outside near the basins.

An eccentric screw pump that pumps sludge to a thickener is also controlled by an Emotron FDU.

An Emotron M20 shaft power monitor on the screw conveyor sends a warning or stops the process if a blockage occurs.

Mixers placed down in the basins are regulated by Emotron FDUs, as are the sludge pumps that pump sludge to centrifuges where it is dewatered.

Seven Emotron MSF softstarters control the screw conveyors for the centrifuges.

The sludge is used as fertiliser or sent for final disposal.

As Svenljunga sewage treatment plant was being renovated, the largest local industry, Elmo Leather, built their own treatment plant next to the municipal plant.

The sewage water from the tannery had been putting high demands on its capacity.

'Now our plant is rated at 3000 pe, compared to the 100,000 pe required to treat the sewage from Elmo Leather,' says Johan Arvidsson.

The new Elmo Leather wastewater treatment plant is the first of its kind.

A fully biological process is used that has never been tested before on an operation that uses such large quantities of chemicals.

The EU environmental fund contributed to the financing and the good results mean that the company will show the way for other tanneries in Europe.

The new technique reduces nitrogen emissions by 80%, compared to 30% in the old plant.

Emotron variable speed drives control, amongst other things, the blowers that oxygenate the waste water.

A submersible, free-standing Landia Air Jet has significantly helped the owners of a popular tourist attraction in Ireland with the management of the site effluent treatment plant.

At one of Ireland's most ancient and stunning caves, a submersible, free-standing Landia Air Jet has significantly helped the owners of the popular tourist attraction with the management of the site effluent treatment plant. Aillwee Cave, which is situated in the Burren in County Clare, attracts 180,000 to 200,000 visitors every year - but as with many tourist attractions, visitor numbers can be unpredictable, causing irregularities for their effluent plant balance tank, as Nick Johnson, managing director, explains: 'When the plant was running at typical levels it worked quite efficiently', he said, 'but when it wasn't being fed continuously with the right amount of liquor, we had problems'. He added: 'The Landia Air Jet has successfully kept the balance tank aerated and homogenised, giving us much better management of our effluent treatment plant, as well as removing any unpleasant odours.

It is fair to say that without the Landia aeration equipment, which is proving very reliable, we may have been forced to change the effluent plant completely'.

The Landia DG-I Air Jet (3.0 kW), which was supplied through Fergon Enterprises, is a highly effective non-blocking system that is very easy to install in aeration or storm water retention tanks, and requires no ancillary equipment.

One of the key attractions on the inspiring, almost moonscape Burren, which is a paradise for geologists, botanists, ornithologists, speleologists and archaeologists, Aillwee Cave treats visitors to a guided, informative walk through 1.3 km of passageways, where they can see animal remains, waterfalls and numerous spectacular cave formations.

1st May 2006 is the date when new guidelines govern all new applications for the adoption of sewers and their accompanying contracts and pumping stations.

Mayday 2006 is the date when new guidelines come in to govern all new applications for the adoption of sewers and their accompanying contracts concerned with the planning, designing and construction of sewers and pumping stations. Water and environment consultants WRc has launched the sixth edition of its 'Sewers For Adoption' guide to alleviate problems and issues as well as making it easier for developers to complete adoptions faster and more economically. This latest edition covers changes in the law from the Water Act 2003, new developments in technology as well as details and opportunities for lateral drain adoption.

The guide also encompasses changes to the adoption process allowing an earlier release of the bond - 1 year earlier than previously, and includes information on which SUD systems could be adopted.

'This is a definitive guide giving the latest information to all those involved in sewer adoption.

Using this new edition, developers will be able to complete adoptions faster, easier and get their money (bond) back faster, ' confirms Dr Iain Naismith, Head of WRc Standards, Testing and Approvals.

The latest Siemens range of ultrasonic transducers for level measurement is delivering accurate and reliable measurement to the water industry.

The latest Siemens range of ultrasonic transducers for level measurement is delivering accurate and reliable measurement to the water industry. For most level measurement applications in the environmental industries, ultrasonic technology is a highly desirable solution. Ultrasonic sensors (transducers) emit acoustic pulses and receive an echo from the material being measured.

The sensor is connected to a transceiver that calculates level by processing the time between the original signal and its echo.

Siemens Echomax transducers are built to provide accurate, reliable measurement even in harsh and hazardous environments.

They're impervious to dust, moisture, corrosion, vibration, flooding and temperature extremes.

Siemens ultrasonic transceivers feature Advanced Sonic Intelligence echo-processing capabilities to ensure reliable data even in conditions with obstructions, turbulence and foam.

The transducers also have an integral temperature sensor to compensate for sound velocity variations caused by changes in air temperature.

Siemens transducers are easy to install, and the non-contacting design makes them low maintenance by avoiding the corrosion, material build-up, and general wear and tear associated with contacting devices.

Higher maintenance costs and repairs associated with contacting devices can easily exceed any initial savings.

The Echomax device has become the preferred choice in a wide range of applications including wet wells, weirs and flumes, storage tanks, penstock and sluice gate control, and rake screens.

Ductile iron pipes are relatively inexpensive and long lasting, so they are quite common in waste water installations, but they are not a problem for Fluxus clamp-on ultrasonic meters.

Ductile iron pipes are quite common in waste water installations: they are relatively inexpensive and last a long time. For ultrasonic flow measurement, such pipes can present quite a problem. Clamp-on ultrasonic flow meters are the ideal solution in cases where the flow disruption is impossible, or very expensive.

Unfortunately, ductile iron tends to attenuate sonic energy, and it can be a problem for clamp-on ultrasonic flowmeters..

If such pipes are furthermore lined with cement, the attenuation becomes even stronger, thus presenting a considerable problem.

Recently, a dual channel Fluxus ADM 7407 was successfully installed in a waste water treatment plant in New Jersey, where the facility operator needed to measure the influent and effluent of the primary treatment portion of the plant.

Thanks to its high output voltage and power, Fluxus succeeded where all other tested ultrasonic clamp-on meters had failed.

After a series of tests, Fluxus meters were permanently installed on both wastewater lines.

The installation went flawlessly - with no flow interruptions, because the unit was installed onto fully operational pipework.

The new Tsurumi 'Poma' submersible pump produces an exceptionally large flow from its highly efficient 150W motor, making it ideal for continuous running and many other industrial applications.

The new Tsurumi 'Poma' submersible pump produces an exceptionally large flow from its 150W motor, making it ideal for many industrial applications. It is especially suited for pumping needs within narrow sumps where a traditional pendant type float switch could be fouled. Constructed from reinforced plastic and stainless steel, 'Poma' pumps are highly resistant to corrosion and rust and will pump water to a maximum head of 5.5m.

Outlet size is 50mm with a maximum flow rate of 250 litres per minute.

The optional integral tube float switch provides start and stop levels of 285mm and 175mm respectively and the vortex impeller gives generous 35mm suspended solids handling.

Other features include a 403 stainless steel shaft fitted with an ultra hardwearing silicon carbide double mechanical seal installed in an oil chamber to give efficient, long-life sealing; automatic motor protection and an air release valve to prevent air locks; a common occurrence with other competitive pumps in its class.

The 'Poma' can be offered with or without float switch in 110 and 230V versions and comes with a generous 1-metre cable in HO7 rubber for indoor or outdoor use.

Overall dimensions (mm) are 225L x 183W x 354H.

Low power consumption from the highly efficient 150W (output) motor makes it ideal for continuous running applications.

Tsurumi submersible pumps are available from UK agents, Obart Pumps and their MD, Matthew Hill states: 'A large part of our business has resulted from the ability of Tsurumi pumps to operate reliably in the most arduous of conditions.

I am convinced that the introduction of the new 'Poma' will strengthen that position and, for those especially needing to pump within restricted space, we will offer this particular pump with confidence'.

The 'Poma' can be seen on the Obart website, or further information can be had from the Obart Pumps sales office in the UK.