Inflow of stormwater and infiltration of groundwater into wastewater systems is a constant operational challenge for managers. Now, Håbo municipality in Sweden is tackling the challenge head-on with an innovative digital approach, says Adam Wood, chief product officer at water analytics company Infotiles.

Water utility managers in Håbo, a small municipality north-west of the Swedish capital, Stockholm, began conversations with InfoTiles in 2023, when they suspected infiltration of wastewater and inflow of groundwater into wastewater networks (I&I) was adding massive volumes requiring transport and treatment.

Managers wanted to investigate I&I further and needed tangible evidence to demonstrate the need for investment but were facing budgetary and operational constraints. Using control system data together with weather data and analysis of wastewater networks using in situ sensors, the collaboration sought to determine when and where I&I was occurring and decide on the appropriate response.

Gathering evidence
Inflow is stormwater that flows into wastewater pipes through faults such as holes, cracks, joint failures, and broken connections. Infiltration occurs when groundwater enters the wastewater network through faults in pipes, compounding the flow.

Magne Eide, chief operating officer at Infotiles, said, “InfoTiles set out to show Håbo municipality what the cost of not maintaining its wastewater network to prevent I&I would be, versus investing money now. Water managers wanted to understand what the maintenance opportunities were, so they could create a wider business case to be put forward for funding during the 2025 budget process.”

Servicing a population of around 18,700, Håbo’s water utility treats about 4 million m3 of wastewater per year. InfoTiles discovered that 18% of that water is incurred through I&I, leading to SEK13 million (roughly €1.3 million) of extra operating costs annually equivalent to almost SEK700 per inhabitant (roughly €61).

Energy use is a significant part of the additional treatment and transportation costs involved in processing I&I, which means reducing energy consumption represents a potential saving on operational expenditure when I&I is remedied. Extra energy consumption also represents a higher carbon footprint, so accurately identifying and preventing I&I can help utilities meet carbon commitments, including net zero targets.

Compounded flow
For many utilities and municipalities, I&I can account for an average of 20-50% of the annual flow in sewers, but during snow melt and wet autumns, this figure is much higher.

It is widely acknowledged that most I&I is caused by ageing infrastructure that requires maintenance or replacement, but some is also caused by erroneous connections such as building drainage and rooftops connected to the wrong pipes. When this water penetrates the wastewater network, it can overload the system, which is a particular risk during periods of heavy rain or storm events.

In the worst cases, it can lead to the release of untreated wastewater into the environment and pollution of rivers and seas. It also increases the risk of cross-contamination of drinking water, where polluted water from the environment enters through faults in clean water pipes.

Increases in the frequency and intensity of rainfall as a result of a changing climate is exacerbating the problem, making wastewater networks ever more vulnerable to failure and putting the environment at greater risk. If left untreated, pipeline integrity will only deteriorate over time, increasing the volume of ingress water to be treated.

For Håbo municipality, the overall goal of the collaboration with InfoTiles is to gain a better understanding of the causes of inflow and infiltration into sewerage networks and to understand the options for remediation and impact reduction. The municipality hopes it will help policymakers gain a deeper understanding of decision-making around I&I and show how collaboration and digital solutions can be used as a catalyst for positive change.

Accurate pin-pointing
Inflow and infiltration compounds wastewater operating costs as excess water must be pumped, treated and discharged.

The InfoTiles platform uses SCADA control system data together with data from the Swedish Meteorological Institute to analyse historical rainfall and the dry and wet weather behaviour of wastewater networks. For example, how and when water hits the network and how it affects pump heights.

Sensor devices placed at critical points in the network can collect data such as precipitation, problematic thresholds of rain volume, or seasonally varied sensitivities. That feeds into a central dashboard and these detailed measurements can then be analysed by water managers.

By using information from pump stations in real-time, the model calculates the total and excessive volume transported, allowing managers to see not only weather-related trends but also the resulting costs both in terms of treatment and power expenditure.

Once problem areas have been identified, the search area can be narrowed down using compact internet-of-things (IoT) devices within the same platform. Some pump stations have multiple inputs or long upstream pipeline networks. By selectively measuring different branches, it is possible to identify exactly where the water inflows and infiltrates or exclude areas that are not problematic.

Positive proof
Håbo operates 38 pumping stations, in a network where several smaller pumping stations feed larger stations before the wastewater is ultimately transported to treatment.

InfoTiles and Håbo municipality determined that the pumps closest to the treatment stations were receiving the largest net volume of water, meaning that the largest influx was occurring in the parts of the network directly relating to the largest pumps.

With this information, managers from Håbo went searching for damage in the identified areas and were able to quickly confirm the findings of the analysis. Significant breaches of the pipe were found upon visual inspection. In one location, drained surface water from nearby farmlands was penetrating wastewater pipes at high pressure, causing large and continuous volumes of I&I.

Sara Frid, water and wastewater strategist, Håbo Municipality, said, “The new insight into ingress water, such as volumes, likely sources, and the resulting costs really sparked an interest among our operators to go on the hunt for it.

“Within the first couple of weeks, we had found damages to our wastewater pipelines that we could repair to reduce volumes and save treatment costs.”

Now, water managers can not only use data to identify the areas with the highest need of maintenance and repairs but also see the results of their work in reduced volumes of inflow and infiltration.

Continually reducing the total volumes of I&I remains a high focus for Håbo municipality.

With the InfoTiles solution, they have been able to prove that investments in wastewater maintenance are not only an issue of environmental risk and cost, but in fact, the reduction in volumes will ultimately lead to reduced treatment costs in the long term.

Regulations for hydrostatic pressure testing have taken a significant step forward with the release of Water UK’s Water Industry Standard for hydrostatic pressure testing of PE pipes, a move that will ensure the safety and reliability of the process, says Tony Kitchen of AHS Pipeline Innovation.

Water companies and contractors are adjusting to the requirements of the new Water Industry Standard 4-01-03, released in March 2024, which outlines the required standards for the hydrostatic pressure testing of polyethylene (PE) and polyethylene barrier pipes. The standard replaces previous guidelines from Information Guidance Notice 4-01-03.

The transition from an Industry Guidance Notice (IGN) to a Water Industry Standard (WIS) marks a shift towards more stringent and enforceable standards that aim to improve the safety and effectiveness of the pressure testing process.

WIS 4-01-03 specifies detailed procedures for pressure testing below-ground water supply pipelines and sewer rising mains comprised of PE and PE barrier pipes. It includes guidelines for testing entire systems as well as replacement sections and service connections.

The specifications emphasise the importance of considering the viscoelastic properties of PE, which exhibits what is known as creep behaviour – deformation that occurs when subjected to pressure over time.

Understanding the difference
It is important to understand the distinctions between WIS and IGN:

● An Information Guidance Notice serves as a set of recommendations or guidelines that offer advice on best practice but does not mandate specific actions or procedures.
● A Water Industry Standard is a more formal document that sets out mandatory requirements for products, materials or operational procedures. WIS documents are intended to ensure uniformity and compliance across the water industry, leading to more standardised and reliable outcomes.

Improving safety
The new WIS is designed to improve both the accuracy and safety of pressure testing which means there is now a zero-tolerance policy on pre-pressurisation. Key points are:

● The pipe must be at ambient pressure prior to testing
● If a test has failed, the operator must leave the pipe for four times the length of the ramp-up time before reattempting the test
● The operators must wait for two to three hours between filling and pressurising the pipeline. This takes into consideration the effects of thermal conditioning and allows the temperature of the pipe to stabilise once it has been filled.
● The allowable air content has now been reduced from 8 to 4 per cent
● The air content must also be accurately calculated during the ‘ramp-up’ stage as the pipeline is brought to system test pressure (STP). This means that the test can be immediately abandoned if it is over the acceptable limit.

What WIS means for contractors
There is no question that the new standard represents a significant step towards leak-free networks, but the new requirements potentially impose a greater burden on contractors. The stringent rules around correct preparation prior to testing, including pre-pressurisation, thermal conditioning, and calculating air content prior to starting the test, making it crucial to get the test right first time, to prevent wasting time and resources in retesting.

A reduction in the allowable air content means less margin for error, which highlights, from a compliance and cost perspective, the importance of contractors carefully managing their own and subcontracted pipeline pressure testing.

Due to the increasing complexity of hydrostatic pressure testing and varying levels of expertise among technicians and operators, some pressure testing providers may not meet the standards outlined in the WIS and could lack the knowledge or skills to correctly prepare the pipe for testing.

Contractors must ensure that all pressure testing activity is fully compliant with the new WIS specifications. Substandard testing potentially creates dangerous situations, with risk to life and limb, if air is not properly removed from the pipeline.

It is crucial for contractors to select subcontractors with proven compliance to ensure the safety and reliability of their projects if they are to maintain both contractual obligations and a good reputation in the industry.

Proven expertise
AHS Pipeline Innovation is recognised as an industry leader in hydrostatic pressure testing with over 20 years of experience and almost 50,000 tests completed. The proven expertise of AHS allowed the company to play a key role in the development of the new WIS as part of a multidisciplinary panel which included pipe manufacturers, water company representatives and trade organisations.

Careful consideration was given to onsite implementation of the new requirements, and how contractors can be supported in meeting the standard.

Pressure testing services at AHS are already fully compliant with WIS 4-01-03 and incorporate the latest technology and real-time assistance from the company’s in-house analyst teams to give contractors unrivalled support throughout the testing process, ensuring that testing is right first-time.

AHS is equipped to guide and support teams in adopting these new standards so that their pipeline operations meet the necessary requirements. Should water companies and contractors be unsure about how WIS 4-01-03 affects their operations, or require support to ensure compliance, AHS is available to provide the knowledge and tools necessary to navigate this transition smoothly and effectively.

WIS 4-01-03 not only mandates stricter controls over variables like air content, ambient pressure and temperature, it also effectively identifies and removes any activities undertaken onsite that can affect test performance. Importantly, it reintroduces rules that had been relaxed in previous guidance, restoring rigorous standards that are essential for maintaining the integrity of water systems and creating more defined regulatory expectations.

In addition, pressure tests carried out in accordance with the WIS are measured using sophisticated algorithms that deliver definitive test outcomes, ensuring clarity and reliability.

At a time when the water sector is experiencing reputational challenges, WIS 4-01-03 represents an opportunity for water companies and contractors to get it right from the start. By carefully navigating these changes, and ensuring that every test not only meets but exceeds the latest standards for safety and efficiency, they can mitigate risk to the public and their own teams altogether.

The Royal Air Force has used a blend of sustainable aviation fuel (SAF) with normal jet fuel on routine operations for the first time.

Aircraft including Typhoon and Poseidon submarine hunters, operating from RAF Lossiemouth in Scotland, have been using a blend of conventional and SAF in an apparent first for the air force.

During November 2023 to February 2024 four million litres of blended SAF were delivered to the Royal Air Force through a contract with World Fuel Services. A further five million one hundred and fifty thousand litres of fuel are being delivered over the period July to October 2024.

The fuel is used to power aircraft operating from Lossiemouth in Morayshire, northern Scotland. RAF Lossiemouth is one of the UK’s busiest RAF stations and is home to Typhoon aircraft who are ready to deploy 24/7, 365 as part of the UK’s Quick Reaction Alert – keeping Britain secure.

Sustainable fuel sources include hydrogenated fats and oils, wood waste, alcohols, sugars, household waste, biomass and algae.

Aviation currently accounts for nearly two thirds of fuel used across defence.

In 2020, the MoD updated aviation fuel standards to allow up to 50% sustainable sources to be used in fuel mixes for defence aircraft. The RAF has been trialling different types of fuel since then. In November 2021, an RAF pilot flew a microlight aircraft powered by synthetic fuel created from air and water, described as a world-first. In Spring 2022, a drone was flown on synthetic kerosene made by genetically modified bacteria. The RAF has also tested an electric aircraft flown at RAF Cranwell.

In November 2022, an RAF Voyager trialled the use of 100% SAF, flying for 90-minutes from RAF Brize Norton, said to be a world first for a wide-bodied military aircraft, a joint endeavour between the RAF, DE&S and industry partners Airbus, AirTanker and Rolls-Royce, with the fuel supplied by Air bp.

In 2023, the Royal Air Force used SAF to achieve the first SAF blend air-to-air refuelling of a Typhoon and C-130 Hercules aircraft. This was followed by the RAF’s display typhoon being powered on blended SAF at this year’s Royal International Air Tattoo, the first time this aircraft has displayed to the public on this fuel.

Chemicals play a big part in wastewater treatment. Adeel Hassan, product manager at Watson-Marlow Fluid Technology Solutions looks at how different process challenges can be overcome, and the contribution of pumping technology.

Around 359 billion cubic meters of wastewater is produced globally each year, including municipal wastewater, and the many industrial processes that produce wastewater, which includes chemical manufacturing, food processing and power generation.

For effluent water to be discharged back into the environment, it must be treated to comply with regulatory requirements and prevent damage to ecosystems and human health. Alternatively, many industrial firms want to reuse their wastewater to minimise their environmental impact, reduce costs and overcome water shortages. Iit must be treated to suit it to the new purpose, such as providing industrial cooling water.

Difficulties with disinfection
Chemical disinfection involves the use of oxidising chemicals, such as sodium hypochlorite. However, oxidising chemicals off-gas, causing gas to be present in the fluid. This gas can block a diaphragm pump by preventing correct operation of the ball valves. Wastewater treatment providers can overcome this by selecting peristaltic pumps, which push any gas present in the fluid through the pump without causing any maintenance issues.

Sustainability is driving the use of higher concentration chemicals to minimise transport costs and emissions, as well as reduce the size of dosing systems. However, high concentration chemicals, such as sulfuric acid used in neutralisation, can be hazardous if not contained after a pump failure. Therefore, it is important that plant managers select a pump that is compatible with high concentration chemicals and prevents chemical exposure to the operator.

High concentration chemicals require a very accurate and repeatable pump to maintain process capability. Peristaltic pumps with low pulsation and no ball valves result in parts per million (ppm) concentrations with very low standard deviations, minimising chemical usage and maximising process quality.

Problems caused by coagulants and flocculants
Regulations around preventing eutrophication are driving the removal of phosphates from wastewater. Ferric chloride, commonly used in this process, reacts aggressively with metal pumps. By selecting a pump with a plastic case, wastewater treatment providers can ensure their equipment is compatible with ferric chloride systems.

Furthermore, in diaphragm pumps, ferric chloride can pose a threat of solid content becoming stuck under the ball valves that are keeping the pump open. If both valves become stuck, then the pump can start to siphon, and the fluid will travel in the opposite direction as it can flow out of the pump. This creates inaccuracy as the fluid is leaking out. By selecting a peristaltic pump that does not require any valves, these challenges can be avoided completely.

Polymers are commonly used for dewatering of sludge and solids removal from water. Solids removal helps to clean the water for reuse, while dewatering sludge minimises bulk, which can reduce costs associated with storage and disposal by up to 75 per cent. Efficient polymer activation is essential in increasing the efficacy of the polymer and minimising usage. The creation and integrity of polymer chains requires a constant stream of polymer into the dissolution stage, which can be achieved by using a low pulsation pump.

If condensation gets into the source tank, then polymers can agglomerate together and block the valves of some pumps, such as diaphragm pumps. This plugs the discharge of the pump and can cause it to breakdown. This can be avoided completely with peristaltic pumps, which require no valves to operate.

As well as the variety of different chemicals in wastewater treatment providing dosing challenges, the wastewater industry must contend with external factors. Urbanisation means more people are living closer together in towns and cities, increasing the amount of municipal wastewater in one area. The resultant wastewater means bigger wastewater treatment works with larger processing systems are needed.

Therefore, wastewater treatment providers require more powerful pumps with high flow rates and low pulsation to increase efficiency and meet demand. While diaphragm pumps meet the capacity requirements, they can only offer low pulsation when operated at low flow rates. Instead, plant managers should opt for a peristaltic pump that offers low pulsation even at high flow rates.

Rising to the challenge
The design of the Qdos H-FLO attempts to answer calls from plant managers for more powerful and adaptable pumping equipment that enables accurate, flexible and high capacity dosing . The pump is capable of flow rates up to 600 litres per hour and can handle pressures up to 7 bar via a range of interchangeable pump heads. The different pumpheads enable the pump to be used in a wide range of wastewater applications and allow plant managers to respond quickly as treatment processing requirements change.

The Qdos H-FLO has a pressure sensor that detects leaks and blockages. The pump stops before the system becomes damaged and alerts the operator with diagnostic feedback. In addition, all of the chemicals are safety contained within the pumphead, preventing operator exposure. If there is a problem, the pumphead can just be changed.

The twin-tube technology provides extremely low pulsation, with an offset rotor design protecting pipework integrity and providing consistent chemical supply compared with diaphragm pumps delivering similar flow rates. Unlike diaphragm pumps, the Qdos H-FLO has no valves, eliminating the issue of valves becoming stuck or blocked. In addition, the pump has a high accuracy of ±1%, which prevents chemical waste and saves costs.

Wastewater treatment providers face a variety of operating challenges, including handling a wide range of chemicals, meeting high demand, and becoming more sustainable. However, with the correct pumping technology, wastewater plant managers can ensure their operations run efficiently, accurately and safely.

Notes
[1] https://essd.copernicus.org/articles/13/237/2021/
[2] https://www.wwdmag.com/sludge-and-biosolids/article/10933951/sludge-energy-from-sludge

This article contains paid for content produced in collaboration with Winn & Coales (Denso) Ltd.. (Above) Densoclad 70 Tape is applied over the bitumen-based primer (inset) before the whole system is encapsulated with Denso Glass Outerwrap.

A bitumen tape wrap system from Winn & Coales (Denso) Ltd was utilised for the repair of damaged pipework at the new HS2 terminus at London Euston train station.

Following damage to the existing factory coating, corrosion had already begun to inflict damage upon the pipe and had propagated underneath the coating itself, causing it to delaminate. To eliminate further damage, the Denso Bitumen Tape Wrap System was applied to not only protect the pipe from the effects of further corrosion, but to provide a large degree of mechanical protection too.

Winn & Coales (Denso) Ltd are leading manufacturers and suppliers of corrosion prevention and sealing systems. The bitumen tape wrap system supplied for the project was comprised of a bitumen-based primer (Denso Primer D), a heavy-duty PVC-backed bitumen tape (Densoclad 70 Tape), and a protective outerwrap (Denso Glass Outerwrap). The protective outerwrap offers exceptional mechanical and impact strength for buried pipes exposed to aggressive backfill conditions. Once applied and fully cured, the whole system provides a long-term protective coating that is ready for immediate service.
www.denso.net

This article contains paid for content produced in collaboration with T-T Flow.

Government-backed funding saw a Stockport site become the first in the UK to be retrofitted with an innovative new technology that boosts biogas production by up to 20%. Valves play a critical role in its deployment.

The Stockport Sludge Treatment Centre in Greater Manchester processes over 600 m3 of sludge from local wastewater treatment facilities every day. Anaerobic digestion (AD) transforms the sludge into biogas that is used to produce electricity to power more than 1200 homes p.a.

As part of the retrofit, T-T Flow were asked to provide a complete valve package, including knife-gate valves, swing-check valves and fast-acting relief valves.

The supplied relief valves are set to play a crucial role in on-site safety. Given the pressure produced by the system’s AD processes, the need is all the greater to lessen the likelihood of surge events like water hammer occurring. Flow inefficiencies, damage to infrastructure and explosions are all potential consequences of not effectively managing system pressure. The self-acting relief valves mitigate the risk. Calibrated to maintain the desired pressure, they operate by opening when this pressure is exceeded and discharge excess fluid to avoid an over-pressure event.

T-T Flow have specified relief valves that respond quickly and reliably to pressure fluctuations, featuring fast-acting annealed springs and a smooth, lightweight internal profile that minimises operational resistance. To guarantee long-term operational reliability within the corrosive environment of the sludge treatment facility, the chosen valves are comprised of a high-strength/low-weight ductile iron body, a precision machined stainless steel seat, and A2-70 stainless steel fasteners.

ttpumps.com/products/valves

WWTW pumps: Design is fundamental to controlling costs
Table 1 is a summary of the wide variety of potential wastewater treatment plant pump applications.
Picking the right design for the specific application is critical for ensuring the pump (and the overall system) is going to operate properly. This will in turn be the major influence on the overall cost of ownership (COO).

Much of the cost is determined by the initial system design and pump technology selected. A common rule of thumb suggests that about 80 percent of overall equipment life costs (maintenance, operation, and energy consumption) has to do with the initial design of the overall plant and process equipment, and the pumps used. In other words, whatever is designed comes with a set amount of fixed costs. So, selecting the right equipment (in terms of size, technology and features) will have a major effect on costs; selecting the wrong equipment will result in higher costs and more downtime. Another 10 percent goes to environmental costs (disposal), installation, and downtime. This leaves approximately 10% for the initial purchase of the pump.

There are several progressing cavity (PC) pump configurations that can be used for these applications. Each has advantages and disadvantages, and some are more appropriate than others for a particular application. PC pumps can run a long time without service, but when needed, the service required can depend on the design and options selected for the pump. Joints, access windows, type of seal, stator design, rotor materials and coatings, bearings, and ancillary equipment around the pump impact service. Ultimately the pump needs to be designed for minimal and easy servicing.

When one examines the total cost of ownership, including the initial cost of purchase, the electricity used, parts, and maintenance, what looks like a lower cost option may actually end up being the higher cost option. Reduction of service frequency, reduction of required pump parts, and easier, faster serviceability are critical attributes for pump selection. Focusing on these particular areas and spending a little bit more money upfront, will pay dividends.

Pump design considerations
Most operators will work in collaboration with an engineering firm to select and size the right equipment. Keeping in mind that the correct design is important for reducing costs, operators should consider the following factors when selecting a PC pump. Each one has its own positive and negative impact.

• Speed: The faster you run the pump, the faster it will wear and the more frequently service will be needed. In other words, greater speed = exponential wear. However, a fast pump usually means a smaller footprint and lower upfront cost (but you pay on the back end with more repairs). Slower is usually better for most applications.

• Drive configuration (with bearing frame or direct drive): The key issue is how much space is available for the pump. PC pumps are long in nature. Adding a bearing frame adds more length, but provides a robust drive shaft supported by independent bearings to handle the thrust load of the pump. This is the force (axial load) pushing the opposite direction from flow across the centerline of the pump. This is essentially what the pump undergoes as it pumps against the system backpressure. Whereas the direct drive is shorter and is sufficient for many applications.
Typically bearing frames are used when the need for high pressures exceeds direct drive capabilities, when the desire for easier servicing is required, or when a belt configuration for space restraints is preferred. Piggyback/overhead or L-shaped bases can shorten the installation footprint. Vertical mounting of the pump can also accommodate limited space.

• Viscosity: The thickness of fluid limits the pump speed, suction, discharge piping ID, and pipe length from the pump by significantly influencing the design and the pressure losses of the system. This affects the suction side or the NPSHa (Net Positive Suction Head available) for the pump. Pumps have a specific amount of head pressure required to operate correctly. Otherwise, the result is cavitation and potential failures.

• Pump rotor and stator geometry: For the most part, two geometries dominate the various applications. For simplicity’s sake, we will call them low flow/high pressure and low pressure/high flow. Both have their own inherent ratings for NPSHr (Net Positive Suction Head required) based on the pump’s internal design. There are other geometries that can provide higher flow at higher pressures and another for higher flow at lower pressures. Typically, you trade off flow for pressure and vice versa.

• Number of stages: The maximum discharge pressure and ultimately the pump rating per stage is determined by the number of stages. Typically, each stage is rated for 90 psi (6 bar). Therefore, 2 stages would be rated for 180 psi (12 bar) and so on. Adding more stages for a given rated pressure divides the pressure affecting each stage. More stages equals lower pressure per stage and allows for longer life. With most applications in WWTPs, there is abrasion. Abrasion comes from grit and other inorganics (as well as some organics), that cause wear over time on the pumping elements. This wear is to be expected; it is normal to de-rate the pressure per stage due to the amount of anticipated wear. For example, pumping polymer is very lubricating, has no abrasion factor, and can be rated for the maximum capability of the pump. As another example, 1-2% sludge may only be derated by 20% per stage (90 psi x 80% = ~70 psi) making the rated discharge pressure 70 psi or less. Finally, if you were to pump cake (20% or higher), each stage would need to be derated to 50% or more.

• Stator design: The design of the stator can help facilitate faster and easier replacement. Each stator inherently uses compressive forces in the design that compresses around the outside of the rotor; which in turn creates the sealing line of the pumping elements. These compressive forces are what make the pump work. However, they also make it harder and more time consuming to replace the stator with a new one. A new stator requires a great amount of force to install. NETZSCH offers a time-saving stator replacement option. The iFD-Stator® design allows for the compressive forces to be released/removed during installation (and removal). Unbolting the compressive shell releases the axial and radial compression of the stator on the rotor. This allows for the new stator tube to slide on with relative ease and then be clamped down without the need for extra turning forces. See Figure 2.

Money-saving stator adjustments can also compensate for wear, using compression to re-establish the stator sealing line, increasing operational life and bringing the stator back to factory performance. The process can extend stator life by up to six times. This is a boon to operators, who would otherwise have to take the pump out of service, shut down the entire process, and lose all the revenue from that train. While standard stator replacement may take as much as 6 hours, with the NETZSCH xLC® (stator adjustment device) attached to a pump, it takes less than 2 minutes (while pumping or not) for the stator to be easily adjusted or tightened to renew the performance back to factory standards. See Figures 3 and 4.

• Materials of construction compatibility: Are important to ensure long life, abrasion resistance, temperature, and resistance to upset conditions. For example……

• Polymers, neat vs blended: Neat polymer requires a specific construction to ensure the rubber does not swell (swelling causes excessive compression and premature failure). This typically requires FKM/FPM elastomers with 316SS construction. Whereas made-down polymer can use Buna and carbon steel.

• Ethylene propylene diene terpolymer (EPDM) avoidance: EPDM is not compatible with oils. This should not be used for typical municipal sludge.

• Corrosion: This is normally seen as a chemical attack. It can be an acidic or a base. It eats away at the material or can cause swelling or detrition of the materials, resulting in premature failure.

• Hardness: This attribute helps to promote long life. Typically the harder the materials for rotors, the longer they will last. However the same cannot be said for stators. Sometimes having a softer stator (<60 Shore A durometer), can extend life when pumping very abrasive particles.

• Temperature: It can cause the elastomers to expand resulting in excessive compression or, on the opposite side, shrinkage due to the cold. This will reduce compression of the stator on the rotor resulting in more slip, lower flow or inability to pump against the back pressure of the system. With freezing temperatures, if the fluid is frozen, cast iron castings could crack.

• Adding rotor coatings for increased hardness: Tungsten carbide coatings will make the rotor last 3 to 4 times longer. Re-chroming to add a new layer to the worn rotor is another option and while it is significantly less costly than the rotor coating, it is not recommended. Re-chroming may add a new layer, but the plating is not equally deposited and does not renew to factory tolerances. It also creates high points or low points to the rotor diameter; it does not restore the original diameter. This reduces stator life and may affect pump performance.

• Percent solids: This determines how fast the pump can run and impacts pump configuration. It ultimately dictates the viscosity of the fluid being pumped. Water-like sludges (2% or less), present few limitations on a pump design. However, as the percentage increases, so do the design constraints, such as: mechanical seal, max rpm, motor size, wear resistance, geometry configuration, suction pressure, piping layout, and ancillary equipment.

• Fluid media size (particle and ball sizes): Every pump has a maximum particle size it can handle. When it comes to PC pumps, there are two considerations: particle size and max “ball size”. The particle size relates to the amount of particles and average size of particles in the fluid. The max ball size is the largest soft size particle the pump can handle which is typically 80% of the rotor diameter.

• Type of shaft seal and seal water/flushing options: This is always a highly debated topic. With many options, multiple seal manufacturers, and a wide range of applications, each fluid being pumped has certain requirements, each with pros and cons. Depending on the application the design may require packing, single component seal, cartridge seal, double seal, or some new style of seal. It is best to consult with seal and pump manufacturers for the best solution for your process.

There are a variety of shaft seals for different applications and care must be taken to get the right one for the application. Depending on the seal there may be a complex seal plan that must deliver water or fluid to the seal to ensure it operates properly. Otherwise, operators run the risk of the added expense associated with maintenance to pull the pump apart to get access to the seal – the last piece in the pump. Here are some examples that may not fit every application: wastewater to thin sludges (<6 percent) with or without quench or flush could use single slurry seals with a knife edge, encapsulated component, or a standard single mechanical seal, either a cartridge or component. Thick sludges (6 to 10 percent) with quench and/or flush can use single slurry seals, single inverted slurry seal, double mechanical seals, or packing. Cake calls for packing, double seals (>10 percent) with quench and/or flush, double mechanical, or packing. Neat polymer or made-down/mixed emulsion polymer should use single slurry seals, standard single mechanical seals, or packing, while made-down/mixed/emulsion polymer should opt for single slurry seals or standard single mechanical seals.

• Correct joint type for application along with the right joint options: The joint to be used depends on the pump size, loading, and operation. For smaller pumps, pin joints are adequate. Pin joint longevity can be increased, however, with a double-sealed joint option or the covered-seal joint option which protects against abrasion and sharp objects but, for larger pumps, additional joint options are available.

Pumps that will operate with many stops and starts may function more effectively with a gear joint. Double sealed, oil filled gear joints are preferable to those using grease; oil refills and replenishes itself, whereas grease, once pushed out, does not replenish. This makes for a more robust, long life joint, that will tolerate frequent stops and starts (>3-4 starts/hour).

• Joint angularity: This is the distance between the joints. Increased joint distance provides a longer joint life. Three forces impact joints: axial (X), shear/bending (Y), and rotational (torque). Higher angularity (Y-axis forces) means less joint life. While you do not want too long a pump, one with a longer joint distance will last longer.

• Suction lift requirements, up to 30 feet (ftwc – feet water column): It is common to have suction life requirements for WWTP applications. PC pumps work great for suction lift. However, there are some tricks for ensuring the pump is set up correctly to perform as intended. Having the wrong setup can cause the pump to not work properly or to fail. Consult with your pump manufacturer on their recommendations for suction lift.

• Pump orientation (horizontal, vertical, wall mount, upside down, etc.): The pump orientation can make all the difference for operational longevity, space saving or for simplifying the piping layout. PC pumps can be positioned in many ways. With PC pumps being inherently long due to the design, it is possible and becoming more prevalent to install them vertically as older plants make upgrades with limited room in the existing buildings. This saves space and preserves the benefits and capability of using a PC pump.

Pump serviceability
Pump servicing in place: Most pump manufacturers offer a full service-in-place (FSIP®) option without needing any additional footprint in the often space-constrained process line. In this case the rotor, stator, and mechanical seal can be removed without the need to remove suction or discharge piping, drive, or electrical components. Some can even upgrade existing installed pumps; however, flow and pressure reductions may apply. This can be a time-saving alternative to standard servicing, which may require removing piping to get the space needed to service the pumps, as well as unbolting numerous components to take the stator off, and even calling in an electrician to remove electrical components to access the pump for servicing. See Figure 6.

Piping systems and accessories
The system design should consider these piping system factors:
• Suction side liquid trap for priming
• Large pipe inner dimensions (IDs) to reduce friction losses
• Long Radius Elbows
• Reduce suction and discharge pipe lengths as much as possible
• A discharge check valve
• Expansion joints
• Avoid pipe stress on pump
• Some form of pressure relief, for example a pressure relief valve (PRV), pressure switch, or burst disc

Pump protection
Pump design should include consideration of stator dry run protection, choice of motor thermostats, flowmeter, variable frequency drive (VFD) or over-current. The pump should be designed to avoid cavitation and should include pressure gauges for suction and discharge and isolation from process fluid.

Optimizing pump design for cost-efficiency and longevity
The design of progressing cavity pumps plays a crucial role in controlling maintenance costs and extending product life in wastewater treatment plant applications. By carefully considering key design elements such as speed, drive configuration, sealing options, joint types, and piping systems, operators can make informed decisions that contribute to cost reductions and minimize downtime. Also, selecting the right equipment and implementing money-saving strategies post-installation can further enhance the efficiency and longevity of pump systems. Ultimately, a well-thought-out design benefits the immediate operation and ensures long-term cost-effectiveness and reliability.

By Al Gunnarson, VP of Sales and Marketing, Warren Controls.

The advent of online sizing and selection tools has transformed the process of selecting valves, providing a more efficient and accurate way to determine the best valve for each application. These tools consider varying flow requirements, pressure differentials, and fluid compatibility across different applications within a facility.

Choosing an unsuitable process control valve can result in serious control issues, and lead to premature failure and costly downtime. The consequences include not only increased maintenance costs but also the potential for safety hazards and reduced system reliability.

An unsuitable valve can fail to regulate flow properly, causing pressure surges or water hammer effects that can damage the piping system, leading to further leaks or catastrophic failures. These events not only increase the risk to personnel safety but also amplify the financial burden on the organization due to emergency shutdowns, increased maintenance requirements, and the need for replacement parts.

Choosing valves without using online tools
Before the advent of these online tools, choosing the right valve for a specific application relied heavily on complex differential equations and extensive engineering know-how based on the ISA (International Society of Automation) standards. This method, while precise, was incredibly arduous and error-prone, typically requiring upwards of 45 minutes for each process control valve to determine the correct specifications. Few were skilled or patient enough in the required math to achieve the necessary accurate results. Even when this is accomplished, selecting the correct complete P/N from a manufacturer, and gathering all this into a comprehensive report to present to a customer is another huge drain on time.

Given the complexity and time constraints faced by engineers and specifiers who don’t use online tools, there is too often a tendency to bypass these detailed calculations in favor of educated guesses or approximations.

In a typical scenario where a facility requires 30 process valves, all ostensibly needing to be 4 inches, a specifier might opt to select 30 of the same 4-inch valves rather than doing the arduous calculations to select different valves optimized for each particular application.

This one-size-fits-all approach often results in some valves being oversized or undersized for their specific tasks, resulting in higher initial costs for unnecessary capabilities or future costs due to premature wear, maintenance issues, and even system failures and safety and environmental hazards.

Importance of proper valve selection
Preventing cavitation damage is crucial. Certain valve types are prone to cavitation when exposed to higher flowing differential pressures, while others are not. Cavitation involves the formation and subsequent collapse of vapor bubbles within a liquid, inflicting severe damage to the valve. Such conditions can lead to valve failure in just a few weeks.

The consequences of cavitation go beyond damage to the valve itself; it can also cause leaks that pose safety and environmental hazards, alongside the direct and indirect costs associated with valve failure and replacement.

Vibration is a critical factor to consider, as aerodynamic noise can reach up to 120 decibels. High aerodynamic noise levels tend to occur in conjunction with higher flow rates and higher flowing differential pressures which often necessitate the use of sound insulation blankets or other sound-deadening techniques like silencers. Moreover, excessive vibration can damage the valve, leading to premature wear and failure. In some cases, one or more valves in series, sharing the pressure drops can be more cost-effective than a single valve with expensive, aerodynamic noise tuning trim.
Selecting the appropriate trim material for valves is crucial, especially in applications involving higher flowing differential pressures. Often, there is a lack of awareness regarding the impact of differential pressure on trim material selection. The reality is that the higher the flowing differential pressure, the more durable the trim material needs to be. This ensures that the valve trim can withstand the conditions and remain functional over an extended period.

Temperature is also crucial in valve selection, especially for processes above 450°F (about 232ºC). Materials like engineered plastics or elastomers, which don’t withstand these temperatures, limit choices. Selecting valves that can handle high temperatures without degrading is essential for maintaining process integrity and safety.

The actuator is as important as the valve
Choosing the correct actuator to pair with a valve is just as critical as selecting the valve itself. An actuator, responsible for the mechanical operation of opening and closing the valve, must be robust enough to operate reliably under the specific conditions of its environment.
If an actuator fails to actuate the valve when required, serious consequences can follow. This may lead to situations where critical flows are not properly regulated or the valve does not shut off properly to the advertised leakage rating of the valve, resulting in overpressure or overtemperature incidents, uncontrolled chemical reactions, or significant leaks.

Leveraging online tools
Online tools like ValveWorks® mitigate these risks by offering a precise, scientifically-based process that considers all relevant factors of the valve’s intended use. By inputting specific process conditions — such as fluid type, temperature, pressure, and flow requirements — users can leverage advanced algorithms to identify a range of suitable options.

This not only saves time and reduces efforts in the specification process but also enhances safety and reliability by ensuring compatibility with the application’s demands. Furthermore, these tools provide in-depth analysis of the trade-offs between different options, equipping users with comprehensive documentation. This documentation facilitates clearer communication and efficient record-keeping and streamlines the procurement process, making it easier to make informed decisions.
Online tools for selecting process control valves are a critical advance. professionals can avoid the twin pitfalls of over-engineering and under-specification, ensuring that their facilities operate smoothly, efficiently, and cost-effectively.

A ground-breaking project that is enabling continuous remote monitoring of a 16km trunk main has been recognised at the Water Industry Awards.

The Blairlinnans SoundPrint Acoustic Fibre Optic System, a joint project between Xylem and Scottish Water – and described as a European first, was named Asset Management Initiative of the Year at the awards ceremony on 4 July 2024.

The Blairlinnans water main is a 42 inch (1,067mm) pre-stressed concrete (PSC) pipeline that runs from the Blairlinnans Water Treatment Works to a service reservoir in West Dunbartonshire, Scotland. The pipeline was installed in 1974 and is critical to the ongoing operation of Scottish Water’s supply network.

Scottish Water identified the main as a high-risk asset, which prompted a complete engineering assessment to understand its true condition and prevent an unexpected burst.

Inspections using Xylem’s SmartBall and PipeDiver technologies provided the data necessary to conduct a thorough engineering analysis. The insights showed while most of the pipeline was in good condition, several sections had broken pre-stressed wires, which are critical to support operational pressures. If the wires break, a trunk main can lose its structural integrity, with a risk of failure.

In the first project of its kind in Europe, Scottish Water selected Xylem’s SoundPrint Acoustic Fibre Optic (AFO) system to continually monitor sections of the pipeline. SoundPrint AFO detects breaks in the pre-stressing wire that hold PSC pipelines together.

The system set-up comprises bundled, reinforced fibre-optic cable fed though the water main, which is connected to a data acquisition system to monitor the acoustic activity in near real-time. If a wire break occurs, it is detected by the AFO system, which is connected to Xylem’s AFO analysts via the cellular network.

Wire break events are investigated by the analysts and with the help of machine learning, the break location is pinpointed. An email notification is sent to the customer and the results posted on a cloud-based system, which displays the pipeline status on colour-coded dashboards.

The monitoring, combined with further analysis by Xylem’s engineering service, enables utilities to make proactive decisions about which sections of pipe need to be replaced or repaired as deterioration continues over time.

Ian Dunsmore, team leader – strategic water infrastructure at Scottish Water, said: “Replacement of major pipelines is often cost prohibitive, extremely complex and causes major disruption – however it is rare that the entire pipeline needs to be replaced.

“Leveraging Xylem’s AFO system and engineering experience enabled us to understand the true condition of the Blairlinnans water main at a single point in time and have confidence that the pipeline is being continuously monitored for any further deterioration. It is great news that the success of this joint initiative has been recognised by the sector.”

Andrew Welsh, water utility director at Xylem said: “Xylem is extremely proud that this innovative partnership with Scottish Water has been recognised by the Water Industry Awards.

“The AFO system has enabled Scottish Water to reduce the risk of failure by pre-emptively repairing areas known to be in poor condition, make significant cost savings by extending the life of remaining pipe sections and minimise disruptions to customers, while maintaining the utility’s reputation as a forward-thinking, reliable service provider.”

New data seem to show that only two percent of polluting vans scrapped under the ULEZ scrappage scheme have so far been switched to electric vehicles despite Transport for London (TfL) committing over £100 million in funding to businesses.

TfL reported that of the 16,207 approved applications to scrap a petrol or diesel van between January 2023 to May 2024, only 372 were replaced with an electric vehicle.

The figures were revealed in new analysis from campaign group Clean Cities on 26 June, and during London Climate Action Week as Defra was forecasting the first summer smog of the year in London and southeast England.

In 2023, the Mayor of London launched a ULEZ scrappage scheme to provide financial assistance to help Londoners and businesses scrap the highest polluting vehicles to prepare for the expansion of the ULEZ across all London boroughs.

The scheme provides grant payments to scrap, donate or retrofit vehicles that do not meet the emissions standards and switch to cleaner modes of transport.

Analysis published this week by Transport & Environment, Europe’s leading clean transport group, shows the number of vans on UK roads has increased by over a million since 2014.

The campaigners’ analysis shows carbon emissions from vans in the UK have risen 63 percent since 1990, threatening climate targets despite the growing push for electric vehicle (EV) adoption. Carbon emissions from private cars and taxis have decreased by 19 percent over the same period.

The majority of new van sales are diesel, accounting for 90 percent of all new van sales in 2023.

In contrast diesel cars registered on UK roads have fallen by 13 percent between the end of 2018 and the end of 2023 but diesel vans rose about 13 in that same period

This is reflected in harmful nitrous oxide emission levels in the UK. With emissions from HGVs and cars falling by 91 percent and 88 percent respectively since 1990 but vans have only managed a fall of 38 percent.

Recent polling, commissioned by Clean Cities, has revealed 67 percent of Londoners believe small businesses still need more support to help them switch to electric vehicles.

The survey of 4,000 UK adults also finds that three-in-five (59%) Londoners want their councils to take stronger action against air pollution and protect the environment. Nearly half (46%) also believe delivery vehicles have a negative impact on their local roads.

Campaigning for policy change, Clean Cities is launching Clean Cargo Capital, a campaign focused on accelerating the uptake of electric or pedal powered commercial vehicles in London.

The campaign is calling on Mayor Sadiq Khan to improve incentives for businesses to switch to electric vehicles, such as reviewing and reprioritising the ULEZ scrappage fund and extending the Congestion Charge Cleaner Vehicle Discount for SMEs, ride-hailing, and car-sharing services until late 2027.

The discount is set to be discontinued at the end of 2025, meaning it will cost businesses the same to drive a diesel or electric vehicle in central London, despite electric van sales lagging and diesel being one of the largest contributors to air pollution in this area.

Oliver Lord, UK Head of Clean Cities, said, “The Mayor’s van scrappage scheme is a leading endeavour but something isn’t right if only two percent of businesses in London have ditched diesel and switched to electric instead. Londoners rightly expect businesses to step up and play their part in cleaning the air and protecting the environment but more support is needed to make cleaner electric vans a viable option.

Our polling shows a majority of Londoners believe small businesses should have more support to help them switch to electric vehicles, so it’s puzzling that the Mayor is set to remove the Congestion Charge discount next year.

A newly elected Mayor and a new government offers a unique opportunity to double down and deliver the regulatory certainty, incentives and infrastructure that businesses need so that electric vans become the norm and not a nice to have.”

Ralph Palmer, UK Electric Vehicle and Fleets Officer at Transport and Environment, said: “The continued rise in van emissions in the UK is alarming. Despite the push for more electric vans on our roads, we are still witnessing a surge in greenhouse gas emissions from vans as a result of sustained sales of diesel vans, countering trends we are seeing in the car market.

It’s clear that more action is needed to boost electric van demand among fleets to ensure we achieve the triple-win of tackling emissions, reducing running costs for small businesses and boosting energy security. The new Government should bring forward plans for stronger financial support and action to improve the nation’s charging infrastructure for van drivers to ensure the UK doesn’t continue to fall behind other European countries.”