Increasing demands show why it pays to futureproof

Ofwat is urging water companies to rethink their pricing strategies. With the AMP5 spending round and Water Framework Directive in the mix, treatment works will have to stretch their committed monies in many ways. Simon Lambert reports.

DUE TO be fully implemented by 2015, the objective of the Water Framework Directive (WFD) is to integrate every aspect of the control of water quantity and quality in the water cycle across Europe, so that all parties work to one timetable and objective.

A central concern of the WFD is how water used for domestic, commercial and industrial purposes is treated and returned to the watercourses and, not surprisingly, upgrading the effectiveness of treatment processes has been a priority in the current five-year spending round (AMP4).

The forthcoming AMP5 spending round from April 1, 2010 is set to continue this progress by focusing on improving the lifetime cost-effectiveness of the treatment processes. As such, treatment works management will be encouraged to focus on lifetime costs and their improvement through better specification and assessment of equipment.

In addition to impending frameworks and directives, there are other factors that are affecting treatment plants that need to be addressed. Many treatment works are now centralising duties to improve efficiency and help deliver cost savings, so it is therefore essential that all equipment, and pumps in particular, can handle the larger capacities processed at main sites.

There is additional pressure placed on pumps due to the increase of non-disposable waste entering the drains that needs to be processed. Items such as facial wipes, cleaning cloths and disposable toilet brushes are being flushed into the sewers instead of being thrown in the bin.

Asset management

For water and wastewater treatment works this can cause serious ragging issues at pump station collection. These inclusions are particularly damaging to centrifugal pumps, as the propeller vanes and shaft can be totally entangled.

To add to these challenges, the water and wastewater sector has also seen a decline in on-site engineers due to the automation of many plant processes. Where there were once more than 100 engineers and staff members on site, there may now only be a handful. This has resulted in a need for extra support and advice from pump manufacturers.

As key elements of the treatment process, the performance of pumps has a bearing on how energy and cost efficient a treatment works is, as well as its quality of discharge. As such, process and maintenance engineers need to look at the whole life cost and effective asset management of their equipment.

Although centrifugal pumps have traditionally been a familiar part of the internal workings of wastewater treatment transfers, progressing cavity pumps are proving invaluable when it comes to handling the more viscous media such as filter cake and primary, secondary and dewatered sludges.

Progressing cavity pumps incorporate a hardened steel rotor and resilient stator, which form discrete cavities within the pump. This unique design enables them to transfer difficult to handle media. They can pull suction and vacuum without the need for constant priming, which is why they can be used above vessels and sumps.

These pumps have been designed so that flow volume is effectively linear to running speed, which means they are easy to adjust to required changes in flow demands. Unlike centrifugal pumps, progressing cavity pumps are not greatly affected by pressure.

Even with the use of screens and grinders, PC pumps can still suffer from ragging and maintenance issues. AMP5 spending is set on improving the lifetime cost-effectiveness of the treatment processes, it is important that treatment works pay attention to on-going maintenance costs and their improvement through better specification and assessment of equipment and parts.

Minimising cost

To provide a solution to rising whole life costs, one leading PC pump manufacturer has developed a range of spare parts that offers cost-effective alternatives to OEM PC pump parts.

Often the cost of replacing spare parts from OEMs can be extremely expensive, but the parts manufactured by this manufacturer are designed to be compatible with all major PC pump brands, to help minimise that cost, as well as the frequency of maintenance.

Ranges can include rotors, stators, coupling rods, shafts, pins/bushes, seals and drive train assemblies. Fully assembled rotating units are also available, which helps to reduce operational expenditure by minimising assembly and installation time, as well as delivering cost savings, because the complete unit is purchased rather than individual components.

These universal pump parts are also available from an online e-commerce system so that all parts in their ranges can be purchased online, and customers can also check stock levels and lead times. The next generation of PC pump parts have been designed to ensure treatment works can continually improve their processes and cope with the demands of our growing population.

The right pump part, which offers plant engineers a reliable and cost effective solution, can play a key role in sewage treatment works considerably improving maintenance downtime and whole life costs. And this enables them to meet the requirements of the AMP5 spending round and the WFD, helping them to safeguard funding moving forward.

Simon Lambert is general manager for Europe at NOV Mono. T: 0161 339 9000.

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