Pump performance key to treatment

With OFWAT urging water companies to rethink pricing strategies and with the current AMP 5 spending round and Water Framework Directive (WFD) on the horizon,Simon Lambert,general manager for Europe at NOV Mono, explains why treatment works need to stretch their money in many different ways

Due to be fully implemented by 2015, the objective of the European 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 is how water used for industrial, commercial and domestic purposes is treated and returned to the water courses and, not surprisingly, upgrading the effectiveness of treatment processes has been a priority in the current five year spending round.

The forthcoming AMP 5 spending round (from 2010) is set to continue this progress by focussing on improving the lifetime costeffectiveness of the treatment processes. Following the news that OFWAT has ordered water companies to rein in spending budgets and cut bills, these companies must hunt for efficiencies in the supply chain or face the prospect of job losses across the board. As such, treatment works management will be encouraged to focus on lifetime costs and their improvement through better specification and assessment of equipment.

Processing trends Many treatment works are now centralising certain duties to improve efficiency and help deliver cost savings, so it is essential that all equipment, and pumps in particular, can handle the larger capacities processed at main sites. In addition, pumps are being put under more pressure by 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. 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.

As key elements of the treatment process, the performance of pumps has a considerable bearing on the energy and cost efficiency of a treatment works, 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. They have a hardened steel rotor and resilient stator, which form discrete cavities within the pump. This design enables them to transfer difficult-to-handle media, even types that appear non-flowing.

However, even with screens and grinders, PC pumps can still suffer from ragging and maintenance issues.With the forthcoming AMP 5 spending 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.

Often the cost of replacing spare parts from OEMs can be expensive, but to provide a solution to rising whole life costs, one of the leading PC pump manufacturers has developed a range of spare parts which offer cost effective alternatives to OEM PC pump parts. The range offers same day delivery on stock items, with a dedicated aftermarket team, making it an attractive offering for engineers looking to control pump maintenance costs without sacrificing high quality service and parts. The range includes rotors, stators, coupling rods, shafts, pins/bushes, seals and drive train assemblies.

Fully assembled rotating units are available, which help 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.

Futureproofing treatment works The next generation of PC pump parts have been designed to ensure treatment works can improve their processes and cope with the increasing demands of a growing population.

The combination of the right pump and the right maintenance approach will enable them to meet the requirements of the forthcoming AMP 5 spending round, as well as the WFD, and importantly, help them to safeguard funding while moving forward.