Many sewage sludge mixing applications use submersible, guide-rail paddle type mounted mixers, usually because they are relatively easy-to-install and remove. However, these systems are vulnerable to failure usually due to rag and debris accumulating on their rotating parts. The result is expensive repair or replacement and in the most severe cases, the build-up of rag becomes so severe that the lifting davits exceed safe working limits. This can lead to possible safety implications whilst process throughput and the associated equipment reliability, can also be seriously affected.


P&M Pumps Ltd the UK distributor of VAUGHAN chopper pumps and their mixing technology partner SYSTEM MIX Ltd have established a reputation for developing innovative bespoke design turnkey and retrofit in-tank mixing systems including ROTAMIX, STM (Small Tank Mixing) and STORMTHRUST (storm tank washdown). Their experienced and versatile approach to sludge mixing has resulted in numerous successful installations across the UK which now includes the success of their ‘MINI DROP’ retrofit mixing system.

This option can be installed into a tank without having to empty and clean it and in most cases it utilises existing guide rails and lifting equipment, previously used for unsuitable submersible mixers which failed due to rag accumulation. This type of system provides effective mixing for tanks where a suitable suction connection is available for re-circulation through the guide rail mounted vertical nozzle manifold header.

Good examples of the success of the Mini Drop system are at several Southern Water and Anglian Water sites where the designs were able to utilise the original box section guide rail used by the existing failing submersible mixers.

A simple installation process in the Southern Water system was also aided by using an existing discharge manifold resulting in even more reduced downtime and lower capital costs.


It is not uncommon for users of submersible mixers where fibrous material causes frequent and expensive breakdowns having to tolerate the situation because of the cost-implications associated with emptying and cleaning sludge tanks.

However, the Mini-Drop system significantly reduces these costs by eliminating the need to empty and clean the tank as it utilises existing guide rail and lifting davit arrangements and in some situations even the existing tank openings can also be utilised. The associated Vaughan Chopper Pump required for the system is competitively priced when compared against the frequent submersible mixer repair costs and can also be supplied on a hire basis if required.


The System Mix Mini-Drop system is operating at numerous sites and proving to be a reliable and cost-effective alternative to submersible mixers where capital projects are unlikely to be allocated. The main features and benefits are; utilisation of the powerful and effective external Vaughan Chopper Pump, tank entry is not required to install or remove the system, orientation of the nozzle can be adjusted as required, the pump conditions as it mixes, all submersible parts in 316 stainless steel, quick installation, even into full tanks and full bespoke design service available if required.

Further information on the Mini-Drop System is available from:
Andy Parr, System Mix Ltd, Sawtry, Huntingdon, UK.

Tel: +44 (0) 1487 830123

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