THE efficiency of the mixing process is fundamental to the success of an AD installation says Huntingdon based System Mix, a company that specialises in eliminating the operational and biological issues occurring in AD systems.
System Mix works in conjunction with P&M Pumps, the company which markets the Rotamix system (incorporating the popular Vaughan chopper pump). The two have been supplying digester mixing systems to UK wastewater companies over the past 20 years and more recently to numerous private sector food waste AD plants. One user of the Rotamix system is Southern Water where currently over 90% of its total digester volume (82007m³) is mixed using it.
The success of these plants depends on a durable mixing technology supported by reliable Vaughan Chopper Pumps. Andy Parr, director of System Mix, says: “It is crucial to the AD process that suitable pre-conditioning of solids is carried-out prior to digestion and our system has been proven to be one of the most effective in achieving this. The Vaughan pump prevents re-accumulation of fibrous and fatty material in the digester and this means that material continues to pass through the nozzles.
This in turn ensures that digestate is adequately conditioned and actually benefits all post-digestion equipment”. He concluded, “As many AD operators now need to maximise the sustainable credentials of their plant and equipment even further, we are confident that the benefits of our mixing systems are becoming even more important”.
Over the last few years System Mix has been involved with ‘retrofit’ projects at existing AD plants where existing mixing systems were contributing to operational and biological issues. For example, high grit deposition was reducing the active volume of digesters and threatening to significantly reduce output outside compliance requirements. Also, compressors were requiring high levels of maintenance and were proving costly to keep running. Furthermore, as deposition increased, the maintenance issues escalated because not only did the rag mass reweaving within the digester impair their efficiency, it also caused blockage problems in the heat exchangers and further downstream pumps and systems.
• For further detail on how System Mix can help eliminate some of the issues occuring in AD systems see www.pumpmix.co.uk.