BOC technology 'extends the life of wastewater plants'

BOC's new AXENIS™ wastewater processing technology offers operators 'extended life and better final water quality' without having to replace or extend existing facilities. The technology, developed by BOC's parent, The Linde Group, uses an oxygen-based membrane bioreactor (Oxy-MBR) process to increase both throughput and performance.

The costs of water continue to rise, while the environmental treatment standards are becoming more stringent. Meanwhile, changes in product or process can lead to higher requirements for effluent treatment. These can combine to push the existing treatment facilities beyond their design specifications. At this point, conventional wisdom might indicate expansion or replacement of the existing equipment.

According to BOC, their AXENIS solution enables a significant reduction in the costs of treatment by producing an exceptionally high standard of final water quality, suitable for either reuse or discharge to a sewer or watercourse. Crucially, the process replaces and improves upon the settlement stage as well as increasing the organic load handling capacity.

The AXENIS process is a unique system which provides a means of oxygen transfer, pH control by air stripping CO2, ultra-filtration (UF) membrane separation of biomass together with some mixing energy as the biomass retentate is delivered back into the bioreactor.

This Oxy-MBR process can therefore operate at elevated dissolved oxygen levels (35 mg/l), at slightly elevated temperatures because of better heat retention and optimal accurately controlled pH levels. This ensures a robust biological and membrane performance with lower surplus sludge production compared to similar plants operating at lower temperatures.

The whole process can be easily containerised and is aimed at providing an easily integrated and substantial upgrade to any industrial aeration plant, as it can include the required additional oxygen transfer as well as the means of biomass separation. The overloaded settlement tanks become redundant and the process becomes an Oxy-MBR capable of operating at between 1525 kg/m3 biomass concentration. Typical increase in performance can be up to 100% in both flow and load. This will depend on ultimate biodegradability, on food wastes up to 99.5% Chemical Oxygen Demand (COD) removal has been seen.

This compact, reliable and robust technology reduces the cost of wastewater treatment, delivering savings in trade effluent charges relating to volume, COD and suspended solids, and potential water supply costs based on less use.

Stuart Pigott, BOC Senior Technical Specialist, commented: 'The AXENIS system addresses the needs of industry in extending the life of wastewater treatment facilities while at the same time enhancing environmental performance. The savings it can make are significant in the current climate of austerity and difficult investment conditions.'

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