GEA Westfalia Separator UK Ltd Make DAF Sludge Reduction Pay for Itself
2 March 2009, News release from GEA Westfalia UK Ltd
Today's drive for sustainable industrial processing solutions and environmental best practices is paralleled by the demand for cost effective waste recycling and disposal options. With utility costs escalating and waste disposal costs and landfill taxes increasing year on year many companies are seeking ways to reduce these expenses and evaluating ways to create revenue streams from by-products and waste once discarded as worthless.
A recent DAF sludge dewatering system installation from GEA Westfalia Separator UK Ltd. demonstrates how, with minimal investment, one company has not only reduced waste disposal costs but can potentially generate an income from a new revenue source from their raw material and further develop best environmental practices.
Results from the installation that integrates two tried and tested technologies, dissolved-air flotation and centrifugal separation, at a specialist tannery in Cambridgeshire, demonstrate how sustainable profits can be achieved from sustainable practices.
DAF systems are increasingly used in animal/meat/food processing applications to remove suspended solids, fats, oils and greases from a variety of waste waters. Their high process rates, small footprints and flexibility of operation being seen as advantageous in these applications. DAF systems use air to create microbubbles to which the solids attach and float to the surface to be skimmed off.
'One of the disadvantages of such systems is the cost of disposal of the very wet waste, and it was this problem we addressed at the Hutchings and Harding Ltd. tannery.' explains David Cawdery, Market Manager - Industry, GEA Westfalia Separator UK Ltd.
'Hutchings & Harding Ltd is a renowned and long established tannery producing chamois leather from sheep pelts and they utilise a DAF (dissolved air flotation) system to recycle and clean the water used in the processing of skins. The largely liquid DAF sludge was previously transported off site to landfill and it was these costs that we were asked to reduce.'
Using previous knowledge of similar installations and applications, liquid/solid separation specialists GEA Westfalia Separator UK Ltd. prepared system designs and costing projections for reducing the amount of DAF sludge for disposal by approximately 45% to produce weekly disposal cost savings. The system is based upon a UCD205, high efficiency decanter that is compact, reliable and simple to use and maintain. DAF sludge is fed to the decanter using a Seepex pump, specially designed for handling a high volume of fatty solids.
'When GEA Westfalia Separator UK Ltd presented their proposals to us for dewatering the DAF sludge utilising a UCD205 Decanter we were confident the system would work and give us cost savings but were finally convinced after a weeks on site trial with their mobile unit.' confirms Steve Pool, Technical Manager, Hutchings & Harding Ltd.
The installation includes a specially designed chemical dosing unit from Biochemica that supplies regulated amounts of polymer chemicals that help breakdown the solids and liquids in the DAF sludge to effect improved dewatering rates. The dosing rate is easy to adjust and together with decanter controls ensures the acceptable 'dryness' of the end waste product.
'Now that the equipment is installed and working at production capacity we have been surprised just how effective it is and have been astounded by the amount of water that is removed from the DAF sludge. We are now seeing an actual 90% reduction in the DAF sludge, through the system. We believe this could be improved upon even further but as we have no need for an absolutely dry product we are very happy with the production results.' says John Ettling, Managing Director, Hutchings and Harding Ltd.
' The disposal cost saving potential we are seeing means we can also now see the potential for us in removing from the protein fibre and fat rich sludge, the oil as a separate fraction to produce a saleable by-product. We are also investigating further cost savings and revenue generation in putting the fleshings through the decanter.' he continued.
Plans to optimise the use of the GEA Westfalia Separator decanter have been discussed as it is currently running for only 3 hours a day with a half to one tonne of DAF sludge throughput per hour, which is well under the machines capability. This secondary use may yet produce the largest financial benefit for Hutchings & Harding Ltd. and involves mascerating the fleshings and adding water to produce a slurry which can then be fed through the decanter system to separate off the saleable oil fractions. Costs are also saved on the removal of a lower weight dewatered end product, potentially making this a self funding and profitable alternative to current disposal routes.
'The cost savings on the DAF sludge disposal plus the additional or optimised service of the decanter system shows an acceptable payback time on this system with a very pleasing return on the customer's investment. There are also the added environmental benefits associated with water recycling, reduced vehicular transport of waste, minimal landfill requirements and the best use practice of a natural resource, the sheep skins themselves.' says David Cawdery.
'This installation demonstrates clearly how DAF system users can add a further stage to their process that can reduce the amount of sludge for disposal and create cost savings that equate to rapid payback of investment.'
For further information please email GEA Westfalia UK Ltd