Tuesday, December 09, 2014

Why Better Digestate Enhancement and Treatment is What the Biogas Industry Needs

Digestate Enhancement is Important!

The operating capacity of biogas plants in the UK is rising faster all the time. The technology has recently also been extended from the original use on farms with energy crops, into new areas. Two of these rapidly expanding Anaerobic Digestion (AD) Plant sectors, in the UK, are in sewage sludge treatment, and food waste disposal.

Both of these applications for AD makes real sense due to the energy that this releases which can be used in turn to power the wastewater treatment works at which the AD facility is located, and similar uses also exist at facilities accepting food waste

In our opinion this goes further because of the use of biogas digesters for the treatment of sewage sludge with the ability to pay for the AD Plant, at least in part, from the sale of the biogas or electricity generated from it. This is now becoming the accepted practise in the UK, and we are certain that the same applies in a number of other nations.

However, using biogas digesters for organic wastes from sources such as food waste has much less of a proven performance history. In fact, only in 2011, there were concerns that completely food waste fed anaerobic digestion plants might not be feasible in the long term due to process instability problems.

This anticipated obstacle has been eliminated by the results of published studies carried out by the University of Southampton, however, this example just goes to show how very recently the scientific community was still talking about whether this kind of biogas digester would work dependably, or go sour! Fast foward to today, we still are no more than 2 to 3 years after that event, and many large food waste biogas plants have actually now already been commissioned! In addition it is likely that in less than 5 years there will be legislation in the UK which will legally require that food waste be separately collected by all councils, and anaerobically digested.

The end-result of this rapid take-up of a new technological application, has in-truth been that there has actually been hardly any time for much study work to be  done on digestate disposal and/ or sales/ product improvements, when compared to other aspects of biogas manufacturing.

It is an inescapable fact that 90 to 95 % of the original feed product which goes into a biogas digester re-appears as digestate from the digester as digestate, and if the digester is running properly the mass decrease is merely the mass of the biogas created. the techniques by which any AD Plant handles digestate is therefore of big relevance to plant operation and to the financial practicality of each plant.

With the undeniable increased popularity of waste digestion, the need to enhance the available strategies for managing digestate, as a helpful resource, and not just as a waste for disposal, is pressing.

The next breakthrough the Anaerobic Digestion industry badly now needs is certainly in improving the optimization of digestate by inventing better techniques, and treatment, with the aim being to open-up this product to new, much bigger, and more rewarding markets.

Barriers encountered in the UK to finding better ways to enhance and treat digestate were identified in a recent study for WRAP. Read more abut those barriers to digestate enhancement here. 

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