As those of you dedicated followers of Marches will know, we have built a few tanks in our time, large ones, small ones, closed and open. All have their functions, and continue doing their jobs as designed, for usually many years. Open tanks tended to be popular as storage vessels, sometimes for imports of feedstocks but generally for the digestate before it’s taken out of the AD plant to be recycled. The beauty of open tanks are they tended to be cheaper to erect than a closed tank, but have the disadvantages that water can get in, diluting the product. On top of this there are the losses of gases such as ammonia which means that a valuable nitrogen source is not going to agriculture with the added curse of being an odour nuisance and a cause of global warming! 

In these enlightened times we are looking in much more detail at the sustainability criteria for new plants, with drivers coming from the green gas support scheme to reduce emissions everywhere possible. But on top of this there is a review of the permitting regulations coming down the tracks from the Environment Agency that may well force existing plants with open tanks to cover them up. There are options out there, to either put small clay balls onto the surface of the liquors to form a barrier to reduce gas escape and in theory provide a medium for bacteria to break down odorous compounds.  But, this may well not be enough, meaning that a new roof may have to be retrofitted in order to be compliant.  

So don’t panic if you find yourself in this position; give Marches a call and we can talk you through all the options and project manage the whole process, including liaison with regulatory bodies, ensuring that you remain compliant to your permit in the safe knowledge that the whole operation will be done in a safe and timely fashion!