We get a fair bit of crusting on our digestate storage tank and so are thinking of investing in a separator so the liquor goes into storage and the solids can be stacked. What I am wondering is about recirculation of the separated solids into the digester again. We have just a single tank, and if we fed them through feeder it would work out as a longer retention time wouldn't it? Also it should reduce the solid fraction further? Does anyone else do this, what I am specifically thinking is separating solids and refeeding for a certain period, and then separating and storing/spreading solids for a period to remove material that is non digestable and when the gas yield of refeeding it drops- say when average retention is X2 where it is presently. Alternatively could you just keep recycling it into the digester? We are feeding grass silage, slurry and some maize/wholecrop. Be interested of anyone elses experience?