Is it too late for AD

Discussion in 'Renewable Energy' started by mawleymoos, Nov 28, 2016.

  1. thesilentone

    thesilentone Member

    Hi, most of what you are suggesting has already been done, by the likes of WRAP, see: effects of AD on common crop pests diseases.pdf

    The issue of un-digested material and retention time is a subject that can be complex, as it has many influences such as regulations, type of feed-stock, gate-fee's etc. However as a general rule of thumb a reasonably well designed and operated plant will ' wash through ' around 1-1.5% of the feed-stock un-digested as each batch is fed. This material can cause a problem if stored in sealed tanks, or covered lagoons. in hot weather. In general it is not to much of an issue, and in some cases as described by sjt01 above, it can be recirculated again through the process. The basic design criteria for retention time is that it should not exceed the life of the longest living bacteria. These vary with temperature, so higher operating temps require less retention time than lower temps.
  2. They haven't gone into the kind of detail I want, and only did blackgrass, I am doing a lot more species than that, and at differing temperatures and residence times. There are tonnes of studies but many of them were conducted abroad, and hence don't cover the species I am interested in or have near ridiculous residence times- one study kept samples in for 70 days, I want to establish the lower limits of viability if you see what I mean.
    thesilentone likes this.
  3. Elj

    Elj Member

    Thinking that I may have missed the boat as far as AD is concerned,but wondered if anyone new of any gas engines with the right accreditation that have been or are for sale.
    Ad plants not working or in administration are my first thought.
  4. sjt01

    sjt01 Member

    North Norfolk
    These folks seem to have a few, not sure how keen their prices are
  5. puntabrava

    puntabrava Member

  6. ADMaestro

    ADMaestro New Member

    I'm a bit late on the uptake here, but this still might be of some help. Any PAS110 accredited plant is required to assess the stability of their digestate/separated liquid by means of Residual Biogas Potential testing. The upper limit for the final product(s) is 0.45 l/g VS. This type of testing is also of use to any non-accredited plant to compare the biogas potential from the beginning of the process to the end.

    Depending on plant pipework/mixer orientation it is possible that maximum residence times are sometimes not achieved, when new feedstock is prematurely moved from the start of the process to the end without ample time to sufficiently digest.
    ollie989898 likes this.
  7. Fantastique. Thank you. I knew there was a reason work on my lit review had stalled.

Share This Page