Friday, August 12, 2011

Five Good Reasons You Should Support Anaerobic Digestion Including Co-Digestion With WWTW Sludge

Ever thought about endeavoring to support anaerobic digestion including co-digestion of the organic fraction of MSW with sewage sludge? Most people just consider this briefly, then never do anything whatsoever regarding it Most people have no idea of just how to start, so they really never do. Thinking that it'd require too much time to understand the concept discourages some others. Others are too lazy to try, or don't have motivation!!


Now just hang on here a minute! Are those really valid reasons? Did the reasons for receive a fair hearing? Was there enough info on which to base a reasonable decision? The possible benefits don't appear to have been very well considered...

Maybe that needs to be reconsidered. Let's look at 5 top reasons to support anaerobic digestion including co-digestion of MSW with sewage sludge to see how things look from that perspective.

To start with, AD (including co-digestion) has great potential to minimise the impact on the carbon economy by replacing fossil fuel derived power and heat. You've got a valid point as you note that replacing fossil fuel derived power and heat is going to become scarcer and even more expensive. That's a very good point. Even so, take into account that, anaerobic digestion isn't exactly cheap, and to rely on government AD subsidies and incentives lasting as long as they say they will is quite a leap of faith. Moreover, consider that most governments don't last more than 4 to 5 years, when investment is returned on these AD plants over a much longer period.

Second, anaerobic digestion enables diversion of wastes from landfill. That is because all of the output from the anaerobic digester will in future be used in the process. One of several results of this is the fact that there will be virtually no waste from AD Plants that they will need to send to landfill.

Third, by co-digestion (if OFWAT's review gives it the go-ahead in AMP5) society would be avoiding the carbon cost of full treatment of wastes through sewage treatment processes by feeding directly to co-digestion. Moreover, biogas yields may rise by up to 50%, with little or no further investment. Co-digestion simply uses existing headroom in AD Plants that the Water Plcs's engineers have already made more efficient!

Fourth, production of digestate to act as a fertiliser will provide a big phosphate benefit, and this is good as phosphate reserves are finite and may run out sooner than oil.

5th, the locality of AD plants can lead to reduced transportation - optimising the use of embedded carbon in existing assets.

So just look at those points and examine them mentally. All five reasons are persuasive points as to the reasons you really should support anaerobic digestion including co-digestion of MSW with sewage sludge.

Just think it over for a moment. Those reasons were sufficient to convince a lot of people before you. Will they not also persuade you to support anaerobic digestion including co-digestion of msw with sewage sludge?

Find out how you can get involved in the growing Anaerobic Digestion scene, and understand what "digestate" is by going to our What is digestate? page at

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