Sense or Nonsense ? Fossil Carbon energy wasted just to destroy more Carbon energy at "advanced" WWTP's?

Dear Colleagues,
In reference to "CIWEM Report - A Blueprint for Carbon Emissions Reduction in the UK Water Industry", I would like to start this topic, so practitioners and visioners may exchange views and "believes" about the future of ongoing water based WWTP's around the world, regardless "warm" or "cold" countries or political systems and -ism's involved.

For the time being "we" use much fossil carbon energy just to destroy very much more carbon energy at so called "advanced" WWPT's in "developed" countries, the "3 upper class-castles". This wasting might be fine if cheap fossil carbon energy would be endless available. But soldiers could and do make this fossil carbon energy just for a short time longer available for this 3 "upper class" castles EU, USA and China ( .... This is my general view on our energy wasting "system" around us.
But to simplify it, lets talk now only about technology, despite if all is seen only from the technology point of view, it will not be helpful...

To get more touchable on the topic, let me put up a technology hypothesis by using AD-systems:

An ABR e.g., is in my opinion just an improved UASB by purposely simplifications, as it is made from a number of UASB-tanks in series and do not need inoculate to start up, just anaerobic sludge is good enough. Even in 8-20 gradC it is OK for ABR under cold Europe condition. Larger HRT and voluminas are OK and planed, as a "cold" system like this produces energy instead of using it, with a by-effect 90% less FS (theoretical )!!! It will minimizing problems on agriculture contamination or costly incineration too. Under "cold" conditions much Methane will be in solution within effluent. So it needs Downstream Separations by simple cascades or cheap membranes, to make use of Methane and prevent GHG-emmisions. After AD and methane-gas separation simple aerobic treatment via simple bio-film plants (like engineered wetland or CW) and so on (or even a secondary costly ANAMOX-system, if no space is available).

This "low- to medium tech" is "good enough" for simple domestic sewage (mass-volumes), no need for high-tech AD +++ as it is used rightly within industrial-wwtp's for difficult industrial-sewage.

Make use of chemical energy content is the first step to recover nutrients like P & N too in an economical way. Because past nutrients recover developments been based only on additional energies from "outside".

For industrial and special sewage and e.g. for removal of trace organics in water/waste-water advanced techniques are highly necessary. This trace organics should not be used to argue for and to establish expensive "end of pipe" systems in domestic sewage-wwtp just for simple domestic mass sewage. It would be a very costly over-engineering "at this ends of pipes".

No need "to take a sledgehammer to crack a nut".

Over-engineered examples like DEUS 21 & CARISMO, in my opinion just swallowing R&D-money. This high-tech will not be a technology solution for existing domestic WWTP's, for the mass volumes on sewage:
- "DEUS 21" Frauenhofer Institut and
- "CARISMO"(Carbon is money) Kompetenzzentrums Wasser Berlin
- and others, you name it please!

I would appreciate your inputs, views, "believes" and reply's on this topic.

All the Best
Detlef SCHWAGER MSc Tropical Water Engineering
Sanitation-Solutions without external energy
Low-Tech Solutions with High-Tech Effects
"Inspired by Circular Economy"