Domestic Wastewater Treatment as a Net Energy Producer–Can This be Achieved?

2011 pubs.acs.org/doi/full/10.1021/es2014264

Abstract
In seeking greater sustainability in water resources management, wastewater is now being considered more as a resource than as a waste—a resource for water, for plant nutrients, and for energy. Energy, the primary focus of this article, can be obtained from wastewater's organic as well as from its thermal content. Also, using wastewater’s nitrogen and P nutrients for plant fertilization, rather than wasting them, helps offset the high energy cost of producing synthetic fertilizers. Microbial fuel cells offer potential for direct biological conversion of wastewater’s organic materials into electricity, although significant improvements are needed for this process to be competitive with anaerobic biological conversion of wastewater organics into biogas, a renewable fuel used in electricity generation. Newer membrane processes coupled with complete anaerobic treatment of wastewater offer the potential for wastewater treatment to become a net generator of energy, rather than the large energy consumer that it is today.

see Table 1. Energy Characteristics of a Typical Domestic Wastewater

and
June 2014 energy.gov/sites/prod/files/2014/06/f16/...rt%20June%202014.pdf
In an effort to bring more integrated research across its programs, the DOE’s Water-Energy Tech Team issued a new report this month,
The Water-Energy Nexus: Challenges and Opportunities.

One set of promising possibilities involves the replacement of aerobic treatments, which consume 50 percent to 65 percent of the electricity in traditional treatment streams, with anaerobic alternatives (McCarty et al. 2011). Another entails pretreatment techniques that enhance the production of biogas from anaerobic digesters, reduce the volume of sludge requiring disposal, and enhance the resilience of such facilities to power outages (Neyens and Baeyens 2003). A third group of opportunities offers significant energy savings in the removal of nitrogen, a growing area of energy consumption, driven by expectations of expanded regulatory requirements (Joss et al. 2011).

slowly but surly...

Regards,
Detlef

4 min video: Brian Mercer Award for Innovation - David Stuckey

2008

The Brian Mercer Award for Innovation provides funding for individuals or groups to develop an already proven concept or prototype in the general areas of the built environment and nanoscience/ nanotechnology through to the creation of a near-market product for commercial exploitation, ie to a stage where an approach for venture capital becomes a reality.

Dear Colleagues,

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 www.deus21.de and
- "CARISMO"(Carbon is money) Kompetenzzentrums Wasser Berlin www.kompetenz-wasser.de/CARISMO.519.0.html)
- and others, you name it please!

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

All the Best
Detlef SCHWAGER