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I suggest turning waster water into a source of fuel and fertilizer for energy plants



I suggest producing biogas from waste water trough anaerobic digestion. The remaining sludge can be used to grow energy crops, enhancing the production of biogas. The resulting biogas can be used in the production of electricity and heat. After proper cleaning, it can also be used to replace fossil fuels in buses, personal cars and other vehicles. 

What actions do you propose?

In an conventional linear thinking the resulting sludge from waste water cleaning will be a problem to take care of, in a modern circular economy it will be a valuable resource: a source of clean energy and fertilizer. Treating waste water as a resource instead of as an problem will bring several benefits:

1) Trough anaerobic digestion of wastewater we can produce biogas which can be be upgraded to utility gas quality replacing fossil gas used for heating.

2) Fertilizers, which can be used to grow energy crops, that can be added to the biogas digester as well. Altenatively, it use as fertilizers to trees that binds carbon dioxide as they grow.

Biogas bus, Stockholm CityAfter proper treatment the resulting biogas can be used to run buses and converted automobiles.

Here is an example of an biogas tanking station at Brommaplan waste water treatment plant in Stockholm, Sweden. It seems to be especially popular among taxidrivers appreciating its lower price compared to gasoline. During the last three years biogas has constantly been at least 1 SEK cheaper than gasoline per liter. An additional bonus is that gas buses and automobliles emit less noise and particulate matter than vehicles they replace.

The production of biogas can be further enhanced by planting energy crops and trees as protection zones along waterways to catch run-offs from agricultural lands. Adding these to the biogas digester will create a similar double dividend: energy production and avoided eutrophication.

Who will take these actions?

The main actors will be municipal and industrial waster water treatment plants. 

Bus companies, taxi companies and citizens are incentivized to convert the vehicles to run on biogas with lower fuel costs.

Farmers needing extra incomes, can turn protection zones into cash generators.


Where will these actions be taken?

Anywhere, where waste water are currently considered a problem, and cost effective climate friendly electricity, heat or vehicle fuels are needed.

Anywhere, where protection zones are needed along waterways.

How will these actions have a high impact in addressing climate change?

  • It will climate friendly fuel to replace fossil fuels,
  • minimize methane leakage at waste water treatment plants,
  • and provide fertilizer to grow energy plants replacing further fossil fuels.

What are other key benefits?

What are the proposal’s costs?

It will save money compared to the current situation where the energy & fertilizer content in waste water is wasted.

Time line

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