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Could Natural Water Treatment Work for Cambridge?

Anglian Water are one of the largest users of power in the East of England, so I was pleased to see that they have set themselves a target of being Net Zero Carbon by 2030.  As construction accounts for about 15% of their carbon footprint, it’s also good that they’re being thorough by including both operational and capital emissions in this target. But we now have a good opportunity to see if this ambition is real..

A few weeks ago, Anglian Water announced the start of their consultation on moving the Water Treatment Works from its current site near Cambridge North Station to one of 3 possible alternatives. While making nice claims about aiming to be more modern and carbon efficient, the primary reason for the move is because Anglian Water have been told to release the land for housing.

The problem is that unless they demonstrate serious ambition, the construction and operation of the new plant will make it harder to get to Net Zero Carbon. I’ve been asking them what they plan to make the relocation compatible with the target, but as yet I have received no clear reply…

Pumping the sewage to the new site will increase energy demand. Although a more modern Treatment Works should require less energy to run and the steady decarbonisation of the electricity grid will help, there will be important choices to make.  They could install huge areas of PV, either on land or on water. They could scale up their anaerobic digestion (ie poo power). They could install massive batteries to allow them use and trade their renewables more efficiently. But there are still likely to be some net emissions.

Potentially they could offset these by paying for plant tree-planting in the catchment. Trees will absorb carbon emission and help clean up agricultural phosphates: a damaging pollutant that costs Anglian Water a lot to remove. This seems like a nice “win-win” solution but will need a LOT of trees.

Another, more radical solution is to use natural treatment processes, such as reedbeds and wetlands to reduce the need for the traditional tanks and concrete.   These have been used very successfully at Anglian Waters Ingoldisthorpe Water Treatment Works in Norfolk, where they proudly say that it “vastly reduc[es] our carbon footprint, costs and most importantly, enhance[es] the local environment and ecosystems.”   Could this form part of the solution for Cambridge too?

Things are never as simple as they seem, but there are important choices to be made.

The community should be involved in this, so do respond to the consultation before its deadline of 19th August, and make it clear that, whichever site is chosen, we want it “Net Zero Carbon”.

Anne Miller Carbon Neutral Cambridge