Created by potrace 1.16, written by Peter Selinger 2001-2019

Carbon Capture in the Water Industry: Enhanced Mineral Weathering

WRc provided research and high-level assessment of potential applications of Enhanced Mineral Weathering (EMW), a technique to accelerate the natural weathering process which stores carbon as ocean alkalinity, removing CO2 from the atmosphere.

Utilised

our wealth of technical and strategic expertise to provide comprehensive insights into potential technique transfer from beginning to end

Delivered

research and high-level assessment of potential waste materials and mechanisms of Enhanced Mineral Weathering within the water sector

Outlined

clear steps for effective transition of an innovative long term carbon capture solution to advance the water industry towards net zero goals

Water industry aim for net zero

The water industry has made an ambitious pledge to achieve net zero carbon by 2030. It’s a big challenge, but water companies are committed to protecting and enhancing the environment and intend to be part of the solution to the climate crisis.

The water industry has already taken some significant steps to reduce gross operational emissions, cutting them by 43% in under a decade, and is now working hard to develop a collaborative action plan to identify further options to reduce carbon. Current focuses involve energy consumption best practices, 'green' energy approaches, increasing biogas availability, and reducing wastewater treatment plant emissions.

There is a need, however, to look at more radical and innovative solutions to ensure the industry meets the 2030 pledge.

Carbon capture acceleration

In the natural system, the weathering of silicate minerals plays an important role in removing CO2 from the atmosphere. This process generates alkalinity which is transmitted through rivers to the ocean where it is permanently stored, enabling reversal of anthropogenic ocean acidification (human-induced atmospheric CO2 causing a reduction of ocean PH).

However, this process is very slow, so research is currently being carried out to understand the potential for enhancing the rate of silicate weathering as a technique for carbon capture and storage - a technique commonly referred to as Enhanced Mineral Weathering (EMW)

Several alkaline waste streams in the UK meet the basic requirements for EMW, namely high pH and high mineral silicate or hydroxide content, and as wastes, do not pose the same level of carbon intensity to obtain as virgin materials, as well as avoiding landfill and promoting a circular economy. Another major consideration for EMW application is the mechanism used to enhance the rate of mineral dissolution.

Our circular economy solution

To further the development of this promising technique, WRc's Portfolio project delivered research and high-level assessment of potential waste materials and mechanisms of EMW within the water sector

Investigations and suggestions for further project development outlined a mixed approach; agricultural application through expertise in catchment management techniques alongside wastewater treatment works deployment.

Alkaline waste material candidates

Investigations highlighted five suitable candidate materials:

  • Paper sludge ash
  • Construction wastes
  • Waste mineral fines (e.g., basalt)
  • Steel slags
  • Biochar

While having good carbon capture potential and low environmental risk, the list includes fine grade material with both increased reaction rates and less current end-user demand. The realistic dissolution rates of these materials would need to be assessed in their potential applications.

Possible application routes

The work uncovered the EMW potential for wastewater treatment works via tailoring treatment processes and monitoring effluent, though further research is required to understand rates and effects of an optimised reactor.

  • Anaerobic digestion (and the acidic conditions generated) has the highest potential to increase dissolution rates
  • Co-benefits to EMW deployment may even prevent clogging
  • Possible risks include increased suspended solids present in the system

Investigations revealed the potential for CO2 drawdown from agricultural EMW application using existing machinery, which may even benefit soil PH, thus nutrient availability. Future work can establish these findings and their resulting environmental impacts.

Catchment impacts of delivery

Research, and historical attempts to reverse acidification, point toward the potential for river systems to transport significant volumes of alkalinity to the ocean with minimal impact of altered PH on biota. Further study can better understand this risk and possible impacts on inorganic carbonate precipitation in rivers. Also suggested, is evaluation of water chemistry changes with regards to local river conditions, organisms present, and the riverine inorganic carbonate system. 

This work clearly outlines steps for EMW delivery in the water sector, and can feed into the development of an appropriate management strategy to ensure safe deployment of this technique across a catchment, to ensure stable long-term carbon capture.

Research driven by environmental evidence

Optimising avenues for sustainability

Varied services delivering combined solutions 

Experienced consulting on emerging technologies

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Created by potrace 1.16, written by Peter Selinger 2001-2019

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