Aeroflow Sustainable Active Treatment (SAT) Phase 2

Abandoned metal mines cause multiple failures of WFD standards in Wales, with c.1,300 mines impacting over 700 km of rivers. The Failing Waterbodies Report (Coal Authority, 2020) commissioned by NRW identified that remedial works at the 129 highest priority sites would be circa 278 million GBP. The Metal Mine Programme is therefore committed to identifying new treatment technologies that could reduce on-going operation and maintenance costs.

Typical categorisation of active or passive treatment systems does not account for recent technological advancement. Passive systems typically require maintenance/refurbishment during their whole life (40 years) to ensure that performance remains effective, enabling metal removal. Fully active systems, such as High Density Sludge (HDS), often have high CAPEX and OPEX costs, and a large constituent of OPEX are energy and reagent costs as well as sludge disposal. Spent media in passive systems and sludge possess high metal content and current advice is that this must be disposed of as hazardous waste to landfill in England. Metal recovery from sludge is also difficult, warranting separate research and development. At higher mine water flow rates, greater energy or treatment media is required, increasing costs.

CET has presented a potential alternative solution for treating circum-neutral pH mine water. CET is a newly formed 50/50 joint venture research company owned and managed by Mine Environment Management Ltd (MEM) and Maelgwyn Mineral Services Ltd (MMS). CET has created a technical team from MMS and MEM that has identified degassing circum-neutral mine water using the MMS-patented Aachen™ reactor and oxidation using patented slot aerator can increase the pH sufficiently enabling sorption to remove metals.

The CET Aeroflow SAT system has been developed based on the need for a flexible and adaptive modular system to account for the complexity and site-specific nature of water treatment requirements in a mining context. Degassing and oxidation as options have the potential to be less expensive in material, energy and carbon than traditional HDS systems. Metal removal by sorption can be achieved by adding media, with the process eliminating or vastly reducing sludge production, improving potential metal recovery and reducing residual waste costs.

The Aeroflow SAT provides an opportunity to develop a flexible, cost-effective and more sustainable remediation solution for our treatment toolbox with lower energy and waste disposal costs.

Following the completion of Phase 1 (lab trials), this VEAT notice is being published to cover the additional costs for Phase 2 (field trials).