Environment and Climate Change Canada (ECCC) is expected to introduce the Coal Mining Effluent Regulations (CMERs) in 2026. The CMERs will specify national water effluent quality limits for selenium, nitrate, and total suspended solids (TSS), alongside new monitoring and reporting requirements. These regulations will apply to both existing and new coal mines across Canada.
WHY SELENIUM AND NITRATE MATTER IN COAL MINING WATER
Selenium and nitrate removal in mining wastewater are now top priorities for coal operators. Selenium and nitrate can be released through coal deposits and processing operations, with contaminants often carried in run-off into groundwater. This in turn creates a potential risk to receiving waters and their aquatic ecosystems. Alongside selenium and nitrate, total suspended solids (TSS) will also be regulated under the CMERs, adding further compliance requirements for operators.
The CMERs will increase compliance pressure on operators to achieve reliable, verifiable performance at consistently low concentrations, a critical step both to protect aquatic ecosystems and to safeguard mining operations from regulatory and reputational risk.
PROVEN TREATMENT PATHWAYS
For more than a decade, Envirogen has been developing and operating treatment solutions for coal mining water. These technologies are proven in the field internationally and are directly applicable to Canadian coal mining operations. They are designed to meet stringent discharge limits under challenging, variable conditions.
Biological Fluidized Bed Reactors (FBRs) for selenium and nitrate:
- Proven reduction of selenium to low micrograms per litre (µg/L) and nitrate to less than 0.1 milligrams per litre (mg/L), to meet the strictest effluent requirements.
- Faster treatment with shorter residence time compared to other biological systems.
- Reliable performance that adapts to variations in feed flow and composition.
- Modular, all-weather designs with built-in protection to suit challenging site conditions.
Regenerable Ion Exchange (IX) for mining water treatment:
- High-efficiency removal of selenium and nitrate to low micrograms per litre (µg/L) and less than 0.1 milligrams per litre (mg/L), respectively, to meet the strictest effluent requirements.
- Staggered bed approach extends resin life and reduces regeneration frequency and salt usage.
- Flexible operation, continuous or intermittent, with no decline in performance.
- Prepackaged in a containerized unit or skidded to be placed in a building, minimizing installation costs.
DESIGNING FOR COMPLIANCE, RESILIENCE, AND LIFECYCLE COST
Each site presents different geology, flows, and seasonal variability. Choosing between FBR and IX (or deploying them in series) depends on influent quality, flow-profile, footprint constraints, power and reagent availability, and operator preference. Envirogen applies a life cycle cost approach to balance capital and operating costs while safeguarding long-term compliance and uptime.
DATA, MONITORING, AND REPORTING
With the upcoming coal mining effluent regulations in Canada expected to include monitoring and record-keeping requirements, reliable instrumentation and data management are as important as the process design.
GETTING READY FOR CMERS
Canadian mines preparing for the CMERs should review current water quality, assess risk from variability and storm events, evaluate treatment options against discharge targets, and plan for data and reporting workflows. Envirogen supports desktop assessments, pilot testing, and phased deployment to de-risk full-scale implementation.
COMPLIMENTARY CONSULTATION
Working on a mining wastewater treatment project in Canada? Contact Envirogen to discuss options for selenium and nitrate removal in mining wastewater, pilot validation, and a clear pathway to CMER compliance.
North America Head Office
Envirogen Technologies
700 Rockmead Drive, Suite 100
Kingwood, TX
77339
T: +1 713 766 6270
United Kingdom Head Office
Envirogen Group
Unit 9, Wimsey Way
Alfreton Trading Estate
Alfreton, DE55 4LS
T: +44 (0) 1773 441029
Europe Head Office
Envirogen Technologies bv
Penningweg 71
1507 DG Zaandam
The Netherlands
T: +31 75 204 7200