Contaminated Storm Water Treatment and Reuse

Stormwater, storm water, enviro concepts

Our client, is an aluminum smelting plant and was collecting surface water runoff with high levels of contaminants in their 4 Million Litre stormwater collection pond. The agreement with EPA local authorities allowed them to discharge water at a cost, as long as it was filtered to an acceptable level of impurities. The main concern and challenge was to maintain or lower the level of Fluoride, or face shut downs and large fines.

Solution

After a review by Enviro Concept Process Engineer, in collaboration with onsite objectives and local regulations for compliance, we provided a solution that met EPA requirements.
The highlights of the project are:

  • Collection and Settling was already being done through the Stormwater Collection Pond. We pumped from here into our System Feed Tank.
  • The first stage ofmechanical filtrationused an Ultra Filtration (UF) Membrane. This technology allows for a reduction of suspended solids in the waste stream to less than 0.01 micron. Ultra Filtration is a common way to remove the larger particles and suspended solids found in the water and is often the primary stage of treatment. In this case, it is the pre-treatment for our second stage.
  • The UF Filtrate was then pushed through theReverse Osmosis (RO)Membrane which is capable of screening 75% of the water stream down to 0.0001 micron. This meant the fluoride and all other pollutants were removed, producing pure water.
  • TheRO Reject Water(balance 25%) from the membrane now containing higher concentrations of impurities, was sent through an Absorption Filter (in this case Activated Alumina). This was able to filter the water to an acceptable quality for re-use in factory processes.

storm water, stormwater, enviro concepts

Outcome & Benefits

Our Stormwater Treatment Plant was able to treat nearly 100% of the collected stormwater and turn it into a useful product source replacing up to 400,000 Litres of fresh mains water every day.

The result is almost no discharge to the environment.

No Discharge Costs

No Impact to the Environment

No Shutdowns or Fines.

Almost as importantly, the SAVINGS on 400KL per day for fresh water are huge. And this saving will be ongoing for the life of the plant.

Return on Investment

Within 2 years of continuous use, the client achieves positive ROI by combining cost savings from reduced discharge costs and reduction in fresh water use.