As a licensed operation, there are clear guidelines and stringent requirements on emission levels. The environmental authorities have tough standards for the 12 annual water sampling tests.

– The water quality is continuously monitored. Out of the 12 monthly average values, 10 must meet the approved limits set by the County Administrative Board, says Lina Hamel, project manager at Swedish Hydro Solutions.

Specific Requirements – Custom-Designed Solution

The conditions for such an operation are highly specific, and Swedish Hydro Solutions has therefore designed a water treatment plant tailored to meet these needs. The water treatment facility is a permanent installation, so the directives for its construction and performance have been very clear. Among other things, it was specified that serially connected carbon filters should be used.

– We spent a lot of time finding the right solution, says Lina Hamel. The planning phase began as early as April 2023 and continued until October, when we started installing the plant. The initial startup took place in early November, and after several tests, water analyses, and adjustments, the system was put into operation on November 20th, explains Lina Hamel.

– This is an operation with unique conditions, and it requires a unique solution, she continues.

Large Paved Areas Require Redundancy

The process involves separating the valuable metals in the cables from their protective casings. In cheaper cables, the casing is often made of plastic, while in more expensive variants, it’s made of Teflon. The plastic casings' softeners and Teflon mean that the water treatment system must handle both PFAS and various phthalates, in addition to obvious pollutants like copper, lead, zinc, and aluminum.

The waste management area is very large. The material to be recycled is sorted and placed on paved surfaces, where rain and snow carry contaminants into the stormwater. But before the contaminated water reaches the treatment facility, it passes through several stages. First, it flows into a gravel bed laid on a waterproof liner. Drainage pipes then guide the water to a collection well equipped with filters, from where it is led to two parallel oil separators. From the stormwater area, the water is pumped to two separate pond structures, one of which holds 990 m³, providing a balancing effect.

– When it rains after a long dry period, the concentration of pollutants can be particularly high. Having a pond as part of the treatment facility serves two purposes. First, it provides built-in redundancy, enabling the system to handle temporarily large volumes of water. Second, it ensures a more consistent incoming water quality during times when pollution levels are high early in the process, explains Lina Hamel.

How the System Works

From the pond, the water is pumped into a specially designed HydroBox, where chitosan is added. From the HydroBox, the water is pumped to a lamella clarifier and then passes through a sand filter. After that, it flows through two serially connected carbon filters and finally into an IBC tank, where continuous water samples are taken. Swedish Hydro Solutions’ measuring equipment is also installed here, and its values can be monitored in real-time via our cloud service. A geotube is also present on-site, which dewaters the sludge from the lamella clarifier.

The facility handles 3 m³ of water per hour, and sampling shows good treatment results.

– This demonstrates that it’s possible to treat difficult industrial stormwater with good results, simply by choosing the best available technology, says Lina Hamel.

Since mid-October last year, the facility has processed 3,700 m³ of water. When pumping occurs, nearly 5 m³ of water is treated per hour. The permanent installation must handle 14,000 m³ of water per year, as required by the County Administrative Board.