Case study · Completed July 2026

Molybdenum removal and rapid drawdown of a 12.8 ML tank in 31 days

A thermal energy storage tank holding 12.8 ML of contaminated water had to be emptied fast. We used ion exchange for molybdenum removal so the water met the trade waste discharge permit, discharged it to sewer and cleared the sludge from the tank floor, handing back a clean, empty tank.

Molybdenum removal: eureka Mobile Pure Water container in front of the thermal energy storage tank

The challenge

The tank had to be drawn down quickly, but the water could not simply be released. Molybdenum was above the limit in the site’s trade waste permit, and the permit also capped discharge at 9 L/s. At that rate, treating and discharging 12.8 ML inside the timeframe left little room for delays.

Five ion exchange vessels in a row beside a holding tank — Ion exchange vessels set up to target molybdenum

Molybdenum removal: what we did

We set up ion exchange vessels selected to target the dissolved molybdenum, with our containerised reverse osmosis unit polishing the water and keeping throughput steady. Water quality was sampled and tested throughout, keeping molybdenum below 10 mg/L and discharge below 9 L/s, in line with the trade waste permit.

Reverse osmosis unit inside the Mobile Pure Water container — Containerised reverse osmosis treating the tank water

Once the tank was drawn down, our team removed the sludge that had settled on the tank floor, working under confined space entry procedures.

Worker clearing sludge from the floor inside a drained storage tank — Final step: clearing sludge from the empty tank

The result

The tank was drawn down, treated and discharged within the 31-day window. Closeout testing confirmed molybdenum and flow were within the permit limits, and the tank was handed back empty and clear of sludge.

At a glance

Water treated

12.8 ML

Timeframe

31 days, mobilisation to closeout

Molybdenum at discharge

Below 10 mg/L

Discharge rate

Below 9 L/s

Discharge route

Sewer, under a trade waste permit

Completed