Key points
- TMC releases return water from its nodule collection system at a depth of 2,000 meters, a level chosen because most fisheries and zooplankton live in the top 1,000 meters of the water column.
- The company says discharging at 2,000 meters bypasses roughly 95% of marine life, with the sediment diluting to background levels within a few hundred meters.
- During the pilot, a vibrating-deck separator on the service vessel had a 1 mm cut level, and nodule abrasion produced fragments below 1 mm found in the return water.
- Sediment picked up with seawater during collection is separated from the nodules and discharged through a dedicated return pipe.
