Sediment is insoluble particles in the foam concentrate.
Source: IMO MSC.1/Circ.1312, Revised Guidelines for the performance and testing criteria, and surveys of foam concentrates for fixed fire-extinguishing systems, 10 June 2009, International Maritime Organization. Regulatory Guidance
“Sediments” means matter settled out of Ballast Water within a ship.
Source: International Convention for the Control and Management of Ships’ Ballast Water and Sediments, 2004. Legislation