Building on the success of our earlier work, we now propose to use SANS to examine the floc structure and sedimentation behaviour of silver nanoparticles in wastewater matrices and the effects of addition of a chemical coagulant (ferric chloride, FeCl3) commonly used in wastewater treatment. The information we will obtain is of strategic importance to regulatory agencies assessing the risks posed to contemporary wastewater treatment processes by this emerging environmental pollutant and cannot be obtained by any other technique.