EDIT: ^ That paragraph will reduce turbidity as wellEutrophication can be counteracted by reducing the use of builders (phosphate based substances) in detergents that enter waterways - This often changes the nitrogen to phosphate ratio from the desired 10:1 (This ratio is a good indicator when the concentration of nitrates is >600 ppm and the concentration of phosphates is >60 ppm). Researchers are currently developing stronger non-ionic detergents to reduce the use of builders in detergents.
This will be easier to understand if you do Industrial ^
I guess you can relate reducing TDS to microscopic membrane filters or the filtration and clarification step in water sanitisation where lime is added to the water to increase pH which encourages the formation of precipitates. Then a flocculant such as aluminium chloride is added to flocculate these particles together, etc.