Because phosphorus has a strong affinity for soil, little dissolved phosphorus will be transported in runoff. Instead, the eroded sediments from mining and agricultural areas carry the adsorbed phosphorus to the water body. An additional source is the overboard discharge of phosphorus-containing sewage by boats. A normal adult excretes 1.3 - 1.5 g of phosphorus per day. Additional phosphorus originates from the use of industrial products, such as toothpaste, detergents, pharmaceuticals, and food-treating compounds.
Tertiary treatment is required to remove additional phosphorus from the water.
The amount of additional phosphorus that can be removed varies with the success of the treatment technologies used. Phosphates are primarily discharged directly into the water body by sewage treatment plants. Nitric Acid-Sulfuric Acid Method Recommended for most samples. This simple method should be cross-checked with one or more thorough techniques and adopted if results are identical. Ammonium molybdate and potassium antimonyl tartrate react with orthophosphate to form a heteropoly acid that is reduced to molybdenum blue by ascorbic acid.