Technical help: Request for clarification regarding the concept of phosphorus
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This post was last edited by hesonchang214 on 2012-11-22 at 09:12. Could someone please explain the concepts, differences, and relationships between total phosphorus, orthophosphorus, organic phosphorus, and inorganic phosphorus in recirculating water? Thank you!
Total phosphorus includes orthophosphorus, organic phosphorus, and inorganic phosphorus, being the sum of these three. Orthophosphorus exists mainly in the form of phosphate ions, and it is also the main factor contributing to phosphate scale formation. Inorganic phosphorus presumably includes both orthophosphorus and phosphorous. It is the organic phosphines that actually play a key role in pesticides, existing primarily in the form of organic phosphonic acids. This is my personal understanding; I welcome everyone to discuss it together!
Total phosphorus includes organic phosphorus and inorganic phosphorus. Inorganic phosphorus is divided into orthophosphates and pyrophosphates
Total phosphorus = organic phosphorus + inorganic phosphorus. Inorganic phosphorus = orthophosphorus + hypophosphorus. Since hypophosphorus is unstable, it is usually expressed in the form of orthophosphorus; therefore, total phosphorus = organic phosphorus + orthophosphorus. In normal use, it is the organic phosphorus that plays a role, but organic phosphorus cannot be measured directly. It can only be determined by measuring total phosphorus and orthophosphorus and then calculating accordingly. Orthophosphate in circulating water is a product of the metabolism of organic phosphorus; it serves as a nutrient required for the growth of certain bacteria and algae. Therefore, its concentration should not be too high. It can be reduced by means of blowdown.
Reply to 4# zhongnanchem: Thanks! Very rewarding!
The conventional testing methods measure total phosphorus, which includes organic phosphorus, inorganic phosphorus, and phosphorous acid. In circulating water, the amount of phosphorous acid is very small and can be ignored; therefore, it can be said to be the sum of organic phosphorus and inorganic phosphorus! !
Excuse me, what should the respective limits for organic phosphorus and inorganic phosphorus be? Is it a 1:1 relationship between them?
Generally, different water treatment companies have varying standards for controlling total phosphorus in circulating water, and there are also differences in the total phosphorus content in the chemicals used as well as in the quality of the circulating water. There is no real standard for total phosphorus yet; we generally ask our customers to keep the total phosphorus level at 3-5 ppm, with inorganic phosphorus at less than 1 ppm. Meanwhile, some manufacturers can achieve a total phosphorus level of seven to eight ppm. Some manufacturers also use phosphorus-free agents, eliminating the need to control total phosphorus. My personal suggestion: if the water used for irrigation is reclaimed water or water from the Yellow River basin, where the COD level is relatively high, it is advisable to use low-phosphorus or phosphorus-free formulations. Where the Yangtze River system or groundwater is used for replenishment, the total phosphorus level can be increased appropriately.