The analysis of phosphorus or phosphate is a critical measurement in the monitoring and control of wastewater and industrial effluent treatment. By taking care to select the most appropriate analysis technique, taking a representative sample and preparing it correctly this measurement is readily achieved. Once a reliable, repeatable measurement is made the correct control technique can be applied.
The removal of phosphate during the sewage treatment process has become a crucial area of interest as more and more works have a phosphorus discharge consent and with the ever increasing use of detergents containing phosphate the problem is growing. The natural removal of both nitrate and phosphate is the method of choice, however, in most cases it is not possible and therefore the operators have to resort to chemicals. In all cases the amount of chemical used is critical for the performance of the works, cost control and meeting the metal discharge consent.
The removal of phosphate is carried out by dosing metal salts commonly, aluminium and iron (aluminium sulphate, sodium aluminate, ferric/ferrous chloride, and ferric/ferrous sulphate). Traditionally the metal salts are dosed at a rate determined by a pre-set diurnal profile derived by analysing a series of samples over a period of time or by using a flow proportional control algorithm. However, recent developments in on-line analysers have made control algorithms based on phosphate loading a practical proposition.
Reliable, accurate and cost effective monitoring of phosphate and total phosphorus is achieved by Partech using the MicroMac analyser, this analyser is successfully making measurement at all stages of the waste water treatment process including the inlet.