Phosphate measurement system

The STIP Helios in situ phosphate measurement system is typically used for monitoring the dosing of precipitants and nutrients in wastewater, but is extendable for use in biochemical applications such as fermentation, and even in lower phosphate concentration ranges like drinking water.

Accurate monitoring of the phosphate concentration can reduce the costs of running a wastewater treatment plant significantly. The modular construction of the phosphate monitoring buoy is of benefit, especially with regard to maintenance. The lowest module of the buoy is the filtration cell which is also used for storage of filtered sample. From here the clear measuring solution is transported up to the next level where all fluid mechanical components are stored. This system is designed as a continuous flow analysis with segregated fluid transportation which only needs one pump.

In the fluidic module the sample is treated with all the required reagents. The resulting colour complex is then photometrically detected in an optical cell with a monolitical set-up. Two different wavelengths of light are used to compensate for matrix effects.

In the next two upper-positioned modules there are the electronics of the analyser along with the compressor unit which is responsible for filling and discharging the filtration cell. In the top level a carousel with five colour-coded storage bottles for reagents and a cleansing solution is placed. After lifting the cover of buoy the individual chemical containers can be easily replaced.

The unit operates in situ, directly in the wastewater or activated sludge. The system has an integrated filtration system with automatic back wash by ejecting the filtrate from the previous measurement, thus ensuring reliable effective filter cleaning and only requires maintenance every four weeks. The self-sufficient photometer automatically cleans the sample chamber and cuvette and self-calibration is automated daily.