SAMOS clean-up for water system
15 Jan 2000
Southern Water's Testwood treatment plant is well equipped to detect herbicides and pesticides contaminating the water supply. An on-line diode-array chromatography system, dubbed SAMOS (system for the automatic monitoring of organic substances) detects, analyses and quantifies any contaminants in the river water, and adjusts the plant's activated carbon beds to cope with the influx of pollution.
Ironically, the accuracy of the analysis depends on how clean the water is. The SAMOS only works on samples that contain only the dissolved pollutants, so the plant design incorporates membrane filters to remove particulates before the analysis stage. However, even these filters need to be protected. The `raw' water, containing silt, weeds and many other contaminants, would quickly block them.
Hewlett Packard, which makes the SAMOS, recommended that Southern Water should install a Cross pre-filtration system ahead of the membrane filters. The Cross EasyClean Auto system is based around a stainless steel coiled filter element with raised `nidges' on the surface to provide a precise filtration gap. The system operates at flow-rates up to 1.3 litres per second, and incorporates a controller, a pressure vessel for backwash water and backwash actuator. The filter coil opens up completely during backwashing, to ensure complete cleaning with the minimum of water.
