Figure 1. Developmental Stages of Monitoring Technologies |
Biosensors
Until recently, the development of online monitoring equipment focused on the detection and analysis of physical/chemical compounds. Now, there is a shift toward sensors that can rapidly and reliably detect harmful microorganisms such as Legionella, Cryptosporidium, Giardia, and E. coli.
The rapid and accurate detection of micro-organisms is of particular value in the drinking water sector. Currently, analysis still relies on slow culturing methods, or polymerase chain reaction (PCR) methods, both of which can only be performed in a laboratory.
Optical sensors
The arrival of solid-state electronics and small high-powered light sources (LEDs, laser diodes, small Xenon lamps) has triggered a rapid development of optical sensor technology during the last decade. The most interesting aspect of the current generation of these sensors is that they operate without the need for chemicals and use components that are less prone to fouling.
When replacing wet-chemical analyzers, the elimination of the use of chemicals also eliminates the production of waste products during the analysis. This is a major advantage optical sensors have over wet-chemical analyzers.
New developments in the field of optical sensors focus on the following approaches:
- Development of luminescence-based technologies based on the success of the luminescent dissolved oxygen (LDO) probes, to measure other important parameters such as pH
- Use of optical imaging techniques, for example, in the detection and classification of particles and micro-organisms
- Use of unconventional physical properties as water quality indicators (e.g., refractive index)
- Contact-free measurement (remote sensing)
Recent developments in water quality sensor networks include:
- Miniaturized sensors for monitoring color, sum organics (COD, TOC, DOC) and turbidity in a drinking water distribution network (s::can, AT; Vitens Water Company, NL; funded by the European Commission)
- Non-mobile wireless sensors located in ponds and streams to measure various parameters such as turbidity, salinity, pH, and nitrate (University of Minnesota, USA)
- Robotic fish equipped with tiny chemical sensors to locate sources of potentially hazardous pollutants in the water, such as leaking underwater pipelines (University of Essex, UK; funded by the European Commission)
Maintenance requirements and battery life are currently two important barriers to the successful large-scale implementation of smart water quality sensor networks.
See also:
"Tracking water flow with floating robots"
"Water quality monitored by smart robot"
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