20 Water/Wastewater
Second Generation Water Monitoring Using Biological Early Warning Systems and Biological Assays
Currently water monitoring is performed according to EU Directives and National laws and is organised in temporal sampling and analysis of contaminants. Over several decades a wide range of tools, commonly called biosensors, have been developed for monitoring water quality. These devices can produce an early warning, a precocious alarm that can be used for sampling the “same” water that produces the warning; furthermore, this water sample can be used for biological assays, including biomarkers and ecotoxicology tests that provide extremely useful information on classification of pollutants.
Biological early warning systems
Although highly effective, this is only one of the many possible set-ups and for every application a suitable combination of one or more biosensors as well as instruments and facilities should be carefully evaluated.
Changes in the behaviour or properties of on-line biological early warning systems (BEWS) may indicate the sudden occurrence of a pollutant not detected by conventional, analytical warning systems (ILSI, 1999).
The goal of an early warning monitoring system is to reliably identify low probability/high impact contamination events (chemical, microbial or radioactive) in source water or distribution systems, in time to allow an effective local response that reduces or avoids entirely the adverse impacts that may result from the event (ILSI, 1999).
In long-term monitoring, the water quality is usually well known and so in this case expensive analysis costs may not prove to be cost effective; conversely, funding of early warning system could be effective.
As stated by ILSI (1999), the ideal EWS has these requirements: 1. Provides warning in sufficient time for action 2. Cost is affordable 3. Requires low skill and training 4. Covers all potential threats 5. Is able to identify the source 6. Is sensitive to quality changes at regulatory levels 7. Gives minimal false positive or negative responses 8. Is robust 9. Is reproducible and verifiable 10. Allows remote operation 11. Functions year-round
One single device alone, may not provide a good early warning system. In particular, requirements 1, 5 and 6 are very difficult to have together and 7, 9 and 11 are difficult to have with a biosensor. Requirement 1, 3, 8 and 10 need an engineering development, whereas 2 is only possible if the technologies are widely used in a public organisation having a leading role in and managing an early warning system network (EWSN). A EWSN may be useful for homogeneous environments such as for rivers and coastal areas.
Biosensors
A biosensor is an instrument that continuously records an organism’s behavioural and/or physiological response, and evaluates changes that could indicate pollution in the environment. These systems have several advantages and have been developed to fulfil any monitoring needs for a wide range of organisms. Furthermore because biosensors directly measure toxic effects, it provides an important tool to use in association with chemical monitoring technology. Biological measures of water quality can detect unexpected materials and evaluate the toxic effect of multiple chemicals. (EPA, 2001).
Epidemiological studies of drinking water will always address mixtures of agents and are unlikely to be able to identify which specific components of a mixture are associated with any adverse effect that might be identified (ILSI, 2002).
Depending on expected pollutants, biosensors can use the most suitable organism, as fish, bivalves and crustaceans are more sensitive to different classes of chemicals. Every organism provides a specific behavioural response to pollution, such as a change of position and movement in fish or a long closure of valves in bivalves.
Author Details: Federico Brunelli
Independent Consultant Address: 92 Saraceno, I-44121, Ferrara, Italy
Email:
f.brunelli@
bruneco.com View of instrument and accessories (left – ph. DeltaConsult®) and top view (right – ph. Brunelli) of Mosselmonitor® IET March / April 2012
www.envirotech-online.com
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