| Resumo: |
The threat of a deliberate contamination of water supplies is permanently under consideration, by governmental bodies, national security agents and scientific community. Several points of vulnerability of water distribution systems are identified, as for example, drinking water can become contaminated at the original water source, during treatment, in the treated water reservoirs or in the pipes of the distribution network.
Measures against deliberate contamination have been intensified in the last few years, mainly through surveillance and protection procedures. Major knowledge gaps exist with regards to the feasibility of the detection and remediation methods to quickly detect the contamination, especially that originated by emergent chemicals. Besides that fact, the access to a great variety of chemicals is globalized and some countries do not have so effective control measures, as those implemented by UE and USA. Therefore the risk of obtaining some restricted chemicals with potent toxic effects at extremely low doses, is real. Moreover, the operational procedures to restore the water quality after a detected contamination need to consider the difficulty of cleaning pipe walls, where deposits and/or biofilm s may represent an additional "vulnerability". Even after the bulk water is disinfected, sorption of the contaminants by depositslbiofilms has to be considered, because unexpected detachment of these materials from the wall pipes may reactivate at some extent the contamination.
Because the physical-chemical characteristics of the contaminants affect the sorption, the dispersion and the
accumulation patterns, target compounds with different characteristics were selected, in order to define the best remediation strategy. Those include two different kinds of chemicals: (a) "old" toxicants that may be easily acquired and manipulated (an organophosphate fungicide chlorfenvinphos, a carbamate insecticide carbofuranand an herbicide p  |
Resumo
The threat of a deliberate contamination of water supplies is permanently under consideration, by governmental bodies, national security agents and scientific community. Several points of vulnerability of water distribution systems are identified, as for example, drinking water can become contaminated at the original water source, during treatment, in the treated water reservoirs or in the pipes of the distribution network.
Measures against deliberate contamination have been intensified in the last few years, mainly through surveillance and protection procedures. Major knowledge gaps exist with regards to the feasibility of the detection and remediation methods to quickly detect the contamination, especially that originated by emergent chemicals. Besides that fact, the access to a great variety of chemicals is globalized and some countries do not have so effective control measures, as those implemented by UE and USA. Therefore the risk of obtaining some restricted chemicals with potent toxic effects at extremely low doses, is real. Moreover, the operational procedures to restore the water quality after a detected contamination need to consider the difficulty of cleaning pipe walls, where deposits and/or biofilm s may represent an additional "vulnerability". Even after the bulk water is disinfected, sorption of the contaminants by depositslbiofilms has to be considered, because unexpected detachment of these materials from the wall pipes may reactivate at some extent the contamination.
Because the physical-chemical characteristics of the contaminants affect the sorption, the dispersion and the
accumulation patterns, target compounds with different characteristics were selected, in order to define the best remediation strategy. Those include two different kinds of chemicals: (a) "old" toxicants that may be easily acquired and manipulated (an organophosphate fungicide chlorfenvinphos, a carbamate insecticide carbofuranand an herbicide paraquat) and (b) "emergent" substances with lethal effects at extremely low doses (a brominated flame retardant- BDEIOO) .
This project brings together some expertise gained in the past with EU projects (e.g. SAFER) and national programmes in the field of analytical methodologies for trace analysis, of advanced oxidation processes and of biofilms behavior). From past experience of the research team related to organic micropollutants , some target compounds are defined to act as model s aiming the development of fast screening analytical methods and the development of sorption models. Also from past experience, we recognize that wall/deposits/biofilms are crucial zones where contaminants may accumulate with unexpected consequences. Sorption/desorption to pipe walls and deposits may often control the dispersion and accumulation of contaminants throughout the network and that is an important innovative approach to be considered.
The main objective of this proposal is to prevent the negative effects upcoming from a deliberate (or even accidental) contamination of water distribution networks, by launching an adequate response for rapid detection and identification of the problem , as well as decontamination of the system. Specific questions whose answers are expected to arise from this investigation are:
How can unexpected changes in water quality, related with a deliberate chemical contamination, be
quickly detected, by applying commercially available sensors throughout the distribution systems? How can known analytical methods be adapted to quickly identify the contaminants in the bulk water and also in the deposits/biofilms/pipe walls?
How to evaluate the extent of contamination (via sorption/desorption modeling and reactive transport) considering feasible scenarios?
What are the best decontamination procedures, including the bulk water, the pipe walls and the deposits/biofilms?
The expected impacts are addressed to human safety and they include: (i) the implementation/design of innovative devices, as for example online sensors to detect emergent contaminants, or coupon devices for pipe wall analysis; (ii) the adaptation of existing analytical methods for trace analysis to detect relevant contaminants in complex matrices, as biofilms and pipe walls; (iii) development of cleaning/neutralisation techniques able to efficiently and permanently remove the threat, by treating not only the bulk water but also preventing unexpected detachment of contaminated biofilmsldeposits from pipe walls. |