Monitoring of water quality and remediation: Innovative multifunctional micro-sensor – AQUAE

There is an urgent need to develop reliable and reproducible sensing technologies for in situ and continuous water monitoring for surface water and wastewaters. The AQUAE project will address this need by specifically developing dedicated chemical sensors that are versatile and adaptable enough to monitor priority substances and their degradation in a wide range of aquatic environments.
Real-time monitoring of water quality using these chemical sensors will be performed in the real environment and at the point of discharge, which is necessary to prevent micropollution, define appropriate corrective actions for environmental remediation and decide when they should be undertaken (SCIRPE, BRGM, IFREMER with CEDRE).

The AQUAE project will provide an attractive solution for real-time monitoring of nutrient concentration to control sustainable remediation processes such as phytoremediation (SCIRPE with DEEP INSA) and nutrient recovery treatment (Bioengine Laboratory, U. Laval, Canada). The development of chemical sensors for on-site detection will skillfully combine infrared photonics (IR) and electrochemical (EC) technology, both well mastered by the consortium (ISCR, KLEARIA, I.FOTON, BRGM & IFREMER). These two spectroscopic methods will be coupled in a portable device with a common microfluidic system for a fast, multivariate and in situ monitoring of organic contaminants. This hybrid prototype combining IR and EC sensors is oriented towards water pollution problems and wastewaters treatment by phytoremediation or nutrient recovery treatment.

In addition to its fabrication for on-site use, a major challenge of the project is to overcome a new scientific barrier by designing and fabricating IR & EC sensors on a unique Lab-on-Chip. This AQUAE's LOC multifunctional sensors with an adapted microfluidic system will be designed to detect various priority substances (BTEX, PAH, pesticides, phthalate, drug residues and nitrates). Its efficiency will be tested at the laboratory scale for a first proof of concept.

The detection concentrations in the AQUAE project for considered micropollutants will be at laboratory scale : BTEX and PAHs in case of vicinity of accidental pollution range from 50-150 µg/L, phthalate DEHP often in the range of 1-100 µg/L in wastewater and rain water, pesticides more than 5 µg/L in polluted sites for which the standard at 0.1 µg/L can be largely exceeded like in the north of France (metolachlor), non-steroidal anti-inflammatory drugs (diclofenac and ibuprofene) with tested range µg/L-mg/L.

For nitrates detected by electrochemical sensor, we will consider the Nitrates Directive (91/676/EEC) which requires Member States to respect the quality standard not to be exceeded for the good status of groundwater (50 mg/L). The recommendation for discharges to water are about 15 mg/L of total nitrogen in the case of a treatment plant with a capacity of more than 600 kg/d. At the national level, the nitrate pollutant load of small treatment plants remains marginal. Reduction efforts must be concentrated on agricultural inputs especially in “vulnerable zones" where specific agricultural practices are imposed to limit the risks of pollution. In the AQUAE project, the sensors robustness will be demonstrated in the range 1-100 mg/L, at least with daily measurements to prevent any accidental event and with a t of 30 min to follow the denitrification process, in agreement with surface water analysis and industrial applications. The 0.05-1 mg/L range is a bonus for seawater analyses.