Airport Runoff Applications
Since 1996, Envitech Ltd have been involved in monitoring airport runoff at Seven major airports
Surface water runoff from runways can contain high levels of contaminants including de-icer. On-line analysers can provide a valuable control tool to optimize storage capacity and ensure consent discharges are maintained.
For de-icing, chemicals such as glycol, acetates or formates are used which are additionally mixed with thickening agents in order to improve adhesion to surfaces. This adhesion works like a sponge so that a certain amount of the winter precipitation is absorbed and liquified by the de-icing agents. This is necessary as ice and snow negatively influence the weight and aerodynamics of an aircraft.
Because of its adhesive characteristics, de-icing water causes huge memory and carry-over effects with online monitoring systems. Residual traces of previous measurements falsify the results of the current measurement. Furthermore, due to this characteristic neither filtration nor transportation through thin tubing is recommended.
Another challenge is the strongly fluctuating loads. On one hand, the critical values for public discharge are very low, the discharge regulation for the river Rhine for example stipulates 150 mg/l O2.
On the other hand, it must be possible to measure high concentrations of up to 50.000 mg/l C accurately. Therefore, a very fast and precise measurement technique is required in order to discharge most of the water into the discharge system in a cost efficient way.
Depending on the concentration / load it can be discharged into a WWTP or storage basin.