New Stable Biodegradable Scale Inhibitor Formulations for Cooling Water: Development and Field Tests

The increased demand for more sustainability of inhibitor systems in open cooling water circuit applications has dominated much of the development activity in this area in recent years. Biodegradability has been a top priority in this context due to ever more restrictive legislation in Europe regarding the discharge of chemicals into flowing waters. Various biodegradable scale inhibitor formulations based on biodegradable carboxylic acids have been developed recently and exhibit good scale inhibition performance in pilot plant tests along with low toxicity and reasonable raw material cost. The widespread use of such systems throughout the industry has thus far been prevented by a fundamental concern: depending on circuit conditions, biodegradation of inhibitors may commence within the cooling systems as opposed to the desired degradation after discharge. Consequently, inhibition performance will be diminished and additional problems with increasing biological activity in the circuit are posed. The necessary countermeasures would be increased dosages of oxidizing biocides which in turn would diminish the effectiveness of the inhibitors, thereby substantially reducing the environmental and financial customer benefit. A novel water treatment composition by Henkel Surface Technologies counteracts this effect, combining good biodegradability of the discharged inhibitors with high inhibition performance at low concentrations in conjunction with effective biological control. We present field tests from an industrial plant in Germany which clearly show the enhancement of overall performance derived from the full integration of scale inhibition and biological control treatment programs.