Effect of Phosphorous Addition to Model Cooling Towers Using Coal Gasification Wastewater as Makeup

摘要

Cooling towers are an integral part of in-plant water reuse systems in industries such as the Great Plains Gasification Plant being constructed at Beulah, North Dakota. Cooling towers can be used to reduce water requirements, remove biodegradable organics, and concentrate non-biodegradable compounds for ultimate disposal while accomplishing the basic water cooling function. The gasification wastewater used in cooling towers at coal gasification plants must be pretreated using solvent extraction and ammonia stripping to produce stripped gas liquor (SGL). The SGL remains contaminated with organics, ammonia (NH sub 3 ), cyanides (CN), and thiocyanates (SCN) but at levels that microorganisms can acclimate to in cooling towers. The objective of this investigation was to examine the effects of adding phosphorous to the nutrient deficient SGL in order to improve organics removal and to evaluate changes in biofouling and corrosion in the model cooling towers. The removal of contaminants from SGL was shown to be enhanced by the addition of phosphorous to makeup water for use in cooling towers. Unfortunately, the attached and suspended deposits became an increasing problem in terms of clogging the tower packing and tubing. (ERA citation 09:019636)