Airborne emissions from power plant cooling towers. Final report

The atmospheric emission and recirculation water of several electric power plant recirculation systems were monitored for the production of haloorganics from chlorination. Trihalomethanes (THMs) were the only haloorganics identified as products of chlorination in each of the systems tested. Chloroform (CHCl/sub 3/) was the predominant THM species formed, though brominated THM production was higher in one system where the bromide ion concentration was high. Maximum total THM concentrations in the recirculation water ranged from 6 to 16 ng cm/sup -3/. THMs were formed regardless of whether breakpoint chlorination was achieved. A low-flow, low-volume atmospheric sampling system was developed using sorbent traps containing Tenax-GC adsorbant to collect the emission of volatile haloorganic vapors from cooling tower fan stacks. THM emission concentrations up to 41 ..mu..g m/sup -3/ were measured. In the mechanical draft cooling systems tested, annual THM emissions were estimated to range from 0.5 x 10/sup 2/ to 1.1 x 10/sup 2/ kg per tower (0.2 x 10/sup 2/ to 0.8 x 10/sup 2/ kg of CHCl/sub 3/ per tower). Maximum downwind ground level THM exposure concentrations from one test were estimated to range from 0.05 ..mu..g m/sup -3/ to 0.8 ..mu..g m/sup -3/, depending on atmospheric conditions. These emissionmore » concentrations found were very low and are comparable to ambient concentrations in rural areas of the United States. Recirculation system chlorination resulted in peak concentrations of total residual chlorine ranging from 0.8 to 4.0 ..mu..g cm/sup -3/ in the mechanical draft towers tested.« less