Page 288 - Air Pollution Control Engineering

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Wet and Dry Scrubbing 267

Fig. 15. Height of transfer unit for scrubbing sulfur dioxide. (Courtesy of Lantec Products Inc.)

3. The situations when two-stage or three-stage scrubbing process may be used for
hydrogen sulfide removal.
4. Other alternative technologies for odor control at wastewater-treatment plants
(WWTPs).
Technical information is presented in Fig. 15 and Tables 20 and 21, which are actual oper-
ating data generated from a countercurrent wet scrubbing tower. With a suitable scrubbing
solution and an optimized wet scrubber, hydrogen sulfide air emissions in the typical range
of 100 ppm or less at municipal sewage-treatment plants are easily controlled. Table 20
presents minimum vessel diameters needed to treat various airflows to remove 99.9% of
the H S present. The depth of packing is 10 ft; the pressure drop across the packed bed is
2
2 in. of H O. The packing used is Q-PAC from Lantec Products. Table 21 and Fig. 15 give
2
additional operational parameters for such a scrubbing system.
Solution

1. The feasible wet scrubber design, tower media (packing), and scrubbing liquor for
a single-stage scrubbing process are presented in the following discussion. One
feasible air pollution control system for removal of malodorous hydrogen sulfide
commonly emitted by municipal sewage-treatment plants can be a single-stage