This paper presents the results of the most recent series of tests at the EPRI 2.5 MW(e) Integrated Environmental Control Pilot Plant. These tests were conducted with spray dryer/electrostatic precipitator (ESP). The results from the two previous test configurations, the fabric filter/wet scrubber (FF/WS) and the ESP/wet scrubber (ESP/WS) are compared with the results of the SD/ESP.