The proceedings are of The 1990 SO2 Control Symposium held in New Orleans, Louisiana, from May 8 through May 11. The objective of the Symposium was to provide a forum for the exchange of technical and regulatory information on sulfur oxide control technology, including wet and dry scrubbing, emerging processes, and international developments in clean coal/acid rain technologies. Specific topics covered during the Symposium included: SO2 control economics, furnace sorbent injection, byproduct utilization, spray dryer technology, wet FGD reliability and full scale operation, combined SOx/NOx technologies, vendor designs, post-combustion dry injection, and laboratory/pilot research. The audience included approximately 800 representatives from electric utilities, government agencies, industrial users of FGD, academia, consultants, process suppliers, equipment manufacturers, and R and D firms. The volume covers: FSI Recycle, Wet FGD Reliability, Spray Dryers, and Wet Full Scale Operation.