The coal-gasification wastewater treatment is the most difficult pollution control task for coal-gasification plants. It is identified that there are two serious problems occurring in the current treatment process, i.e., low performance of phenols removal and plugging induced by ammonia salts. A new treatment process is proposed in this paper to solve these severe problems and pursue clean production. Three technical improvements are introduced in the coal-gasification wastewater treatment process. First, ammonia stripping is accomplished before phenols recovery to reduce pH value of the wastewater and to improve the phenols removal performance of extraction. Second, a complex stripper with a side draw is introduced to stripping ammonia and sour gas simultaneously. It is done to eliminate the ionic interaction during stripping and to improve the removal performance of ammonia and sour gas (carbon dioxide and hydrogen sulphide). Finally, methyl isobutyl ketone (MIBK) is used as extraction solvent instead of diisopropyl ether (DIPE) for further improvement of the phenols removal performance. Conceptual design of the proposed process is accomplished for a large-scale coal-gasification plant based on process simulation. With the proposed process, the concentration of carbon dioxide, hydrogen sulphide and ammonia in wastewater are reduced to trace, less than 10 mg/L, and about 30 mg/L, respectively. As a result, pH value of the wastewater is reduced from >9 to <7 before extraction, thus the phenols removal performance is greatly improved. Compare to the current process, the removal ratios increase from 60% to 99% for carbon dioxide, 96% to 99.6% for ammonia, and 80% to 94% for total phenols using the proposed process. In consequence, the biochemical treatment of wastewater becomes easier. The economical analysis shows that the operating cost of the proposed process is much lower than that of the current process. (C) 2007 Elsevier B.V. All rights reserved.