Oily sludge is found mostly in oil storage, waste water treatment unit of refinery and as a result of oil spill on clean soil.

Under normal conditions, the major odor pollutants come from alkali waste treatment unit, sour water stripping unit, ammonia refining unit, sulfur recovery unit as well as waste water treatment site.

This paper deals with the treatment of arsenic_containing waste water in the purification section of sulfuric acid unit, and its process and mechanism are also introduced.