Petroleum refineries discharge industrial waste such as waste oils, sludge, waste acids, waste alkalis and etc. However, thanks to the adoption of reuti-lization and recycling activities, petroleum refineries discharge only 329 thousand to 594 thousand tons of industrial waste per year and the ratio of discharged industrial waste from petroleum refineries have dropped to about 0.1 to 0.2 percent of all discharged industrial waste. Therefore, petroleum refineries haven't particular problems on industrial waste treatment.
