Environmental Contamination by Mercury (Hg Series No.12)

The author conducted a survey of two acetaldehyde factories, two soda factories and a vinyl chloride factory regarding mercury contamination.At each step of the waste disposal at factories, concentration of the total mercury and methylmercury was determined.1. In the process of acetaldehyde synthesis from acetylene using a mercury catalyst, 0.100.93ppm of methylmercury was found as the by-product in hot wash water for distillating crude acetaldehyde. After an effective disposal of waste water, methylmercury was no longer detected in the final remains of waste water. However, safe disposal of sludge in sedimentation ponds containing much methylmercury will be the serious problem in the future.2. At the soda factory, waste water contained a total mercury of one tenth that of the aldehyde factory with no methylmercury detectable.3. The sludge (so-called brine mud) precipitated and filtered from the circulating brine contained 40200ppm of total mercury and around 0.001ppm of methylmercury.Safe disposal of sludge remains for future study.4. In the process of vinyl chloride monomer synthesis from acetylene, 0.010.11ppm of total mercury was found in alkaline wash water from the reaction tower, of which 0.001ppm was detected to be methylmercury.5. In each factory, the final waste water flowing into the river contained less than 0.01ppm of mercury with no detectable methylmercury at the time of survey in 196668.However checking of concentration alone is not reliable as the reduction of mercury concentration is possible by dilution in non-contaminated water.Therefore, the total quantity of mercury flowing into the river per day or per month is the key point for surveillance.