DICHLOROMETHANE LEVELS IN WASTE-WATER DIS CHARGED FROM CHEMICAL LABORATORIES AND ITS REMOVAL EFFICIENCY USING ACTIVATED CARBON ADSORPTION

Dichloromethane levels in wastewater discharged from chemical laborato ries were measured. The average concentrations of this compound in was tewater untreated and treated by a chemical wastewater treatment plant were 0.17 and 0.07 mg/l, respectively. Using a vacuum pump instead of aspirator to evaporate this solvent in the laboratories effectively r educed the amount of dichloromethane in wastewater. Furthermore, the r emoval efficiency of dichloromethane in the treatment plant of chemica l wastewater by use of activated carbon adsorption and coagulation pre cipitation processes was investigated. The results of monitoring for o ne year showed that the removal efficiency of dichloromethane from was tewater in the treatment plant was on the average 67.4%. Our experimen ts showed that the prolongation of reaction time of activated carbon a dsorption to 30 min sufficiently improved the removal efficiency of di chloromethane. Activated carbon adsorption process was very effective to remove this compound, but coagulation precipitation process was not effective.