The Quantity of Heavy Metals in Wastewater from Wire Electrical Discharge Machining

Abstract

The objective of this research was to investigate the contamination of heavy metals in wire cutting process by Wire Electrical Discharge Machining (WEDM) wastewater. The wastewater before and after filtration were sampling by 1,000 milliliters. Cadmium, copper, lead, mercury and zinc were determined by Atomic Absorption Spectrophotometer (AAS) in 5 replicates. The mean and standard deviation of the heavy metal concentration detected in the wastewater samples were then evaluated. The results demonstrated that the wastewater samples taken before and after the filter were not contaminated with cadmium. However, the wastewater was determined to be slightly contaminated with copper, lead, and mercury. The mean values before filtration were 0.52 ± 0.06, <0.001, <0.001 mg/l and after filtration were 0.40 ± 0.04, <0.001, 0.0011 mg/l, respectively, which did not exceed the standard of the Ministry of Industry's declaration, factory effluent from B.E. 2560. The quantity of zinc found in wastewater samples before and after filtering was greater than the prescribed level (5.0 mg/l), with mean values of 6.72 ± 0.01 and 6.51 ± 0.03 mg/l, respectively. Therefore, the usage of WEDM in the metal industry, the wastewater should be removed and disposed of any heavy metal pollutants using the highly effective methods of chemical precipitation and electrochemistry to eliminate contaminated zinc from water before releasing into the environment further.