Wastewater control in welding electrode manufacturing - a case study

Metal finishing plants, although the wastewaters and treatment schemes for this category are well defined, require a case by case evaluation to find a ppropriate solutions and to solve specific problems. In this paper, a case study conducted on a welding electrode plant is presented. The wastewater s ources were surface cleaning, copper plating and soap solutions used for dr awing which were frequently included in waters. The plant was subjected to pretreatment standards, which necessitated the control of sulfate and organ ic matter in addition to standard parameters of metals, oil, suspended soli ds etc. following a source-based characterization, treatability studies wer e conducted to treat high concentration of sulfate, organic matter as well as heavy metals and oil-grease. The proposed treatment scheme involved sepa rate treatment of copper bath for recovery, chemical oxidation for soap sol utions, sulfate precipitation for sulfuric acid bath and application of hyd roxide precipitation to proper combination of other wastewater sources.