Characterization and treatability of alkyd resin production wastewater

Wastewaters originating from alkyd resin production are typical examples of strong organic effluents containing toxic compounds. In this study, characterization and pretreatment of alkyd resin production wastewaters were experimentally assessed. The study aimed to remove toxics, reduce the strength of wastewaters to provide safe storage and their acceptability by joint treatment systems. Physical– chemical treatment methods were employed for pretreatment to ensure their applicability at every industrial scale. Wastewaters originating from the production were strong containing 23–40 g/L COD. Air stripping tested as a first stage of treatment proved to be efficient reducing COD up to 40% removing solvent residues and volatile matter and increasing the BOD₅/COD ratio 0.57 of raw wastewater to 0.70. Acid cracking process made use of acid character of wastewater which had been enhanced by FeCl₃ addition provided additional 10%–33% COD removal (overall COD removal 60%). Coagulation– flocculation with FeCl₃ or alum worked better following aeration and acid cracking and increased COD removal with an additional 25%. Saponification provided limited COD removal. Aeration was the key process in removing toxics and reducing wastewater strength. The tested physical–chemical treatment after aeration worked well with varying efficiencies reaching total COD removals exceeding 60%.