Treatability of strong wastewaters from polyester manufacturing industry

In this paper, the treatability of strong wastes originating from an organic chemicals industry was studied. Literature data were evaluated to assess the applicability of conventional and advanced methods of treatment to highly concentrated wastewaters. A detailed treatability study was conducted on the wastewater, which was provided from a small-scale polyester manufacturing plant. The manufacturing process involved only esterification reactions, generating a wastewater with a COD content of over 200,000 mgl^-1. The applicable treatment methods to be tested were determined as biological treatment of activated sludge process with low organic loading and chemical oxidation with H₂O₂. Results of the biological treatability study indicated that 80% COD removal could be obtained with 10 days retention time, provided that the system was fed with a 1/100 diluted raw wastewater. Chemical oxidation of raw wastewater with H₂O₂ in acid conditions and using ferric chloride as catalyst yielded 70% COD removal. However, the dosage required to obtain this efficiency was about 1 kg H₂O₂ per m³ of wastewater. With these applications the wastewater was treated to yield a COD of lower than 2000 mg/l. Results of the study were discussed and evaluated considering complexity and cost of treatment.