Ana Rita Da Silva Prazeres,Maria de Fátima Nunes de Carvalho,Francisco Javier Rivas Toledo, Escola Superior Agrária de Beja-Instituto Politécnico de Beja, TECNOLOGIAS E CIENCIAS APLICADAS, mfcarvalho@ipbeja.pt
Abstract
Cheese whey wastewater (CWW) is characterized by a relative high chemical and biological oxygen demand values (COD and BOD), accordingly appropriate treatments are required. The precipitation of CWW in acidic conditions has been investigated. Decreasing the initial pH of CWW to values in the range 1-3 results in the formation of a white precipitate. This precipitate presents flocculent sedimentation involving the subsequent partial removal of organic load. Removal efficiencies of 21% of COD and 41% of BOD, were obtained in optimal conditions (pH=1,0). The supernatant obtained presents a high redox potential value and biodegradability (BOD/COD≈0,89±0,10). Moreover, the acidic precipitation allows an average phosphorus depletion≈18% and similar results were obtained when the kjeldahl nitrogen was monitored. The supernatant showed an average of 12% in turbidity removal and a decrease of 33-54% in the absorbance measured at 220, 254, 292 and 410 nm.
Keywords: Cheese whey wastewater; acidic precipitation; organic matter removal; biodegradability