| Acetaldehyde wastewater is a typical high-concentration toxic organic wastewater,containing some refractory organics. Refractory organics were also generated during alkaline decomposition pretreatment of the wastewater. Refractory organics removal was the theme of this study. The operation parameters of alkaline decomposition pretreatment was optimized.On this basis, removal of refractory organics by ozone oxidation and Fenton process were investigated.One combined process of aerobic biological treatment and advanced treatment was developed for acetaldehyde wastewater.(1)Optimized conditions for alkaline decomposition of acetaldehyde wastewater was as follows,pH of 7,NaOH dosage of 2.4g/L,then heated to 70℃ for 6h。Reduction of alkaline dosage,reaction temperature and duration, resulted in unsufficient detoxification, and then stable operation of biological treatment.(2)Ozone oxidation could remove refractory organics from acetaldehyde wastewater effectively, which reduced chemical oxygen demangd(COD) and improved biodegradation.When catalytic ozone oxidation was used to treat effluent of anaerobic treatment, final effluent COD of the whole process decreased to 160mg/L.(3) Fenton process could also remove refractory organics from acetaldehyde wastewater effectively. When the process was used to treat effluent of anaerobic treatment,optimized H2O2 dosage was 0.6g/L with a COD removal efficiency of 61.5%.When the process was used to treat original wastewater, after alkaline decoposation-anaerobic-aerobic treatment, COD could reduce to 240mg/L.(4) Aerobic biological treatment could remove COD of acetaldehyde wastewater effectively. When the wastewater was neutralized below 40℃,final effluent COD of the whole process reduced to 160-180mg/L, with COD removal efficiency of 93.2%-94.3%.When catalytic ozone oxidation was used to treat effluent of aerobic treatment, final effluent COD of the whole process decreased nearly to the limit(60mg/L) of Emission standard of pollutants for petroleum chemistry industry(GB31571-2015). |
