VB₆ Pharmaceutical Wastewater Treatment By Combined Catalytic Wet Air Oxidation And Biological Process

In the present work, an integrated process includes catalytic wet air oxidation (CWAO), Internal circulation reactor (IC) and SBR was developed to treat chemical pharmaceutical industry wastewater which has high concentration, complicated component and low in biodegradability. Process feasibility and influencing factors, which provided reliable information for wastewater engineering and design, were investigated. The wastewater was firstly treated by catalytic wet air oxidation in which most of the organic matter was removed, and the biodegradability was improved; Subsequently, the effluent was pumped into an IC reactor to remove organic matter and reduce the organic load; Finally, a sequence batch activated sludge reactor was followed to ensure the effluent to meet with the discharge standards of water pollutants for pharmaceutical industry Chemical Synthesis Products Category (GB21904-2008).The MnCe catalyst prepared by co-precipitation method was used to treat the pharmaceutical wastewater. The reaction temperature, pH, oxygen partial pressure, stirring rate, catalyst dosage and other parameters which had an effect on the treatment was investigated. Results showed that the maximum of COD removal rate was 60% when the temperature below 200℃, whilst the removal rate was enhanced significantly as the temperature increased; the oxygen partial pressure was only accelerate the response rate of the CWAO process, but it showed no effect on pollutant degradation; CWAO reaction preferred to acidic conditions. After wet oxidation treatment, the BOD5/COD ratio was enhanced from 0.1 to 0.8, thereby the biodegradability of pharmaceutical wastewater was greatly improved.When keeping influent COD as 6000mg/L, organic loading as 17kgCOD/(m3?d), the COD from IC process effluent was determined as1000mg/L, thereby the COD removal rate reached 80%. In the reactor, the size of most of the granular sludge particles with a certain mechanical strength was larger than 1mm, sedimentation properties were also improved. Biogas production increased with the increasing of the organic load, the methane content of biogas gradually increased in the operation, and finally stabilized at 70%. The SBR reactor was used to treat the IC effluent. With the COD concentration increased, the SBR reactor COD removal efficiency gradually increased. In the condition that COD concentration of 400-1600mg/L, pH 6.5-7.5, the aeration time was 12 h, the effluent COD concentration is 100-120mg/L.