Research On The Effect Of Ultrasonic Pre-treatment Combined Biotechnology On Pharmaceutical Sludge

The treatment technologies on pharmaceutical sludge are the hotspots of current research with the development of the pharmaceutical industry due to the large yield, poor stability, residual toxic substances of pharmaceutical sludge. It’s necessary to study the cost-effective new treatment technologies for pharmaceutical sludge based on the traditional treatment processes. Compared with other pre-treatment technologies, ultrasonic technology has some advantages like operating automatically, remarkable craking effect, no secondary pollution, etc. This paper researchs on optimizing the process parameters of ultrasonic pretreatment, as well as ultrasonic pretreatment combined anaerobic or aerobic digestion for sludge stabilization and mass reduction. The main results are as follows:(1) Batch experiments were conducted to study the optimum conditions of ultrasonic treatment on pharmaceutical sludge. After sonication of optimum condition (ES250OOOkJ/kgTS, power500W), the B/C of the supernatant increased from0.183to0.331, indicated the biodegradability of sludge enhanced, and the temperature of sludge increased21℃. The sludge after sonication was conducive to the effect of subsequent digestion process.(2) The solubilisation, settleability, temperature, pH and particle size distribution of sludge treated by ultrasonication were studied. Results showed that ultrasonic pre-treatment intensified the solubilisation of sludge. The SCOD, TOC, TN and TP increased with the Specific Energy input (ES) of ultrasound. For a given ES value, the "high power input-short duration" sonication procedure proved to be more effective for sludge disintegration. After sonication, the temperature of sludge increased to40～52℃, pH fluctuated in6.9±0.2, floc size decreased, and mean particle diameter decreased58.75～72.81%. The settling ratio of sludge obviously increased from35%to95%, indicating the deteriorate of dewaterability.(3) Effect of ultrasonic pre-treatment on pharmaceutical sludge anaerobic digestion was studied. Compared with the untreated sludge anaerobic digestion, the methane production increased36.81%by250000kJ/kgTS sonication. The reduction of TS increased from19.79%to24.26%, the reduction of VS increased from33.89%to53.11%, and the reduction of TCOD increased from16.65%to89.23%. The sludge retention time reduced from8d to3.6d. Ultrasonic pre-treatment also decreased the deterioration of sludge settleability by anaerobic digestion. The acute biological toxicity of sludge reduced after anaerobic digestion.(4) Effect of ultrasonic pre-treatment on pharmaceutical sludge aerobic digestion was studied. Compared with the untreated sludge aerobic digestion, after sonication of250000kJ/kgTS, the reduction of TS increased from15.20%to23.87%, the reduction of VS increased from40.13%to56.06%, the reduction of TCOD increased from50.00%to62.50%, and the reduction of TN increased from19.81%to31.82%. The sludge retention time reduced from19.6d to6d. Aerobic digestion reduced organic acute biological toxicity of sludge, but increased water-soluble acute biological toxicity.