Treatment Of Highly Concentrated Pharmaceutical Wastewater With Flat MBR And Oxygen-Enriched Aeration

Oxygen-enriched aeration in activated sludge processing, is one of the most effective methods in improving the mass transfer rate of oxygen and therefore the efficiency in water treatment. This paper describes a method of generating 28%~30% O2 using a membrane as an aeration source and the biodegradation of organics with both oxygen-enriched aeration and conventional aeration. In addition, the effect of oxygen-enriched aeration with a flat membrane bioreactor in the treatment of highly concentrated biopharmaceutical wastewater was investigated. The experimental results show that the efficiency of oxygen-enriched aeration in biological degradation is much higher than that in conventional oxygenic aeration, especially at a reaction time of 30-45 min and in a concentration range of 2000-2500 mg/L. The use of oxygen-enriched aeration in a flat membrane bioreactor results in a high quality effluent in biopharmaceutical wastewater treatment. When COD of inlet is fluctuant and the COD of outlet is less than 200 mg/L, the removal of COD was up to 80%; the outlet ammonia nitrogen is less than 10 mg/L, the removal of ammonia nitrogen was up to 85%. The effluent has a low turbidity and un-detectable SS. It has been shown from the experimental result that the bioreactor efficiency is greatly increased by this method; therefore it exhibits great advantages over conventional method in high concentration wastewater treatment. When 0.1μm pore sized polyvinylidene fluoride flat membrane bioreactor was used, the shorter of suction/suspended time, the more slowly of flux attenuation, so the suction/suspended time is controlled for 10 min/2 min. The flux of membrane is less affected by initial pressure and the low-voltage operation is beneficial to easing the flux attenuation. Increasing aeration flux resulted in an increase in flux, and the flux independent of aeration flow above a critical value. Control of the aeration flow 450 L/h, sludge concentration of 5~6 g/L, it is beneficial to easing the flux attenuation and decreasing the rate of pollution. The PVDF membrane has advantage in anti-pollution. The outlet flux was restored to above 80% of its original flux when physical and chemical cleaning were applied.