Study On Treatment Of Pesticid Wastewater By Pressurized Activated Sludge

Pressurized activated sludge process is an innovative wastewater treatment technology, which derived from traditional activated sludge process. Oxygen transfer barrier has been overcome by improving system dissolved oxygen level. It has the advantages of high treatment efficiency, especially for the treatment of high concentration and hard-biodegraded organic wastewater. Three parts are included in this research, first, study on the oxygen transfer in pressurized bio-reactor; second, the treatment of pesticide wastewater by pressurized activated sludge; third, the kinetics of pollutant degradation in pressurized activated sludge.In the study of mass transfer performance in pressurized bio-reactor, the reactor is a polypropylene column, 200mm in diameter and 1000mm high. System operated at pressure ranging from 0 up to 0.2MPa(suffuse pressure), flow rate ranging form 2 L/min up to 12L/min.Mass transfer model was based on bobble column reactor. Oxygen saturation concentration (Cs) and volumetric mass transfer coefficient (KLa) are influenced by system pressure, and oxygen saturation concentration increases with pressure increasing. The volumetric mass transfer coefficient decrease with system pressure increase, and Volume oxygen transfer rate (VOTR) become higher with system pressure increase during 0-0.2MPa, when the pressure over 0.2MPa, the effect of increase pressure is inconspicuous. Volume Mass transfer coefficient has a tread of linear increase with flow rate. In range of our study, gas hold up is an important factor influencing oxygen transfer in pressurized bioreactor. The ratio (KLa/ ) is found to be practically independent of superficial gas velocity and system pressure. The value of this ratio is approximately equal to 0.46 in our reactor. This result provides a simplemethod for predicting KLa using the model developed for estimation of e. Pesticide wastewater treated by pressurized activated sludge, carried out in polypropylene column, 150mm in diameter and 1000mm high. System operated at pressure ranging from 0 up to 0.3MPa(suffuse pressure), and the concentration of COD in the influent is 2500-5000mg/L. All results are compared with those of an identical reactor operated at atmospheric pressure. Within the range of pressure (0-0.3MPa), the COD reduction increases steadily with increase of operating pressure and aeration time and sludge concentration. The optimum conditions of pressurized activated sludge were determined by orthogonal experiments. The concentration of COD in the influent is 2900-3800mg/L, the operating pressure is 0.1 MPa and the aeration time is 6 hours, the COD volume load of the equipment is5.8-7.6kgCOD/m3.d, the comparison system operated at atmospheric pressure, its COD volume load is 2-2.8kgCOD/m3.d. Research on dynamics illustrated that the COD reduction can be best described by Monod model,the expression is v = v , biochemical kinetics parameter isSn=122mg/L,Vmax=2.31 d-l,Ks=487mg/L.