Research On Disruption Behavior Of Microbial Cells Within Waste Activated Sludge Under Pulsed Electric Field Assisted By DC Corona

With the accelerated process of urbanization,urban wastewater increased year by year,which resulted in the increasing discharge of waste activated sludge?WAS?produced in the wastewater treatment process.For the WAS contains a lot of toxic substances,if it is discharged with no stabilization treatment,the WAS will seriously endanger people`s health and ecological environment.Anaerobic digestion has been widely used in the sludge stable general processing method in the world.However,how to break the microbial cell membrane in sludge so as to release the intracellular organic matters is one of the key problems for improving anaerobic digestion efficiency.In this paper,pulsed electric field?PEF?and direct current?DC?corona have been employed for the pretreatment of WAS through the mechanism of electroporation and low temperature plasma,which are aimed at the disruption of microbial cells in WAS and release of the intracellular organic matters.Research on disruption behavior of microbial cells within WAS under different conditions has been carried.The main conclusions are summarized as follows:1?The WAS was selected as sample in the experiments,and the DC corona discharge was generated by applying DC voltage on the multi needle-plate electrodes system to treat the WAS sample.Several parameters including soluble chemical oxygen demand?SCOD??ammonia nitrogen?NH₃-N??total phosphorus?T-P?and pH are measured before and after the treatment of WAS,and relative changes of SCOD?NH₃-N?T-P are calculated to analyze the effect of corona treatment time?PEF treatment time and treatment temperature on the microbial cell disruption.The results showed that the increase of organic matters in the WAS increased with the increase of DC voltage,in which the positive corona was higher than that of the negative corona.With the prolongation of the treatment time,the organic matters in the WAS showed a decreasing trend.The organic matters in the WAS increased gradually and the content of the negative corona was higher than that of the positive as the treatment temperature increased.The experimental results show that the voltage amplitude and treatment temperature have a significant effect on the growth of organic matters in the WAS.2?After the corona treatment,the high-voltage pulsed electric field was applied to the sludge by using the plate-plate electrodes to treat the sludge samples with DC corona-PEF combined treatment.The change of organic matters in the WAS samples before and after the combined treatment was measured and calculated.The effect of corona treatment time,pulsed electric field treatment time and treatment temperature on the combined treatment was analyzed.The experiment results showed that the increase of corona treatment time,the increase of pulsed electric field treatment time and the increase of treatment temperature all increased the content of organic components in WAS,and the effect of positive corona treatment was better than negative corona combined treatment.3?The process of DC corona and PEF treatment is changed,and the combined treatment of first pulse electric field and post DC corona treatment is carried out.The effects of corona treatment time,pulsed electric field treatment time and treatment temperature on the contents of organic matters before and after the combined treatment in the sludge samples were measured and calculated.The results showed that the organic matters in the sludge were increased more than that in the positive corona treatment.The content of the organic matters in the sludge increased with the increase of the PEF treatment time and the treatment temperature.The corona treating time increased and the organic matters in the sludge increased with the negative corona treatment,while the organic matters in the WAS was firstly increased and then decreased under the positive corona combined treatment.