Research On Waste Water Treatment Technology By Plused Arc Electrohydraulic Discharge

Water quality has improved and bacterial content also has dropped significantly after secondary sewage treatment. But the absolute number of bacteria in the water is still considerable and there may have pathogens. The microorganisms in water must be removed before waste water can be discharged into urban water body or recycled. Therefore, impact of effluent from sewage treatment plant on urban water body gradually attracts people's attention. Effluent sterilization of sewage treatment plant has become an important step in sewage treatment. But there is no ideal method for disinfection of sewage. Pulsed arc electrohydraulic discharge, as an advanced oxidation technology, in recent years has been used to kill microorganisms in water. This method has several advantages: simple technology, low investment, no need additive, no secondary pollution and wide application. This paper researched deeply on the technology and its application problems. The main results of the work carried out and results are as follows:First, this paper studied the model of pulsed arc electrohydraulic discharge. This paper studied characteristics of the development process including: electrohydraulic shock pressure, ion beam density and plasma channel radius, conductivity, resistivity, temperature. And the basic law of the development process of pulsed arc electrohydraulic discharge was calculated and analyzed. This paper also researched spectral properties, electrohydraulic cavitation, radical oxidation effect and electromagnetic radiation effects produced by pulsed arc electrohydraulic discharge.Then we designed the pulsed arc electrohydraulic discharge power, water reactor for disinfection sterilization and established experimental research platform for disinfection sterilization by the pulsed arc electrohydraulic discharge. The experiments studied the influence of discharge parameters on the inactivation rate for E. coli of the system for sewage. The reactor structure, the energy density and pulse waveform parameters were optimized. Research proved the feasibility of this method for disinfection of sewage.The results showed that:1. Pulsed arc electrohydraulic discharge included four processes: initial bubble formation process, pre-breakdown process, severe discharge process and spherically symmetric pulsations.2. Resistance value of arc produced by pulsed arc electrohydraulic discharge changed with time like U-shaped.3. Along with increased of liquid conductivity, pre-breakdown delay of the main discharge decreased, such as from 200 ms to 1ms.4. The intensity of shockwave, ultraviolet rays, living radical produced by pulsed arc electrohydraulic discharge were closely related with the high-voltage pulse power supply parameters(pulse capacitor size, discharge voltage) and the discharge electrode parameters(distance between electrodes, electrode diameter and electrode materials).5. Pulsed arc electrohydraulic discharge process produced electrohydraulic cavitation, photo decomposable effect, free radicl oxidative degradation effect, high energy particle bombardment. The physical and chemical effects made the inactivation rate of E. coli and degradation rate of polyacrylamide reach 99% that could meet sewage discharge standards.