Studies On Constructed Rapid Infiltration System At Various Oxygen Supply Conditions

With the advantages of less construction investment and high efficiency of treatment, wastewater land treatment has gained rapid development as a replacement technology of wastewater eco-treatment in recent years. Developing the land treatment technology is an effective approach to wastewater harmless and reuse on the base of serious water pollution and shortage of funds in our country.According to the decrease mechanism and main influence factors we can see that bio-oxidation-reduction is the fundamental reason of the pollutants removal. The oxidation and de-oxidation environment relation to normal operation and purification effect of land treatment system. It is beneficial to improve the pollution removal rate if we can control the oxidation and de-oxidation environment. However, studies mainly focused on infiltration media, operation mode and improvement of technology at present. Studies on oxidation and de-oxidation environment and correlation between redox reaction and the degradation of contaminant are rare although it plays a key role.In order to study the distribution and Changes of oxidation and de-oxidation environment, we studied the variations of oxidation and de-oxidation environment and treatment effect of COD,NH₃-N and T-N though experiment of CRI system on various oxygen supply conditions.Results from lab-scale experiment show that:(1) Oxygen supply could significantly improve the ORP of CRI system.(2)Oxygen supply have different effects to different depths of CRI system, 30～40cm is a line of demarcation of CRI system, ORP show different tendency about 30cm depth.(3)ORP of the surface layer from 0cm to 30cm decreased down to negative value in a short time, which indicates that oxidation reaction is strong during this period.(4)The various of ORP correlation with the distance of pollution source.(5)Removal efficiency of COD and N is positive correlation with oxygen supply.(6)The ORP of the surface layer show positive correlation to the decrease rate of COD in CRI system.