ORGANIC MATTER DEGRADATION KINETICS AND FILTER LAYER HEIGHT CALCULATION MODEL IN CONSTRUCTED RAPID INFILTRATION SYSTEM

The constructed rapid infiltration system (CRIS) is a new wastewater treatment technique. At present, the research on pollutant degradation kinetics is relatively scarce and the height of the CRIS filter layer is determined mostly by empirical judgement. In order to solve these two problems, a simulation CRIS column was applied to treat domestic wastewater and the characteristics of organic matter degradation kinetics were studied on the basis of the Chemical Oxygen Demand (COD) degradation law and the research of Mann and Stephenson. Then the mathematical calculation model of the filter layer height was built based on the COD degradation kinetic equation in CRIS. Through experimental verification, it was shown that within a certain range, this model could precisely calculate the economic and appropriate height of the filter layer in line with the requirements of influent COD concentration, hydraulic load and effluent quality in CRIS. However, since this model derived within a certain range, when hydraulic load or influent concentration was beyond the applicable scope, there would be a certain deviation between model calculated values and actual results. Therefore, in the actual project, the parameters of the model must be ascertained or revised according to the characteristics of the specific filter and reactor themselves.