Application of constructed wetland to partial nitrification process: Relations betweenparameter values and effluent outcome using response surface methodology

Guangxu Qin, Yancheng Li, Yi H

Abstract

Partial nitrification has a unique advantage in dealing with low carbon/nitrogen (C/N) ratio streams but is rarely applied to streams with low-ammonia concentration. A constructed wetland was used to develop a partial nitrification system based on low-ammonia stream. Response surface methodology was employed, with temperature (X), filler thickness (Y), and filler size (Z) identified as the independent variables, whereas ammonia oxidation rate (AOR) and nitrite accumulation rate (NAR) were the response variables. Using the Box–Benhnken design and second-order polynomial, following response equations were obtained: AOR=51.44+10.82X-0.15Y -8.15Z-0.26XZ -0.14X2+0.69Z2; NAR= –3.31+11.67X – 0.54Y+5.03Z+0.03XY – 0.37X2– 0.32Z2.Analysisofvariance indicatedthat the equations could appropriately describe their corresponding relations. The equations can illustratethe parameter value selection of the reactorto make the effluent stream suitable for post anaerobic ammonia oxidation or for post short-cut denitrification.