EFFECTS OF SAMPLING FREQUENCY IN SEWAGE QUALITY SURVEY ON ESTIMATION ACCURACY OF SEWAGE CONCENTRATION: A CASE STUDY OF HUE

Abstract

 Facing a phase of developing sewerage in Southeast Asian countries, it is urgent task to establish a methodology to grasp the representative sewage concentration. This study aimed to estimate a relation between sewage sample number and accuracy of computing representative value, and ran simulations with resampling method for raw sewage data observed in Hue, Vietnam. With sequencially observed electron conductivity (EC) data, the simulations were conducted in terms of two parameters: number of samples per day and number of days for sampling. Additionally, we examined a difference in the accuracy of representative value estimation among water quality parameters. Results indicated that number of days for sampling contribute more to the accuracy of computing representative value than number of samples per day. Moreover, for accurate representative value estimation of BOD, COD and TN, more sample numbers likely be required than for SS, TN and EC. The findings of this study based on raw data are expected to contribute on the development of appropriate sewage sampling methodology.