2019 Volume 17 Issue 1 Pages 40-53
The study was aimed at developing an alternative method to catch biodegradable concentrations in municipal wastewater, especially for designing wastewater treatment plants receiving storm water where the influent concentrations significantly changed in time. As conventional water analytical methods required lots of samples and numerous analysis, which was practically infeasible, a lab-scale nitrifying activated sludge reactor having on-line DO meter and quick-test nitrate kit was installed at the experimental site in Hue, Vietnam. By fixing the hydraulic retention time with 2.0 hours and aeration intensity, the biodegradable concentrations in the influent including carbonaceous and nitrogenous compounds were back-calculated from the dynamic response of dissolved oxygen concentration in the aeration tank and the nitrate concentration in the effluent using IWA Activated Sludge model. During the data collection event for 24 hours, the influent was also sampled at 1-hr interval and its concentrations were compared with those calculated. The field experiment successfully demonstrated that the back-calculation method could reasonably estimate the influent biological concentration on the basis of biological oxygen demand where the concentration was highly fluctuated in time. Based on the experiment, the feasibility to measure sudden elevation and decrease of pollutant load in the first flush was discussed in the paper.
