Dynamic Estimation of Hourly Fluctuation of Influent Biodegradable Carbonaceous and Nitrogenous Materials Using Activated Sludge System

Abstract

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.

A Novel Method to Determine Blower Capacity of Wastewater Treatment Plants for Dry and Wet Weather Conditions

“…As mentioned in the introduction section, the continuous operation of the field-test activated sludge reactor(s) equipped with DO and nitrate sensors was needed to estimate the dynamic change of influent oxygen demand (biodegradable substances) together with off-line batch analysis to measure the kinetics and biomass concentration in the reactors. The datasets obtained from the field experiments were dynamically analysed in the IWA-Activated Sludge Model #1 (ASM1) to perform the back-calculation for the influent characterisation [12,14]. From the numerical calculation, the estimated concentrations of biodegradable substances were expressed in a discrete form (discrete concentration in every 1-hour).…”

“…The DO concentration of the reactors and the nitrate concentration in the effluents were chosen as the target variables (the variables to fit to the data) according to Nguyen et al (2019) [14]. The soluble biodegradable organics (S B ), soluble biodegradable nitrogen (S B,N ), particulate biodegradable organics (XC B ) and particulate biodegradable organic nitrogen (XC B,Org,N ) were also selected as the optimised variables of the influent (the regression variables to match the target variables of the data).…”

“…In this study the data densities of the target variables (= logging interval of the sensors) were evaluated among every 5-minute per day (12 data per hour) and every 30-minute per day (2 data per hour). Maximum Likelihood method was chosen for the regression [14]. The total days of the influent analysis were 40-day for Site #1, 30-day for Site #2 and 20day for Site #3 respectively.…”