Alternative Method to Determine Blower Capacity against Peak Pollutant Load in Wastewater Treatment System

摘要

For designing aeration tanks for wastewater treatment plant (WWTP), estimation of required blower capacity to meet the peak loading is essential. As the peak loading is highly site specific and cannot be accurately obtained in conventional wastewater sampling methods because of the need of numerous samples. To cope with the challenge, an alternative method using a set of on-site lab-scale activated sludge reactors was developed. The activated sludge reactors were composed of units with and without primary settler fed coagulant, where the reactors with the primary settler monitored soluble biodegradable pollutants in the influent whilst the reactors without the primary settler responded from the total biodegradable pollutants. By logging the dissolved oxygen (DO) concentrations in the aeration tanks and the nitrate-N in the effluents, carbonaceous and nitrogenous biodegradable pollutant concentrations were dynamically back-calculated based on IWA Activated sludge model. The experiment was conducted at a municipal WWTP in Kitakyushu, Japan for 2 months and 60 datasets of hourly change were obtained where hydraulic retention time of the system and aeration rate were kept constant. Based on statistical analysis (extreme-value distribution) of the hourly maximum influent oxygen demand, the site-specific minimum blower capacity to keep DO at 2 mg-O_2 /L was calculated.