Conservation principles suspended solids distribution modelling to support ATS introduction on a recirculating WWTP

Area of Science:

• Environmental Engineering
• Water Treatment Technologies
• Process Modeling

Background:

• Wastewater treatment plants (WWTPs) face challenges in managing solids distribution.
• Accurate prediction of solids loads is crucial for efficient operation of secondary clarifiers.
• The aeration tank settling (ATS) process is key to managing solids in activated sludge systems.

Purpose of the Study:

• To develop and validate a model for describing solids (SS) distribution in a full-scale recirculating activated sludge WWTP.
• To assess the potential benefits of implementing the ATS process using the developed model.
• To evaluate the impact of rainfall events on solids load management.

Main Methods:

• Development of a solids distribution model based on conservation principles.
• Utilization of on-line plant data for model calibration and input.
• Application of the calibrated model in a case study to simulate ATS implementation.
• Analysis of predicted reductions in peak and cumulative solids loads.

Main Results:

• The calibrated model accurately predicts solids load to secondary clarifiers.
• Implementation of ATS reduced maximum SS peak load by 24.9%.
• Cumulative SS load reduction was 22.5% for short (4-hour) and 16.6% for long (24-hour) rain events.

Conclusions:

• The developed SS distribution model is a valuable tool for off-line evaluation of ATS benefits in WWTPs.
• ATS implementation offers significant reductions in solids load to secondary clarifiers.
• The model aids in optimizing WWTP operation and improving treatment efficiency, particularly during adverse conditions like rainfall.