Construction and start-up of continuous flow aerobic granular sludge reactors with side stream selective wasting

Abstract

This study upscales a previously examined continuous plug flow conventional activated sludge (CAS) process with side stream selective wasting to gather comprehensive data for process optimization and uncover potential issues that may not be apparent at a smaller scale. The proposed side stream selective wasting mechanism was uniquely designed to facilitate granulation within a continuous plug flow system. It requires a small footprint and can be seamlessly integrated into existing continuous flow systems without introducing the adverse effects of aggressive shear stress, which is a common issue with hydrocyclones. The study was conducted in three stages: the first stage focused on testing split feeding, the second stage evaluated combined feeding, and the third stage assessed the implementation of side stream selective wasting. Although mechanical challenges occurred, the system achieved general biological nutrient removal. However, maintaining a consistent hydraulic retention time (HRT) and solids retention time (SRT) within the given process installation emerged as the most significant challenge throughout the study. This research contributes valuable insights into the optimization of medium size CAS pilot processes and highlights the potential of side stream selective wasting as a viable solution for granulation. The findings underscore the importance of careful process design and system integration in overcoming operational challenges, ultimately paving the way for more efficient and scalable wastewater treatment solutions.