Which activated sludge process mode is operated with the shortest solids retention time?

The modified aeration process is recognized for its shorter solids retention time compared to other activated sludge process modes. This method combines elements of both conventional and extended aeration systems, allowing for efficient treatment of wastewater while minimizing retention time.

In modified aeration, aeration is typically shorter than in extended aeration systems, which are designed to maintain organisms longer to enhance treatment for high-strength influents. This shorter retention time leads to a quicker turnover of activated sludge, which can be beneficial for certain types of wastewater characteristics.

This operational efficiency allows facilities using modified aeration to adapt quickly to variations in influent quality while maintaining treated effluent standards, making it suitable for facilities that need to handle fluctuating loads efficiently.