Abstract: A wastewater treatment system and method are provided to nitrify and remove residual CBOD and solids from a secondary wastewater pretreatment system. The system can be configured to maintain a population of nitrifying bacteria year-round, and is therefore capable of providing a high nitrification rate during prolonged periods of cold weather.

Abstract: Described herein are methods and devices for biologically treating water and/or wastewater. The methods and devices for treating waste water may be enhanced using an air-lift device which moves water and/or solids using volumes of air. This device can provide occasional surges of water using large bubbles which are able to move great volume of liquid while minimizing dissolved oxygen transfer to the surrounding liquid. Use of the devices and processes herein provides a simple, eloquent approach to waste water treatment with less operation and maintenance costs than conventional devices and/or processes.