Method and apparatus for treating waste streams

A method for treating a waste stream, the method including the steps of:

• providing a waste stream that includes waste solids suspended in water;
• feeding the waste stream to the top of a hydraulic downdraft column;
• conducting the waste stream to the bottom of the hydraulic downdraft column;
• conducting the waste steam to a first reaction zone;
• introducing nitrogen-containing oxides into the first reaction zone so that the waste stream is contacted with the nitrogen-containing oxides;
• conducting the waste stream up a hydraulic updraft column into a second reaction zone, where the second reaction zone is configured to provide sufficient time so that a reaction between the nitrogen-containing oxides and waste solids can take place and substantially consume the nitrogen-containing oxides;
• introducing oxygen gas into the waste stream after the nitrogen-containing oxides are substantially consumed, thereby providing a second reactant that reacts with waste solids suspended within the stream;
• conducting the stream to the top of the hydraulic updraft column where the step of introducing nitrogen-containing oxides results in the formation of ammonium ions, and where said ammonium ions are recovered from the stream after the stream is conducted to the top of the hydraulic updraft column.