On-site biological treatment transforms waste into resources that can be used on the building
site. Figure 1 shows the steps for on-site treatment. As solids settle in the anaerobic septic tank,
microbes begin to feed and break down the waste. The closed aerobic reactor is aerated by
pumps to help remove aromatic compounds. The open aerobic reactors contain plants, algae,
snails, and fish that further break down the organic waste. In the constructed wetland, aerobic
and anaerobic reactions remove the remaining impurities and nitrates. This creates clean,
nonpotable water that can be used in irrigation systems, water closets, or cooling towers