The bacteria eat the NH4+ and regenerate the zeolite in-situ (it never becomes saturated).
4) SINGLE STAGE
Overall, the process is single stage as the anammox take NH4+ and convert it directly to nitrogen gas.
Bacteria find ammonium-coated zeolite very attractive, and colonize it. A biofilm forms attaching the bacteria to the zeolite.
The zeolite-anammox process uses zeolite to immobilize ammonium by cation exchange (CEC).
LIMITATIONS OF TRADITIONAL ANAMMOX WITHOUT ZEOLITES
Needs high NH4 concentrations.
Needs high temperatures.
Removal of high nitrogen loads from wastewater in mining or from water in detention ponds from hydraulic fracturing.
Treatment of excess ammonia from explosives manufacturing.
Removal of ammonia from leachate coming off landfills.
Recycling of high ammonia waste streams in fertilizer manufacturing.
Treatment of high ammonia concentrations in pulp and paper manufacturing.
Potable reuse of wastewater for powerplants.
The primary advantages of zeolite-anammox are:
1) Cost reduction – it is less expensive than conventional alternatives;
2) Simplicity – it is straight forward and low maintenance;
3) Energy efficiency – it requires less energy;
4) Greenhouse gas reduction - it lowers greenhouse gas emissions;
5) Reduced carbon footprint – it has a small carbon footprint.
Most nitrogen pollution is encountered as either ammonia or nitrate. Ammonia is the precursor to nitrate, and by converting ammonia directly to nitrogen gas zeolite-anammox bypasses the steps required for nitrate to be formed.
A dual composite zeolite filter is recommended: the zeolite-anammox component will remove the ammonia; the nitraze component will remove the nitrate. Both components are biologically regenerated in-situ by natural bacteriological processes, and never need to be removed from the pond.
Ammonia is toxic to fish, especially in the non-ionic NH3 form. Zeolite will adsorb the ammonia and the bacteria will regenerate the zeolite by converting ammonia to nitrogen gas.
Excess nitrate will not harm fish, but nitrate is a potent fertilizer and algal growth will turn the pond green. In hot weather oxygen demand fueled by high algal concentrations can lead to a pond full of dead fish. An unobtrusive zeolite-anammox filter can blend into a natural pond so that it is almost invisible.
Whereas nitrate issues are most severe in hot weather, ammonia levels are usually highest during colder winter temperatures.
Ammonia is directly toxic to fish, and concentrations must be kept to very low levels. Ammonia concentrations as low as 0.1mg/L can be harmful to fish, and concentrations above 2mg/L (i.e. 2 parts per million) are usually lethal. In addition to its direct toxicity to fish, ammonia also acts as a very potent fertilizer for aquatic plants.
Nitrate is not toxic to fish, except in very high concentrations, but nitrate is a very effective fertilizer. Algal growth is often limited by the amount of available nitrogen nutrients. Algal blooms, red tides, and excessive algal growth are usually caused by nitrate pollution.