How Can I Remove Ammonia from My Wastewater Plant?

Operators of wastewater plants, lakes, lagoons, and ponds that suffer from high ammonia levels come to us for solutions. We use microorganisms to oxidize ammonia to nitrate. Our nitrification products are specifically adapted to work with your entire system, taking into account the chemistry you use, any physical limitations of the plant, and the present microorganism population.

Ammonia is found in many places in the environment, including fertilizers, human waste, and industrial waste (dairy, meat, corn ethanol). Nitrosomonas (AOB), Nitrobacter, and Nitrospira (NOB’s) are chemoautotrophic bacteria that contribute to ammonia and nitrite removal. Ammonia that enters a wastewater plant is oxidized from ammonia to nitrite by Nitrosomonas. Nitrobacter and Nitrospira then oxidize the nitrite to nitrate.

Chemoautotrophic bacteria use CO₂ as their carbon source and oxidation of non-organic material to generate cellular energy. The oxidation of inorganic material does not yield as much energy as the oxidation of organic carbon sources, as performed by heterotrophic bacteria, so nitrifiers have a very slow growth rate within the microbe community in wastewater plants.

Nitrifying bacteria are autotrophs, and use CO₂ as the source of carbon for their cellular building material, so they do not contribute to the removal of BOD in the system. However, nitrifying bacteria are important to the system since decrease levels of ammonia to a concentration where heterotrophic bacteria are able to survive.

Although Nitrosomonas, Nitrobacter, and Nitrospira are commonly found in the soil and can easily wash into wastewater plants (WWTPs), many plants loose these bacteria because of environmental conditions, contamination with toxic compounds, low dissolved oxygen, or competition with other microorganisms.

We Have a Plan!

1. Call or email the Bugman to get more information or to order VitaStim Nitrifiers and possibly VitaStim Polar Blend to help your reseed your system.
2. If the water temperature is less then 50°F you may need activated sludge from another plant that is nitrifying nicely. Make sure the other plant dose not have problems with filamentous foaming or bulking so you do not introduce a new problem.

Our seven steps to nitrification show the operator each step and how and why it is vital to the survival of the nitrifying cultures. These organisms are very sensitive to toxicity, and are strict aerobes and prefer a kind and gentle wastewater operator. Our seven steps guide operators back to nitrification, and more importantly impart an understanding of what to work on.

1. Retention Time

   

2. Temperature

   

   At temperatures less than 20°C (68°F), cellular metabolism slows down and fewer cells are nitrifying and dividing. Above 40°C (104°F), the proteins will be inactive and the cell membranes may break apart resulting in cell death.

3. Dissolved Oxygen

   

   Heterotrophs have greater numbers than nitrifiers in wastewater and are more efficient at scavenging oxygen. In mixed populations with low D.O., the heterotrophs will be able to quickly use the available oxygen faster than the nitrifers since oxygen is also consumed in heterotrophic metabolism. It is a good idea to increase the D.O. levels with high incoming BOD or NH₃.

   Remember: D.O. levels increase with colder temperatures and decrease in warmer temperatures.

4. Carbonate Alkalinity

   

   High rates of ammonia oxidation will acidify the environment and must be neutralized with additions of carbonate alkalinity (e.g., Na2CO3, CaCO3, or K2CO3) since 4 – 7 ppm alkalinity are used for every 1 ppm of ammonia. The enzyme in Nitrosomonas that carries out the first part of ammonia oxidation is inhibited (rendered inactive) by pH less than 7.

5. pH

   

   AOB only utilize ammonia not the ammonium ion. The levels of ammonia to ammonium vary depending on temperature and, more importantly, on pH. At lower pH values, most of the ammonia is in the ammonium form leaving you with a lot of nitrogen that the AOB cannot get rid of and conditions that would inactivate the ammonia-oxidizing enzyme. The ideal pH for ammonia oxidation is between pH 7-8.

6. Floc Formation

   

   Nitrifiers typically form aggregates of AOB and NOB along the edges of flocs made up of heterotrophic bacteria where the D.O. concentrations are high and they can still retain the protection of the biofilm. NH₃ contains more energy per mol than NO₂- so AOB may synthesize a capsule to encompass both cell types.

7. Toxicity

   Heavy metals such as nickel, copper, zinc, cadmium and chromium can be toxic to nitrifiers. Exact levels of each are difficult to determine. Over chlorination can also cause toxicity. Also too high of ammonia (thousands of ppm) or a buildup of the intermediate nitrite can also cause toxicity. In short nitrifiers are toxic to a lot of things, they are fickle and when temperatures get cold they are more subject to toxic affects.n of plant design, capacities, efficiency, and plant operation.

1. Hooper and Terry (1973) J. Bact. 115 (2) : 480-485
2. (1999) Water SA 25 (2): 167
3. (1985) J. Biochem. 226: 499-507

At AQUAFIX, we have the expertise to help our customers resolve even the toughest cases where wastewater plants lose nitrification and need fast answers.

Questions or Comments? Please call or email us with your concerns. Our advise is comprehensive yet practical.

• Call us at 1-888-757-9577 (8:00 am – 5:00 pm CST, Monday through Friday)
• Send an e-mail to bugman at teamaquafix.com