• Blog
  • Wastewater Testing
  • Bioaugmentation Applications
  • Useful Information
  • About Us
BIOLOGICAL WASTE TREATMENT EXPERT
Contact Us

Ammonia & nitrite controls in aquaculture

1/8/2017

 
Picture
I often get requests for Ammonia Oxidizing Bacteria (AOB) and Nitrite Oxidizing Bacteria (NOB) for use in aquaculture ponds. Most often, the delicate AOB and NOB cutures are not what the aquaculture facility needs as the problem isnot readily solved by adding in such specialized cultures. 

First, we need to look at aquaculture pond ecology to understand the role of AOB/NOB bacteria. In the pond, ammonia evolves from degradation of animal wastes and excess feed (especially high protein feeds). The ammonia is partially consumed by heterotrophic bacterial growth as they use ammonia as a nitrogen source to build new cells, proteins, enzymes etc. Additionally, nitrite and nitrate are used as an electron acceptor (oxygen sources) in anoxic zones in the bottom sludge. This is why ponds with deep sludge layers often have small nitrogen gas bubbles appearing in quiescent zones. 

Most of the remaining nitrogen is used by beneficial eukaryotic algae. These algae uptake nitrogen and produce biomass that is consumed by the animals. Additionally, during daylight hours the algae help to oxygenate the water via photosynthesis. Algae can become a problem when prokarytoic cyanobacteria take over the photosynthetic organism niche. These organisms produce compounds that can cause off-flavor, are often associated with pH swings, and are often not as efficient at reducing ammonia/nitrite concentrations.

A healthy pond has a small background population of AOB/NOB bacteria just like the surrounding soils. This population is small because the amount of substrate (food) for the AOB/NOB populations is actually low. A wastewater tretament plant with 30 - 40 mg/L ammonia does not support an extensive population of AOB/NOB - so imaging an aquaculture pond with only 3 - 4 mg/L ammonia. Adding a concentrate of AOB/NOB may cure the problem quickly, but the population of AOB/NOB will rapidly drop to natural background levels.

An addiitional problem with AOB/NOB concentrates is their need to be refrigerated and their short shelf-life (3 - 6 months maximum). Without refrigeration, the AOB/NOB concentrate drops in activity to what you see in natural waters. So what can be done to prevent ammonia and nitrite from impacting the fish or shrimp?
  1. Provide aeration to keep dissolved oxygen throughout the pond
  2. Do not over feed or use too high a protein feed - it just becomes waste
  3. Before stocking - look how much sludge is in the pond. Sludge adds to ammonia, harbors opportunistic pathogens, and consumes dissolved oxygen
  4. Heterotrophic bacteria additions help balance the pond - they degrade sludge/wastes on the pond bottom, remove nitrite/nitrate under anoxic conditions, and uptake nitrogen to build new cells. 
  5. Add alkalinity if necessary - we want stable pH for animals, bacteria, and beneficial algae.

My key answer is that microbial additives in aquaculture need to be started before problems arise. Using waste degrading microbes early will help with pollution related stress, disease, and keep the desired ecological blance between animal stock, waste degrading microbes and algae.

Rick link
10/29/2018 06:19:02 pm

Aquaponics is a great way to grow healthy plants with the help of fish wastes acting as food for plants.


Comments are closed.

    Author

    Erik Rumbaugh has been involved in biological waste treatment for over 20 years. He has worked with industrial and municipal wastewater  facilities to ensure optimal performance of their treatment systems. He is a founder of Aster Bio (www.asterbio.com) specializing in biological waste treatment.

    View my profile on LinkedIn

    RSS Feed

    Click to set custom HTML

    Archives

    December 2022
    November 2022
    October 2022
    September 2022
    August 2022
    June 2022
    May 2022
    March 2022
    February 2022
    January 2022
    November 2021
    October 2021
    September 2021
    August 2021
    June 2021
    April 2021
    March 2021
    February 2021
    December 2020
    November 2020
    October 2020
    September 2020
    August 2020
    July 2020
    June 2020
    May 2020
    April 2020
    March 2020
    February 2020
    January 2020
    December 2019
    November 2019
    October 2019
    September 2019
    August 2019
    July 2019
    June 2019
    May 2019
    April 2019
    March 2019
    February 2019
    January 2019
    December 2018
    November 2018
    October 2018
    September 2018
    August 2018
    July 2018
    June 2018
    May 2018
    April 2018
    March 2018
    February 2018
    January 2018
    December 2017
    November 2017
    October 2017
    September 2017
    August 2017
    July 2017
    June 2017
    May 2017
    April 2017
    March 2017
    February 2017
    January 2017
    December 2016
    November 2016
    October 2016
    September 2016
    August 2016
    July 2016
    June 2016
    May 2016
    April 2016
    March 2016
    February 2016
    January 2016
    December 2015
    November 2015
    October 2015
    September 2015
    August 2015
    July 2015
    June 2015
    May 2015
    April 2015
    March 2015
    February 2015
    January 2015
    December 2014
    November 2014
    October 2014
    September 2014
    August 2014
    July 2014
    June 2014
    May 2014
    April 2014
    March 2014
    February 2014

Proudly powered by Weebly
Photos used under Creative Commons from Picturepest, marcoverch, perzonseowebbyra, Picturepest, Picturepest, dsearls, dungodung, Massachusetts Office of Travel & Tourism, aqua.mech, vastateparksstaff, hile, Aaron Volkening, amishsteve, Neil DeMaster, mklwong88, KOMUnews, Picturepest, kaibara87