UPSC Prelims 2023 Question:

With reference to the role of biofilters in Recirculating Aquaculture System consider the following statements

1. Biofilters provide waste treatment by removing uneaten fish feed.
2. Biofilters convert ammonia present in fish waste to nitrate.
3. Biofilters increase phosphorus as nutrient for fish in water.
   
   

How many of the statements given above are correct?

Explanation:

• In recent decades, the use of biofilters to remove of contaminants from wastewater and waste gases is being developed. Biofilters use microorganisms, which are capable of degrading many compounds, fixed to an inorganic/organic medium (carrier) to break down pollutants present in a fluid stream. They also provide waste treatment by removing uneaten fish feed. So, statement 1 is correct.
  
  

• A properly designed biofilter will keep ammonia and nitrite concentrations at levels that are not harmful to the fish. Biofilters convert ammonia nitrogen to nitrite nitrogen and then to the less toxic nitrate nitrogen for the fish. So, statement 2 is correct.
  
  

• Biofilters do not increase phosphorus as nutrient for fish in water. Phosphorus (P) is in fact removed to reduce the potential for eutrophication in waters. So, statement 3 is not correct.
  
  

Therefore, option (2) is the correct answer. 

Subject: Science & Technology | Miscellaneous(s&t)