STRATEGIES FOR FISH DISEASE CONTROL AND PREVENTION
Location: Harry K. Dupree Stuttgart National Aquaculture Research Center
Title: Disinfection of water in recirculating aquaculture systems with peracetic acid (PAA)
Submitted to: International Conference on Diseases of Fish and Shellfish
Publication Type: Abstract Only
Publication Acceptance Date: May 1, 2011
Publication Date: September 12, 2011
Citation: Meinelt, T., Rau, A., Matzke, S., Straus, D.L. 2011. Disinfection of water in recirculating aquaculture systems with peracetic acid (PAA) [abstract]. Diseases of Fish and Shellfish: 15th International Conference on Diseases of Fish and Shellfish, European Association of Fish Pathologist, September 12-16, 2011, Split, Croatia. p.231.
The disinfection behaviour of peracetic acid (PAA) in recirculating aquaculture systems (RAS) was investigated. Peracetic acid is a strong oxidizing agent found in various concentrations in different products. Three Wofasteril PAA products (E400 (c), Lspecical; AC 150) were tested in vitro for their ability to remove bacteria in RAS water. Colony forming units (CFUs) were determined using the Pour-plate method (Bast, 2001) with Plate Count Agar (PCA) before and after PAA treatment. Four nominal concentrations of PAA (0.5, 1.0, 2.0, and 3.0 ppm) and three exposure times (10, 20, and 30 min) were tested. All concentrations reduced CFUs by 92% or more. A Nitrifying Bacteria Inhibition Test (NBIT) was used to test the resistance of ammonia oxidizing (AOB) and nitrite oxidizing bacteria (NOB) against the Lspecial PAA product. Filter pall covered with nitrifying bacteria were transferred into Erlenmeyer flasks containing culture medium (AOB or NOB Medium), shaken at 27 deg C and exposed to 0.5, 2.0 or 3.0 ppm PAA, respectively. At 2 h intervals, samples were taken and ammonia or nitrate/nitrite concentrations were determined. Concentrations of 0.5 ppm PAA did not affect the performance of AOB or NOB. Concentrations of 2.0 or 3.0 ppm PAA affected ammonia oxidation but not nitrite oxidation. These high concentrations should not be used. In vivo tests were also performed in tanks of a RAS. Fish tanks were disconnected from the system for 15 min, disinfected with 1.0 ppm PAA and reconnected. Water samples were taken immediately before, immediately after and 24 h after disinfection and cultured for 48 h in PCA. The CFUs were reduced to 3.8% directly after PAA exposure and 48% by 24 h after disinfection. In conclusion, facultative and obligatory fish pathogenic bacteria can be reduced by PAA exposure.