Title: Salinity, water hardness, and dissolved organic carbon modulate degradation of peracetic acid (PAA) compounds in aqueous solutions Authors
|Liu, Dibo -|
|Steinberg, Christian -|
|Pedersen, Lars-Flemming -|
|Meinelt, Thomas -|
Submitted to: Aquaculture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: August 6, 2013
Publication Date: N/A
Interpretive Summary: Peracetic acid (PAA) is a mixture of acetic acid (concentrated vinegar) and hydrogen peroxide that is used as a disinfectant in food preparation, hospitals and aquaculture. It works very well on hard surfaces, but in aquaculture, we don’t know what effect water hardness (i.e., calcium concentration), salinity or dissolved organic carbon (i.e., sources of decomposing plants) has on neutralizing this compound. We used 3 commercial PAA mixtures and 3 different concentrations of these mixtures in waters with different hardness, salinity or dissolved organic matter, to track the rate that the PAA concentrations diminished. The results showed that salinity and dissolved organic carbon increased the rates of degradation of PAA, while hardness had little effect. This compound is being investigated to replace banned chemicals, especially in the EU where very few chemicals can be used, it is safe and effective to use on fish at a low dose, and breaks down into harmless residues.
Technical Abstract: Peracetic acid (PAA) is used in aquaculture under different conditions for disinfection purposes. However, there is a lack of information about its environmental fate, particularly its persistence in aquatic systems with different chemistries. Therefore, the impact of water hardness, salinity, and dissolved organic carbon (DOC) on PAA-degradation within 5 h was investigated in this study. Three PAA formulations (Wofasteril (c) E400, Wofasteril (c) E250, and Wofasteril (c) Lspez) at 3 concentrations (0.5 mg/L, 1 mg/L and 3 mg/L) were selected. Salinity, water hardness, and dissolved organic carbon (DOC) were the specific variables investigated in this study. Salinity was adjusted with NaCl or sea salt dissolved in purified water at concentrations of 1 % (10 g/L) and 3 % (30 g/L); water hardness was adjusted to 0.5- (pH 7.5, low water hardness) and 5-fold (pH 8, high water hardness) standard dilution water (DIN EN ISO 7346-3:1997); DOC was maintained with HuminFeed (c) dissolved in purified water resulting in DOC concentrations of 8 mg/L and 24 mg/L. The results showed that salinity, especially sea salt, and DOC increased the PAA-degradation rate while water hardness likely stabilized PAA. For full scale aquaculture application, the fate of PAA has to be carefully monitored, since a brief exposure time or low dosage will result in insufficient treatment, and could provoke the opposite effect and stimulate the pathogens.