Degradation and effect of hydrogen peroxide in small-scale recirculation aquaculture system biofilters

Abstract

From an environmental point of view, hydrogen peroxide (HP) has beneficial attributes compared with other disinfectants in terms of its ready degradation and neutral by‐products. The rapid degradation of HP can, however, cause difficulties with regard to safe and efficient water treatment when applied in different systems. In this study, we investigated the degradation kinetics of HP in biofilters from water recirculating aquaculture systems (RAS). The potential effect of HP on the nitrification process in the biofilters was also examined. Biofilter elements from two different pilot‐scale RAS were exposed to various HP treatments in batch experiments, and the HP concentration was found to follow an exponential decay. The biofilter ammonia and nitrite oxidation processes showed quick recuperation after exposure to a single dose of HP up to 30 mg L−1. An average HP concentration of 10–13 mg L−1 maintained over 3 h had a moderate inhibitory effect on the biofilter elements from one of the RAS with relatively high organic loading, while the nitrification was severely inhibited in the pilot‐scale biofilters from the other RAS with a relatively low organic loading. A pilot‐scale RAS, equipped with two biofilter units, both a moving‐bed (Biomedia) and a fixed‐bed (BIO‐BLOK®) biofilter, was subjected to an average HP concentration of ∼12 mg L−1 for 3 h. The ammonium‐ and nitrite‐degrading efficiencies of both the Biomedia and the BIO‐BLOK® filters were drastically reduced. The filters had not reverted to pre‐HP exposure efficiency after 24 h, suggesting a possible long‐term impact on the biofilters.

Low‐Dose Hydrogen Peroxide Application in Closed Recirculating Aquaculture Systems

“…This decay pattern is in line with previous findings (Rach and Ramsey 2000;Saez and Bowser 2001), in which the effects of dilution could not be assessed. These decay rates, similar to those obtained by Pedersen et al (2006) and Møller et al (2010) are orders of magnitude faster than those reported by Tort et al (2003). Tort et al (2003) investigated low-dose HP degradation in a number of water tanks without fish and observed half-lives ranging from 20 h to several days.…”

“…Bench-scale biofilter performance test.-Biofilter elements from the submerged biofilter (www.expo-net.dk) were removed from a high-intensity RAS and transferred to temperatureadjusted, aerated system water, as described by Møller et al (2010). Individual Bioblok cylinders were then placed in an experimental setup with an HP sensor and dosage feedback mechanism (ElectroCell; Tarm, Denmark) that allowed automatic regulation of the HP concentration in the water.…”

“…Individual Bioblok cylinders were then placed in an experimental setup with an HP sensor and dosage feedback mechanism (ElectroCell; Tarm, Denmark) that allowed automatic regulation of the HP concentration in the water. Biofilter elements were exposed to a fixed concentration of 15 mg HP/L for 30 min, 1 h, or 3 h in triplicate and transferred to separate bench-scale setups, as described in Møller et al (2010). Concomitantly, sodium nitrite was added to each reactor at a level of approximately 3 mg NO − 2 -N/L, and periodic water sampling was performed to assess nitrite oxidation performance.…”

“…This risk can be minimized by applying lower doses for prolonged periods of time, but this may create the risk of underdosing. The effects of HP and HP-releasing products in biofilters have previously been investigated, and substantial variation between types of systems has been observed (Pedersen et al 2006;Møller et al 2010).…”

Removing organic and nitrogen content from a highly saline municipal wastewater reverse osmosis concentrate by UV/H2O2–BAC treatment

“…Schwartz et al (2000) showed 80% reduction in ammonium removal in a fluidised sand bed filter at a H 2 O 2 concentration of 100 mg L À1 . Møller et al (2010) found that the nitrification process could be moderately affected with a low dose of H 2 O 2 (10-13 mg L À1 ) in a biofilter for a recirculating aquaculture system, thereby reducing ammonia and nitrite removal. They noted that the nitrification process was severely inhibited when the biofilter was exposed to H 2 O 2 for a prolonged period even with a lower H 2 O 2 concentration.…”