Hydrogen peroxide concentrations in hatchery culture units and effluent during and after treatment

A raceway in a fish hatchery was treated with hydrogen peroxide (H2O2), as 1-h flow-through treatments, to simulate the New York State maximum allowab le concentration (11.5 mg/L) in the receiving stream. Hydrogen peroxide con centrations were measured at various locations in the hatchery and in the r eceiving stream over a 96-h period. At the discharge pipe opening in the re ceiving stream, maximum mean H2O2 concentration was 9 mg/L at the end of th e 1-h treatments and 2 mg/L 1 h later; at a point 15 m downstream (midstrea m) from the discharge pipe, maximum mean H2O2 concentrations were 2 mg/L: a t discharge and 1 mg/L or less (method detection limit) 1 h later. In a sec ond set of experiments, a desired 100 mg H2O2/L was achieved in 1-h flow-th rough treatments only when the test tank was pretreated to initially establ ish an H2O2 concentration of 100 mg/L before initiating the flow-through tr eatment. When the 1-h flow-through treatment was administered without pretr eatment of the test tank, a maximum H2O2 concentration of 75 mg/L was achie ved.