pH stabilization during testing of lethality of wastewater effluent to rainbow trout: chapter 3

Section 3: Reporting Requirements

In addition to the reporting requirements outlined in the Reference Method for Determining Acute Lethality of Effluents to Rainbow Trout, EPS 1/RM/13, the following supplementary information must be reported when conducting a pH stabilized test with wastewater effluent. Specific reporting requirements are as follows:

• type of pH stabilization technique used (pH Controller, Recycling or CO₂ Injection);
• for CO₂ Injection technique, percentage of CO₂ gas mix used during testing;
• for pH Controller technique, percentage of CO₂ gas mix or CO₂ used during testing;
• measured concentrations of the following parameters in the 100% wastewater effluent sample, after all effluent to be used in testing has been composited, thoroughly mixed and temperature of the sample has been adjusted to 15 ± 1 °C - pH i (pH i = pH as measured on composite 100% sample at 15°C before any aeration of the test solutions), total ammonia, and hardness;
• for the CO₂ Injection technique, alkalinity in the 100% wastewater effluent sample;
• calculated un-ionized ammonia concentration, based on the measurement of total ammonia, a temperature of 15 °C and the initial pH (pH i) of the 100% wastewater effluent sample;
• total residual chlorine in the wastewater effluent sample, if fish display stressed or atypical behaviour at test initiation;
• for multiple concentration (LC50) tests, pH of the diluted effluent concentrations at the start of testing (before any aeration is started at 15 °C) in each individual exposure concentration;
• for the CO₂ Injection technique, pH readings taken at t = 0 h (test start, when fish are introduced) and at t = 0.5, 1, 2, 3, 24, 48, 72, and 96 h in the control and all exposure concentrations;
• for the pH Controller and Recycling techniques, pH readings taken at t = 0 h (test start, when fish are introduced) and at 24, 48, 72, and 96 h in the control and all exposure concentrations;
• for the Recycling technique, report additional pH readings (if taken) at t = 0.5, 1, and 2 h;
• any additional pH readings taken during testing, or after adjustment of CO₂ or CO₂ gas mix, or removal of Recycling lid; and
• average pH based on all readings taken during testing.