Rainbow Trout pH Stabilization Toxicity Test Procedure

In 2012, Pollutech added a pH stabilization technique to our current Scope of Accreditation through CALA. This pH stabilization capability will allow Pollutech to better serve clients in the wastewater systems sector, and has already expanded our available Toxicity Indentification Evaluation (TIE) methods.

In 2012, the Canadian Department of the Environment, implement the Wastewater Systems Effluent Regulations under the Fisheries Act. This means that municipal sewage treatment plant effluent will be required to pass the rainbow trout 96-hour single-concentration (100% effluent) toxicity test according to the criteria outlined in the "Biological Test Method: Reference Method for Determining Acute Lethality of Effluents to Rainbow Trout”, Report EPS 1/RM/13, Second Edition (December 2000 including May 2007 Amendments). Pollutech’s biological testing facility has provided rainbow trout toxicity testing services since the mid 70's; we have excellent experience in handling all sample types and in conducting this test.

In the event that an effluent from a sewage treatment plant fails the regulatory trout test, and the effluent meets specific criteria as it relates to ammonia toxicity, a pH stabilization procedure may be added to the regulatory trout test (EPS 1/RM/13) according to the criteria outlined in the "Procedure for pH Stabilization During the Testing of Acute Lethality of Wastewater Effluent to Rainbow Trout”, Report EPS 1/RM/50.

During a trout test, the pH may change, usually due to the chemical or biological composition of the sample. Pollutech's pH stabilization method uses CO₂ to maintain pH (concentration of the hydrogen ion, H^-), countering the influence of these factors. Flow of CO₂ is controlled by solenoids that are activated by pH meters.

Stabilizing the pH for an effluent sample during testing stabilizes the balance of NH₃ and NH₄^- in the sample. If toxicity in a sample is pH dependant (such as the toxicity from these nitrogenous compounds) the effects can be neutralized by maintaining a constant pH. By controlling the pH, it can be determined if there are other factors causing a toxic response in the fish.

This pH stabilization technique has already been beneficial in investigating other pH-dependant toxic effects. When standard toxicity testing identifies a sample as being "toxic”, the first question is often "What is causing this toxicity?” A TIE is an organized progression through a number of published methods to isolate and identify the toxicity causing agent. Pollutech’s experts are well experienced in TIE. Each evaluation is unique, and each expands our ability to effectively help our clients.

Pollutech is accredited to ISO/IEC 17025:2005 by the Canadian Association for Laboratory Accreditation Inc. (CALA) for a specific scope of toxicity tests; including aquatic, sediment and soil toxicity tests using appropriate test organisms.

If you have any questions or require further details regarding our capabilities, please contact us.