Using Molecular Diagnostics for Early Detection of Chronic Toxicity

Published on September 10, 2018 16:56 by Erik Rumbaugh, Vice President at Aster Bio

While acute toxicity rapidly kills or harms your biomass, chronic toxicity tends to be a longer-term loss of activity. Instead of an instant kill, chronic toxicity works by growth inhibition. As organism reproduction slows, the desired microbes can start to decrease as a percentage of total biomass. For example, ammonia oxidizing bacteria (AOB) have a very slow growth rate compared to most heterotrophic microbes. If we inhibit this slower growth rate, the AOB population drops resulting in eventual ammonia breakthrough into the effluent.

Since it does not happen instantly, chronic toxicity can creep up on operators. There has been little way to detect chronic toxicity problems until you have a significant microorganism loss or inhibition. Aster Bio's Environmental Genomics platform offers a new way to detect chronic toxicity before treatment efficiency falls.

DNA is present in all organisms and we can use this DNA to identify which organisms are present. Using Environmental Genomics testing, Aster Bio can do a complete microbial census of all microbes present in MLSS. For routine chronic toxicity testing, we monitor the population of target organisms such as AOB/NOB, sulfur-reducing organisms (SRB), and bulking/foaming filaments among other organisms. In fact, we can customize our rapid qPCR tests for any target organism in a wastewater plant.

The advantages of using routine qPCR testing include:

Rapid results - can be rushed, no waiting weeks
Quantitative - unlike microscopic exam or trailing indicators, DNA can be quantified
Sensitive - for detecting chronic toxicity you need early detection. qPCR will pick up changes in the population before any other test including plate counts, respiration, ATP, or microscopic exam.

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