Case study Whole-effluent assessment using a combined biodegradation and toxicity approach

The current thinking is that whole effluent toxicity assessment provides a practical, biologically relevant mechanism for providing additional hazard data on the combined effects of all the contaminants present in a complex effluent. There is reasonable confidence that an appropriate set of acute, and to a lesser extent chronic, toxicity assessments exist that have been used in many countries over the past two decades. Consequently, there is guidance on limit conditions for 

In the study described in this chapter we have used this approach to assess the toxicity of three complex effluents  

We describe the methodology adopted for the combined biodegradation and toxicity assessments and discuss how the data can be interpreted and used to improve risk assessment in the context of these three effluents. 

Prior to undertaking the study it was important to ensure that the methods selected for the biodegradation and toxicity assessment were practical, cost-effective and capable of providing environmentally relevant toxicity and biodegradation data over a reasonably short time period (say 15 days). It was decided that biodegradation of the effluents would be assessed using an electrolytic respirometer - this approach met the above criteria and had several advantages  

Biodegradation is followed as biochemical oxygen demand (BOD), which enables descriptors such as BOD5 to be obtained. 

---

Case study Whole effluent assessment using a combined biodegradation and toxicity approach... 

---