The Effect of Chlorination of wastewater treatment effluents in the Avalon Coastal Ecosystem.
The formation of disinfection byproducts (DBPs) is a main environmental concern associated with chlorine disinfection. Free chlorine can react with organic and inorganic compounds to produce different DBPs which can be toxic to aquatic life. Chlorinated wastewater must often be dechlorinated to remove the free and combined chlorine residuals before discharge into receiving water bodies. However, research has shown that dechlorination has no effect on the quantities of some of these chlorinated byproducts.
NAACAP is currently undertaking a project to determine levels of chlorine disinfection byproducts that are released from wastewater treatment facilities on the Northeast Avalon Peninsula. The Riverhead treatment facility in St. John’s and the Cronin’s Head treatment facility in Conception Bay South were selected to obtain samples from. Both the facilities use chlorine for disinfection and then have subsequent dechlorination before effluent is discharged from the plant. In both locations grab samples are selected before the chlorination phase and after the dechlorination phase of the wastewater treatment process. Analyses of these samples include Microtox testing for toxicity, AOX (adsorbabale organic halides), THMs (trihalomethanes), and HAAs (haloacidic acids).
There will be three sampling visits to each plant, the first of which occurred successfully in Fall 2011. The management and staff of both wastewater treatment facilities were very cooperative and helpful during our past visits which NAACAP is very appreciative of.
Another aspect of the project is obtaining water samples from the water bodies that the wastewater effluent is discharged into. This aspect of sampling has not been performed yet, as a better understanding of the flow patterns in the water bodies was necessary to obtain representative results. These samples will be tested for THM and HAA content, as these byproducts are very specific to the use of chlorine in disinfection.
