Civil and Natural Resources Department Seminar Series

Doctoral Confirmation


Sky Halford


University of Canterbury

Time & Place

Thu, 08 Jul 2021 10:00:33 NZST in E13 Lecture Theatre

All are welcome



Sky Halford, PhD Candidate 


Antidepressant medications are used primarily to treat major depressive disorder and dysthymia, and give many people the opportunity to live enjoyable and fulfilling lives. They are one of the most prescribed groups of medications globally, with approximately 1 in 8 New Zealanders taking an antidepressant in 2018. After excretion, antidepressant compounds pass through most wastewater treatment facilities with little degradation and remain biologically active. Subsequent exposure to antidepressant compounds in the environment has resulted in negative impacts on non-target organisms, including reduced embryo production and escape responses in fish, altered mating behaviours in birds, and reduced camouflage efficiency in invertebrates.

Currently, there is a paucity of information regarding the presence of antidepressant compounds in New Zealand waste streams (i.e. wastewater effluent and sludge) and consequently entering the environment. There is likewise little information discussing the potential negative impacts on New Zealand native species. Regulating and banning antidepressant medications is virtually impossible due to the positive effect they have on lives and livelihoods; therefore, as the primary route to the environment, wastewater treatment facilities must be designed to remove these compounds before entering the environment.

The aim of this research project is to assess the presence and fate of antidepressant compounds in New Zealand waste streams, and develop processes to reduce these compounds reaching the environment. The first study will analyse three New Zealand wastewater treatment plants and determine which antidepressant compounds are most prevalent and at what concentrations. The second and third studies will subsequently investigate abiotic and biological wastewater treatment options that have the potential to degrade and/or remove the most common antidepressant compounds found in New Zealand. The final study will assess the relative toxicity of degradation products to ensure the final products are less toxic and harmful than the original compounds.

This research will contribute to a greater understanding of chemical pressures placed on New Zealand environments and provide useable solutions for decision makers to mitigate negative effects of antidepressant medications. Ultimately, this research aims to support those who require antidepressant medications, while also fostering healthy and resilient ecosystems.