Experimental data: pharmaceuticals and personal-care products impact on nitrification

Nitrification is an important microbial process in wastewater, by which ammonia is oxidised to nitrate by two guilds of bacteria: Nitrosomonas and Nitrobacter. As a community, their synergistic interactions are important for the complete removal of ammonia from, not only wastewater, but also agricultural/terrestrial and freshwater/marine ecosystems. Decoupling the process by chemical inhibitors, e.g., pharmaceutical and personal care products, can disrupt the system’s to detoxify ammonia and complete the nitrogen cycle.

In a series of microcosm experiments, enriched wastewater consortium of ammonia oxidising bacteria (Nitrosomonas sp.) and nitrite-oxidising bacteria (Nitrobacter spp.) were exposed to four antimicrobial agents (ampicillin, colistin, ofloxacin, and triclosan), insect repellent (N,N-diethyl-m-toluamide (DEET)) and a caffeine (a stimulant). Liquid cultures were exposed a range of toxicant concentrations, and the production of nitrite and nitrate were monitored (along with pH) over time. Allythiourea (ATU, 0.3 mg/L) was added as a selective inhibitor (control reaction).

The aims of the project were:
1. to determine the extent that ammonia-oxidising performance can withstand the toxic effects of pharmaceuticals into wastewater
2. to develop a refined toxicological assessment tool for microbial communities.