Influence of Sorption and Nitrification Processes on Pharmaceutical Attenuation During Biological Wastewater Treatment.
treatment plants (WWTPs) provide a direct route for pharmaceuticals to enter the
environment. Although WWTPs are not currently designed to specifically treat
pharmaceuticals, biological treatment holds potential for pharmaceutical attenuation
through sorption and biodegradation. Interestingly, recent observations suggest that
WWTPs operated to achieve nitrification may pr... read moreovide greater pharmaceutical attenuation.
This idea is explored by elucidating pharmaceutical sorption and cometabolic
biodegradation by nitrifying organisms. Pharmaceutical sorption during biological
wastewater treatment is assessed through the development and implementation of
quantitative structural property models. Results highlight the need to include both
hydrophobic and hydrophilic interactions, as well as characteristics of the biosolids
surface. Interestingly, the charge of the dominant species at the reactor conditions is
the best single predictor of pharmaceutical sorption. Biodegradation of atenolol,
metoprolol, naproxen and sotalol is examined during nitrification using results from lab
scale batch experiments. Although all are degraded during biological wastewater
treatment, only atenolol and naproxen are biodegraded by nitrifiers, specifically
ammonia oxidizing bacteria (AOB). Importantly, atenolol competitively inhibits AOB
growth at environmentally relevant concentrations. Rates of biodegradation are well
described by a cometabolic process based (CPB) model developed using transformation
coefficients to quantify rates of cometabolism by AOB under growth and non growth
conditions. The CPB model developed herein is the first model to mechanistically
integrate PhAC biodegradation with AOB process kinetics. This research demonstrates the
feasibility of developing predictive models to describe pharmaceutical attenuation
during biological wastewater treatment. Further research is warranted evaluating the
generalizability of these models and integration into process simulators utilized for
design and operation of WWTPs.
Thesis (Ph.D.)--Tufts University, 2013.
Submitted to the Dept. of Civil Engineering.
Advisor: C. Andrew Ramsburg.
Committee: Natalie Capiro, Steven Chapra, Mark Laquidara, and H. David Stensel.
Keywords: Environmental engineering, Water resources management, and Environmental management.read less