Browsing by Author "Aziz, Tarek"

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    Improving performance and examining expansion of constructed wetlands for tertiary treatment of nitrogen from domestic and municipal wastewater
    (NC WRRI, 2021-12-20) Burchell, Michael R.; Birgand, Francois; Aziz, Tarek; Kamrath, Brock
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    Improving startup and operation of anaerobic co-digestion of grease interceptor waste
    (NC-WRRI, 2017-07) de los Reyes, Francis; Aziz, Tarek
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    Sunlight-mediated removal of emerging contaminants in treatment wetlands and surface waters
    (NC Water Resources Research Institute, 2020-09-04) Aziz, Tarek; Sardana, Arpit
    In this project, we evaluated the photodegradation kinetics of wastewater derived emerging contaminants in treatment wetlands. We used dissolved organic matter (DOM) characterization tools and simulated irradiation experiments to investigate the relationship between photochemical behavior and wetland processing of wastewater effluents. Samples were collected from a treatment wetland site and a wastewater treatment plant (WWTP) in North Carolina. Cimetidine (CME), amoxicillin (AMX), 17𝞪-ethinyl-estradiol (EE2), and atenolol (ATL) were selected as target contaminants to evaluate photoreactivity of sampled waters. Target compounds were individually dissolved in the collected samples and their decay during irradiation was measured using HPLC methods. The direct photolysis photodegradation rates and quantum yields were calculated for AMX, EE2, and ATL, as these pharmaceuticals have been shown to undergo both direct and indirect photodegradation in sunlit waters. Photochemically produced reactive intermediates, such as excited triplet states of dissolved organic matter (3DOM*), singlet oxygen (1O2), and hydroxyl radical (•OH) were found to be substantially sensitized by both treatment wetland samples and WWTP effluents. •OH acted as the main photoreactant responsible for the phototransformation of AMX, ATL, and EE2. Photodegradation of CME was entirely due to singlet oxygen formation from irradiated DOM. Phototransformation rates and quantum yield coefficients were calculated to estimate the photochemical fate of the pharmaceuticals in sampled waters. Overall, photodegradation was fastest for CME, followed by EE2, and then AMX and ATL. It was observed that photoreactivity was higher in lagoon treated wastewaters than compared to vegetated wetland cells and secondary wastewater effluents. Some samples were observed to have an enhanced •OH formation yield which led to significantly higher phototransformation rates. This was suggested to be due to the activity of photo-Fenton reactions and DOM dependent hydroxylators. Optical indices for DOM characteristics were computed from ultraviolet–visible (UV-Vis) spectroscopy and excitation-emission matrix (EEM) fluorescence spectroscopy. ATL and EE2 photoreactivity was observed to be negatively correlated to humic and fulvic DOM components. The absorbance ratio (E2:E3) was found to be positively correlated only to CME phototransformation rates. Results from this study suggest that plant-derived organic matter from vegetated wetland cells can decrease photoreactivity of treatment wetland waters.
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    Sustainable Anaerobic Co-Digestion of Grease Interceptor Waste
    (Water Resources Research Institute of the University of North Carolina, 2014-11) Aziz, Tarek
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    Tertiary Anammox for Sustainable Nitrogen Removal
    (NC Water Resources Research Institute, 2022-04-28) Aziz, Tarek; de los Reyes, Francis; Young, Anthony
    Concentrated discharges of nitrogen into our waterways have led to serious environmental impacts, such as eutrophication and algae blooms. Due to these discharges, stringent total nitrogen (TN) discharge limits have been placed on Water Reclamation Facilities (WRFs). Mainstream deammonification offers a novel approach for improving nitrogen removal at these facilities by harnessing anaerobic ammonia oxidizing bacteria (Anammox). However, the success of this process has been limited. Previous research at NC State explored the conversion of tertiary filters to mainstream deammonification filters which were shown to be capable of an average total inorganic nitrogen (TIN) removal rate of 91%, with effluent TIN reaching below 2 mg/L-N. However, this research suggested that nitrate loading concentrations were the limiting factor in meeting 2 mg/L-N TIN effluent limits. Incorporating partial denitrification (PdN), the conversion of nitrate to nitrite for subsequent use in Anammox, offers a promising solution. The goal of this research was to explore the TIN removal capability and feasibility of a PdN-Anammox (PdNA) filter under typical filter loading conditions, in comparison to a conventional denitrification (FdN) filter. Different carbon loading strategies in pilot scale filters confirmed that maintaining a nitrate residual of >1.5 mg-N/L allowed for the highest PdN conversion efficiencies and in turn increased Anammox activity. Furthermore, the carbon requirement (C/N ratio) of 5.1 g COD/g TIN in pilot scale FdN was higher than the 2.08 g COD/g TIN achieved in the PdNA filters, demonstrating the cost benefits associated with mainstream deammonification and the application of PdNA. In addition to greater than 50% reduction in supplemental carbon, other benefits include nearly 38% reduction in oxygen demand and reduction in excess sludge in comparison to conventional BNR processes. Through this pilot study, PdNA was demonstrated to provide TIN removal efficiencies of greater than 80%. With further research, stable TN removal at WRFs at typical filter loading rates can be achieved, and with that, the possibility for substantial operational expenditure (OPEX) savings.