Education

Research Description

Dr. Aziz's research focuses on environmental systems where biological, chemical, and/or physical processes are closely coupled to fluid dynamics. Dr. Aziz and his team use field monitoring, lab-based experiments, and numerical modeling to develop solutions and gain insights into both natural and engineered environmental processes. Research topics that Dr. Aziz is working on include studying the effects of artificial mixing on harmful algal blooms and the use of engineered wetlands for the removal of emerging contaminants like pharmaceuticals and personal care products.

Honors and Awards

• NCSU Outstanding Teacher Award Recipient, 2014

Publications

Dissolved organicmatter processing and photoreactivity in a wastewater treatment constructed wetland

Sardana, A., Cottrell, B., Soulsby, D., & Aziz, T. N. (2019), SCIENCE OF THE TOTAL ENVIRONMENT, 648, 923–934. https://doi.org/10.1016/j.scitotenv.2018.08.138

Determination of biosolids phosphorus solubility and its relationship to wastewater treatment

Jameson, M., White, J. G., Osmond, D. L., & Aziz, T. (2016), Water Environment Research, 88(7), 602–610. https://doi.org/10.2175/106143016x14609975746406

Municipal solid waste conversion to transportation fuels: a life-cycle estimation of global warming potential and energy consumption

Pressley, P. N., Aziz, T. N., DeCarolis, J. F., Barlaz, M. A., He, F., Li, F. X., & Damgaard, A. (2014), Journal of Cleaner Production, 70, 145–153.

Determining the limits of anaerobic co-digestion of thickened waste activated sludge with grease interceptor waste

Wang, L., Aziz, T. N., & Reyes, F. L. (2013), Water Research, 47(11), 3835–3844.

Anaerobic co-digestion of fat, oil, and grease (FOG): A review of gas production and process limitations

Long, J. H., Aziz, T. N., Reyes, F. L., & Ducoste, J. J. (2012), Process Safety and Environmental Protection, 90(3), 231–245.

Field characterization of external grease abatement devices

Aziz, T. N., Holt, L. M., Keener, K. M., Groninger, J. W., & Ducoste, J. J. (2012), Water Environment Research, 84(3), 237–246.

Assessment of internal and external grease interceptor performance for removal of food-based fats, oil, and grease from food service establishments

Gallimore, E., Aziz, T. N., Movahed, Z., & Ducoste, J. (2011), Water Environment Research, 83(9), 882–892.

Performance of grease abatement devices for removal of fat, oil, and grease

Aziz, T. N., Holt, L. M., Keener, K. M., Groninger, J. W., & Ducoste, J. J. (2011), Journal of Environmental Engineering (New York, N.Y.), 137(1), 84–92.

Simulation of vertical plane turbulent jet in shallow water

Aziz, T. N., & Khan, A. A. (2011), Advances in Civil Engineering (Online).

Numerical Simulation of Turbulent Jets

Aziz, T., Raiford, J., & Khan, A.-A. (2008), Engineering Applications of Computational Fluid Dynamics, 2(2), 234–243.

View all publications via NC State Libraries

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Grants

Improving performance and examining expansion of constructed wetlands for tertiary treatment of nitrogen from domestic and municipal wastewater

NCSU Water Resources Research Institute(6/01/18 - 5/29/19)

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Improving performance and examining expansion of constructed wetlands for tertiary treatment of nitrogen from domestic and municipal wastewater

Sponsor: NCSU Water Resources Research Institute

Start Date: 6/01/18

End Date: 5/29/19

Abstract

Nitrogen (N) loading to our streams and rivers has improved since the mid-1990s through management practices that have reduced discharges from stormwater and agricultural sources. However, load reductions to surface waters like the Neuse River have not reached targeted goals, and eutrophication remains a major concern. Problems with N fluxes from our watersheds are expected to continue and worsen. Projected population increase and shifts in precipitation patterns will lead to significant increases in N loads to our surface waters, requiring new management strategies to reduce inputs by an additional 20-30%. Large facilities that treat wastewater for major municipalities are most heavily scrutinized, but what about the hundreds of small towns and communities that do not have advanced wastewater facilities? Often overlooked, the discharge limits for smaller systems for ammonia-nitrogen (NH4-N) are often high (10 mg/L) or even non-existent. Package plants that use aerobic processes to treat wastewater in smaller, rural communities often successfully treat NH4-N to low levels through the process of nitrification, but the effluent contains the byproduct nitrate-nitrogen (NO3-N). Discharge of this form of nitrogen is often similar to loads discharged from agricultural facilities on an areal basis and will continue to contribute to eutrophication problems if left unchecked. To help meet current and future N reduction goals, the time is now to address these often overlooked sources using alternative technologies. Installation of constructed wetlands, known for high N removal potential, placed strategically in the landscape to intercept N from smaller rural wastewater treatment facilities, could be a solution to help NC get closer to its N reduction goals. Constructed wetlands are often used across the country and the world for advanced nitrogen removal from wastewater. In NC, these systems have been successful, but very few are in operation. The objectives of this research and outreach project are 1) to help small towns improve nitrogen removal performance of older existing constructed wetlands and 2) advance the understanding and use of constructed wetlands to remove nitrogen from domestic and municipal wastewater. 3) demonstrate the impact constructed wetlands could have on overall watershed N reduction when coupled with existing wastewater package plants.

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Predicting the Effectiveness of Artificial Mixing for Controlling Algal Blooms in Piedmont Reservoirs

NCSU Water Resources Research Institute(3/01/16 - 12/01/18)

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Predicting the Effectiveness of Artificial Mixing for Controlling Algal Blooms in Piedmont Reservoirs

Sponsor: NCSU Water Resources Research Institute

Start Date: 3/01/16

End Date: 12/01/18

Abstract

The use of artificial mixing has been proposed as a means of suppressing the formation of algal (phytoplankton) blooms in freshwater and coastal waterbodies. However, there are conflicting reports on the performance of such systems, with sparse data relating to how artificial mixing affects bloom formation in North Carolina (NC) reservoirs. An understanding of the linkages between blooms, artificial mixing, climate variability, and other water quality constituents is critical to effectively managing water supplies and developing useful geo-engineering solutions. In this proposed research we aim to (1) conduct field campaigns in multiple Piedmont reservoirs to measure vertical diffusivity, water quality, and phytoplankton assemblages in natural and artificially mixed conditions, (2) perform statistical (hierarchical) modeling of vertical diffusivity and phytoplankton concentrations to help identify and quantify key biophysical relationships, (3) perform mechanistic water-column modeling to generalize the results obtained in (2), and (4) develop a decision-support tool from the data and analysis performed in objectives (1) – (3) to predict algal type and abundance under different artificial mixing and background physical and chemical scenarios. Findings from this research will provide new insights into the impacts of both natural and artificial mixing in Piedmont reservoirs, and aid engineers and managers in developing strategies to protect the beneficial uses of these reservoirs.

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Effects of Enhanced Circulation on Vertical Mixing and Algal Blooms In Freshwater Reservoirs

National Science Foundation (NSF)(6/01/15 - 5/31/18)

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Effects of Enhanced Circulation on Vertical Mixing and Algal Blooms In Freshwater Reservoirs

Sponsor: National Science Foundation (NSF)

Start Date: 6/01/15

End Date: 5/31/18

Abstract

The use of enhanced circulation has been proposed as a means of suppressing the formation of harmful algal blooms (HABs) in freshwater and coastal waterbodies. At present, there are conflicting reports on the performance of such systems, with sparse data relating to how enhanced circulation affects the biophysical processes controlling bloom formation. In late 2014, the state of North Carolina began a 1.5-year pilot study to determine if a large-scale deployment of solar-powered, surface-layer circulators can reduce algal bloom concentrations on Jordan Lake, a 56 km2 reservoir used for water supply, flood control, and recreation. This geoengineering study represents a rare opportunity to directly investigate how large-scale enhanced circulation affects mixing and algal dynamics in a large waterbody. For this research project, the principle investigators (PIs) will perform a series of field activities to determine how these circulators are affecting physical and biological conditions within the lake. Activities will be conducted in different arms of the lake, representing treatment (circulators present) and control (circulators absent) conditions. Physical measurements will include vertical profiles of temperature micro-structure to infer vertical diffusivity, near-surface current velocities to determine extent of circulation, and wind velocities. Biological measurements will include vertical profiles of chlorophyll (total algae) and phycocyanin (indicating blue-green, cyanobacteria algae). Monitoring will be coordinated with the North Carolina Department of Water Resources, who will be measuring a series of conventional water quality parameters that will also be used in this study. Using the data from these field activities, we will determine how the synergistic impacts of wind speed and artificial circulation affect vertical diffusion within the surface layer, which is expected to be a primary control on algal dynamics. We will further test hypotheses related to how mixing (natural and artificial) affects the abundance and vertical distribution of total chlorophyll and cyanobacteria. Intellectual Merit: At present, characterization of artificial mixing and its effect on phytoplankton community structure has been limited to whole-lake mixing (i.e. destratification), which may be impractical for larger waterbodies. The proposed research represents the first comprehensive characterization of how enhanced surface-layer circulation affects vertical diffusion rates and HABs formation potential. The project takes advantage of a uniquely large deployment of surface-layer circulators, to answer scientific and engineering questions at multiple scales. Overall, the project will help provide critical insight into the potential role of geoengineering as a tool for the abatement of HABs. Broader Impacts: Jordan Lake, like many similar reservoirs around the world, is impaired due to excessive algal growth. The lake provides drinking water to 300,000 people, and it serves as a recreational attraction for many more. The state of North Carolina is presently considering a permanent deployment of circulators for this and other reservoirs. However, there is currently insufficient information to determine when and where this type of geoengineering is likely to be effective. As such, this project will provide critical information to decision makers and the general public, allowing for more informed water resources management. Furthermore, the study will provide data and fundamental insights required to create biophysical models that incorporate the linkages between enhanced circulation and algal dynamics, allowing us to predict the probability of HABs in different water bodies and under different management and climate change scenarios.

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Improving Start-up and Operation of Anaerobic Co-Digestion of Grease Interceptor Waste

NCSU Water Resources Research Institute(3/01/15 - 12/31/16)

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Improving Start-up and Operation of Anaerobic Co-Digestion of Grease Interceptor Waste

Sponsor: NCSU Water Resources Research Institute

Start Date: 3/01/15

End Date: 12/31/16

Abstract

Our current WRRI-funded research (ending June 2014) has shown the potential of anaerobic co-digestion of GIW with wastewater-derived biosolids as a value-added disposal option. Our research resulted in several key findings4,5: 1) We achieved the highest methane yield ever reported for co-digestion (0.785 L CH4/g VS added, representing a 336% increase over the baseline). 2) We showed that step feeding as a strategy allows up to 75% (w/w) of volatile solids (VS) without overloading. 3) We demonstrated that high load pulses increased the digester resistance to GIW overloading. 4) Molecular microbial analysis using next generation sequencing is ongoing, but our pulse experiments suggest that changes in acid oxidizing bacterial communities are key. These results directly impact the economic feasibility of operating GIW co-digesters, specifically with respect to maintaining high methane yields. The overall objective of this project is to understand substrate-community interactions to optimize anaerobic co-digestion, particularly to minimize start-up time, and increase process resilience and resistance. The specific objectives are to: (1) Determine the key microbial populations that limit the anaerobic pathway to methane under different stress conditions such as overloading and GIW variability, (2) Influence these populations through active adaptation, and (3) Develop a procedure for producing a high yield yet resilient anaerobic co-digestion system that can be used in full scale applications.

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Sustainable Anaerobic Co-Digestion of Grease Interceptor Waste

NCSU Water Resources Research Institute(3/01/13 - 6/28/14)

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Sustainable Anaerobic Co-Digestion of Grease Interceptor Waste

Sponsor: NCSU Water Resources Research Institute

Start Date: 3/01/13

End Date: 6/28/14

Abstract

Fat, oil, and grease (FOG) generated at food service establishments pose a threat to public health and the environment by reducing the conveyance capacity of our collection systems and causing sanitary sewer overflows. Grease abatement device pumping is a necessary step to maintain system performance. Presently in North Carolina, FOG waste pumped from the food service industry is treated as septage and either land applied or composted as a soil amendment. The anaerobic co-digestion of grease interceptor waste (GIW) provides a value added disposal option whereby GIW can be used to generate electricity at wastewater treatment facilities. No facilities in North Carolina currently utilize the anaerobic co-digestion of GIW. Preliminary research at NC State has shown the addition of GIW to result in increases in biogas production of up to 317%. The proposed research aims to: (1) Explore the limits to anaerobic co-digestion by varying the composition of GIW, (2) Explore bioreactor process and microbial community that is functionally resilient to variations in FOG loading and (3) Evaluate the quality of co-digested biosolids during experimentation for tasks (1) and (2). Findings from this research will provide guidelines for the sustainable disposal of GIW via anaerobic co-digestion and move wastewater treatment facilities towards renewable energy generation.

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Utilizing Municipal Solid Waste as a Biofuel Feedstock

Biofuels Center of North Carolina(7/01/11 - 4/30/13)

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Utilizing Municipal Solid Waste as a Biofuel Feedstock

Sponsor: Biofuels Center of North Carolina

Start Date: 7/01/11

End Date: 4/30/13

Abstract

Although crop and timber-based biomass have traditionally been viewed as primary choices for biofuel production, recent research suggests that municipal solid waste (MSW) may overcome a number of limitations, such as limited availability and accessibility, as compared to first-generation feedstocks . North Carolinians generate more than 9.9 million tons of MSW per year according to the N.C. Dept. of Environment and Natural Resources. Roughly 60% of this mass consists of paper, plastic, and food scraps that can be converted into biofuels via gasification technologies. If all of the MSW generated in N.C. were directed towards biofuels production, this feedstock would generate 297 million gallons of biofuels (assuming a conservative conversion rate of 50 gal biofuel per ton MSW), which is roughly 5% of the State?s total fuel consumption annually . This quantity would meet half of the state?s 2017 goal to have 10% of liquid fuels come from N.C. produced biofuels. However, the concept of converting MSW into liquid biofuels is relatively new. As a result, the mechanisms and infrastructure needed to make this technology a viable industry are poorly understood. Thus, the primary objectives of this proposal are to: 1. Compare conversion of MSW into biofuels with current methods used to generate electricity/heat from MSW (e.g. landfill gas to energy, waste-to-energy). 2. Summarize MSW management and operational infrastructure and evaluate how it can be used to support needed infrastructure for the biofuels industry. 3. Develop a report that can be used to educate the public and policymakers about the biofuel production feasibility/capability using MSW as a feedstock. To achieve these objectives, the Environmental Research and Education Foundation (EREF) and its partners (NC State University, Maverick Biofuels, Waste Industries) will conduct a meta-analysis to acquire data related to: process conversion efficiencies, processing capacity, environmental metrics, energy production, waste quantity and composition, and geospatial factors (Obj. #1). This data will then be used to examine MSW management infrastructure (Obj. #2) and develop information that can serve as a basis for a plan for integrating the use of MSW as a biofuel feedstock (Obj. #3). Issues such as waste reduction initiatives, shifts in waste composition, and their effect on the suitability of MSW as a biofuel feedstock will be considered. The primary deliverable from this $93,119 project will be a report describing the study findings. The project will be completed in 16 months. The EREF?s stakeholder base represents the majority of the solid waste industry. Thus, the EREF has the ability to leverage these results to support MSW to biofuel conversion technologies in NC and beyond.

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