Project Goal: Design and build a wastewater treatment laboratory for the University of Arizona Chemical and Environmental Engineering Department to use in a novel hands-on course.

The UA Department of Chemical and Environmental Engineering is developing a wastewater treatment laboratory. It will combine several unit operations to purify artificial wastewater for demonstrating classic techniques. The feed streams are modeled after raw water concentrations seen as runoff from common industries in southern Arizona.

The project addresses coagulation, flocculation, gravity filtration and advanced oxidative treatment processes as well as design of the three chemical broths for separation. These were incorporated into a previous team design that uses reverse osmosis and a membrane bioreactor. An interchangeable valve setup varied the order of flow through the subsystems. Separation was characterized by monitoring pH, density, turbidity and electric conductivity throughout the process.

The design included researching, sizing, selecting and building each unit operation and associated equipment so the laboratory can feasibly operate in a safe, cost-effective and environmentally responsible manner.

Project Goal: Separate the components of guayule resin into high-value products, and evaluate their market potential.

Guayule is a desert plant that contains 5% to 7% rubber, primarily in the stalk. It is extracted to make tires. The guayule plant also contains 5% to 9% resin, which can be turned into products to keep the guayule industry economically feasible. Thus, this project explores the separation of the guayule to make marketable products.

The team used ASPEN software to simulate the separation process, including flash and distillation to fraction the resin into terpenes, terpenoids, sesquiterpenes and fatty acids. Resin content varies depending on the environmental conditions under which guayule is grown, and this simulation can be used to predict the required operating conditions depending on the feed composition.

The expected outcome is production of natural products, such as terpenes and terpenoids, which can be sold at approximately $1 a pound.

Project Goal: Recover solvent waste from a polymer processing facility.

In polymer processing facilities, solvent waste contributes to profit and loss and environmental damage. A process to recover wasted solvents can mitigate financial loss and reduce environmental impact.

This design uses various separation techniques to recover solvent from plant waste streams. Flash distillation, column distillation and air scrubbing remove and separate waste stream components. Lash drums remove excess water to use for air scrubbing of vented solvents. After the excess water is removed, column distillation separates remaining components for plant reuse. Trace amounts of unrecovered solvent are sent to a bio pond for biodegradation.

Facility expansion can handle a wide range of flow and concentration fluctuations downstream from the polymer processing facility.

Project Goal: Design a hydrodesulfurization unit that can process 30,000 barrels of diesel per stream day and reduce the sulfur content to at most 15 parts per million to meet EPA standards.

The unit’s design consists of a high-temperature, pressure-packed bed reactor that catalyzes the removal of sulfur compounds from diesel oil.

Integration of heat exchangers and a single cold high-pressure separator reduces energy consumption. An amine contactor recycles unspent hydrogen to ensure large amounts of reactive hydrogen are present in the reactor’s cycle. The catalytic reaction creates other unwanted side products that are removed further down the design.

The design factored in reactor sizing, separation of liquids and vapors, mass and energy balances, and modeling of various chemical reactions. ASPEN PLUS simulated the process to ensure the goal of 15 ppm sulfur.

Project Goal: Design an optimized compact catalytic reactor system for diesel powered vehicles to capture and remove carbonaceous particles.

Because of incomplete combustion, diesel-powered vehicles emit carbonaceous particles. The carbonaceous particles, or PM, contain microscopic solids and liquids less than 10 micrometers in diameter. The particles can go deep into the lungs and bloodstream and cause serious health problems. They also are a major environmental concern.

A diesel particulate filter, or DPF, can be installed in the exhaust system to reduce PM emissions to a level that meets U.S Environmental Protection Agency regulations. In this design, the DPF has a cordierite substrate in a monolith channel configuration to capture 95% of PM. A monolayer catalyst, which combines a transition metal and a noble metal, is applied to the substrate using an impregnation method to aid the regeneration process that oxidizes the PM and controls the thickness of the carbon deposit layer. System pressure and temperature sensors monitor the engine and filtration to prevent failure.

DPF simulations used mathematical models that imitate the flow of exhaust gases through the wall and carbon deposit layer.

Project Goal: While minimizing power input, design a system to recover helium from crude natural gas at the nitrogen removal stage of gas refinement.

Helium, a nonrenewable resource, is used in magnetic resonance imaging, gas-leak detection, welding and many other systems. Helium typically is extracted from crude natural gas, but the separation process to purify helium has high energy requirements and is costly, leading to steep annual increases in its price.

This design uses a double separation column cycle and cryogenic distillation techniques to extract helium from natural gas. The process produces three product streams containing nitrogen, helium and methane. To reduce production costs, the system uses vapor-liquid equilibrium within the process streams to mitigate the need for additional external refrigeration cycles.

The team verified efficiency using hand calculations and simulations in ASPEN modeling software. The design achieves recovery of 96% of helium, and the purified natural gas contains less than 2% nitrogen.

Project Goal: Design a sustainable fish pond in San Carlos, Arizona.

Officials in San Carlos, Arizona, are planning a sustainable fish pond to provide a community recreational area as well as help educate youth and connect them to their culture. This project assesses the design and installment plans.

The location rests on an accessible water well that has a high arsenic concentration. The team considered mass transfer balance, water and soil quality, livestock, cost and life cycle, among other factors.

The project applied fluid flow, evaporation, process design, and process control to determine the success of the pond based on the level of human intervention, livestock and use of the resource.

Project Goal: Regulate temperatures inside the silo to a safe and noncombustible range.

Silos store a variety of materials. However, unexpected heat sources can cause materials to combust and sometimes explode. Combustion can be prevented by monitoring silo temperatures and integrating a cooling system.

In this design, an automated system monitors the temperature throughout the silo and deploys dehumidified purge air to ensure that heat dissipation is greater than heat generation. Additionally, a nitrogen tank provides an emergency purge if the temperature reaches dangerous levels.

This project aims for a system that uses minimal power and operates at low cost.

Project Goal: Design an environmentally and economically friendly process for using sugarcane waste.

Sugar is among the most valuable commodities and traded agricultural products worldwide. The two common forms are white (refined) and brown (unrefined or raw), which can be granulated or ungranulated. The raw sugar crystallization process produces a large amount of solid waste from the cane stalks. The proposed process recycles the waste as a renewable energy source and synthesizes a biofuel from the molasses byproduct.

The cane stalks are crushed and milled to extract the cane juice, with the solid waste burned as an energy source. Suspended solids are removed from the juice. The resulting clarified juice continues through a series of evaporators to a crystallizer, attaining the optimal sugar crystals. The molasses byproduct goes to a fermentation reactor, where ethanol is produced to be sold as a fuel. During the process, steam is recycled to ensure sustainability.

The process minimizes energy cost and creates economic stability for the processor.

Project Goal: Successfully filter out 99.97% of dust particles from a lunar surface habitat airlock as part of the NASA 2021 Big Idea Challenge.

Lunar dust accumulation limits extended-stay missions. NASA’s Artemis program aims to establish a lunar base to test new systems and designs, ultimately for visiting other astral bodies with more challenging environments.

The Space Operated Lunar Surface Total Internal Contamination Elimination system, or SOLSTICE, effectively mitigates lunar dust accumulation in the habitat airlock via an intricate permanent magnet filtration system. Directed airflow during repressurization and a vacuum pump creating a pressure differential rapidly force dust to the bottom of the airlock. There, the stream of dust and air is sucked through a large particle filter then across an array of precisely designed magnets, which rely on the charged nature of lunar regolith to pull the dust from the air.

Multiple passes through the filtration system ensure highly efficient purification of at least 99.97%. The clean air is recycled back to the main habitat cabin, while the dust is returned to the lunar surface. A compact, lightweight design with minimal power requirements and negligible need for maintenance or upgrades deem this filtration system suited for space applications.