Enzyme-induced carbonate precipitation (EICP) is a biocementation technique that produces comparatively fewer carbon dioxide emissions than traditional cementation. However, the use of synthetic reagents for EICP is costly, and the process produces an ammonium byproduct which is a harmful pollutant. This study utilizes fresh urine as a source of urea and calcium-rich zeolites as an ammonium adsorbent and a source of calcium ions for the EICP cementation technique. Batch hydrolysis and adsorption experiments were conducted to determine the effects of zeolite type, zeolite form, and solution composition on ammonium adsorption and calcium release. Cementation experiments were then conducted to determine the effects of different hydrolysis and adsorption times on ammonium adsorption and calcium carbonate precipitation. The results showed that calcium-rich chabazite could be used as a source of calcium ions and as an effective adsorbent of ammonium for EICP. Additionally, synthetic, fresh urine and real, fresh urine had comparable ammonium adsorption and calcium release trends. Finally, inclusion of a pre-hydrolysis step reduced the ammonium adsorption and calcium release, but longer adsorption times lead to calcium carbonate precipitation outside of the sand column, which is an undesirable outcome for soil biocementation; even with this limitation, the calcium carbonate content of sand columns ranged from 0.48% to 0.92%, which signifies the potential of the proposed process for cementation, given a higher initial concentration of urea.
Is there a mismatch between urban farmers’ perceptions of their farm’s environmental sustainability and its actual environmental impact? Focusing on the use of water and nutrients on each farm as described by the farmers through interviews, it is evident that there is some level of disconnect between ideals and practices. This project may aid in bridging the gap between the two in regard to the farmers’ sustainability goals. This project will move forward by continuing interviews with farmers as well as collecting soil and water from the farms in order to more accurately quantify the sustainability of the farms’ practices. This project demonstrates that there is some degree of misalignment between perception and reality. Two farms claimed they were sustainable when their practices did not reflect that, while 2 farms said they were not sure if they were sustainable when their practices indicated otherwise. Samples from two farms showed high concentrations of nutrients and salts, supporting the idea that there may be a mismatch between perceived and actual sustainability.
This study investigated the difference in biofilm growth between pristine polypropylene microplastics and aged polypropylene microplastics. The microplastics were added to Tempe Town Lake water for 4 weeks. Each week the microplastic biofilms were quantified. Comparing the total biofilm counts, the results showed that the aged microplastic biofilms were larger than the pristine each week. By week 3 the aged microplastic counts had almost doubled in size increasing from 324 to 626 Colony Forming Units per gram in just one week. There was a significant difference in the diversity found from week 1 to week 4. About 40% of the diversity for the pristine microplastic biofilm was seen as light-yellow dots and about 60% of these dots were seen on the aged microplastic biofilms in both weeks. As the microplastics were submerged in the lake water, new phenotypes emerged varying from week 1 to week 4 and from pristine to aged microplastic biofilms. Generally, it was found that as the microplastics stay in the environment there is more biofilm on the particles. The aged microplastics have a larger amount of biofouling, and the pristine microplastic biofilms were found to have more diversity of phenotypes.
When we examine the word “dignity” regarding the built environment, we must look at how the building creates a sense of respect and honor. Buildings placed into communities without thoughtful consideration in how they will make occupants feel is undignified design. Design decisions that place the form of a building over its function allows aesthetics to become the primary criteria for judgement. When it comes to well-designed spaces, they should not just be a matter of aesthetics since they can shape our ideas about who we are and what we deserve. We need design that addresses the inhabitants needs, enhancing their overall experience. This is dignified design. We can ensure good design is a fundamental right by understanding the impact that the education system has on architects, and on shaping design to meet people’s needs. In this paper, I will address how a shift in the Architectural Education system could lead to more dignified design
While it may be complex, the prevention and treatment of contaminated water is possible. Founded in 2010, 33 Buckets is a registered 501(c)(3) nonprofit organization based out of Tempe, Arizona who partners with vulnerable communities and local partners to provide sustainable access to clean drinking water and WASH (Water and Sanitation for Health) training. Prior to 2018, 33 Buckets had completed drinking water projects in Bangladesh, the Dominican Republic, and Peru. In the summer of 2018, the 33 Buckets team returned to the Cusco region of Peru in an effort to assess more communities in need of clean drinking water infrastructure. In Cusco, 33 Buckets works closely with the Peruvian university, Universidad San Ignacio de Loyola (USIL). The primary purpose of this partnership is to identify communities in the Cusco region with contaminated water sources and a strong interest in improvement of current systems. Throughout this assessment trip, two communities were initially identified as potential partners, Occopata and Mayrasco. The results of bacteria tests showed a presence of Escherichia coli, commonly known as E. coli. When consumed, especially repeatedly, select strains of E. coli will cause severe diarrheal illness. Interviews with community members confirmed that common symptoms of water related disease are prevalent, especially in children. In Occopata and Mayrasco, there is an absence of support for water services from the municipality. Consequently, there is a volunteer-based water advisory board known as Junto Administración de Agua Sanitemeniento (JAAS). JAAS, in most nearby communities, currently utilizes a drip chlorination system in an attempt to disinfect bacterial pathogens from their water source. However, chlorine disinfection requires a precise dosing in order to be effective. In excessive amounts, chlorine will taste and smell of chemicals, likely producing negative feedback from community members. As a result, chlorine levels often are below the necessary level for disinfection. Chlorine tests performed by the 33 Buckets team confirmed that chlorine levels were insufficient to disinfect E. coli.
During the assessment trip, the 33 Buckets team provided a temporary solution to make chlorine disinfection more effective. Following the 2018 assessment trip, 33 Buckets formed a team of student engineers with the primary goal of furthering the technological development of a chlorine disinfection system to be implemented in communities with bacterial infected water sources. This student team was formed through the EPICS (Engineering Projects in Community Service) program at Arizona State University. The purpose of the program is providing a platform for undergraduate engineers to design solutions that create positive impact the greater community. From August of 2018 through April of 2019, the team developed the design for a continuous chlorine disinfection system that automatically tests for residual chlorine levels at multiple points throughout a community. The system is powered entirely from a low-cost solar panel, requiring a minimal amount of sunlight for full functionality. Moving forward, the goal of project development is to create an autonomous feedback loop that will adjust the amount of chlorine exposure to incoming water flows based on the results of the automatic residual chlorine test. The team also hopes to implement automatic data collection for remote monitoring of water quality in addition to onsite test results. The vision of the proposed solution is a network of chlorine disinfection systems around the Cusco region that ultimately will provide access to clean drinking water, indefinitely. This model of user-friendly purification, automatic testing, and data collection can be adjusted and applied to any region around the world experiencing health issues from consumption of contaminated water. A low-cost, scalable, and reliable water disinfection system has the potential to make significant increases in the quality of life for millions of people.
Optimizing cathodes for microbial fuel cells is important to maximize energy harvested from wastewater. Cathodes were made by modifying a recipe from previous literature and testing the current of the cathode using linear sweep voltammetry. The cathodes contained an Fe-N-C catalyst combined with a Polytetrafluoroethylene binder. Optimizing the power resulting from the microbial fuel cells will help MFCs be an alternative energy source to fossil fuels. The new cathodes did improve in current production from −16 𝐴/𝑚 to −37 𝐴/𝑚 at -0.4 V. When fitted using a Butler-Volmer model, the cathode linear-sweep voltammograms did not follow the expected exponential trend. These results show a need for more research on the cathodes and the Butler-Volmer model, and they also show that the cathode is ready for further and longer application in a microbial fuel cell.
