Educating Engineers to Work Ethically with Global Marginalized Communities.

Ethical reasoning is an important ability for engineers working with marginalized communities in global contexts. However, the ethical awareness and development that are critical for this work may not be included in traditional engineering education. This article presents faculty perspectives on the ethical and societal issues (ESI) that should be taught and the pedagogies that are used to prepare students for development engineering. Among 60 survey respondents who taught courses focused on global and/or development (GD) issues, the ESI topics that were particularly congruent included poverty, sustainability, social justice, and engineering decisions under uncertainty. Faculty interviews highlighted that GD should foreground the human side of engineering, respectful partnerships with communities grounded in an asset perspective, and considerations of historical elements. Discussions, case studies, design, and reflection are impactful pedagogies that can complement learning through service to achieve ESI educational goals.

Exploratory Investigation of Personal Influences on Educators' Engagement in Engineering Ethics and Societal Impacts Instruction.

Cultivating an understanding of ethical responsibilities and the societal impacts of technology is increasingly recognized as an important component in undergraduate engineering curricula. There is growing research on how ethics-related topics are taught and outcomes are attained, especially in the context of accreditation criteria. However, there is a lack of theoretical and empirical understanding of the role that educators play in ethics and societal impacts (ESI) instruction and the factors that motivate and shape their inclusion of this subject in the courses they teach and co-curricular activities they mentor. The goal of this research was to explore the role of faculty's personal influences on their inclusion of ESI instruction in these settings. Personal influences are distinguished from external or environmental drivers such as teaching assignments, university policies, and department curriculum decisions. This research employed a grounded theory methodology and extracted data from interviews with 19 educators who teach ESI to engineering students to develop an emergent conceptualization of personal influences. Four categorie were identified: intrapersonal (drawing on self-interests and beliefs), interpersonal (drawing on relationships to engage in the intersectional field of ESI), academic (using their experiences as a student), and professional (leveraging non-academic work to understand the application of ESI and bring ESI into the classroom). The findings suggested a wide range of entry points (based on varying interests, beliefs, interactions, and backgrounds) into ESI instruction for faculty members who do not currently teach ESI and for those looking to expand the inclusion of ESI in their courses. Based on these findings, departments and administrators are encouraged to foster educators' agency, support access to professional development and engagement, facilitate interdisciplinary collaboration, and broaden hiring decisions to account for the impact of educators' holistic identity on their instruction.

Evolution of Students' Varied Conceptualizations About Socially Responsible Engineering: A Four Year Longitudinal Study.

Engineers should learn how to act on their responsibility to society during their education. At present, however, it is unknown what students think about the meaning of socially responsible engineering. This paper synthesizes 4 years of longitudinal interviews with engineering students as they progressed through college. The interviews revolved broadly around how students saw the connections between engineering and social responsibility, and what influenced these ideas. Using the Weidman Input-Environment-Output model as a framework, this research found that influences included required classes such as engineering ethics, capstone design, and some technical courses, pre-college volunteering and familial values, co-curricular groups such as Engineers Without Borders and the Society of Women Engineers, as well as professional experiences through internships. Further, some experiences such as technical courses and engineering internships contributed to confine students' understanding of an engineer's social responsibility. Overall, students who stayed in engineering tended to converge on basic responsibilities such as safety and bettering society as a whole, but tended to become less concerned with improving the lives of the marginalized and disadvantaged. Company loyalty also became important for some students. These results have valuable, transferable contributions, providing guidance to foster students' ideas on socially responsible engineering.

Inhibition of Biodegradation of Hydraulic Fracturing Compounds by Glutaraldehyde: Groundwater Column and Microcosm Experiments.

The rapid expansion of unconventional oil and gas development has raised concerns about the potential contamination of aquifers; however, the groundwater fate and transport of hydraulic fracturing fluid compounds and mixtures remains a significant data gap. Degradation kinetics of five hydraulic fracturing compounds (2-propanol, ethylene glycol, propargyl alcohol, 2-butoxyethanol, and 2-ethylhexanol) in the absence and presence of the biocide glutaraldehyde were investigated under a range of redox conditions using sediment-groundwater microcosms and flow-through columns. Microcosms were used to elucidate biodegradation inhibition at varying glutaraldehyde concentrations. In the absence of glutaraldehyde, half-lives ranged from 13 d to >93 d. Accurate mass spectrometry indicated that a trimer was the dominant aqueous-phase glutaraldehyde species. Microbial inhibition was observed at glutaraldehyde trimer concentrations as low as 5 mg L-1, which demonstrated that the trimer retained some biocidal activity. For most of the compounds, biodegradation rates slowed with increasing glutaraldehyde concentrations. For many of the compounds, degradation was faster in the columns than the microcosms. Four compounds (2-propanol, ethylene glycol, propargyl alcohol, and 2-butoxyethanol) were found to be both mobile and persistent in groundwater under a range of redox conditions. The glutaraldehyde trimer and 2-ethylhexanol were more rapidly degraded, particularly under oxic conditions.

Changes in the Social Responsibility Attitudes of Engineering Students Over Time.

This research explored how engineering student views of their responsibility toward helping individuals and society through their profession, so-called social responsibility, change over time. A survey instrument was administered to students initially primarily in their first year, senior year, or graduate studies majoring in mechanical, civil, or environmental engineering at five institutions in September 2012, April 2013, and March 2014. The majority of the students (57 %) did not change significantly in their social responsibility attitudes, but 23 % decreased and 20 % increased. The students who increased, decreased, or remained the same in their social responsibility attitudes over time did not differ significantly in terms of gender, academic rank, or major. Some differences were found between institutions. Students who decreased in social responsibility initially possessed more positive social responsibility attitudes, were less likely to indicate that college courses impacted their views of social responsibility, and were more likely to have decreased in the frequency that they participated in volunteer activities, compared to students who did not change or increased their social responsibility. Although the large percentage of engineering students who decreased their social responsibility during college was disappointing, it is encouraging that courses and participation in volunteer activities may combat this trend.

Effects of chlorine and other water quality parameters on the release of silver nanoparticles from a ceramic surface.

A quartz crystal microbalance was used to determine the effects of different water quality parameters on the detachment of silver nanoparticles from surfaces representative of ceramic pot filters (CPFs). Silver nanoparticles stabilized with casein were used in the experiments. The average hydrodynamic diameter of the nanoparticles ranged from 20 nm to 100 nm over a pH range of 6.5-10.5. The isoelectric point was about 3.5 and the zeta potential was -45 mV from pH 4.5 to 9.5. The silver nanoparticles were deposited onto silica surfaces and a quartz crystal microbalance was used to monitor silver release from the surface. At environmentally relevant ranges of pH (4.8-9.3), ionic strength (0 and 150 mol/m(3) NaNO3 or 150 mol/m(3) Ca(NO3)2), and turbidity (0 and 51.5 NTU kaolin clay), the rates of silver release were similar. A high concentration of sodium chloride and bacteria (Echerichia coli in 10% tryptic soy broth) caused rapid silver release. Water containing sodium hypochlorite removed 85% of the silver from the silica surface within 3 h. The results suggest that contact between CPFs and prechlorinated water or bleach CPF cleaning should be avoided.

Toxicity and inhibition of bacterial growth by series of alkylphenol polyethoxylate nonionic surfactants.

Laboratory experiments measured the effects of five alkylphenol polyethoxylate nonionic surfactants on the microbial degradation of glucose and pentachlorophenol (PCP) by a pure culture of Sphingomonas chlorophenolicum RA2 (RA2) that was unable to biodegrade the surfactants. The surfactants with mid-range hydrophile-lipophile balance (HLB) values of 13.5-15 were the most biocompatible with substrate degradation. Monomers of the surfactant with the lowest HLB value of 12.3 inhibited RA2 growth on both glucose and PCP. The surfactant with the highest HLB of 17.9 was only inhibitory to glucose biodegradation at 3000mg/L, a concentration well above its CMC. The surfactants were more inhibitory of RA2 biodegradation of PCP compared to glucose, which is likely due to interactions with membrane-associated PCP-degrading enzymes rather than bioavailability limitations. These results may prove helpful in selecting surfactants for use enhancing surfactant-amended remedial applications involving biodegradation or oil dispersion.

Removal of virus to protozoan sized particles in point-of-use ceramic water filters.

The particle removal performance of point-of-use ceramic water filters (CWFs) was characterized in the size range of 0.02-100 microm using carboxylate-coated polystyrene fluorescent microspheres, natural particles and clay. Particles were spiked into dechlorinated tap water, and three successive water batches treated in each of six different CWFs. Particle removal generally increased with increasing size. The removal of virus-sized 0.02 and 0.1 microm spheres were highly variable between the six filters, ranging from 63 to 99.6%. For the 0.5 microm spheres removal was less variable and in the range of 95.1-99.6%, while for the 1, 2, 4.5, and 10 microm spheres removal was >99.6%. Recoating four of the CWFs with colloidal silver solution improved removal of the 0.02 microm spheres, but had no significant effects on the other particle sizes. Log removals of 1.8-3.2 were found for natural turbidity and spiked kaolin clay particles; however, particles as large as 95 microm were detected in filtered water.

Bacterial treatment effectiveness of point-of-use ceramic water filters.

Laboratory experiments were conducted on six point-of-use (POU) ceramic water filters that were manufactured in Nicaragua; two filters were used by families for ca. 4 years and the other filters had limited prior use in our lab. Water spiked with ca. 10(6)CFU/mL of Escherichia coli was dosed to the filters. Initial disinfection efficiencies ranged from 3 - 4.5 log, but the treatment efficiency decreased with subsequent batches of spiked water. Silver concentrations in the effluent water ranged from 0.04 - 1.75 ppb. Subsequent experiments that utilized feed water without a bacterial spike yielded 10(3)-10(5)CFU/mL bacteria in the effluent. Immediately after recoating four of the filters with a colloidal silver solution, the effluent silver concentrations increased to 36 - 45 ppb and bacterial disinfection efficiencies were 3.8-4.5 log. The treatment effectiveness decreased to 0.2 - 2.5 log after loading multiple batches of highly contaminated water. In subsequent loading of clean water, the effluent water contained <20-41 CFU/mL in two of the filters. This indicates that the silver had some benefit to reducing bacterial contamination by the filter. In general these POU filters were found to be effective, but showed loss of effectiveness with time and indicated a release of microbes into subsequent volumes of water passed through the system.

Partitioning of dissolved chlorinated ethenes into vegetable oil.

Food-grade soybean oil (SoyOil) has been used to enhance in situ anaerobic bioremediation at sites contaminated with chlorinated ethenes (CEs). The abiotic interactions of SoyOil with the CEs may be significant and need to be better understood. The oil: water partition coefficients (Kp) of dissolved CEs into SoyOil were measured in batch tests and ranged from 22 to 1200 with increasing chlorination. CE mixtures significantly reduced the Kp for tetrachloroethene (PCE), but not the other CEs. Simple flow tests were used to quantify the mass transfer coefficients (kL) of dissolved CEs into SoyOil. Higher kL values corresponded to the CEs with higher diffusivity in water. CE mixtures reduced the kL for all of the CEs. The results can be used to predict abiotic interactions and distribution of contaminant mass expected after SoyOil injection, and thus provide a more accurate estimate of the mass of CEs removed due to enhanced biodegradation.

Non-ionic surfactant flushing of pentachlorophenol from NAPL-contaminated soil.

Column studies were conducted to assess the suitability of a non-ionic surfactant Tergitol NP-10 (TNP10) for washing pentachlorophenol (PCP) from soil and non-aqueous phase liquids (NAPLs). Flushing of 50 and 200 pore volumes of 5 g/L TNP10 was required to exhaust the surfactant sorption capacity of the soil and soil plus NAPL, respectively. The sorption of surfactant to the soil in the columns was four times greater than the quantity previously observed in batch tests. Flushing with 5 g/L TNP10 removed 71-79% of the 200mg/kg soil-sorbed PCP after 160 pore volumes compared to 0.7-2% PCP removal without surfactant. In columns additionally containing 0.2% and 0.4% PCP-contaminated heavy oil NAPL, the PCP removal efficiency after flushing 200 pore volumes of 5g/L TNP10 was nearly 100%. Therefore, removal of the PCP was more efficient in the NAPL-containing columns, potentially due to competition of the NAPL for PCP sorption sites. Rate-limited desorption of PCP and TNP10 likely occurred.

Dual substrate biodegradation of a nonionic surfactant and pentachlorophenol by Sphingomonas chlorophenolica RA2.

The simultaneous biodegradation of the nonionic surfactant Tween 20 (Tw20) and pentachlorophenol (PCP) by Sphingomonas chlorophenolica sp. Strain RA2 (RA2) was measured. As a sole substrate, Tw20 biodegradation was best described by the Contois kinetic model. During concurrent biodegradation of Tw20 and PCP, the biodegradation rates of Tw20 were not significantly affected by 50 or 100 mg/L PCP, but were significantly inhibited by 500 mg/L PCP. Decreases in cell yield in the presence of PCP suggest that PCP was acting as an uncoupler. Cultures were pre-grown on PCP or Tw20 before degradation of PCP to evaluate enzyme induction effects, and long lags before PCP biodegradation after growth on Tw20 occurred. Although biokinetic models could accurately describe some of the data sets of RA2 growth and Tw20 and PCP degradation, finding a single set of kinetic parameters that predicted all dual substrate tests was not achieved. The complicating factors to modeling PCP and Tw20 interactions are described and may be more widely applicable to the biodegradation of toxic organic compounds in the presence of a biodegradable surfactant.

Aqueous chemistry and interactive effects on non-ionic surfactant and pentachlorophenol sorption to soil.

Non-ionic surfactant addition was investigated as a method to remediate pentachlorophenol (PCP) contaminated soil. The goal was to quantify surfactant (Tergitol NP-10 (TNP10)) and PCP sorption to soil and their interactive effects under varying pH, ionic strength, and soil conditions. Up to 16,700 mg/kg of TNP10 partitioned to soil, with increasing sorption far above the critical micelle concentration (CMC) and with greater amounts of PCP present. Approximately 40-45 times more TNP10 and 20-30 times more PCP sorbed to the finer soil with higher organic matter content. Aqueous TNP10 concentrations well above the CMC (>/=5500 mg/L) were required to enhance PCP desorption from the soil. As pH increased by 0.5-0.85 units, TNP10 sorption decreased by 14-25% and PCP sorption as measured by the log of the equilibrium partition coefficient decreased by 1-1.5. A lower ionic strength of 0.03 versus 0.112 M increased PCP desorption from contaminated soil by 5-17% in the presence of TNP10. This work is relevant to designing ex situ soil washing or surfactant-aided PCP remediation.

Equilibrium partitioning of a non-ionic surfactant and pentachlorophenol between water and a non-aqueous phase liquid.

The partitioning of the non-ionic surfactant Tergitol NP-10 (TNP10) and pentachlorophenol (PCP) into a mineral oil light non-aqueous phase liquid (NAPL) were quantified in batch tests. Due to the ionizable nature of PCP, the effects of pH and ionic strength (micro) on the equilibrium partitioning were evaluated. NAPL:water partition coefficients (K(n:w)) of TNP10 ranged from 3 to 7 l(water)/l(NAPL). Enhanced PCP dissolution into water from the NAPL was achieved at aqueous TNP10 concentrations > or =200mg/l. Surfactant addition of 1200 mg/l TNP10 increased the aqueous PCP concentrations by 14-fold at pH 5 versus 2 to 3-fold at pH 7 as compared to PCP aqueous solubility. The more significant response at the lower pH is likely due to the greater hydrophobicity of PCP at the lower pH, which is approaching PCP's pK(a) of 4.7. Higher ionic strength (micro 0.11 versus 0.001 M) increased K(n:w) of PCP by 10-33% without surfactant, compared to a more than 150% increase with a dose of 4000 mg/l TNP10. This work contributes information relevant to the application of surfactants to remediate sites contaminated with NAPLs.

Low-temperature chromium(VI) biotransformation in soil with varying electron acceptors.

Effective and low-cost strategies for remediating chromium (Cr)-contaminated soil are needed. Chromium(VI) leaching from contaminated soil into ground water and surface water threatens water supplies and the environment. This study tested indigenous Cr(VI) microbial transformation in batch systems at 10 degrees C in the presence of various electron acceptors. The effects of carbon addition, spiked Cr(VI), and mixing highly contaminated soil with less contaminated soil were investigated. The results indicated that Cr(VI) can be biotransformed in the presence of different electron acceptors including oxygen, nitrate, sulfate, and iron. Sugar addition had the greatest effect on enhancing Cr(VI) removal. Less dissolved organic carbon (DOC) was consumed per amount of Cr(VI) transformed under anaerobic conditions [0.8-93 mg DOC/mg Cr(VI)] compared with aerobic conditions [1.4-265 mg DOC/mg Cr(VI)]. Toxicity of high concentrations (< 160 mg/L) of spiked Cr(VI) were not evident. At Cr(VI) concentrations > 40 mg/L, aerobic conditions promoted faster Cr(VI) reduction than anaerobic conditions with nitrate or sulfate present. Biotransformation of Cr(VI) in highly contaminated soil (22,000 mg Cr/kg) was facilitated by mixing with less-contaminated soil. The study results provide a framework for evaluating indigenous Cr(VI) microbial transformation and enhance the ability to develop strategies for soil treatment.

Biodegradation of propylene glycol and associated hydrodynamic effects in sand.

At airports around the world, propylene glycol (PG) based fluids are used to de-ice aircraft for safe operation. PG removal was investigated in 15-cm deep saturated sand columns. Greater than 99% PG biodegradation was achieved for all flow rates and loading conditions tested, which decreased the hydraulic conductivity of the sand by 1-3 orders of magnitude until a steady-state minimum was reached. Under constant loading at 120 mg PG/d for 15-30 d, the hydraulic conductivity (K) decreased by 2-2.5 orders of magnitude when the average linear velocity of the water was 4.9-1.4 cm/h. Variable PG loading in recirculation tests resulted in slower conductivity declines and lower final steady-state conductivity than constant PG feeding. After significant sand plugging, endogenous periods of time without PG resulted in significant but partial recovery of the original conductivity. Biomass growth also increased the dispersivity of the sand.

A kinetic model for surfactant inhibition of pentachlorophenol biodegradation.

A kinetic model is used to describe the effect of the nonionic surfactant Tergitol NP-10 (TNP10) on pentachlorophenol (PCP) biodegradation by Sphingomonas chlorophenolica sp. strain RA2. Different initial biomass to initial substrate ratios ranging from 13 to 418 were tested with 23 TNP10 concentrations ranging from 0 to 1500 mg/L. Tests were also conducted at 10 degrees C and 20 degrees C. No PCP biodegradation inhibition was observed at concentrations below the critical micelle concentration (CMC) of 50 mg/L. TNP10 concentrations above 100 to 200 mg/L were increasingly inhibitory to PCP biodegradation rates. This inhibition was best described by the Monod kinetic equation wherein the effect of TNP10 inhibition is reflected in the half-saturation constant (Ks). The value of the Ks increased from between 1.5 and 13.5 mg/L with no surfactant present to 44 to 131 mg/L at 1000 mg/L TNP10. Using a standard competitive inhibition approach, the inhibition constant for TNP10 was approximately 100 mg/L at both 10 degrees C and 20 degrees C.

Nonionic surfactant effects on pentachlorophenol biodegradation.

Several potential mechanisms of surfactant-induced inhibition of pentachlorophenol (PCP) biodegradation were tested using a pure bacterial culture of Sphingomonas chlorophenolicum sp. Strain RA2. PCP degradation, glucose degradation, and oxygen uptake during endogenous conditions and during glucose degradation were measured for batch systems in the presence of the nonionic surfactant Tergitol NP-10 (TNP10). TNP10 did not exert toxicity on RA2 as measured by dissolved oxygen uptake rates under endogenous conditions and glucose biodegradation rates. TNPIO reduced the substrate inhibition effect of PCP at high PCP concentrations, resulting in faster PCP degradation rates at higher concentrations of TNP10. Calculations of a micelle partition coefficient (Kmic) show that PCP degradation rates in the presence of surfactant can be explained by accounting for the amount of PCP available to the cell in the aqueous solution. A model is discussed based on these results where PCP is sequestered into micelles at high TNP10 concentrations to become less available to the bacterial cell and resulting in observed inhibition. Under substrate toxicity conditions, the same mechanism serves to increase the rate of PCP biodegradation by reducing aqueous PCP concentrations to less toxic levels.