Journal of Environmental Engineering

Per- and polyfluoroalkyl substances (PFAS) are increasingly of interest to drinking water utilities due to state regulations, the release of federal and state health advisories, and public concern. Pilot-scale data were fitted for 16 PFAS species and five commercial-activated carbons using an open-source pore and surface diffusion model that includes an automated parameter-fitting tool. The estimated model parameters are presented, and an uncertainty analysis was evaluated considering the expected temporal variability of influent concentrations. Expected treatment performance differed between two seasons in the pilot phase for the same carbon, which was not captured by modeled uncertainty. However, modeling results can support a utility’s decision to choose activated carbon, and make design and operational decisions that can address changing water production rates and treatment goals. For the utility that undertook this pilot study and their desired treatment goals, granular activated carbon (GAC) was found to be an effective treatment technology for PFAS removal.

Roadway infrastructure is spatially extensive, linear, and by design restricts infiltration. Traffic impacts the coupled hydrology, chemistry, and loads transported by increased runoff and hydraulic stresses. Green infrastructure or low-impact development (LID) such as a partial exfiltration reactor (PER) can mitigate impacts by infiltrating and sequestering runoff and loads. This study modeled surface–subsurface hydrologic quantities for an infiltrating–exfiltrating linear PER as integrated infrastructure at a highway monitoring station with a database and calibrated modeling. The PER combined cementitious permeable pavement (CPP) as an infiltrating-filtration surface over an oxide-coated media (OCM) bed as a green infrastructure retrofit to conventional roadway underdrainage. Calibrated surface [Storm Water Management Model (SWMM)] and subsurface [Variably Saturated 2D Transport Interface (VS2DTI)] model components for the catchment and PER were implemented based on published studies. In contrast to previous design and historical storms, 1 year of hydrologic and dissolved Zn loads was simulated. The PER infiltrated 95% of catchment runoff, exfiltrated 27.1% to clayey glacial till soil, evaporated (potential) 3.9%, and discharged 63.9% to the underdrain. The CPP separated 80% of particulate matter (PM). With a simulated macropore in the oxide-coated sand media (OCS) bed, Zn was reduced by 99%, compared with 98% from event-based published data. Traffic turbulence increased evaporation from the catchment by 28.9%. A calibrated continuous simulation model is a viable tool to examine longer-term behavior of green infrastructure and LID systems for implementation, functionality, and sustainability in roadway and paved urban land uses.

A lab-scale study of the symbiotic ecosystem between Tubificidae and microbes (SETM) was carried out. The sludge reduction ability and ammonia removal performance of the system were investigated, and the nitrogen transfer pathway in the system was studied. In SETM, the substrates, microbes, and Tubificidae interacted with each other and reached equilibrium. During the experimental period (50 days), the amount of SETM sludge reduced by 30% compared to the control group (without Tubificidae). A considerable amount of nutrients was released in the presence of Tubificidae. Conceptual models of nitrogen flow were proposed, and the nitrogen transfer in the systems was described. In SETM, 21% more nitrogen was removed via assimilation compared with the control group, and the net nitrogen removal (including endogenous nitrogen) was higher than in the control group. The effective ammonia removal in SETM was 13% higher than in the control group. This result was supported by fluorescent in situ hybridization data showing that ammonia-oxidizing bacteria were 5% more prevalent in SETM than in the control group.

This study explored mineral catalysts for ${\mathrm{H}}_2{\mathrm{O}}_2$ quenching after $\mathrm{UV}/{\mathrm{H}}_2{\mathrm{O}}_2$ advanced oxidation as an alternative to granular activated carbon or chlorine (two of the most common methods). The following mineral catalysts were evaluated in batch reactors: activated alumina, aluminum oxide, iron (III) oxide, titanium dioxide, titanium, silver, zinc, and magnesium oxide. Of these, aluminum oxide and iron (III) oxide were the most promising catalysts and were further tested in column studies and compared with granular activated carbon (GAC). Aluminum oxide performance in column studies was inferior to the results obtained from GAC and iron (III) oxide, possibly due to the hygroscopic nature of the material. Additional rapid small-scale column tests (RSSCTs) were conducted with iron (III) oxide to mimic a three-year full-scale column operation and achieved 90%–99% removal of ${\mathrm{H}}_2{\mathrm{O}}_2$. The decomposition of ${\mathrm{H}}_2{\mathrm{O}}_2$ on the catalytic surface appears to generate hydroxyl radicals, although not at a sufficient level to provide considerable additional contaminant destruction after advanced oxidation. The process did not elevate iron concentration in the treated water to a level above the secondary USEPA standard of $0.3\mathrm{mg}/\mathrm{L}$ ($0.12\mathrm{mg}/\mathrm{L}$ maximum, $0.03\mathrm{mg}/\mathrm{L}$ average). Longer-term pilot-scale study is necessary to determine operational requirements, such as backwashing, and to determine whether the observed loss of activity over time can be regenerated. Overall, the process appears to be a viable option for ${\mathrm{H}}_2{\mathrm{O}}_2$ quenching, making application of $\mathrm{UV}/{\mathrm{H}}_2{\mathrm{O}}_2$ advanced oxidation more practical for drinking water treatment where residual ${\mathrm{H}}_2{\mathrm{O}}_2$ can interfere with chlorination.

The creation of the Caribbean Ocean and Aquaculture Sustainability faciliTy (COAST) is used as a case study of community-engaged design addressing safety needs. COAST is a parametric insurance product, sold to national governments, which was designed to meet the food and nutrition security of small- and medium-scale fisherfolk. The design of COAST is an example of convergence research, where the discipline of engineering was integrated with another discipline to solve pressing societal needs of Caribbean fisherfolk. This case study demonstrates that community-engaged design helps to (1) identify and include historically underrepresented stakeholders, (2) emphasize the importance of professional responsibility for project implementation, and (3) achieve long-term sustainability of the design (i.e., COAST has been renewed for a third policy year, 2021/2022).