A unit process log reduction database for water reuse practitioners.

Pathogen reduction for the purpose of human health protection is a critical function provided by water reuse systems. Pathogen reduction performance potential is dependent on a wide range of design and operational parameters. Poor understanding of pathogen reduction performance has important consequences-under treatment can jeopardize human health, while over treatment can lead to unnecessary costs and environmental impacts. Documented pathogen reduction potential of the unit processes that make up water reuse treatment trains is based on a highly dispersed and unstructured literature, creating an impediment to practitioners looking to design, model or simply better understand these systems. This review presents a database of compiled log reduction values (LRVs) and log reduction credits (LRCs) for unit processes capable of providing some level of pathogen reduction, with a focus on processes suitable for onsite non-potable water reuse systems. Where reported, we have also compiled all relevant design and operational factors associated with the LRVs and LRCs. Overall, we compiled over 1100 individual LRV data entries for 31 unit processes, and LRCs for 8 unit processes. Results show very inconsistent reporting of influencing parameters, representing a limitation to the use of some of the data. As a standalone resource, the database (included as Supplemental Information) provides water reuse practitioners with easy access to LRV and LRC data. The database is also part of a longer-term effort to optimize the balance between human health protection, potential environmental impacts and cost of water reuse treatment trains.

LCA model validation of SAGD facilities with real operation data as a collaborative example between model developers and industry.

There has been a notable disagreement between life cycle GHG emission estimates reported by research communities and key energy sector stakeholders as many LCA models are not validated against real operation data. This is originated from lack of collaboration and knowledge exchange between model developers and company experts. We present a pragmatic procedure for engaging company experts to advance the assumptions, models, and information used in an open-source LCA simulator (OPGEE). Using real operation and local emission factor data, two oil sands SAGD fields GHG emissions are compared rigorously against the scope 1 and 2 reported emissions. By introducing consistent region-specific input data, system boundaries, and assumptions, OPGEE carbon intensity estimates are within 1%-5% of reported data by companies. The system boundary expansion (e.g., expanding from direct emissions to also include offsite emissions from natural gas co-production, diluent source emission) impacts the GHG intensities estimates for both fields.

Assessing hydrothermal carbonization as sustainable home sewage management for rural counties: A case study from Appalachian Ohio.

Improper management of home sewage treatment systems (HSTS) presents major challenges in the developing world, and even in many parts of developed countries, which contribute to health, environmental, economic, and social problems. Hydrothermal treatment, a thermochemical conversion process that is particularly useful for wet wastes, can produce fertilizers from septic tank wastes while eliminating human pathogens. However, hydrothermal treatment requires high temperature and high pressure, which might need additional economical justification when targeted for rural communities. The aim of this study was to investigate the economic feasibility of a hydrothermal treatment facility that can treat septic waste generated in Athens County, Ohio, a rural Appalachian county in the U.S., where failing HSTS have been observed quite frequently. Two different cases were considered for economic analysis, where Case I assumed a decentralized facility and Case II assumed a centralized facility. Results showed that both cases are economically feasible, where Case I and II reached breakeven in years 4 and 6, respectively. Additionally, despite the greater capital investment requirement for Case I, there was also a greater return on investment (ROI) of 2.85 compared to 1.52 for Case II. A sensitivity analysis was examined to determine the effect of solid content in either the septic tank or the reactor's feed, selling price of the fertilizer, and septage pumping costs on the project feasibility. The sensitivity analysis showed that pumping cost is the most significant factor affecting the project feasibility, while the ROI varied about ±80% and ± 200% for Case I and II, respectively, due to only about ±18% change in pumping cost.

Liquid-Liquid Extraction of Furfural from Water by Hydrophobic Deep Eutectic Solvents: Improvement of Density Function Theory Modeling with Experimental Validations.

This study outlines the methodology to model hydrophobic deep eutectic solvent (HDES) interactions to obtain computational results that accurately represent experimental results of furfural removal from water. Computational prediction with high accuracy of HDES behavior could elucidate hydrogen bond interaction in HDES. COSMOtherm modeling and experimental evaluation demonstrated that both decanoic and dodecanoic acid-based HDES can remove furfural from water even at very low concentrations of 0.1 mol %. The modeling methodology considered salts as independent cations, which were paired with the hydrogen bond donor (HBD) species. These resulted in computational predictions of liquid-liquid equilibrium (LLE) between tetra n-alkyl ammonium bromide salt-based HDES with >95% accuracy of experimental results. The COSMOtherm modeling methodology strengthens the understanding of HDES by considering intermolecular forces that affect electron density (σ) of the HDES components to determine the LLE of the HDES-aqueous system. This results in a deep eutectic phase that has a positive sigma potential (potentials, µ(σ), up to 0.1 kcal/mol Å2) at charge densities associated with hydrogen bonding (±0.0084 e/Å2). Though n-alkyl ammonium salts ranging from tetramethyl- to tetraoctylammonium bromide were considered in the computational model, only pentyl- and longer alkyl chains displayed hydrophobic behavior with less than 1% salt loss to the aqueous phase. However, there was still significant water uptake in the eutectic phase (final phase composition containing greater than 60 mol and 12% by mass) for the hydrophobic DES.

Recovery of Macro and Micro-Nutrients by Hydrothermal Carbonization of Septage.

In this study, septic tank waste (i.e., septage) was hydrothermally carbonized (HTC) in order to recover macro and micronutrients, while tracking the fate of residual heavy metals. Three different HTC temperatures (i.e., 180, 220, and 260 °C) at autogenous pressures and two reaction times (i.e., 30 and 120 min) were applied on both solid and liquid septages. Hydrochar and HTC process liquids were characterized using ICP, CHNS, and UV-vis spectroscopy. Treatment at 260 °C for 120 min maximized ammonia recovery, producing a liquid with 1400 mg/L of ammonia. Overall, about 70% of available nitrogen ended up in the liquid phase as nitrate or ammonia. Solid hydrochars show potential for fertilizer use, with high phosphorus content of 100-130 kg/tonne. It was found that heavy metals mainly remained in the solid phase, although the concentrations of heavy metals are mostly lower than U.S. EPA regulation for biosolids with the exception of selenium.