•Demonstrated effective biogas upgrading to hythane gas using electrochemical process.•Analyzed the benefits of converting renewable electricity to hythane for energy storage and transport.•Different ...voltages and conditions were investigated and performance was reported.•Preliminary technoeconomic analysis showed the benefits of such conversion process.
This study investigates the feasibility of using an electrochemical process to convert excess renewable electricity and biogas into hythane gas, which has higher value than biogas and can be stored and transported using current natural gas infrastructure. The electrochemical process utilizes the protons generated in water electrolysis to liberate cations in silicate minerals, which in turn forms metal hydroxide and efficiently captures the CO2 present in biogas. The H2 produced in electrolysis is blended with purified biogas to generate mixed hythane product, which has a higher combustion rate in methane fueled vehicles. Results show that under a voltage of 3.5–4.0V, the system reduced CO2 in biogas from the original 40% to less than 15% and increased the heat value of the gas product from 534kJ/mol to over 669kJ/mol. Preliminary techno-economic analysis showed a net profit of $0.28 per thousand ft.cu hythane generated when standard grid electricity is used, and the profit may be increased by orders of magnitude if excess renewable electricity is used. The process offers a new route for renewable energy storage and upgrade.
In this study, we present a holistic analysis of the stock and emissions of poly- and perfluoroalkyl substances (PFAS) in California carpet in 2000-2030. Our high estimate is that, in 2017, the total ...PFAS accumulated in in-use carpet stock and landfilled carpet are ∼60 and ∼120 tonnes, respectively, and the resultant PFAS emissions are ∼800 and ∼100 kg, respectively. Among the three subclasses (side-chain polymers, PFAA, and nonpolymeric precursors), side-chain polymers dominate the in-use stock and landfill accumulation, while nonpolymeric precursors dominate the resultant emissions. Our low estimate is typically 8-15% of the high estimate and follows similar trends and subclass breakdowns as the high estimate. California's new Carpet Stewardship Regulations (24% recycling of end-of-life carpet) will reduce the landfilled PFAS by 6% (7 tonnes) at the cost of increasing the in-use stock by 2% (2 tonnes) in 2030. Aggressive PFAS phase-out by carpet manufacturers (i.e., reduce PFAS use by 15% annually starting 2020) could reduce the in-use PFAS stock by 50% by 2030, but its impact on the total landfilled PFAS is limited. The shift toward short-chain PFAS will also significantly reduce the in-use stock of long-chain PFAS in carpet by 2030 (only 25% of the total PFAS will be long-chain). Among the data gaps identified, a key one is the current area-based PFAS emission reporting (i.e., g PFAS emitted/area carpet/time), which leads to the counterintuitive result that reducing the PFAS use in carpet production has no impact on the PFAS emissions from in-use stock and landfills. Future technical studies should either confirm this or consider a mass-based unit (e.g., g PFAS emitted/g PFAS used/time) for better integration into regional substance flow analysis. Other noticeable data gaps include the lack of time-series data on emissions from the in-use stock and on leaching of side-chain polymers from landfills.
•First estimate of mineral and energy content in US nonhazardous industrial waste.•Current mineral content is 100 million tonnes/year and will increase 50% by 2050.•The largest quantities of bulk ...minerals found were lime and silicon.•Scarce minerals (P and Ti) have high potential (10-20% of total consumption).•California and the Midwest are mineral supply hotspots - should be future focus.
Despite the large volume of non-hazardous industrial waste (NHIW) being generated globally, systematic NHIW reuse policies are lagging, largely owing to piecemeal understanding of generation volumes, locations, chemical constituents, and future trends. Herein, we demonstrate how to estimate the mineral and energy flows embedded in the 200-300 million tonnes of NHIW in the United States using information from process engineering and economic projections. We estimate that the minerals contained in NHIW are on the order of 100 million tonnes and with electricity potential lectricity at 200 billion kWh annually from 1990 to 2016. Both are expected to increase by roughly 50% from 2017 to 2050. The electricity potential and bulk mineral contents (e.g., CaO and SiO2) are modest compared to the total level of consumption of these resources (<3%), but there are county-level hotspots along the west coast with opporunities possibly large enough to yield significant material benefits at the local scale. Two lower-volume minerals, phosphorus and titanium, are noteworthy from a material substitution standpoint. They are estimated at 0.5-2.0 million tonnes in NHIW annually, which is 10-20% of current consumption and up to 50-80% in hotspot states. Although there are difficulties in cross-national generalization, we anticipate that the workflow steps themselves would be transferrable to other countries to be able to yield the chemical, locational and temporal information needed to inform the design of region-specific NHIW reuse programs and the development of NHIW valorization technologies.
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A new matrix framework is presented in this study for the improved ionization efficiency of complex mixtures by matrix-assisted laser desorption ionization (MALDI) mass spectrometry/imaging. Five ...nitro indole (NI) derivatives 3-methyl-4-nitro-1H-indole (3,4-MNI), 3-methyl-6-nitro-1H-indole (3,6-MNI), 2,3-dimethyl-4-nitro-1H-indole (2,3,4-DMNI), 2,3-dimethyl-6-nitro-1H-indole (2,3,6-DMNI), and 4-nitro-1H-indole (4-NI) were synthesized and shown to produce both positive and negative ions with a broad class of analytes as MALDI matrices. NI matrices were compared to several common matrices, such as 2,5-dihydroxybenzoic acid (DHB), alpha-cyano-4-hydroxylcinnamic acid (CHCA), sinapinic acid (SA), 1,5-diaminonaphthelene (1,5-DAN), and 9-aminoacridine (9-AA), for the analysis of lipid, peptide, protein, glycan, and perfluorooctanesulfonic acid (PFOS) compounds. 3,4-MNI demonstrated the best performance among the NI matrices. This matrix resulted in reduced ion suppression and better detection sensitivity for complex mixtures, for example, egg lipids/milk proteins/PFOS in tap water, while 2,3,6-DMNI was the best matrix for blueberry tissue imaging. Several important aspects of this work are reported: (1) dual-polarity ion production with NI matrices and complex mixtures; (2) quantitative analysis of PFOS with a LOQ of 0.5 ppb in tap water and 0.05 ppb in MQ water (without solid phase extraction enrichment), with accuracy and precision within 5%; (3) MALDI imaging with 2,3,6-DMNI as a matrix for plant metabolite/lipid identification with ionization enhancement in the negative ion mode m/z 600–900 region; and (4) development of a thin film deposition under/above tissue method for MALDI imaging with a vacuum sublimation matrix on a high-vacuum MALDI instrument.
•Bacillus cereus isolated from hyperaccumulator was enriched as biosorbents.•Bacillus cereus showed good adsorption performance for Sr.•Langmuir model well described the adsorption ...isotherm.•Adsorption kinetics followed pseudo-second order model.
The biosorption of strontium(II) from aqueous solutions using dead bacteria biomass was investigated in this study. Phylogenetic analysis based on 16S rDNA sequence demonstrates that the isolated strain belonged to Bacillus cereus. The bacteria exhibited the highest strontium sorption capacity at an initial pH of 5.0, contact time of 50min, biomass dosage of 3.0gL−1 and agitation speed of 120rpm. The adsorption profile was better matched by Langmuir than Freundlich model. The maximum biosorption capacity obtained by Langmuir model was 58.79mgg−1. Adsorption kinetics indicate that the pseudo-second order model was appropriate to describe the biosorption process. Fourier transform infrared (FT-IR) spectroscopy analysis indicates that the main functional groups responsible for biosorption of strontium(II) were hydroxyl, carboxyl and amino. The isolated bacteria B. cereus can be a great potential biosorbent to remove strontium ions from aqueous solutions.
Summary
In water‐scarce regions of China, wastewater reuse is increasingly considered as a potential component of China's future water resource management strategy. Currently, the percentage of ...wastewater reuse varies substantially across Chinese provinces, but conditions leading to a high rate of wastewater reuse have not been elucidated clearly. In this work, we use fuzzy‐set qualitative comparative analysis (fsQCA) to identify the drivers of high and low percentages of wastewater reuse in water‐stressed Chinese provinces in 2013. We find that among the five conditions studied (per capita water availability, urban population, access to sea, access to urban space, and access to agricultural land), a high percentage of wastewater reuse is primarily driven by water stress and access to urban green space. Consequently, policies should consider targeting provinces with these attributes where wastewater reuse is more likely to be successful. Further, our results show that there is asymmetry in the conditions that lead to high and low percentages of wastewater reuse, and that the drivers for and against reuse identified in this study are not completely analogous to those identified in previous studies. As such, the drivers for and against wastewater reuse should not be generalized without due consideration of the local context.
•Combination of NF and UV-sulfite more cost effective PFAS degradation method.•NF effective technology to concentrate (> 10x) and reject PFASs (∼95%).•Faster UV-sulfite degradation in alkaline pH ...11.2.•UV-sulfite degradation of all PFCAs < 2 h and PFOS < 4 h in NF reject.•Treatment train EE/O ≤ 13.1 kWh/m3 for all PFCAs and 14.1 kWh/m3 for PFOS.
Previous laboratory scale studies indicate nanofiltration (NF) and UV-sulfite photochemical treatments as promising technologies for the removal and destruction, respectively, of per- and polyfluoroalkyl substances (PFASs) from contaminated water. This study reports on a field demonstration of a pilot-scale hybrid NF and UV-sulfite treatment train for the remediation of 12 PFASs detected in groundwater impacted by aqueous film-forming foam (AFFF) at a U.S. Department of Defense installation. For most of the detected PFASs, NF rejection was consistently ≥ 95% over a 30-day field trial when operating at 90% total permeate recovery. Rejection of short-chain perfluorosulfonic acids (PFSAs) by NF decreased when recoveries increased from 90 to 97%; tests with a reverse osmosis (RO) membrane showed ≥ 99% rejection of all PFASs regardless of increasing recovery. UV treatment of the NF reject following 90% permeate recovery resulted in variable destruction of individual PFASs, with rates also being dependent on pH and the identity and concentration of UV photosensitizer. Rates of perfluorocarboxylic acid (PFCA) degradation were greater than those measured for PFSAs and perfluoroalkyl acid (PFAA) precursors and were independent of perfluoroalkyl chain length. In contrast, rates of PFSA degradation increased with increasing chain length. Consistent levels of PFAS degradation by UV-sulfite were observed during a 30-day demonstration experiment in NF reject water amended with 10 mM sulfite and adjusted to pH 11.2. Collectively, > 75% of the detected PFAS mass in the NF reject was destroyed after 4 h of UV treatment, increasing to > 90% after 8 h of treatment. An analysis of electrical energy inputs for the hybrid NF/UV-sulfite treatment train showed energy per order magnitude (EE/O) requirements ranging from ≤ 13.1 kWh/m3 for PFCAs and 14.1 kWh/m3 for PFOS to values > 100 kWh/m3 for more recalcitrant short-chain PFSA analogues. The UV reactor and water-cooling system were the major contributors to overall energy requirements and represent the greatest opportunities for improving efficiency of the technology.
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Bio-electrochemical denitrification (BED) is a promising organic carbon-free nitrate remediation technology. However, the relationship between engineering conditions, biofilm community composition, ...and resultant functions in BED remains under-explored. This study used deep sequencing and variation partitioning analysis to investigate the compositional shifts in biofilm communities under varied poised potentials in the batch mode, and correlated these shifts to reactor-level functional differences. Interestingly, the results suggest that the proliferation of a key species, Thiobacillus denitrificans, and community diversity (the Shannon index), were almost equally important in explaining the reactor-to-reactor functional variability (e.g. variability in denitrification rates was 51% and 38% attributable to key species and community diversity respectively, with a 30% overlap), but neither was heavily impacted by the poised potential. The findings suggest that while enriching the key species may be critical in improving the functional efficiency of BED, poised potentials may not be an effective strategy to achieve the desired level of enrichment in substrate-limited real-world conditions.
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•Metagenomic sequencing was conducted for bioelectrochemical denitrification.•Denitrification species were found to be the dominant species.•Relative abundance of T. denitrificans significantly correlated with denitrification.•Poised potential was insignificant in inducing microbial community and functional changes.
•Uses wastewater to capture CO2 from ambient air and convert it to useful products.•Energy can be generated during microbial electrolysis and carbon capture.•Carries significant environmental and ...economic potential in large scale.
This study reports that wastewater can be used to capture and store CO2 directly from ambient air and produce energy. The proof-of-concept system consisted of an ion exchange resin column that captures and concentrates ambient CO2 using a moisture-driven cycle. The concentrated CO2 was then transferred into a microbial electrochemical carbon capture (MECC) reactor for carbon sequestration and hydrogen production. Data from an average batch cycle showed that approximately 8mmol/L CO2 was captured in the MECC cathode when 0.14g/LCOD was removed in the anode. With 90% hydrogen conversion efficiency, the energy intensity and CO2 absorption from the process could be 11.3kJ/gCOD and 0.49gCO2/gCOD respectively. If the proposed process is applied, over 68milliontons of atmospheric CO2 can be captured yearly during wastewater treatment in the US, which equates to significant economic values if CO2 taxes were to be implemented more widely.
Microbial fuel cell (MFC) is an emerging biotechnology to convert the organic substrates in wastewater to electricity by anaerobic electrogenic bacteria. The main challenge for MFC research is to ...elucidate the fundamental mechanisms of electron generation and transfer and to apply these mechanisms to improve the power production in the engineering operation. This study extensively investigated the effects of three inocula (
Geobacter sulfurreducens
, soil, and wastewater) on the power production and electrochemical characteristics (i.e., internal resistances, Coulombic Efficiency) of MFCs. The results showed that the extents of bacterial adhesion varied between mixed cultures (soil) and pure cultures (
G. sulfurreducens
). The voltage output increased 30% when bacterial adhesion was well-developed in the soil inocula. Meanwhile, the inoculum types clearly affected the internal resistance (
R
in
) and power production of MFCs. Pure culture inoculum (
G. sulfurreducens
) had the lowest
R
in
(165 Ω) and the highest Coulombic Efficiency (CE, 25.8%) and Energy Conversion Efficiency (ECE, 7.2%), while the mixed culture inocula (soil) with the high concentration of nonelectrogenic bacteria, exhibited the highest
R
in
(620 Ω), lowest CE (9.2%) and lowest ECE (2.4%). Additionally, a second-order correlation was established between the anode potential (
P
A
) and power output while an exponential correlation was established between the difference between anode and cathode potentials (Δ
P
C−A
) and power output.
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