Water, Air Emissions, and Cost Impacts of Air-Cooled Microturbines for Combined Cooling, Heating, and Power Systems： A Case Study in the Atlanta Region

The increasing pace of urbanization means that cities and global organizations are looking for ways to increase energy efficiency and reduce emissions. Combined cooling, heating, and power （CCHP） systems have the potential to improve the energy generation efficiency of a city or urban region by providing energy for heating, cooling, and electricity simultaneously. The purpose of this study is to estimate the water consumption for energy generation use, carbon dioxide （CO2） and NOx emissions, and economic impact of implementing CCHP systems for five generic building types within the Atlanta metropolitan region, under various operational scenarios following the building thermal （heating and cooling） demands. Operating the CCHP system to follow the hourly thermal demand reduces CO2 emissions for most building types both with and without net metering. The system can be economically beneficial for all building types depending on the price of natural gas, the implementation of net metering, and the cost structure assumed for the CCHP system. The greatest reduction in water consumption for energy production and NOx emissions occurs when there is net metering and when the system is operated to meet the maximum yearly thermal demand, although this scenario also results in an increase in greenhouse gas emissions and, in some cases, cost. CCHP systems are more economical for medium office, large office, and multifamilv residential buildings.

Measurement and Modeling for the Solubility of Hydrogen Sulfide in Primene JM-T

The primary aliphatic amine Primene JM-T was investigated as a potential absorbent for H2S removal. The solubility of HzS in JM-T was measured at 298, 313,333,353, and 368 K with H2S partial pressures from 20 to 760 kPa and HzS loading from 0.02 to 0.8 mol H2S per mol JM-T. Relevant physical properties, such as density, viscoslty and dielectric constant, ot the matenal were measured. ＇The thermodynamlc model with two-suttlX Margules equation was used to correlate the experimental vapor-liquid equilibrium data. Furthermore, the absorption mechanism in non-aqueous system is suggested and the difference between non-aqueous and aqueous absorption system is pointed out.

The preparation and performance of lignin-based activated carbon fiber adsorbents for treating gaseous streams

Two types of lignin-based carbon fibers were prepared by electrospinning method. The first was activated with Fe304 （LCF-Fe）, and the second was not activated with Fe3O4 （LCF）. Gas phase adsorption isotherms for toluene on LCF-Fe and LCF were studied. The gas phase adsorption isotherm for 0% RH showed LCF-Fe have about 439 mg/g adsorption capacity which was close to that of commercially available activated carbon （500 rag/g）. The Dubinin-Radushkevich equation described the isotherm data very well. Competitive adsorption isotherms between water vapor and toluene were measured for their RH from 0 to 80%. The effect of humidity on toluene gas-phase adsorption was predicted by using the Okazaki et al. model. In addition, a constant pattern homogeneous surface diffusion model （CPHSDM） was used to predict the toluene breakthrough curve of continuous flow-packed columns containing LCF-Fe, and its capacity was 412 mg/g. Our study, which included material characterization, adsorption isotherms, kinetics, the impact of humidity and fixed bed performance modeling, demonstrated the suitability of lignin-based carbon fiber for volatile organic compound removal from gas streams .

Chemical poison and regeneration of SCR catalysts for NOx removal from stationary sources

Selective catalytic reduction （SCR） of NOx with NH3 is an effective technique to remove NOx from stationary sources, such as coal-fired power plant and industrial boilers. Some of elements in the fly ash deactivate the catalyst due to strong chemisorptions on the active sites. The poisons may act by simply blocking active sites or alter the adsorption behaviors of reactants and products by an electronic interaction. This review is mainly focused on the chemical poisoning on V2O5-based catalysts, environmental-benign catalysts and low temperature catalysts. Several common poisons including alkali/alkaline earth metals, SO2 and heavy metals etc. are referred and their poisoning mechanisms on catalysts are discussed. The regeneration methods of poisoned catalysts and the development of poison-resistance catalysts are also compared and analyzed. Finally, future research directions in developing poisoning resistance catalysts and facile efficient regeneration methods for SCR catalysts are proposed.

Activated carbon enhanced ozonation of oxalate attributed to HO·oxidation in bulk solution and surface oxidation: Effect of activated carbon dosage and pH

Ozonation of oxalate in aqueous phase was performed with a commercial activated carbon（AC）in this work. The effect of AC dosage and solution pH on the contribution of hydroxyl radicals（HOU） in bulk solution and oxidation on the AC surface to the removal of oxalate was studied. We found that the removal of oxalate was reduced by tert-butyl alcohol（tBA） with low dosages of AC,while it was hardly affected by tBA when the AC dosage was greater than 0.3 g/L. tBA also inhibited ozone decomposition when the AC dosage was no more than 0.05 g/L, but it did not work when the AC dosage was no less than 0.1 g/L. These observations indicate that HOUin bulk solution and oxidation on the AC surface both contribute to the removal of oxalate. HOU oxidation in bulk solution is significant when the dosage of AC is low, whereas surface oxidation is dominant when the dosage of AC is high. The oxalate removal decreased with increasing pH of the solution with an AC dosage of 0.5 g/L. The degradation of oxalate occurs mainly through surface oxidation in acid and neutral solution, but through HOUoxidation in basic bulk solution. A mechanism involving both HOUoxidation in bulk solution and surface oxidation was proposed for AC enhanced ozonation of oxalate.

An electrochemical process that uses an Fe^0/TiO2 cathode to degrade typical dyes and antibiotics and a bio-anode that produces electricity

In this study a new water treatment system that couples （photo-） electrochemical catalysis （PEC or EC） in a microbial fuel cell （MFC） was configured using a stainless-steel （SS） cathode coated w th Fe / TiO2. We examined the destruction of methylene blue （MB） and tetracycline. Fe^0/TiO2 was prepared using a chemical reduction-deposition method and coated onto an SS wire mesh （500 mesh） using a sol technique. The anode generates electricity using microbes （bio-anode）. Connected via wire and ohmic resistance, the system requires a short reaction time and operates at a low cost by effectively remowng 94% MB （initial concentration 20 mg·L^-1） and 83% TOC/TOCo under visible light illumination （50 W; 1.99 mW·cm^-2 for 120 rain, MFC-PEC）. The removal was similar even without light irradiation （MFC-EC）. The EEo of the MFC-PEC system was approximately 0.675 kWh·m^-3. order-l whereas that of the MFC-EC system was zero. The system was able to remove 70% COD in tetracycline solution （initial tetracycline concentration 100 mg·L^-1） after 120 min of visible light illumination; without light, the removal was 15% lower. The destruction of MB and tetracycline in both traditional photocatalysis and photoelectrocatalysis systems was notably low. The electron spinresonance spectroscopy （ESR） study demonstrated that. OH was formed under visible light, and. 02 was formed without light. The bio-electricity-activated O2 and ROS （reactive oxidizing species） generation by Fe^0/TiO2 effectively degraded the pollutants. This cathodic degradation improved the electricity generation by accepting and consuming more electrons from the bio-anode.

Life cycle assessment of low impact development technologies combined with conventional centralized water systems for the City of Atlanta, Georgia

Low-impact development （LID） technologies, such as bioretention areas, rooftop rainwater harvesting, a_nd xeris_caping can co_ntrol stormwater runoff, supply non-potable water, and landscape open space.TillS study examines a hybrid system （HS） that combines LID technologies with a centralized water system to lessen the burden on a conventional system （CS）. CS is defined as the stormwater collection and water supply infrastructure, and the conventional landscaping choices in the City of Atlanta. The study scope is limited to five single-family residential zones （SFZs）, classified R-1 through R-5, and four multi-family residential zones （MFZs）, classified RG-2 through RG-5. Population density increases from 0.4 （R-1） to 62.2 （RG-5） persons per 1,000 m2. We performed a life cycle assessment （LCA） comparison of CS and HS using TRACI 2.1 to simulate impacts on the ecosystem, human health, and natural resources. We quantified the impact of freshwater consumption using the freshwater ecosystem impact （FEI） indicator. Test results indicate that HS has a higher LCA single score than CS in zones with a low population density; however, the difference becomes negligible as population density increases. Incorporating LID in SFZs and MFZs can reduce potable water use by an average of 50%. and 25%,respectively.; however, water savings are negligible in zones with high population density （i.e., RG-5） due to the diminished surface area per capitaavailable for LID technoogies. The results demonstrate that LID technologies effectively reduce outdoor water demand and therefore would be a good choice to decrease the water consumption impact in the City of Atlanta.

Key findings of the 2016 symposium on the frontiers of chemical science and engineering： Environment and sustainable development

There were 30 speakers and the proceedings contained 28 abstracts that discussed the start-of-the art applications of sustainable chemical engineering [1]. We summarized topics that were discussed in the 28 abstracts using the non-negative matrix factorization （NMF） algorithm. The ＂topics＂ were synthesized without reading the abstracts. Here we will not discuss the algorithm of NMF in detail because of the space limitation and please refer to references for the description of NMF [2,3]. Topic modeling will be more valuable as the number of the abstracts increases.

PVDF ultrafiltration membranes of controlled performance via blending PVDF-g-PEGMA copolymer synthesized under different reaction times

Polyvinylidene fluoride grafted with poly（ethylene glycol） methyl ether methacrylate （PVDF-g- PEGMA） was synthesized using atomic transfer radical polymerization （ATRP） at different reaction times （9 h, 19 h, and 29 h）. The corresponding conversion rates were 10%, 20% and 30%, respectively. PVDF was blended with the copolymer mixtnre containing PVDF-g-PEGMA, solvent and residual PEGMA under different reaction times. In this study, we explored the effect of the copolymer mixture additives with different synthesis times on cast membrane performance. Increasing the reaction time of PVDF-g-PEGMA causes more PVDF-g-PEGMA and less residual PEGMA to be found in the casting solution. Incremental PVDF-g-PEGMA can dramatically increase the viscosity of the casting solution. An overly high viscosity led to a delayed phase inversion, thus hindering PEGMA segments in PVDF- g-PEGMA from migrating to the membrane surface. However, more residual PEGMA contributed to helping rnore PEGMA segments migrate to the membrane surface. The pure water fluxes of the blended membrane with reaction times of 9 h, 19 h, and 29 h are 5445 L. m 2.h I 1068 L- m 2.h land 1179 L.m 2.h I respectively, at 0.07 MPa. Delayed phase inversion can form smaller surface pore size distributions, thus decreasing the water flux for the membranes with PVDF-g-PEGMA at 19 h and 29 h. Therefore, we can control the membrane pore size distribution by decreasing the reaction time of PVDF-g-PEGMA to obtain a better flux performance. The membrane with PVDF-g-PEGMA at 19 h exhibits the best foulant rejection and cleaning recovery due to its narrow pore size distribution and high surface oxygen content.

New Editors-in-Chief＇s Message

Frontiers of Environmental Science ＆ Engineering （FESE） published its first issue in 2007. Since then, 38 issues comprising over 630 articles have been published. FESE has become an active platform serving the international community in all areas of environmental science, engineering, and technology. FESE has a broad interdisciplinary scope with an emphasis on pollution mitigation and environmental quality improvement. Additionally, FESE publishes invited feature papers as well as special issues on selected topics. FESE was conceived as a truly international scientific journal and it could not have achieved the great reputation that it has without ongoing contributions from authors, reviewers, editors, and especially from our former Editor-in-Chief, Professor Yi Qian. As the new Editors-in-Chief of FESE, we are proud to fill this role and look forward to the challenge it will present.