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Arup K Sengupta - One of the best experts on this subject based on the ideXlab platform.

  • field validation of self regenerating reversible ion exchange membrane rix m process to prevent sulfate and silica fouling
    Desalination, 2019
    Co-Authors: Arup K Sengupta, Michael German, Hang Dong, Andrew Schevets, Ryan C Smith
    Abstract:

    Abstract Desalination of brackish water and municipal wastewater will be integral to water resource resiliency during uncertain climate conditions. Higher efficiency and higher recovery than conventional desalination is achievable if biofouling and inorganic scaling can be avoided on membranes or heating surfaces. Temporary hardness is well addressed through acid and antiscalant dosing, but permanent sulfate hardness lacks selective removal techniques that do not require external Chemicals or produce large volumes of sludge. Self-regenerating reversible ion exchange-membrane (RIX-M) processes have been proposed using a tunable anion exchange blend to remove silica and sulfate selectively from influent water with efficient regeneration via brine reject. A 2.5GPM RIX-M process was tested at the US Bureau of Reclamation (USBR) Brackish Groundwater National Desalination Research Facility (BGNDRF, Alamogordo, NM). High sulfate-containing brackish groundwater was desalinated at high recovery (80%) without membrane fouling through selective sulfate removal and regeneration via desalination brine reject, without external Chemical Addition. Ten treatment-regeneration cycles were performed without degradation in system performance. High efficiency silica removal from complex groundwater backgrounds at BGNDRF was also achieved across varying water chemistries. RIX-M offers a new pre-treatment opportunity to protect RO membranes from sulfate and silica fouling without dosing anti-scalants, while attaining high recovery.

  • In-Situ Stability Control of Energy-Producing Anaerobic Biological Reactors through Novel Use of Ion Exchange Fibers
    2017
    Co-Authors: Yu Tian, Arup K Sengupta, Derick G. Brown
    Abstract:

    Anaerobic biological treatment of high-strength organic industrial wastes is preferred over aerobic treatment as it produces a methane-rich biogas, has much lower energy requirements, and produces significantly less biosolids. Process stability and reactor failure are of concern, however, for waste streams that exhibit large variations in organic loading, which can cause detrimental pH fluctuations, and that have the potential for accidental input of toxic metals. Here, we demonstrate for the first time that the use of ion exchange fibers (IXFs) can provide passive resilience to these failure modes, without requiring operator oversight or reactive process control via Chemical Addition. IXFs have the advantage of rapid kinetics due to their small size, and they can be readily inserted and withdrawn as woven mats or porous pillows. This approach is demonstrated here using the weak-acid IXF FIBAN X-1 and the strong-base FIBAN A-1. FIBAN X-1 passively stabilized anaerobic reactors by (i) buffering pH fluctuations resulting from organic overloading due to both an increase in organic concentration and a decrease in hydraulic residence time and (ii) moderating shock-loads of copper and nickel. FIBAN X-1 also retained ∼95% of its exchange capacity after one year of operation in anaerobic reactors, demonstrating its long-term performance. In Addition, FIBAN A-1 stabilized anaerobic reactors to input of chromate. These results demonstrate that IXFs can be used to passively stabilize anaerobic biological reactors from upset and failure and that this technology can be used to enhance energy recovery from high-strength organic waste streams

  • use of arsenxnp a hybrid anion exchanger for arsenic removal in remote villages in the indian subcontinent
    Reactive & Functional Polymers, 2007
    Co-Authors: Sudipta Sarkar, Lee Blaney, Anirban Gupta, Debabrata Ghosh, Arup K Sengupta
    Abstract:

    Abstract Many of the arsenic removal units operating in remote villages of West Bengal, India now use a hybrid anion exchanger (HAIX) which are essentially spherical anion exchange resin beads containing dispersed nanoparticles of hydrated ferric oxide (HFO). HAIX, now commercially available as ArsenX np , offers a very high selectivity for sorption of oxyanions of arsenic due to the Donnan membrane effect. The sorption columns used in the field for removal of arsenic are either single column or split-column design. The sorption columns allow flow of atmospheric oxygen, thereby promoting oxidation of dissolved Fe(II) species of arsenic-contaminated raw water to insoluble Fe(III) oxides or HFO particulates. Apart from the usual role played by the sorbents like ArsenX np or activated alumina towards arsenic removal, HFO particulates also aid in the treatment process. Each unit is attached to a hand-pump driven well and capable of providing arsenic-safe water to three hundred (300) households or approximately one thousand villagers. No Chemical Addition, pH adjustment or electricity is required to run these units. On average, every unit runs for more than 20,000 bed volumes before a breakthrough of 50 μg/L of arsenic, the maximum contaminant level in drinking water in India, is reached. In Addition to arsenic removal, significant iron removal is also achieved throughout the run. Upon exhaustion, the media is withdrawn and taken to a central regeneration facility where 2% NaCl and 2% NaOH solution are used for regeneration. Subsequently, the regenerated resin is reloaded into the well-head sorption column. Following regeneration, the spent solutions, containing high arsenic concentration, are transformed into solids residuals and contained in a way to avoid any significant arsenic leaching. Laboratory investigations confirmed that the regenerated ArsenX np is amenable to reuse for multiple cycles without any significant loss in capacity.

  • well head arsenic removal units in remote villages of indian subcontinent field results and performance evaluation
    Water Research, 2005
    Co-Authors: Sudipta Sarkar, John E Greenleaf, Anirban Gupta, Ranjan K Biswas, Arun K Deb, Arup K Sengupta
    Abstract:

    Abstract Since 1997, over 135 well-head arsenic removal units have been installed in remote villages in the Indian state of West Bengal bordering Bangladesh. Every component of the arsenic removal treatment system including activated alumina sorbent is procured indigenously. Each unit serves approximately 200–300 households and contains about 100 L of activated alumina. No Chemical Addition, pH adjustment or electricity is required for operating these units. The arsenic concentration in the influent varies from around 100 μg/L to greater than 500 μg/L. In the treated water, arsenic concentration is consistently below 50 μg/L. The units are capable of removing both arsenites and arsenates from the contaminated groundwater for several months, often exceeding 10,000 bed volumes. In the top portion of the column, the dissolved iron present in ground water is oxidized by atmospheric oxygen into hydrated Fe(III) oxides or HFO particles which in turn selectively bind both As(III) and As(V). Upon exhaustion, these units are regenerated by caustic soda solution followed by acid wash. The arsenic-laden spent regenerant is converted into a small volume sludge (less than 500 g) and contained over a coarse sand filter in the same premise requiring no disposal. Many units have been operating for several years without any significant operational difficulty. The treated water is used for drinking and cooking. Most importantly, the villagers are responsible for the day to day operation and the upkeep of the units.

Yujie Feng - One of the best experts on this subject based on the ideXlab platform.

  • a novel electro coagulation fenton for energy efficient cyanobacteria and cyanotoxins removal without Chemical Addition
    Journal of Hazardous Materials, 2019
    Co-Authors: Jingkun An, Nan Li, Shu Wang, Chengmei Liao, Lean Zhou, Tian Li, Xin Wang, Yujie Feng
    Abstract:

    Abstract Harmful cyanobacterial bloom is a serious threat to global aquatic ecology and drinking water safety. Electro-Fenton (EF) has emerged as an efficient process for cyanobacteria and cyanotoxins removal, but high consumption of energy and Chemicals remain a major bottleneck. This study presents a novel convertible three-electrodes Electro-Coagulation-Fenton process for cyanobacteria and cyanotoxins removal with low energy consumption and no Chemicals Addition. We for the first time demonstrated the freely alternating between Electrocoagulation (EC) and EF by switching electrodes. The optimal aerated EC was operated at pH 8 and 100 mA to remove 91 ± 2% of cyanobaterial cells and 15% of Microcystins (MCs). Coagulants generated in EC were adsorbed on cyanobacterial cells to form a protect layer against algae disruption and cyanotoxins releasing. Residual MCs and cyanobaterial cells were completely mineralized by EF at 28 mA with iron ions and H2O2 generated in-situ. Compare to traditional EF, the optimal Electro-Coagulation-Fenton process increased total organic carbon (TOC) removal efficiency by 30%, yet energy consumption reduced up to 92%. The novel Electro-Coagulation-Fenton process is a promising technology for the efficient treatment of the mixture of suspended solid pollutants and persistent organic pollutants in one system with low energy consumption.

Zhenya Zhang - One of the best experts on this subject based on the ideXlab platform.

  • enhanced hydrolysis and acidification of cellulose at high loading for methane production via anaerobic digestion supplemented with high mobility nanobubble water
    Bioresource Technology, 2020
    Co-Authors: Xuezhi Wang, Tia Yua, Zitao Guo, Zhongfang Lei, Kazuya Shimizu, Zhenya Zhang, Duujong Lee
    Abstract:

    Abstract In this study, CH4 production from anaerobic digestion (AD) of refractory cellulose was investigated at a high loading of 3.5 (VScellulose/VSinoculum) under nanobubble water (NBW) Addition. A longer proton spin-spin relaxation time (2611–2906 ms) of NBW during 35 days’ storage reflected its high mobility and diffusion of water molecules. Higher volatile fatty acids were yielded at the hydrolysis-acidification stage under NBW Addition. Methanogenesis tests showed that Air-NBW and CO2-NBW supplementation accelerated the utilization of crystalline cellulose, achieving methane yields of 264 and 246 mL CH4/g-VSreduced, increasing by 18% and 10% compared to deionized water Addition (the control), respectively. In Addition, under NBW Addition the cellulose crystallinity reduction was enhanced by 14–20% with microbial community being enriched with hydrolytic and methanogenic bacteria. Results from this work suggest that NBW environment with no Chemical Addition and relatively low energy consumption is advantageous for enhanced AD process of cellulosic biomass.

  • enhanced hydrolysis of waste activated sludge for methane production via anaerobic digestion under n2 nanobubble water Addition
    Science of The Total Environment, 2019
    Co-Authors: Xiaojing Yang, Zhongfang Lei, Kazuya Shimizu, Jingmi Nie, Di Wang, Ziwe Zhao, Motoyoshi Kobayashi, Yasuhisa Adachi, Zhenya Zhang
    Abstract:

    Abstract Anaerobic digestion (AD) is a relatively safe and economically feasible disposal technique for waste activated sludge (WAS), in which hydrolysis of complex organic matters is the rate-limiting step. The aim of this study is to explore the efficiency of applying nitrogen gas nanobubble water (N 2 -NBW) to AD of WAS and reveals the possible mechanisms. The possible effects of N 2 -NBW on different processes during AD of WAS were investigated and N 2 -NBW was expected to enhance the hydrolysis step. Results showed that after N 2 -NBW Addition, sludge particles possessed more negative charges (indicated by zeta potential) than the control with deionized water (DW) Addition. The total methane production of NBW group was 402 mL/g-VS reduced , 29% higher than the control group. Moreover, mechanism investigations revealed that N 2 -NBW Addition not only improved the disintegration of high molecular weight compounds (proteins and polysaccharides), but also enhanced the activities of four extracellular hydrolases by 14–17%. Results from the present work showed that the enhancement of N 2 -NBW Addition on methane production from AD of WAS was mainly through the augmentation of hydrolysis of WAS, as little effect on methanogenesis and VS reduction was discerned. The promotion effect of N 2 -NBW on hydrolysis suggests that N 2 -NBW Addition is a promising pretreatment strategy for AD of WAS with no Chemical Addition at low energy consumption, thus, increasing the economic feasibility of WAS disposal.

Luis A Godinez - One of the best experts on this subject based on the ideXlab platform.

  • novel arrangement for an electro fenton reactor that does not require Addition of iron acid and a final neutralization stage towards the development of a cost effective technology for the treatment of wastewater
    Chemosphere, 2018
    Co-Authors: Dennys Fernandez, Irma Robles, Francisco J Rodriguezvaladez, Luis A Godinez
    Abstract:

    A novel arrangement for an electro-Fenton reactor aimed to treat neutral wastewater is presented. The arrangement consists on three-compartments in series, two of them packed with a cation exchange resin and one positioned between these, containing a polarized activated carbon column where the electroChemical generation of the Fenton reagent takes place. While the hydroxyl radicals electroChemically produced in-situ, react with the pollutant species adsorbed on the activated carbon cathode, the resin compartments administrate and collect the iron cation and the hydrated proton species in alternating flow direction cycles. The resulting process is a system that does not require acid or iron Chemical Addition to the process while at the same time, renders decontaminated water free of iron-dissolved species at neutral pH. The proposed electroChemical reactor arrangement is therefore the basis for the design of commercially viable electro-Fenton reactors in which the Addition and subsequent removal of acid and iron Chemicals is avoided; two of the currently most limiting features for the development of electro-Fenton technology for treating wastewater.

David A Dzombak - One of the best experts on this subject based on the ideXlab platform.

  • Scaling Control for Heat Exchangers in Recirculating Cooling Systems Using Treated Municipal Wastewater
    2014
    Co-Authors: Wenshi Liu, Shih-hsiang Chien, David A Dzombak, Radisav D. Vidic
    Abstract:

    Treated municipal wastewater (MWW) is recognized as a viable alternative cooling water source for power generation. One of the key challenges for the successful use of the effluent from wastewater treatment facilities for cooling is the potential for significant condenser fouling when this water is concentrated as much as 4–6 times in recirculating cooling systems. In this study, two types of treated municipal wastewaters, namely secondary-treated MWW with pH adjustment (MWW_pH) and secondary-treated MWW subjected to nitrification and sand filtration (MWW_NF), were evaluated as the sole source of makeup water for recirculating cooling systems in both laboratory and pilot-scale studies. The tests revealed that synthetic MWW_pH had significant crystalline fouling potential on the condenser surfaces when the pH was adjusted at 7.8 and that hydroxyapatite was the main component of the mineral scales formed on condenser surfaces. Addition of antiscalants, e.g., polymaleic acid (PMA), was shown to be effective in fouling mitigation by inhibiting the transformation of amorphous calcium phosphate to hydroxyapatite. In the case of synthetic MWW_NF, significant crystalline fouling was observed at pH 7.2 while bulk precipitation reduced the driving force for crystalline fouling when pH was adjusted to 7.8. Pilot-scale studies with actual MWW revealed that the Addition of PMA alone is not sufficient to control scale buildup and that controlling pH at 7.8 is needed to ensure proper operation of the cooling tower, as predicted by laboratory studies with synthetic wastewater. Alternatively, nitrification and sand filtration would accomplish the same goal without any Chemical Addition. Overall, this study demonstrated that it is possible to manage crystalline fouling on hot condenser tube surfaces associated with the use of treated municipal wastewater just by pH control and antiscalant Addition and that significant Additional treatment of municipal wastewater prior to use in recirculating cooling systems may not be necessary

  • Use of Treated Municipal Wastewater as Power Plant Cooling System Makeup Water: Tertiary Treatment versus Expanded Chemical Regimen for Recirculating Water Quality Management
    2012
    Co-Authors: David A Dzombak, Radisav D. Vidic, Amy E. Landis
    Abstract:

    Treated municipal wastewater is a common, widely available alternative source of cooling water for thermoelectric power plants across the U.S. However, the biodegradable organic matter, ammonia-nitrogen, carbonate and phosphates in the treated wastewater pose challenges with respect to enhanced biofouling, corrosion, and scaling, respectively. The overall objective of this study was to evaluate the benefits and life cycle costs of implementing tertiary treatment of secondary treated municipal wastewater prior to use in recirculating cooling systems. The study comprised bench- and pilot-scale experimental studies with three different tertiary treated municipal wastewaters, and life cycle costing and environmental analyses of various tertiary treatment schemes. Sustainability factors and metrics for reuse of treated wastewater in power plant cooling systems were also evaluated. The three tertiary treated wastewaters studied were: secondary treated municipal wastewater subjected to acid Addition for pH control (MWW_pH); secondary treated municipal wastewater subjected to nitrification and sand filtration (MWW_NF); and secondary treated municipal wastewater subjected nitrification, sand filtration, and GAC adsorption (MWW_NFG). Tertiary treatment was determined to be essential to achieve appropriate corrosion, scaling, and biofouling control for use of secondary treated municipal wastewater in power plant cooling systems. The ability to control scaling, in particular, was found to bemore » significantly enhanced with tertiary treated wastewater compared to secondary treated wastewater. MWW_pH treated water (adjustment to pH 7.8) was effective in reducing scale formation, but increased corrosion and the amount of biocide required to achieve appropriate biofouling control. Corrosion could be adequately controlled with tolytriazole Addition (4-5 ppm TTA), however, which was the case for all of the tertiary treated waters. For MWW_NF treated water, the removal of ammonia by nitrification helped to reduce the corrosivity and biocide demand. Also, the lower pH and alkalinity resulting from nitrification reduced the scaling to an acceptable level, without the Addition of anti-scalant Chemicals. Additional GAC adsorption treatment, MWW_NFG, yielded no net benefit. Removal of organic matter resulted in pitting corrosion in copper and cupronickel alloys. Negligible improvement was observed in scaling control and biofouling control. For all of the tertiary treatments, biofouling control was achievable, and most effectively with pre-formed monochloramine (2-3 ppm) in comparison with NaOCl and ClO2. Life cycle cost (LCC) analyses were performed for the tertiary treatment systems studied experimentally and for several other treatment options. A public domain conceptual costing tool (LC3 model) was developed for this purpose. MWW_SF (lime softening and sand filtration) and MWW_NF were the most cost-effective treatment options among the tertiary treatment alternatives considered because of the higher effluent quality with moderate infrastructure costs and the relatively low doses of conditioning Chemicals required. Life cycle inventory (LCI) analysis along with integration of external costs of emissions with direct costs was performed to evaluate relative emissions to the environment and external costs associated with construction and operation of tertiary treatment alternatives. Integrated LCI and LCC analysis indicated that three-tiered treatment alternatives such as MWW_NSF and MWW_NFG, with regular Chemical Addition for treatment and conditioning and/or regeneration, tend to increase the impact costs and in turn the overall costs of tertiary treatment. River water supply and MWW_F alternatives with a single step of tertiary treatment were associated with lower impact costs, but the contribution of impact costs to overall annual costs was higher than all other treatment alternatives. MWW_NF and MWW_SF alternatives exhibited moderate external impact costs with moderate infrastructure and Chemical conditioner dosing, which makes them (especially MWW_NF) better treatment alternatives from the environmental sustainability perspective since they exhibited minimal contribution to environmental damage from emissions.« less