Bench-scale Performance Research Articles

Observation and mitigation of perimeter artefacts in bench scale membrane characterization

Perimeter artefacts, such as test cell induced membrane damage and unrepresentative hydrodynamics, can significantly affect bench scale performance evaluation using membrane coupons. By comparing separately collected center and perimeter permeate, the effect of perimeter artefacts can be identified. The additional salt passage in the perimeter area (i.e., along the edges of the membrane coupon) depends non-linearly on pressure, and is implicitly affected by flux, temperature and salinity (osmotic pressure), leading to a potential increase of the measured salt passage by a factor two. We observed a very slow dynamic response (τ≈12h) to changes in operational conditions, suggesting that in our case the perimeter artefact was diffusive in nature. Due to this slow response, the perimeter salt passage trails previously evaluated operational conditions, possibly resulting in a false trend, hysteresis or high variance, depending on the sequential ordering and duration of test condition intervals. The effect of perimeter artefacts can be largely mitigated by measuring salt rejection from only the central area of the coupon.

Step-feeding food waste fermentation liquid as supplementary carbon source for low C/N municipal wastewater treatment: Bench scale performance and response of microbial community

Municipal wastewater treatment often lacks carbon source, while carbon-rich organics in food waste are deficiently utilized. In this study, the food waste fermentation liquid (FWFL) was step-fed into a bench-scale step-feed three-stage anoxic/aerobic system (SFTS-A/O), to investigate its performance in nutrients removal and the response of microbial community as a supplementary carbon source. The results showed that the total nitrogen (TN) removal rate increased by 21.8–109.3% after step-feeding FWFL. However, the biomass of the SFTS-A/O system was increased by 14.6% and 11.9% in the two phases of the experiment, respectively. Proteobacteria was found to be the dominant functional phyla induced by FWFL, and the increase of its abundance attributed to the enrichment of denitrifying bacteria and carbohydrate-metabolizing bacteria was responsible for the biomass increase. Azospira belonged to Proteobacteria phylum was the dominant denitrifying genera when step-fed with FWFL, its abundance was increased from 2.7% in series 1 (S1) to 18.6% in series 2 (S2) and became the keystone species in the microbial networks. Metagenomics analysis revealed that step-feeding FWFL enhanced the abundance of denitrification and carbohydrates-metabolism genes, which were encode mainly by Proteobacteria. This study constitutes a key step towards the application of FWFL as a supplementary carbon source for low C/N municipal wastewater treatment.

In-situ grafted amine functionalized metal-organic frameworks for CO2 capture: Preparation and bench-scale performance evaluation

The work includes the preparation of zirconium fumarate (ZrFu) metal-organic framework (MOF) and investigation of the CO2 capture performance of the material. The CO2 adsorption experiments were performed in a bench-scale flow reactor with a simulated flue gas mixture. To enhance the CO2 capture capacity of the ZrFu material, two polydentate amines, namely diethylenetriamine (DETA) and tetraethylenepentamine (TEPA) were incorporated into the ZrFu by an in-situ grafting method. The effects of adsorption temperature, pressure, amine loading, and CO2 concentration in the feed gas mixture on CO2 capture were examined. The obtained value of the CO2 uptake capacity of the pristine ZrFu is 73 g CO2/kg sorbent at 30 ºC under atmospheric pressure. Among the amine-modified MOFs, the DETA-modified ZrFu (10-DETA-ZrFu) showed a maximum adsorption capacity of 86 g CO2/kg sorbent. It is also noted that at 90 °C, the CO2 adsorption capacity of the material is 57 g CO2/kg sorbent, which is about 67% of the capture capacity at 30 °C. This demonstrates that the MOFs can capture and retain the CO2 molecules inside the MOF moiety even at higher temperatures. The study also revealed that the synthesized MOFs are chemically stable with about 10% moisture environment. The prepared MOFs exhibited admirable thermo-chemical stability up to around 150 °C. Among the studied isotherm models, the Langmuir model showed a good agreement with the experimental data for lower values of adsorption pressure. The estimated value of adsorption energy for the adsorption of CO2 on ZrFu is 6.9 kJ/mol at 30 °C.

Friction Mechanism and Application of PTFE Coating in Finger Seals

Due to their special flexible structure, finger seals show good wear and leakage characteristics and has a great application prospects. Under the condition of high speed, the sealing and wear performance of finger seals is directly related to the characteristics of the friction pair between the finger foot and rotor. As a kind of high polymer material with a lower friction coefficient, polytetrafluoroethylene (PTFE) has potential application value in finger seals. Therefore, based on the previous theoretical analysis and optimization design, in this study pin-on-disc tests between the metals applied in finger seals and the PTFE coating and bench-scale performance tests of finger seals with the PTFE coating were carried out. The results show that for finger seals made of the cobalt-base alloy GH605, the friction coefficient of finger seals with PTFE coating is only 0.15, which is 50% lower than that without the PTFE coating; after a 50-h durability test, the leakage performance of finger seals with the PTFE coating was more stable, and its leakage rate and wear rate were reduced by 30 and 39%, respectively, compared to without the PTFE coating. The test results in this article indicate that the PTFE coating has excellent wear resistance characteristics and good application potential for finger seals, which provides valuable reference for the design of the friction pair of finger seals.

Evaluating the potential of waste plastics as fuel in cement kilns using bench-scale emissions analysis

In an effort to reduce emissions and lower fuel costs, cement plants have explored the use of waste materials to displace coal and petroleum coke. A potential candidate is non-recyclable waste plastics. Knowledge of potential changes in cement kiln parameters with a change in the composition of operating fuel prior to full-scale application is necessary for obtaining permits and for plant preparedness. Most bench-scale performance studies have targeted the prediction of full-scale stack emissions with variable degrees of success. In this work, a bench-scale tube furnace and a heated grid reactor (HGR) have been used to compare combustion and emission changes when waste plastics displace an equivalent amount of heat from the coal/coke blend. Trends in the results from bench-scale experiments on residual volatile organic compound (VOC) emissions matched full-scale observations on kiln thermal performance. Bench-scale particulate matter (PM) emissions indicated that no significant changes were likely in full-scale stack PM emissions when using waste-derived fuel (WDF). This bench-scale fuel characterization approach has been used to study the potential impact of waste plastics on the performance of a local cement kiln.

Online Detection of Selenium and Its Retention in Reducing Gasification Atmosphere

The emission of selenium from coal gasification processes can cause harm to the environment and downstream equipment. With upcoming legislation, reliable detection as well as control of such gas species become crucial. This study therefore addresses the development and successful employment of an online analytical method, based on the direct introduction of a simplified flue gas (H2, H2O, H2Se, Ar) into an ICP-MS. In combination with matrix matched calibration, the calculated and verified detection limits of H2Se lie below 1 ppbv, thus being comparable to current offline methods. These low detection limits and the high temporal resolution (>1 Hz) enable the use of this method as a quick and robust tool for the lab- and bench-scale performance evaluation of sorbent materials. As a case study, Zn/Al2O3 was tested toward H2Se capturing at warm temperatures (150–350 °C). The results show that both, the support and the active phase, interact with the contaminant. While γ-Al2O3 can retain H2Se at dry reaction c...

Development of a scale down cell culture model using multivariate analysis as a qualification tool

In characterizing a cell culture process to support regulatory activities such as process validation and Quality by Design, developing a representative scale down model for design space definition is of great importance. The manufacturing bioreactor should ideally reproduce bench scale performance with respect to all measurable parameters. However, due to intrinsic geometric differences between scales, process performance at manufacturing scale often varies from bench scale performance, typically exhibiting differences in parameters such as cell growth, protein productivity, and/or dissolved carbon dioxide concentration. Here, we describe a case study in which a bench scale cell culture process model is developed to mimic historical manufacturing scale performance for a late stage CHO-based monoclonal antibody program. Using multivariate analysis (MVA) as primary data analysis tool in addition to traditional univariate analysis techniques to identify gaps between scales, process adjustments were implemented at bench scale resulting in an improved scale down cell culture process model. Finally we propose an approach for small scale model qualification including three main aspects: MVA, comparison of key physiological rates, and comparison of product quality attributes.

Impact of organic solvents and common anions on 2-chlorobiphenyl dechlorination kinetics with Pd/Mg

The current study evaluates Pd/Mg performance for 2-chlorobiphenyl (2-CB) dechlorination in the presence of naturally abundant anions such as sulfate, chloride, nitrate, hydroxide and carbonates and organic solvents that are used for ex-situ PCB extraction or may accompany PCB contamination. While studies abound on the effect of these species on corrosion rates of pure Mg, literature on the behavior of Mg galvanically coupled with Pd remains limited making their investigation necessary. We also provide insights on the effect of initial PCB concentration and system pH on 2-CB dechlorination rates. Among anions studied, especially interesting results were noted for nitrate, bicarbonate and the sodium salt of humic acid. NO3− underwent reduction to NH4+ thereby competing for electrons and consequently lowering 2-CB dechlorination rate. HCO3− significantly enhanced 2-CB dechlorination rates by serving as a proton donor. Humic acid also showed faster dechlorination rates, probably by acting as an electron ‘shuttle’ to the PCB. Only OH− produced significant impairment Pd/Mg reactivity systems. While ethanol and acetone both led to reduced dechlorination rates through reduced hydrogen production and increased affinity of 2-CB for the liquid phase, acetone lowered rates further by undergoing reduction to 2-propanol. 2-CB dechlorination at high solvent concentrations and in the presence of common anions highlights robustness of Pd/Mg systems and suggests they will fare comparably to their bench-scale performance in presence of interferences expected in natural systems.

Innovative beneficial reuse of reverse osmosis concentrate using bipolar membrane electrodialysis and electrochlorination processes

Reverse osmosis (RO) is a widely used and rapidly growing desalination technology. A major disadvantage of this process is that the concentrate from the RO process, which could be as much as 25% of the feed stream, represents a polluting stream. This waste stream could pose a significant challenge to the implementation of this process, particularly for inland communities which do not have the option of ocean disposal. An excellent environmentally benign approach to disposal could be beneficial reuse of the waste stream. This study presents two innovative beneficial reuse strategies for RO concentrate produced by an integrated membrane system (IMS) from a wastewater reclamation facility. The technologies evaluated in this study included bipolar membrane electrodialysis (BMED) for conversion of RO concentrate into mixed acid and mixed base streams, and electrochlorination (EC) for onsite chlorine generation. Bench-scale studies conducted with BMED demonstrated that RO concentrate could be desalted while producing mixed acids and mixed bases with concentrations as high as 0.2N. Similarly, the EC process was capable of producing a 0.6% hypochlorite solution from RO concentrate. The acids and bases as well as the hypochlorite produced could be directly applied to the RO process as well as upstream pre-treatment processes. A preliminary economic evaluation of the viability of these two approaches was conducted by conducting rough order of magnitude cost estimates based on the bench-scale performance of these processes on RO concentrate. A comparison of the overall costs of an Integrated Membrane System utilizing these innovative reuse strategies with conventional disposal options and thermal zero liquid discharge treatment is presented. This comparison indicates that a reuse approach might be economically viable for inland wastewater reuse facilities that utilize RO membranes and have limited options for concentrate disposal.

Comprehensive fire behaviour assessment of polymeric materials based on cone calorimeter investigations

Abstract Bench scale performance based cone calorimeter investigations were conducted on glass fibre reinforced polyamide 66 (PA-66) and high impact polystyrene (HIPS) materials. Red phosphorus and magnesium hydroxide were used as fire retardants. Dilution, heat sink, barrier and charring mechanisms are considered to be active in the condensed phase. Dilution, cooling and flame poisoning mechanisms are discussed for the gas phase. Cone calorimeter data are used to give a comprehensive fire behaviour assessment in terms of the propensity to cause a quick growing fire and of the propensity to cause a fire of long duration. The external heat flux is varied between 30 and 75 kW/m2 so that the results for combustion behaviour and flame retardancy, respectively, are valid for different fire scenarios and fire tests. Results on the intrinsic contribution of the steady heat release rate per unit area reveal information about the flammability behaviour. UL 94 results are predicted in close correspondence to UL 94 experiments.

Evaluation of kinetic constants for anaerobic fixed film fixed bed reactors treating tannery wastewater

An approach has been made to evaluate the kinetic constants for a two stage anaerobic fixed film fixed bed reactor system treating tannery wastewater. The research reported herein is concerned with the bench scale performance evaluation of the reactor system treating the wastewater and application of the data to various models to evaluate the kinetic constants for substrate bio‐oxidation, biomass growth and biogas yield.

Bench-scale Performance of Pyrene Quinone Production Process by Indirect Electrooxidation of Pyrene Suspension

Bench-scale Performance of Pyrene Quinone Production Process by Indirect Electrooxidation of Pyrene Suspension

Evaluation of kinetic constants for anaerobic fixed film fixed bed reactor system treating herbal pharmaceutical wastewater

Abstract Analysing the importance of kinetic formulations in the successful design and application of a treatment technology, an approach has been made to evaluate the kinetic constant for anaerobic fixed film fixed bed reactor system treating herbal pharmaceutical wastewater. The research reported herein is concerned with the bench scale performance evaluation of the reactor system treating the said wastewater and the application of the data to various models to evaluate the kinetic constants for substrate bio‐oxidation, biomass growth and biogas yield.

Bench Scale Testing of Low-NOx LBG Combustors

The high efficiencies obtained in a combined gas-turbine/steam-turbine power cycle burning low Btu gas (LBG) make it a potentially attractive alternative to the high sulfur emitting direct coal-fired steam cycle. In the gasification process, much of the bound nitrogen in coal is converted to ammonia in the LBG. This ammonia is largely converted to nitrogen oxides (NOx) in conventional combustors. This paper examines the pressurized bench scale performance of reactors previously demonstrated to produce low NOx emissions in atmospheric laboratory scale experiments. LBG was synthesized in a catalytic reformer and fired in three reactors: a catalytic reactor, a diffusion flame, and a stirred reactor. Effects of scale, pressure, stoichiometry, residence time, and preheat were examined. Lowest NOx emissions were produced in a rich/lean series staged catalytic reactor.

Variation in Sludge Settleability with Temperature

Abstract This study examined the effect of temperature on the settleabi1ity of activated sludge at various organic loading rates. Five completely mixed, bench-scale, activated sludge plants, operating under similar conditions at 5, 10 and 19°C, were continuously fed diluted, settled sewage supplemented with carbohydrate (sucrose). Hydraulic loading rates, MLSS and pH were maintained at constant levels during the experiments to eliminate these factors are variables. Dissolved oxygen was kept in excess of 3 mg/1 so that it would not be a limiting factor. Sludge Volume Indices (SVI ) and zone settling velocities were used to indicate changes in sludge settleability. Microscopic examination of the activated sludge indicated significant differences in the morphological features of filamentous microorganisms present at the two temperature extremes. At 19°C, the predominant forms were characterized by long curving trichomes, occasionally falsely branching, containing short cylindrical cells. At 5 °C, much smaller straight filaments, composed of long, narrow, rod-shaped cells appeared to be the principal microorganisms responsible for bulking. Various other filamentous forms were always present at each of the temperatures studied. Stirred sludge settling tests of moderately bulking sludges generally exhibited much higher settling velocities and lower SVI's than unstirred bulking samples. However, extremely filamentous bulking sludge exhibited comparable stirred and unstirred settling velocity and SVI values. The standard SVI test was found to be an inadequate indicator of the extent of bulking when trying to correlate the SVI failures from bench-scale performance with the results from continuous units. Lower temperature had no appreciable effect on COD removal efficiency as long as bulking did not cause a loss of solids in the effluent. However, results suggested that less than half the organic load could be accepted at 5°C, that could be handled at 19°C, before filamentous bulking occurred. A plot of loading versus temperature for various SVI's provided a visual indication of the safe loading limit below which bulking was unlikely to occur. The study clearly demonstrated that temperature can have a significant effect on sludge settleability.