Development and Testing of Membrane Biological Wastewater Processors

Finger, Barry W.; Supra, Laura N.; Dall-Bauman, Liese; Pickering, Karen D.

doi:10.4271/1999-01-1947

Cited by 26 publications

(6 citation statements)

References 8 publications

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“…The bioreactor test was performed using 2000 mg dm −3 solutions (33.3 mmol L −1 ) of urea in 20 mmol L −1 phosphate buffer (pH 7.0) at 35 °C. This concentration of urea corresponds to that which would be expected in the wastewater stream on board a spacecraft 4, 51. Samples (5 mL) of the effluent were obtained daily at the same time to measure the amount of urea in the effluent.…”

Section: Resultsmentioning

confidence: 99%

“…Typical aqueous wastes occurring aboard a spacecraft are crew hygiene waters, which arise from shower, oral hygiene, and hand wash facilities, laundry water, and human urine, in which nitrogen occurs principally as urea 1, 2. Even though various technologies have been proposed for the recycling of wastewater,3–5 it is difficult to remove urea. It is a highly water soluble and polar non‐ionic contaminant that is a remarkably stable molecule (its half‐life for spontaneous degradation in water is 3.6 years at 38 °C) 6.…”

Section: Introductionmentioning

confidence: 99%

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Urease immobilization on an ion‐exchange textile for urea hydrolysis

Yeon

Lueptow

2006

J of Chemical Tech & Biotech

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Ion-exchange textiles are used as organic supports for urease immobilization with the aim of developing reactive fibrous materials able to promote urea removal. A non-woven, polypropylene-based cation-exchange textile was prepared using UV-induced graft polymerization. Urease was covalently immobilized onto the cation-exchange textile using three different coupling agents: N-(3-dimethylaminopropyl)-N -ethylcarbodiimide hydrochloride (EDC), N-cyclohexyl-N -(b-[N-methylmorpholino]ethyl)carbodiimide p-toluenesulfonate (CMC), and glutaraldehyde (GA). The immobilized biocatalyst was characterized by means of FT-IR spectrometry, SEM micrographs, dependence of the enzyme activity on pH and temperature, and according to the kinetic constants of the free and immobilized ureases. The biotextile prepared with EDC in the presence of N-hydroxysuccinimide performs best. The optimum pH was 7.2 for the free urease and 7.6 for the immobilized ureases. The reactivity was maximal at 45• C for free urease, 50• C for biotextiles prepared using EDC or CMC, and 55• C for biotextiles prepared with GA. The activation energy for the immobilized ureases was 4.73-5.67 kcal mol −1 , which is somewhat higher than 4.3 kcal mol −1 for free urease. The urea conversion for a continuous-flow immobilized urease reactor is nearly as good as a continuously stirred tank reactor having a much longer residence time, suggesting that the packed bed reactor had sufficient diffusive mixing and residence time to reach nearly optimal results. Urease immobilized on a biotextile using EDC has good storage and operational stability.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Urease immobilization on an ion‐exchange textile for urea hydrolysis

Yeon

Lueptow

2006

J of Chemical Tech & Biotech

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“…357 J. Michael Finger once portrayed the antidumping regime as a "witches' brew of the worst of policy-making: power politics, bad economics, and shameful public administration." 358 Now, it is time to break the spell cast by this protectionist brew using an antitrust antidote.…”

Section: The Ftc Registration Of the Noerr-pennington Exemptionmentioning

confidence: 99%

Remedying Trade Remedies

Cho

2007

SSRN Journal

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“…Thus, environmental legislation requires the removal of nitrogen compounds from most wastewater ( , ). Furthermore, water reuse necessitates the removal of nitrogen compounds ( − ).…”

Section: Introductionmentioning

confidence: 99%

Membrane Rejection of Nitrogen Compounds

Lee

Lueptow

2001

Environ. Sci. Technol.

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Rejection characteristics of nitrogen compounds were examined for reverse osmosis, nanofiltration, and low-pressure reverse osmosis membranes. The rejection of nitrogen compounds is explained by integrating experimental results with calculations using the extended Nernst-Planck model coupled with a steric hindrance model. The molecular weight and chemical structure of nitrogen compounds appear to be less important in determining rejection than electrostatic properties. The rejection is greatest when the Donnan potential exceeds 0.05 V or when the ratio of the solute radius to the pore radius is greater than 0.8. The transport of solute in the pore is dominated by diffusion, although convective transport is significant for organic nitrogen compounds. Electromigration contributes negligibly to the overall solute transport in the membrane. Urea, a small organic compound, has lower rejection than ionic compounds such as ammonium, nitrate, and nitrite, indicating the critical role of electrostatic interaction in rejection. This suggests that better treatment efficiency for organic nitrogen compounds can be obtained after ammonification of urea.

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Development and Testing of Membrane Biological Wastewater Processors

Cited by 26 publications

References 8 publications

Urease immobilization on an ion‐exchange textile for urea hydrolysis

Urease immobilization on an ion‐exchange textile for urea hydrolysis

Remedying Trade Remedies

Membrane Rejection of Nitrogen Compounds

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