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The goal of this research was to study the effect of dilution on ammonium and potassium removal from real hydrolyzed urine. The performance of two natural zeolites, clinoptilolite and chabazite, was studied and compared with the help of batch equilibrium experiments at four dilution levels: 100%, 10%, 1% and 0.1%

The goal of this research was to study the effect of dilution on ammonium and potassium removal from real hydrolyzed urine. The performance of two natural zeolites, clinoptilolite and chabazite, was studied and compared with the help of batch equilibrium experiments at four dilution levels: 100%, 10%, 1% and 0.1% (urine volume/total solution volume). Further, the sorption behavior of other exchangeable ions (sodium, calcium and magnesium) in clinoptilolite and chabazite was studied to improve the understanding of ion exchange stoichiometry. Ammonium and potassium removal were highest at undiluted level in samples treated with clinoptilolite. This is a key finding as it illustrates the benefit of urine source separation. Chabazite treated samples showed highest ammonium and potassium removal at undiluted level at lower doses. At higher doses, potassium removal was similar in undiluted and 10% urine solutions whereas ammonium removal was the highest in 10% urine solutions. In general, chabazite showed higher ammonium and potassium removal than clinoptilolite. The result showed that ion exchange was stoichiometric in solutions with higher urine volumes.
ContributorsRegmi, Urusha (Author) / Boyer, Treavor H (Thesis advisor) / Delgado, Anca G (Committee member) / Hamilton, Kerry (Committee member) / Arizona State University (Publisher)
Created2019
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Description
Global shortages of urea and unsustainable production of synthetic urea have caused concerns over the future of food production, automobile operation, and other processes. Urine is a waste product that could supplement synthetic urea production. This study utilizes polyamide reverse osmosis (RO) and nanofiltration (NF) membranes in a cross-flow orientation

Global shortages of urea and unsustainable production of synthetic urea have caused concerns over the future of food production, automobile operation, and other processes. Urine is a waste product that could supplement synthetic urea production. This study utilizes polyamide reverse osmosis (RO) and nanofiltration (NF) membranes in a cross-flow orientation to selectively recover urea from fresh human urine. Urea permeation experiments were conducted to determine the effects of urea stabilization via pH adjustment and membrane type on the production of a pure urea product. Fouling mitigation experiments were then conducted to determine the efficacy of microfiltration (MF) pretreatment on the reduction of the membrane fouling layer. The results showed that the NF90 membrane had advantageous performance to the BW30 RO and NF270 membranes, permeating 76% of the urea while rejecting 68% of the conductivity. Urine stabilization via acetic acid or sodium hydroxide addition did not inhibit membrane performance, signifying the use of pH 5 as a suitable pretreatment condition. Real fresh urine had higher rejection of constituents for NF90, suggesting the reduction of flux across the membrane due to interactions with organic material. MF pretreatment reduced foulant thickness and permeate flux loss but did not change the speciation of microorganisms. Finally, different urea-based products, such as fertilizers, biocement, and synthetic polymers, were suggested to show the potential of urine-recovered urea to reduce costs. The results from this work show the efficacy of using polyamide RO and NF membranes to supplement unsustainable synthetic production of urea with sustainably sourced urea from a waste product, human urine.
ContributorsCrane, Lucas Christopher (Author) / Boyer, Treavor H (Thesis advisor) / Perreault, Francois (Committee member) / Westerhoff, Paul (Committee member) / Arizona State University (Publisher)
Created2022