Date

5-1-2018

Document Type

Dissertation

Degree

Doctor of Philosophy

Department

Environmental Engineering

First Adviser

Fox, John

Abstract

Treatment processes that use membranes to manage the flux of ions in combination with manipulation of aqueous systems allows for increased environmentally sustainability. The first process investigated combining the neutralization reaction and ion exchange membrane processes to offer onsite management of acidic or basic industrial wastes at low operational and capital costs that improved the environmental sustainability of the industrial waste management. The second process investigated combining a solid compound and gas to form an aqueous system with high osmotic pressure. In regard to the first process, many waste generators with low waste volumes and/or low acid or base concentrations struggle to justify the required investment to manage onsite industrial waste management; however, this research was gathered to show that through combination of the neutralization reaction and ion exchange processes, the waste generators benefit from reduced costs while gaining treatment of target waters. Synthetic pickle waste with 10% Fe(III) and 2.5% HCl was used in a diffusion dialysis process to produce purified acid. The purified acid was used in a Donnan dialysis process to treat hard water at 250ppm of Mg2+ and brackish water at 2000ppm of NaCl. The flux and percent removal of H+, Mg2+, Na+ and Cl- was determined for all ion exchange processes with varying starting concentration and ion exchange membranes. Removal of Mg2+ was as high as 98% after 2 cycles of purified acid. A three-ion model was developed to predict equilibrium of the Donnan dialysis system which, along with flux data, waste generators may use as a tool for system design of an onsite treatment process. Regarding the second process, a system was created with high osmotic pressure that was used in a Forward Osmosis process to draw water from the target chamber. Traditional Forward Osmosis (FO) processes operate at hydraulic pressures close to zero with the osmotic pressure (OP) gradient between the target and draw solutions providing the driving force for osmosis. A novel FO process, pressurized FO, creates an OP gradient by applying a partial pressure of CO2 (g) on the draw solution and the same pressure of inert gas on the target solution that enables a reaction in the target cell between MgCO3 and H2CO3 to form MgHCO3+, HCO3-. The potential OP is greater than 100 atms with the OP for the system controlled by adjusting the partial pressure of CO2 (g) in the draw solution. Through experimental results, the key process elements were validated. These key process elements included the cycling of the OP system from formation of a high OP system to the reduction of high OP system, and the operation of FO with the high OP system. Specifically, it was demonstrated that the formation of the high OP system (33 atms) and subsequent reduction of the OP to 0.5 atm at the removal of the CO2 (g) coupled with air sparging was accomplished with the process. The high OP draw solution was used to draw deionized water across an HTI membrane under CO2 partial pressure of 8 atm with a flux rate that corresponded with OP of 33 atm for the draw solution. The research objectives were to demonstrate a new configuration of the FO process through the pressurized FO process and a corresponding draw solution that offers less energy consumption versus other conventional FO systems.

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