Application of Conductive Concrete as a Microbial Fuel Cell to Control H2S Emission for Mitigating Sewer Corrosion

Localized biogenic corrosion and extrication of annoying odors caused by hydrogen sulfide (H2S) have long been a big problem in the management of urban sewer systems. H2S emission control in sewers via chemically or biologically normal oxidation processes has also been investigated extensively and is costly. The objective of this work was to develop a new technology to mitigate the concentration of H2S in sewer pipes using conductive concrete. Experimental results after 66 days show that the concentration of hydrogen sulfide significantly decreased when conductive concrete was used as a microbial fuel cell. Both ordinary Portland cement and conductive concrete were utilized for the target experiment. Elemental sulfur was observed in the coating sludge of conductive concrete, whereas this trend was not observed for ordinary Portland cement. These observations demonstrate that conductive concrete provides an electron pathway from deposited sludge in the bottom of sewer pipes to oxygen dissolved in surface water electrons generated from hydrogen sulfide oxidation in an anaerobic environment via conductive concrete. Finally, regarding the mechanism responsible for hydrogen sulfide oxidation, chemical oxidation was the dominant process, and biological processes did not play a significant role

A Mechanistic Study of Arsenic (Iii) Rejection by Reverse Osmosis and Nanofiltration Membranes

273 p.Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 2009.Reverse osmosis/nanofiltration (RO/NF) membranes are capable to provide an effective barrier for a wide range of contaminants (including disinfection by-products precursors) in a single treatment step. However, solute rejection mechanisms by RO/NF membranes are not well understood. The lack of mechanistic information arises from experimental difficulties faced when evaluating water/solute transport phenomena within the ultrathin membrane active layers (< 150 nm) of RO/NF membranes.The main objective of this study was to apply Rutherford backscattering spectrometry (RBS) to determine the partition coefficients of arsenious acid (H3AsO3) and other solutes, and the concentration of charged chemical groups in the active layers of RO/NF membranes with the goal of elucidating the mechanisms underlying the difference in H3AsO 3 rejection between commercial polyamide RO/NF membranes. Then, the role of water permeability, the H3AsO3 partition coefficient, and the H3AsO3 diffusion coefficient in H3AsO 3 removal efficiency was assessed to find key water/H3AsO 3 transport phenomena controlling H3AsO3 removal efficiency. Experimental observations were then used to provide recommendations for physico-chemical properties of polyamide active layers that would result in high H3AsO3 removal efficiency. Another main objective of this study was to investigate the influence of active layer hydrophilicity on solute removal efficiency. This objective has been achieved by characterizing Rhodamine-WT and H3AsO3 removal efficiency by newly developed RO/NF membranes having rigid star amphiphiles (RSAs) as an active layer material. The knowledge obtained from this study will also be useful to guide the development of more effective RO/NF membranes.U of I OnlyRestricted to the U of I community idenfinitely during batch ingest of legacy ETD

Immobilization Process of Soil Contaminated with Selenium (VI) Using Magnesium Oxide and Iron (II) Compounds

The objective of this study was to deepen the understanding of the immobilization process of selenium (VI)contaminated soil when using immobilization agents consist of MgO and iron (II) compounds. The objective was achieved by introducing diffusion cells that allows us to physically separate soil and immobilization agent, and measuring the valence of selenium as well as the concentrations in liquid, soil, and immobilization agent phases. Experimental data showed that the addition of immobilization agents induced desorption of selenium (VI) from the contaminated soil, and the desorbed selenium (VI) was reduced into selenium (IV) by iron (II) compounds. The formed selenium (IV) was then effectively immobilized by re-sorbing on soil particles and immobilization agents. Also found was that more amount of selenium (IV) was sorbed on the immobilization agents as hydration reaction of immobilization agents proceeded. These insights obtained in this study are fundamental but important information to fully elucidate the selenium (VI) immobilization mechanisms that are required to improve the reliability of immobilization technology