James A. Noblet

Membrane filtration for removal of fine solids from aquaculture process water

Abstract In recirculating aquaculture systems (RASs), fine solids (diameters 94% TSS rejection and 76% biochemical oxygen demand rejection. In cross-flow membrane filtration using a 0.05 μm pore size hollow fiber membrane, permeate flux increased with increasing feed temperature. Flux also increased with and transmembrane pressure up to a limit after which a pressure independent flux was observed. On average, pressure independent flux was found to increase with cross-flow rate approximately linearly. Based on a preliminary assessment of process economics, it was determined that membrane filtration was not a cost effective alternative to coarse solids removal processes such as microscreen clarification. However, membrane filtration for fine solids removal has potential niche applications in areas such as rearing high-value products.

Structures and relative stabilities of bisulfite ion isomers

Abstract The structure and equilibria of the bisulfite ion in the gas phase are investigated using ab initio electronic structure methodology. The structures analysed were the C 3v structure and the syn and anti tautomers of the C s structure. Optimized geometries and total energies were determined for a variety of basis sets and levels of theory. Polarization functions had profound effects on both geometries and relative energies. Addition of diffuse functions was found to affect significantly both relative stabilities and geometries at the MP2/3–21 + G ∗ level. However, diffuse functions had minor effects at the MP2/6–31 + G ∗ level. Inclusion of electron correlation via second-order (MP2) and full fourth-order (MP4SDTQ) Moller-Plesset perturbation treatments was found to have moderate effects on geometries and relative stabilities. Normal mode vibrational frequencies were calculated for all isomers studied. The lowest energy structure was found to be an asymmetric form of the syn conformation of the C s tautomer.

Evaluation of selected filters for collection and subsequent supercritical fluid extraction of suspended solids for trace organic analysis

Abstract This study evaluated selected filters in order to find an appropriate filter that can be used to separate suspended solids (SS) from the aqueous phase with minimal sorption of the dissolved organic constituents in the aqueous phase, and that is compatible with subsequent supercritical fluid extraction (SFE) of hydrophobic organic compounds (HOCs) from the SS collected onto them. The sorption study for the filters was limited to the use of analytes in aqueous solution with no SS. Membrane filters and a glass-fiber filter with binder showed considerable sorption behaviour during filtration of aqueous solutions consisting of six polynuclear aromatic hydrocarbons (PAHs) as analytes. The extent of sorption of the analytes by the filters increased with the more hydrophobic compounds. A glass-fiber filter with no binder (MSI TCLP) was found to be non-sorbing towards the PAH analytes, and was further shown to be an appropriate filter for a series of 56 base/neutral/acid extractable organic compounds. SFE of the filter as received showed extractable compounds detectable by GC-MS. Thus, pre-cleaning of the filter is required for the removal of SFE-extractable background compounds prior to its use in the collection of SS for subsequent SFE.

Water Contamination and Pollution

Water pollution is the presence of chemical, physical, or biological components or factors producing a condition of impairment of a given water body with respect to some beneficial use. The level of contamination necessary to render a water body impaired is highly dependent on the type of water body, its location, and the types of beneficial uses it supports. A water deemed unfit for drinking by humans may be suitable for other uses, such as habitat, irrigation, or recreation. Although certain natural events can cause water pollution, we will focus herein on the anthropogenic sources of pollution, that is, pollution arising from human activities.

Structure and vibrational frequencies of the peroxymonosulfate ion HSO5

Abstract The structure and normal mode vibrational frequencies of the peroxymonosulfate ion HSO5− were calculated using ab initio electronic structure theory. The unusual wrap-around structure of the two oxygen and one hydrogen atoms is due to the electronic structure of the ion itself and is not associated with crystal packing forces.