William E. Hill

Induction of phosphorus removal in an enhanced biological phosphorus removal bacterial population

Abstract Volatile fatty acids (VFAs) resulting from prefermentation of influent glucose were used to cultivate a bacterial population capable of enhanced biological phosphorus removal (EBPR) in two identical anerobic/aerobic sequencing batch reactors (SBRs). An identical SBR receiving starch, which did not readily preferment, established only marginal EBPR. The Starch SBR population did not respond in batch tests to any of the substrates studied. In batch tests for the glucose SBR populations the two to five carbon VFAs, except propionic acid, induced greater inorganic phosphate (Pi) removal. Succinic acid also improved removals. Branched VFAs were superior to their linear isomers. Isovaleric acid improved Pi removal the most consistently, and at lower molar concentrations than any other VFA. The C2 and C5 alcohols did not have a significant effect on Pi removal, and neither did formate or methanol. The C3 and C4 alcohols did result in relatively small but consistent improvements in removals. Glucose, as well as amino acid rich synthetic wastewater, were both extremely detrimental to Pi removal. Fructose and starch did not have the same detrimental effect as glucose.

The coordination chemistry of molybdenum and tungsten. Part XIV. Dioxomolybdenum(VI) complexes of bidentate, tridentate, and tetradentate Schiff bases containing oxygen, nitrogen and sulphur donors

A large number of bidentate, tridentate, tetradentate Schiff base ligands containing oxygen, nitrogen, and sulphur donor atoms have been complexed to the cis-MoO2 moiety. The structures of the resulting complexes are postulated on the basis of infrared and proton n.m.r. arguments previously developed by Yamada. In the case of the complexes of the tetradentate ligands, the nature of the backbone between the imine groups determines which cis isomer is found.

Three-fluid retention in porous media involving water, PCE and air☆

Abstract A classical way to obtain three-fluid retention curves in porous media from measured two-fluid retention curves is based on the Leverett concept, which states that the total volumetric liquid content in a water-wet porous medium, containing water, a nonaqueous-phase liquid (NAPL) and air, is a function of the capillary pressure across the interface between the continuous NAPL and air. This functional relationship results from the assumed condition that in a three-fluid porous medium, the intermediate wetting fluid spreads over the water-air interface. Application of Leveretts concept may not be valid, however, for nonspreading NAPLs like perchloroethylene (PCE). This paper discusses measurements of both PCE-air and water-PCE-air retention curves using a long vertical column in conjunction with a dual-energy gamma radiation system. The data indicate that the Leverett concept was applicable only until a critical PCE saturation had been reached.

Platinum(II) complexes containing amine ligands

Abstract New Platinum(II) complexes of o - and p -phenylenediamine, 2-aminopyridine, and 2,3- 3,4-, and 2,6- diaminopyridine have been prepared and characterized by a number of techniques. The complexes of 2- aminopyridine are of the general formula Pt(2- AmPy) 2 X 2 ·nH 2 O where X is Cl or I and n is 1 or 2. In these complexes only the ring nitrogen is coordinated. Complexes of the diaminopyridines have complex stoichiometries Pt 3 L 2 X 6 ·6H 2 O (L + 3,4 DamPy, X = Cl, I), Pt 2 (2,3-DamPy) 3 Cl 3 OH, Pt 3 L 4 I 5 OH (L = 2,3 or 2,6 DamPy), and [Pt(2,6-DamPy) 3 Cl 4 ]·4H 2 O which contain both ring nitrogen and NH 2 groups coordinated to the metal. The phenylenediamine complexes have the general formula PtLX 2 (L = OPDA, PPDA; X = Cl, I) where the amine groups are coordinated. The biological activity of these complexes are reported elsewhere.

Surfactant enhanced removal of PCE in a nominally two-dimensional, saturated, stratified porous medium

Abstract Although surfactant enhanced remediation of nonaqueous phase liquids (NAPLs) by pump-and-treat technology has been studied extensively in the laboratory with one-dimensional columns, very few multi-dimensional investigations have been reported. In this study we focus on the removal of perchloroethylene (PCE) from a two-dimensional, saturated porous medium containing a low permeability sand layer situated in an otherwise high permeability sand. A PCE spill was applied at the surface of the porous medium and allowed to redistribute until static equilibrium was achieved. The porous medium was then flushed with various surfactant and co-solvent formulations injected at the PCE source location and extracted at the bottom of the porous medium using a configuration similar to that of Abdul and Ang [Abdul, S.A., Ang, C.C., 1994. In situ surfactant washing of polychlorinated biphenyls and oils from a contaminated field site: Phase II. Pilot study. Ground Water 32, 727–734]. Effluent samples were analyzed for dissolved PCE concentrations. Volumetric water and PCE content values were determined at a number of locations by means of dual-energy gamma radiation measurements. Once surfactant flushing had started, PCE moved as a distinct separate phase ahead of the surfactant front. Most of this downward moving PCE accumulated on top of the low permeability sand layer. Some PCE, however, passed quickly through this layer and subsequently through the high permeability sand below it. Movement of some of the PCE into and through the low permeability sand layer was attributed to local heterogeneities combined with reduced interfacial tensions associated with the surfactant formulation. Clean-up of PCE in most of the high permeability sand was considered to be effective. PCE accumulated on top of the fine layer, however, posed a significant challenge to remediation and required several pumping configurations and surfactant/co-solvent formulations before most of it was removed.

The donor properties of some α, ω-bis(diphenylphosphino)alkanes towards palladium(II). Polymeric, dimeric and monomeric trans-chelated complexes

Abstract Palladium(II) complexes of 1,6-bis(diphenylphosphino)hexane (dph), 1,8-bis(disphenylphosphino)octane (dpo), 1,10-bis(disphenylphosphino)decane (dpd), and 1,12-bis(disphenylphosphino)dodecane (dpdop) have been isolated. The structures of the complexes seem to be a function of the length of the alkane chain between the donor atoms; generally dph bridges two palladium atoms and forms polymeric complexes, dpo and dpd bridge two palladium atoms and form dimeric 22- or 26-membered rings and dpod acts as a trans -chelating ligand and forms a monomeric complex containing a 15-membered ring.

Platinum(II) complexes of cis chelating phosphines with electronegative substituents containing o-Carbone as a backbone

Abstract The cis ligands (C6H5)2P[B10H10C2]PRR′ (R = R′ = C6H5, NME2 F; R = NMe2, R′ = F) and [Me2N]2P[B10H10C2] PRR′ (R = R′ = C6F5; R = NMe2, R′ = F) form chelates with platinum(II) of the type [PtCl2(ligand)]. These complexes have been characterized by infrared 1H, 19F, and 31P NMR spectroscopy and by element analyses. The predicted order of trans influences for the various donors is P(C6H5)2 > P(C6F5)2 > P(NMe2)2 > P(F)NMe2 > PF2 whereas the cis influence is P(C6F5)2 > P(F)NMe2 > P(C6H5) > P(F)NMe2 > P(C6H5)2 > P(NMe2)2.

Surfactant enhanced removal of PCE in a partially saturated, stratified porous medium

Dense nonaqueous phase liquids (DNAPLs), such as perchloroethylene (PCE), pose a significant threat to the environment, specifically to our drinking water present in aquifers. In many instances, a DNAPL will become trapped and form pools on top of confining layers while migrating through the vadose zone. Residual DNAPL and DNAPL pools form sources of long term contamination, which are difficult to remove by classical pump-and-treat remediation. A physically simulated PCE spill into a large, two-dimensional flow container, packed with a fine sand layer surrounded by coarse sand, was therefore studied in this work. A water table was maintained near the bottom of the flow container, such that the coarse sand just below the fine layer was unsaturated, but the bottom of the fine sand layer was at or near saturation. A PCE spill was applied at the center of the porous mediums surface and allowed to redistribute until static equilibrium was reached. The porous medium was then flushed with a surfactant solution (Triton X-100, 4.0% by volume), using the same application configuration as for the spill, while simultaneously extracting solution at one or more locations at the bottom of the porous medium. Effluent samples were analyzed for PCE concentrations. Volumetric water and PCE content values were determined several times at a number of locations by means of dual-energy gamma radiation measurements. The coarse sand in the upper portion of the porous medium was cleaned rapidly by the surfactant flushing. Removal of PCE from the fine sand layer, however, proved to be more difficult because most of the surfactant solution bypassed the PCE. Lateral spreading of the surfactant plume occurred near the saturated/nearly saturated zones in the fine and coarse sand. This lateral spreading, unfortunately, allowed for solubilized PCE, the concentration of which was enhanced by micelle formation, to move into regions previously uncontaminated. The pumping configuration was subsequently changed in an attempt to force the surfactant solution through the entire fine layer, i.e., to hydraulically control the surfactant flushing, while simultaneously increasing the amount of solubilized PCE.

Observations relating to enhanced phosphorus removal in biological systems

In this work chemical fractionation and 31P-NMR spectroscopy were employed to explore certain unique characteristics of activated sludge exhibiting enhanced phosphorus removal. Two sequencing batch reactors were used in this research. The two reactors have been maintained in an environmental chamber and operated under the same conditions for well over 3 years. The only difference between the reactor systems is one system receives a portion of its organic carbon in the dissolved form as glucose (D-reactor) while the second reactor (P-reactor) receives an equivalent amount of organic material in the particulate form as starch. Chemical fractionation data and 31P-NMR analysis indicate that in the D-reactor, during periods of enhanced P-removal, transient phosphate is stored primarily as high molecular weight polyphosphates and nucleic acids. A portion of the transient polyphosphate is located outside the cytoplasmic membrane and is cell bound. No polyphosphate was found to exist in the mobile form in the cytoplasm. On the other hand, similar analysis on sludge taken from the P-reactor, during periods of enhanced P-removal, indicate that transient phosphate is stored primarily as low molecular weight polyphosphate. The transient polyphosphate is located inside the cytoplasmic membrane. A portion of the polyphosphate is cell bound while the remainder exists in the mobile form in the cytoplasm. Kinetic analysis suggests the possibility of a chemical intermediate(s) being formed in the degradation of polyphosphate to orthophosphate in sludge from the D-reactor while in sludge from the P-reactor the degradation process appears to proceed directly from polyphosphate to orthophosphate.

31P-NMR spectroscopy characterization of polyphosphates in activated sludge exhibiting enhanced phosphorus removal

Abstract In this work 31P-NMR spectroscopy is employed to investigate the characteristics of polyphosphates found in activated sludge exhibiting enhanced phosphorus removal. Sonication and EDTA treatment of this sludge indicated that part of the polyphosphates accumulated are located outside the cytoplasmic membrane and are complexed with metal cations. These polyphosphates along with polyphosphatases are bound to the cell wall and/or the cytoplasmic membrane. Definitive evidence is presented which indicates that polyphosphate degradation is controlled by these immobilized polyphosphatases. Hypochlorite treatment of poly-P activated sludge produced two well resolved peaks in the polyphosphate region. No definitive explanation for the split signal can be provided. However, it is possible that it is a result of cell-bound polyphosphates located both in the periplasmic space and in the cytoplasm. Results from this study also suggest that a portion of the inorganic phosphate released through enzymatic degradation of the polyphosphate may be involved in the transport of readily degradable organic material across the cytoplasmic membrane. It may be this pool which provides phosphorus for the synthesis of biochemical compounds such as nucleic acids.