Copper, Cadmium and Ferrous Removal by Membrane Bioreactor

AbstractOne of the important concerns in Tehran municipal landfill is the production of leachate and its potential for water resources pollution. This paper investigates the removal of heavy metals from landfill leachate by using a membrane Bioreactor (MBR). The leachate was collected from a landfill in the vicinity of Tehran nearly 1 year old, The results of this study indicated that the system provided high removals of Fe, Cu and Cd equal to 96%, 23% and 84% respectively and heavy metal concentration in MBR effluent is a function of aeration ratio and bioaccumulation. Among the metals investigated in the present study it can be concluded that the extracellular adsorption, is the principal removal process of the metals, compared to other removal mechanisms such as bioaccumulation or intracellular accumulation

Methods for removing selenium from aqueous systems

Selenium is among the list of oxyanions that lead to contamination in mining aqueous waste streams. Though the elemental forms are toxic, the aqueous oxyanions are more so. The most common forms of selenium released during mining processes are the aqueous forms, selenite and selenates. The common treatment technologies to date can be summed up in these major categories: media filtration, chemical treatment, and biomediated removal. These methods can often involve many expensive processing steps that may also be limited by variables such as total dissolved solids, presence of other ions, and ability to maintain microbial growth. We have developed an innovative chemical technology that can successfully reduce selenates to a level below the EPA recommendations. This new technology offers a unique and viable solution which is transparent to the above mentioned limitations. [All papers were considered for technical and language appropriateness by the organizing committee.]Non UBCUnreviewedOthe

Self-Assemblies of Extended Hydrogen-Bonded Arrays Using 1,4-Butanebisphosphonic Acid as a Versatile Building Block

Two organic salts of 1,4-butanebisphosphonic acid, bis(ethylenediammonium) butanebisphosphonate hydrate (1) and bis(hexamethylenediammonium) butanebisphosphonate hydrate (2), have been structurally characterized using single-crystal x-ray diffraction analyses. Compound 1 exhibits a H-bonded pillared bilayered structure, in which etheylenediammonium cation acts as a spacer between the anions resulting in the formation of two types of cavities. The larger cavity is filled by four water molecules though having hydrophobic character. Thus, the material behaves as a nanoporous organic solid. Compound 2 shows a multidimensional hydrogen bonding networks: one-dimensional arrays parallel to the b axis and two-dimensional sheets parallel to the ab plane. The N--H···O--P hydrogen bonds, forming H-bonded supramolecular networks, are regarded to be strong and directional hydrogen bonds

The lamellar architecture of 1,6-hexamethylenediammonium tetrachlorocobaltate(II)

In the title compound, (C6H18N2)[CoCl4], organic dications and inorganic dianions interact with each other through N-H...Cl hydrogen bonds, forming infinite two-dimensional sheets of anions parallel to the ac plane. Alkyl chains act as spacers between these sheets. Only three Cl atoms are involved in hydrogen bonding with ammonium groups. The asymmetric unit consists of one anion together with half of each of two cations on inversion centres

A redetermination of cis-aquabis(glycinato-κ2N,O)copper(II)

The crystal structure of the title compound, [Cu(C2H4NO2)2(H2O)], reported by Freeman et al. [(1964). Acta Cryst. 17, 1463-1470], has been reinvestigated and its absolute configuration established by anomalous dispersion effects. The origin of chirality in the crystalline state of this compound is the formation of right-handed helices from a CuII coordination network self-resolved into a pure enantiomeric phase

Layered strontium phenylphosphonate: synthesis, thermal properties and crystal structure from X-ray powder diffraction data

Strontium phenylphosphonate, Sr(PhPO3H)2, was synthesized by the reaction of strontium carbonate and phenylphosphonic acid. The compound was structurally characterized by Rietveld refinement on X-ray powder diffraction data. It consists of a layered structure with inorganic framework of SrO8 polyhedra from which phenyl groups are pointing out. The compound is isomorphous with the already known calcium and barium phenylphosphonates. Infrared spectroscopy analysis shows the presence of (P-)O-H...O hydrogen bonds in the solid material. The thermal behavior of the compound in the range 30650\ub0C, studied by thermogravimetry (TG), differential thermal analysis (DTA) and X-ray powder thermodiffractometry, revealed that strontium phenylphosphonate is stable up to 330\ub0C. The compound undergoes consequent thermal decomposition and phase transitions above 330\ub0C temperatures until it converts to crystalline Sr(PO3)2 above 570\ub0C

Radical Additions of Bis(trimethylsilyl)phosphite to Vinyltrimethylsilane and Vinyltriethoxysilane: Crystal Structure of 2-Trimethylsilylethylphosphonic Acid

Organosilicon-phosphonate compounds with the general formula (R)n(RO)3mnSi(CH2)mP(O)(OSiR\u273)2 are designed for application as novel materials for surface treatments and modifications. A solvothermal method based on the reaction of bis(trimethylsilyl)phosphite with vinyltrimethylsilane and vinyltriethoxysilane in the presence of a peroxide in benzene solvent was used to synthesize the silyl-substituted esters of organosilicon-phosphonate compounds. 2-Trimethylsilylethanephosphonic acid was prepared from its bis(trimethylsilyl) ester by alcoholysis. The crystal structure of the acid consists of two-dimensional arrays built up from the (P--)O--H\ub7\ub7\ub7O--P hydrogen bonds