Reduction of COD and pH of Textile Industrial Effluents by Aquatic Macrophytes and Algae

Effluents samples collected from post discharge of equalization tanks of local compositetextile mills of Saver were treated with aquatic macrophytes, algae and their combination. Theywere found to be effective for the reduction of chemical oxygen demand (COD) and pH. Sixty nineper cent of COD was reduced with the combination treatment of Nostoc, Eichhornia crassipes andPistia stratiotes. With the combination treatment of Nostoc and E. crassipes reduced 65 per centCOD in glass containers. pH was reduced from 11.2 to 8.6. Between earthen and glass containers,glass container was found to be more effective.Key words: Industrial effluents; COD; pH; Aquatic macrophytes; AlgaeDOI: 10.3329/jbas.v34i1.5487Journal of Bangladesh Academy of Sciences, Vol.34, No.1, 9-14, 2010

Sulfur Melting and Polymorphism under Pressure: Outlines of Fields for 12 Crystalline Phases

The polymorphism of sulfur has been investigated by static and dynamic methods up to 500 degrees C at 35 kilobars and up to 350 degrees C at 100 kilobars. The melting curve of sulfur to 31 kilobars and phase boundaries of the so-called "4.04-angstrom phase" have been determined. Evidence has been obtained for phase fields of nine new high-pressure forms of sulfur.

High-Pressure Transitions of Germanium and a New High-Pressure Form of Germanium

Some transitions in germanium and other semiconductor systems have been detected after very long exposure to high pressures followed by various quenching techniques. In the case of Ge, a new high-pressure polymorph, Ge-IV, has been synthesized above 110 kilobars with a body-centered-cubic structure. The pressure for the Ge-I right harpoon-up Ge-III (body-centered-tetragonal structure) transition has been revised from about 120 to 25 kilobars at 30 degrees C. The transition from the Ge-I (diamond structure) to the Ge-II (white tin structure) is metastable up to 140 kilobars. Thus some phase diagrams based on discontinuities observed in essentially dynamic systems may be inaccurate.

Coesite and Stishovite: Stepwise Reversal Transformations

Very marked differences in the metastable persistence of coesite and stishovite have been demonstrated; the former possibly persists indefinitely below 1000 degrees C at 1 atmosphere "dry," and the latter completely decomposes in minutes above 500 degrees to 600 degrees C to an amorphous or short range order phase. Quartz was grown (metastably) at temperatures well above its stability field from both coesite and stishovite, possibly by way of a short range order phase. The absence of stishovite in meteor-impact craters cannot be taken as evidence that it was not formed. If it has "reversed" in normal natural environments the product would almost certainly be a short range order phase or derivative.