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731.
D. K. Uan I. T. Yeom P. Arulazhagan J. Rajesh Banu 《International Journal of Environmental Science and Technology》2013,10(3):495-502
Excess sludge disposal is one of the serious challenges in biological wastewater treatment. Reduction of sludge production would be an ideal way to solve sludge-associated problems rather than the post-treatment of the sludge produced. In this study, a new wastewater treatment process combining anaerobic/anoxic/oxic system with thermochemical sludge pretreatment was tested in a laboratory scale experiment. In this study, the effects of the sludge pretreatment on the excess sludge production in anaerobic/anoxic/oxic were investigated. The system was operated in two Runs (1 and 2). In Run 1, the system was operated as a reference and in Run 2, a part of the mixed liquid was pretreated thermochemically and was returned to the bioreactor. The average solubilization efficiency of pretreated sludge was found to be about 35 % during the study period of 220 days. Sludge production rate in Run 2 was less than that in Run 1 by about 52 %. Total phosphorous was removed by enhanced biological phosphorous removal with the removal efficiency of 83–87 % and 81–83 % for Run 1 and Run 2, respectively. Total nitrogen removal in Run 2 (79–82 %) was slightly higher than that in Run 1 (68–75 %). The mixed liquor suspended solids/mixed liquor volatile suspended solids ratio was identical after both runs in the range 78–83 %. The effluent water qualities were not significantly affected when operated with thermochemical pretreatment at pH 11 and 60 °C for 3 h during 7 months. From the present study it is concluded that thermochemical sludge pretreatment of anaerobic/anoxic/oxic process plays an important role in reduction of sludge production. 相似文献
732.
A. U. Zaman 《International Journal of Environmental Science and Technology》2013,10(3):455-464
Application and development of municipal solid waste treatment technology depends on various socio-economic and environmental factors. All those factors are work as development drivers for waste management systems. The study aims to identify key drivers from case studies of waste management development trend in Sweden. Social, economic and environmental drivers are identified and presented in this study. The study identifies personal behaviour, local waste management practice, consumption and generation of waste as the key social drivers. Resource value of waste, economic benefit from waste treatment facilities and landfill tax have been acknowledged as economic drivers for developing waste treatment technology. Moreover, global climate change, environmental movement and awareness have been working as environmental drivers for developing various waste treatment methods in Sweden. In addition, the study aims to analyse emerging waste treatment technologies based on a number of literature review and questionnaire survey. Dry composting, pyrolysis-gasification, plasma arc, and anaerobic digestion have been identified as potential emerging technologies for waste management systems in Sweden. 相似文献
733.
Division of sedimentary strata according to groundwater chemistry is discussed with implications for petroleum reservoir potential. It is suggested to process multiparametric water chemistry data from West Siberia using formalized clustering techniques. The efficiency of this approach has been tested for Neocomian clinoform reservoirs with reference to regional-scale appraisal and subregional petroleum division. 相似文献
734.
Summary Lovozero, the largest of the world’s layered peralkaline intrusions, includes gigantic deposits of Nb + REE-loparite ore.
Loparite, (Na,Ce,Ca)2(Ti,Nb)2O6, became a cumulus phase after crystallisation of about 35% of the ‘Differentiated Complex’, and its compositional evolution
has been investigated through a 2.35 km section of the intrusion. The composition of the cumulus loparite changes systematically
upwards through the intrusion with an increase in Na, Sr, Nb and Th and decrease in REE and Ti. This main trend of loparite
evolution records differentiation of the peralkaline magma through crystallisation of 1600 m of the intrusion. The formation
of the loparite ores was the result of several factors including the chemical evolution of the highly alkaline magma and mechanical
accumulation of loparite at the base of a convecting unit. At later stages of evolution, when concentrations of alkalis and
volatiles reached very high levels, loparite reacted with the residual melt to form a variety of minerals including barytolamprophyllite,
lomonosovite, steenstrupine-(Ce), vuonnemite, nordite, nenadkevichite, REE, Sr-rich apatite, vitusite-(Ce), mosandrite, monazite-(Ce),
cerite and Ba, Si-rich belovite. The absence of loparite ore in the “Eudialyte complex” is likely to be a result of the wide
crystallisation field of lamprophyllite, which here became a cumulus phase.
Received November 6, 2000; revised version accepted January 18, 2001 相似文献
735.
U-Pb isotopic thermochronometry of rutile, apatite and titanite from kimberlite-borne lower crustal granulite xenoliths has been used to constrain the thermal evolution of Archean cratonic and Proterozoic off-craton continental lithosphere beneath southern Africa. The relatively low closure temperature of the U-Pb rutile thermochronometer (~400-450 °C) allows its use as a particularly sensitive recorder of the establishment of "cratonic" lithospheric geotherms, as well as subsequent thermal perturbations to the lithosphere. Contrasting lower crustal thermal histories are revealed between intracratonic and craton margin regions. Discordant Proterozoic (1.8 to 1.0 Ga) rutile ages in Archean (2.9 to 2.7 Ga) granulites from within the craton are indicative of isotopic resetting by marginal orogenic thermal perturbations influencing the deep crust of the cratonic nucleus. In Proterozoic (1.1 to 1.0 Ga) granulite xenoliths from the craton-bounding orogenic belts, rutiles define discordia arrays with Neoproterozoic (0.8 to 0.6 Ga) upper intercepts and lower intercepts equivalent to Mesozoic exhumation upon kimberlite entrainment. In combination with coexisting titanite and apatite dates, these results are interpreted as a record of postorogenic cooling at an integrated rate of approximately 1 °C/Ma, and subsequent variable Pb loss in the apatite and rutile systems during a Mesozoic thermal perturbation to the deep lithosphere. Closure of the rutile thermochronometer signals temperatures of °C in the lower crust during attainment of cratonic lithospheric conductive geotherms, and such closure in the examined portions of the "off-craton" Proterozoic domains of southern Africa indicates that their lithospheric thermal profiles were essentially cratonic from the Neoproterozoic through to the Late Jurassic. These results suggest similar lithospheric thickness and potential for diamond stability beneath both Proterozoic and Archean domains of southern Africa. Subsequent partial resetting of U-Pb rutile and apatite systematics in the cratonic margin lower crust records a transient Mesozoic thermal modification of the lithosphere, and modeling of the diffusive Pb loss from lower crustal rutile constrains the temperature and duration of Mesozoic heating to °C for ka. This result indicates that the thermal perturbation is not simply a kimberlite-related magmatic phenomenon, but is rather a more protracted manifestation of lithospheric heating, likely related to mantle upwelling and rifting of Gondwana during the Late Jurassic to Cretaceous. The manifestation of this thermal pulse in the lower crust is spatially and temporally correlated with anomalously elevated and/or kinked Cretaceous mantle paleogeotherms, and evidence for metasomatic modification in cratonic mantle peridotite suites. It is argued that most of the geographic differences in lithospheric thermal structure inferred from mantle xenolith thermobarometry are likewise due to the heterogeneous propagation of this broad upper mantle thermal anomaly. The differential manifestation of heating between cratonic margin and cratonic interior indicates the importance of advective heat transport along pre-existing lithosphere-scale discontinuities. Within this model, kimberlite magmatism was a similarly complex, space- and time-dependent response to Late Mesozoic lithospheric thermal perturbation. 相似文献
736.
737.
738.
R. Jayangondaperumal A. K. Dubey K. Sen 《Journal of the Geological Society of India》2010,75(1):225-238
Kinematic information from deformation structures and magnetic fabrics are used to infer recent tectonics around Kangra and
Dehradun recesses, western Himalaya. Three types of magnetic fabrics (Type I & II, III, and IV) are identified based on the
angle between K3 axis and bedding pole. It was observed that Kangra recess shows more mature fabric type IV as compared to
Dehradun recess, where orientation of K3 axes and tectonic fabric reveals dominance of superposed deformation. In the vicinity
of Dehradun recess, normal faults occur in un-indurated Quaternary fan deposits confirming their recent formation. The observations
are in conformity with earlier studies that during the 1905 Kangra earthquake, the Main Boundary Thrust (MBT) (or one of its
subsidiary thrusts) near Kangra showed thrusting whereas the MBT near Dehradun underwent either normal faulting or post seismic
adjustments characteristic of normal faulting. The thrusting could be a result of subsurface processes whereas the normal
faulting was a result of prevailing surface strains. 相似文献
739.
I. S. Krassivskaya E. V. Sharkov N. S. Bortnikov A. V. Chistyakov N. V. Trubkin T. I. Golovanova 《Petrology》2010,18(3):263-277
Altered variolites described for the first time in the axial zone of the Mid-Atlantic Ridge are represented by rounded globules
of andesite (icelandite) composition with light trachyandesite rim embedded in a picrobasaltic matrix. The globules were transferred
with picrobasaltic melt and then floated to the surface of lava flow, while formation of leucocratic rims was presumably related
to thermodiffusion (Soret effect) in a cooling heterogeneous melt. This heterogeneous melt was formed by penetration of ascending
column of picrobasaltic magma in already existing small intracructsal magmatic chamber filled with residual icelanditetype
andesite melt and involvement of the latter into a general upward movement. The rapid ascent of the melts in the oceanic spreading
zones by means of turbulent flowing caused dispersion of the extragenous melt into small drops in a jet of picrobasaltic magma,
without their interaction. Variolites were formed during cooling of such heterogeneous lava flow. No signs of liquid immiscibility
were found in the studied variolites. 相似文献
740.