Effect of the solids retention time on the rate of biodegradation of organic compounds

The paper studies the effect of the solids retention time (SRT) on the rate of biodegradation of morpholine (M), sulfanilic acid (SA), nitrilotriacetic acid (NTA), and ethylenediaminetetraacetic acid (EDTA) in laboratory mixed culture systems, fed semicontinuously on a once-a-day feeding schedule. It has been found that the minimum values of SRT at which microorganisms degrading the above compounds were washed out from the cultivation systems were 3, 1, 1, and 20 days for M, SA, NTA, and EDTA systems, respectively. A critical value of SRT was defined as that below which the rate of substrate removal is lower than the rate of substrate application into the system. The critical values of SRT were found to be 8, 3, 2.5, and above 20 days for M, SA, NTA, and EDTA systems, respectively. In a range between the minimum and critical values of SRT the mixed culture system cannot give stable efficiency of a given compound removal and the effluent concentration can be expected to vary considerably. Above the critical value of SRT, every cultivation system has a potential capability of shock loading treatment.     

Asthenospheric parameters of dipping plate regions by magnetotelluric investigations

The multifrequency resolving capability of the electromagnetic surface impedance parameter, employed in magnetotelluric investigations, has been examined for an upper mantle model incorporating (1) a deep-seated lithosphere-asthenosphere boundary and (2) preferred orientations of olivine crystals in the lithosphere, usually associated with the subducting plate boundary zones. Numerical results display the quantitative errors in the resolution of various anisotropic and dipping plate conditions. It is found that (1) conductivity anisotropy, particularly with higher dips, causes a significant dispersion in the impedance values and higher resolving power, and (2) variations in the geometrical/physical parameters are reflected predominantly in the phase component of the surface impedance. The study has relevance to the understanding of the electrical nature of materials, its relationship with physical properties and associated geothermal and seismic activities in the dipping plate regions.     

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Mathematical Geosciences -     

Assessment of the natural resources of groundwater by using balance-hydrodynamic models

The specific features of formulation and implementation of balance-hydrodynamic simulation during different-scale studies of natural resources of groundwater. Are an example of detailed estimate of the resources and balance of groundwater in the Vologda River basin is given. It is noted that the use of balance-hydrodynamic models, in addition to an increase in the general reliability of estimates, allows the calculation of normal annual characteristics of groundwater resources with different occurrence (exceedance probability), which is impracticable when hydrodynamic methods in other formulations are used.