An assessment of the oxidizing ability of activated sludge used in the process of biological wastewater treatment was carried out when it was treated with a direct electric current on an electrohydrodynamic device. The efficiency of biological wastewater treatment is analyzed when the DC voltage changes, the sign of polarization of the electrode, as well as the values of the Camp criterion. It is shown that the electrotreatment of activated sludge leads to an increase in the efficiency of biological wastewater treatment, determined by the indicator of chemical oxygen consumption. A relationship has been established between the intensity of sludge treatment and the magnitude of the zeta potential of activated sludge at the outlet of the aeration tank.

Keywords: wastewater, biological treatment, activated sludge, electrohydrodynamic device, zeta potential, chemical oxygen consumption

Experimental studies have been carried out to determine the sludge index of activated sludge used in the process of biological wastewater treatment on aerotanks at various doses of sludge. The possibility of changing the sedimentation properties of activated sludge when using its electrical treatment is analyzed. It is shown that the electrotreatment of returnable activated sludge together with aeration leads to a decrease in the value of the sludge index, as well as an improvement in the quality of the treated water after settling. pretreatment of activated sludge in an electrolyzer with aeration allows biological wastewater treatment in an aerotank with increased doses, as well as to increase the flocculating properties of sludge in relation to suspended solids.

Keywords: household waste water, biological treatment, activated sludge, aerotank, sedimentation, sludge index, electrical treatment, aeration

The design of radiation-hardened circuits the use of special technologies and the use of additional circuit techniques. The efficiency of using these methods to improve the scheme qualitative indicators can be assessed by some evaluation. The paper presents the efficiency evaluation method of special voltage feedbacks application in dynamic loads of the classical differential stages. The stages with dynamic loads are apply, for example, in the schemes of differential and multidifferential operational amplifiers. The purpose of the introduction of these feedbacks is the reducing of the effect of transistors low-signal parameters instability under the influence of destabilizing factors (radiation and temperature). For the organization of feedback circuits in the structure of dynamic loads, additional voltage amplifiers based on transistors are introduced into the circuit. It is shown that this approach can increase the output resistance of the dynamic load and increase the gain coefficient of the differential stage under the influence of ionizing radiation and temperature. The efficiency evaluation method is based on the construction of a mathematical model of the scheme expressed through low-signal differential h-parameters of scheme transistors. Thus, the calculation of the main qualitative indicators of the scheme can be carried out by mathematical modeling. The obtained simulation results confirm the efficiency of the proposed circuit design.

Keywords: efficiency evaluation, circuit design, dynamic load, low-signal parameters, radiation

This paper presents a radiation hardened by design of differential stages using dynamic loads. The efficiency of proposed design methods to improve the scheme qualitative indicators can be assessed by some evaluation. The theoretical results of the evaluation of the self-compensation circuit effect of parasitic impedance of the output transistor closed collector in the dynamic loads of classical differential stages, which is realized on the base of current feedbacks, are presented. It is shown that the introduction of the current feedbacks allows to reduce the effect of transistors small-signal parameters instabilities of the dynamic load under the influence of ionizing radiation and temperature on it's quality and the parameters of the differential stages. The efficiency evaluation of the circuit solutions in differential stages of modern operational and multidifferential amplifiers is given. The theoretical results of the evaluation of the self-compensation circuit effect of parasitic impedance of the output transistor closed collector in the dynamic loads of classical differential stages, which is realized on the base of current feedbacks, are presented. It is shown that the introduction of the current feedbacks allows to reduce the effect of transistors small-signal parameters instabilities of the dynamic load under the influence of ionizing radiation and temperature on it's quality and the parameters of the differential stages. For the organization of feedback circuits in the structure of dynamic loads, additional current amplifiers based on transistors are introduced into the circuit. It is shown that this approach can increase the output resistance of the dynamic load and increase the gain coefficient of the differential stage under the influence of ionizing radiation and temperature. The efficiency evaluation of the circuit solutions in differential stages of modern operational and multidifferential amplifiers is given. The efficiency evaluation method is based on the construction of a mathematical model of the scheme expressed through low-signal differential h-parameters of the scheme transistors. Thus, the calculation of the main qualitative indicators of the scheme can be carried out by mathematical modeling. The obtained simulation results confirm the efficiency of the proposed circuit design.

Keywords: efficiency evaluation, circuit design, differential stage, dynamic load, destabilizing factors, low-signal parameters

This article considered individual and unidirectional cooperative mass transfer of two components with a various in the surface-active properties in extraction system carbon tetrachloride - 4% aqueous solution of potassium iodide in the flat interface in the conditions of spontaneous interphase convection. Studied the interaction flow of components in unidirectional cooperative mass transfer on the intensity of mass transfer each other in the conditions of spontaneous interphase convection. Unidirectional cooperative mass transfer acetic acid and iodine increase mass transfer iodine coefficient as compared to its individual mass transfer.

Keywords: spontaneous interfacial convection, Marangoni effect, the cooperative mass transfer, extraction, the mass transfer coefficient, acetic acid, iodine, carbon tetrachloride, the intensity of mass transfer

Block diagram of the active harmonic filter is considered.  State table inverter power switches active harmonic filter is considered. Calculated the capacitance on the DC link active harmonic filters. The calculation takes into account the power converter losses in the active harmonic filter.

Keywords: active harmonic filter, distortion power, energy storage capacitor

The methods and results of designing instrumentation amplifiers multidifferential on two operational amplifiers that significantly reduce the voltage of zero drift circuit and its transfer efficiency of the common-mode voltage. In practical terms, these methods can solve the important task of building a precision analog interface for resistive bridge sensors, which operate over a wide temperature range. Also, it is possible to use multi-bit ADC with a significantly lower reference voltage. Keywords: mixed systems on a chip, instrumentation amplifiers, common-mode signal, multidifferential DU, voltage zero drift, temperature range, multibit ADC.

Keywords: mixed systems on a chip, instrumentation amplifiers, common-mode signal, multidifferential OA, voltage zero drift, temperature range, multibit ADC.

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