Tatyana Kitsenko a, Elena Yegorova a, Alexander Kashirin b
Effect of Waterproofing Admixture «Penetron Admix» on the Properties of Heavy Concrete
a Donbas National Academy of Civil Engineering and Architecture,
b «Penetron-Donetsk», LLC (official representative of «”Penetron-Russia” Group of Companies», CJSC)
Abstract. The effect of the waterproofing admixture «Penetron Admix» on the properties of heavy concrete under normal curing conditions was studied. The expediency of using this chemical admixture at the stage of preparing a concrete mixture has been established. Studies have shown that with the introduction of an admixture in an amount of 1 %, there is an increase in strength by 3,7 % compared to reference concrete without an admixture. A further increase in the amount of added admixture to 1,5 % has virtually no effect on the concrete compressive strength. Also, the introduction of the «Penetron Admix» admixture increases the water resistance of concrete from W4 to W8. In this case, the filtration coefficient decreases from 5,4·10-9 to 7,8·10-11 cm/s. This is due to the fact that with the introduction of the «Penetron Admix» admixture, conditions are created for the crystallization of hydrated calcium silicatein the form of acicular crystals that fill the cavities between the grains. In addition, the pores and capillaries are filled due to the loosening of the tobermorite gel. Which is to say that the admixture actively includes the process of formation of new crystals that fill the cavities between the concrete particles.
Keywords: heavy concrete, «Penetron Admix» admixture, water resistance, strength, concrete structure.
Vitaliy Rozhkov
Pilot-Scale Studies of Wastewater Treatment in Systems with Airlift Bioreactors
Donbas National Academy of Civil Engineering and Architecture
Abstract. The article presents a description and results of pilot-scale studies of biological wastewater treatment from biogenic elements and organic substances in schemes with airlift bioreactors. The substantiation of the main parameters of the operation of such systems was carried out by evaluating the convergence of experimental data with theoretical estimate indicators of the quality of biological treatment obtained using the ASM + Bio-P activated sludge model. Characteristic biochemical profiles of treatment schemes using airlift bioreactors, created on the basis of the Johannesburg and Cape Town processes for improved biological removal of phosphorus, are presented. It has been established that in aerotanks-clarifiers with a flooded airlift aeration system, there is no release of phosphorus during secondary sludge separation, while the efficiency of sludge separation in a fluid bed is at the level of similar gravity sedimentation facilities. Confirmed participation of the clarification zone in biological treatment and the conduction of improved biological phosphorus removal at the level of biological nitri-denitrification with biological removal of phosphorus, which corresponds to the requirements of the Best Available Technologies at lower operating costs than known technologies due to less recirculation and air consumption.
Keywords: biological treatment, airlift bioreactor, improved biological phosphorus removal.
Nikolai Zaichenko, Irina Petrik, Victor Gubar
Properties of Enriched Thermal Power Plant Ash from for High-Performance Concretes
Donbas National Academy of Civil Engineering and Architecture
Abstract. The article presents the results of a study of the properties of enriched thermal power plant ash for high-performance concretes. In order to improve the characteristics of the thermal power plant ash that meet the technical requirements for replacing part of the cement in concrete, an electrostatic separation technology has been developed. This technology produces a material with a low unburned carbon content (loss on ignition 2,52 % in this study) for a high level of replacement of cement (45 % in the binder composition) in concretes. Enriched ash has an improved granulometric and phase composition and a reduced content of unburned carbon. The use of enriched thermal power plant ash in the composition of the binder instead of a part of the cement can provide an acceleration of the cement hydration process, an increase in the rheological properties of the cement paste, as well as the ability of the air-entraining admixture to retain the required volume of entrained air.
Keywords: thermal power plant ash, electrostatic separation, loss on ignition, phase analysis, foam index.
Viktor Nezdoyminov, Anastasia Mogukalo
The Effect of the Oxidation-Reduction Potential on the Reduction of Pathogenic Contamination of Activated Sludge During Aerobic Stabilization
Donbas National Academy of Civil Engineering and Architecture
Abstract. The article considers a biological method of processing excess activated sludge, based on a change in the oxidation-reduction potential of the environment, to reduce the pathogenic contamination of sludge. It is established that the conduct of the nitrification processes and the formation of oxidized nitrogen forms leads to an increase in the oxidation-reduction potential of the mixed liquor. The maximum value of the redox potential reached 500 mV on the second day of stabilization, while the concentration of nitrates was 159,00 mg/dm3. Further growth of nitrates did not affect the subsequent increase in potential. A decrease in the bacterial group of Escherichia coli in the process of aerobic stabilization of activated sludge occurred on the second day, after which the process stabilized and no further decrease in Escherichia coli occurred. Sludge treatment, that lasted for two days, allowed to reduce the pathogenic contamination in terms of the bacterial group of Escherichia coli by 75 %.
Keywords: activated sludge, aerobic stabilization, oxidation-reduction potential, nitrates, pathogenic contamination.