Efficiency and bacterial diversity of an improved anaerobic baffled reactor for the remediation of wastewater from alkaline-surfactant-polymer (ASP) flooding technology

Alkaline-surfactant-polymer (ASP) flooding technology is used to maximize crude oil recovery. However, the extensive use of alkaline materials makes it difficult to treat the water used. Here, an improved multi-zone anaerobic baffled reactor (ABR) using FeSO4 as electron acceptor was employed to treat the wastewater from ASP flooding technology, and the effects on major pollutants (hydrolyzed polyacrylamide, petroleum substances, surfactants suspended solids) and associated parameters (chemical oxygen demand, viscosity) were evaluated. Gas chromatography-mass spectrometry (GC-MS) was used to follow the degradation and evolution of organic compounds while high-throughput DNA sequencing was used to determine the bacterial diversity in the ABR. The results obtained after 90 d of operation showed decreases in all parameters measured and the highest mean removal rates were obtained for petroleum substances (98.8%) and suspended solids (77.0%). Amounts of petroleum substances in the ABR effluent could meet the requirements of a national standard for oilfield reinjection water. GC-MS analysis showed that a wide range of chemicals (e.g. aromatic hydrocarbons, esters, alcohols, ketones) could be sequentially removed from the influent by each zone of ABR. The high-throughput DNA sequencing showed that the bacteria Micropruina, Saccharibacteria and Synergistaceae were involved in the degradation of pollutants in the anaerobic and anoxic reaction zones, while Rhodobacteraceae and Aliihoeflea were the main functional microorganisms in the aerobic reaction zones. The results demonstrated that the improved ABR reactor had the potential for the treatment of wastewater from ASP flooding technology.

Illuminate the hidden: in vivo mapping of microscale pH in the mycosphere using a novel whole-cell biosensor

The pH of an environment is both a driver and the result of diversity and functioning of microbial habitats such as the area affected by fungal hyphae (mycosphere). Here we used a novel pH-sensitive bioreporter, Synechocystis sp. PCC6803_peripHlu, and ratiometric fluorescence microscopy, to spatially and temporally resolve the mycosphere pH at the micrometre scale. Hyphae of the basidiomycete Coprionopsis cinerea were allowed to overgrow immobilised and homogeneously embedded pH bioreporters in an agarose microcosm. Signals of >700 individual cells in an area of 0.4 × 0.8 mm were observed over time and used to create highly resolved (3 × 3 µm) pH maps using geostatistical approaches. C. cinerea changed the pH of the agarose from 6.9 to ca. 5.0 after 48 h with hyphal tips modifying pH in their vicinity up to 1.8 mm. pH mapping revealed distinct microscale spatial variability and temporally stable gradients between pH 4.4 and 5.8 over distances of ≈20 µm. This is the first in vivo mapping of a mycosphere pH landscape at the microscale. It underpins the previously hypothesised establishment of pH gradients serving to create spatially distinct mycosphere reaction zones.

Video registration of physicochemical processes in BOF cavity at bath top blowing at application oxygen lances of various designs. Report 2. The picture of bath blowing at application two-circuit lances

To elaborate blowing and slag modes, a clear picture of BOF bath blowing in various periods of heat is needed. It can be obtained by video registration of physicochemical processes in a BOF cavity. Results of video filming of BOF bath blowing with application two-circuit oxygen lances of five designs presented. Reliable information was obtained on rational form of organization of reaction zone of interaction of ultrasonic and sonic oxygen jets with BOF bath. The picture of physicochemical processes within the reaction zone of interaction of oxygen jets with metal, slag and gas phases of the cavity, preceded to a stable “ignition” of a heat and in the process of the whole heat. A possibility was revealed to accelerate the processes of lime dissolving and slag formation and phosphor removal intensification. The intensification can be accomplished by increase of the number of reaction zones of interaction of ultrasonic and sonic oxygen jets on bath surface and forming of foamed slag-metal emulsion, being stable within the basic part of blowing time. It was shown that at initial period of a heat, it is necessary to ensure consolidation of supersonic oxygen jets, coming out of different reaction zones of interaction. It will enable to oncoming jets to create a curtain on the way of metal and slag drops taking away, to form a flare of CO afterburning to CO2 and ensure heat energy transfer from them to mainly the bath surface. It was established that at the location of the foamed slag-metal emulsion level higher the head end of the lance, the high-temperature products of CO to CO2 afterburning reaction transfer the heat of CO surrounding macro bubble to the shell of slag-metal emulsion. An additional control effect of “hard” supersonic oxygen jets on the bath was also established when replacing the subsonic and sonic oxygen jets by nitrogen ones. At that the flow rate of nitrogen should be big enough to prevent the sealing of cylinder nozzles of the lance head by metal and slag drops during final stage of blowing. The variant of the final stage of blowing was checked experimentally by transfer to the “hard” supersonic oxygen blow, contributing to final metal and slag oxidation decrease.

Numerical Investigation of the Turbulent Flame Propagation in Dual Fuel Engines by Means of Large Eddy Simulation

Dual fuel combustion depicts a possible alternative to reduce emissions from large engines and is characterized by injecting a small amount of diesel fuel into a lean natural gas–air mixture. Thereby, the presence of autoignition, diffusive and premixed combustion determine the high complexity of this process. In this work, an Extended Coherent Flame Model was adapted to consider the effect of natural gas on the ignition delay time. This model was afterward utilized to simulate 25 consecutive engine cycles employing LES. In this framework, the ensemble-average flow field was compared to a RANS solution to assess the advantages of LES in terms of the prediction of the in-cylinder flow field. A detailed investigation of the heat release characteristic showed that natural gas already highly contributes to the heat release at the beginning of combustion. Furthermore, a methodology to investigate the turbulent combustion regimes was utilized. It could be ascertained that the combustion mainly occurs in the regime of thin reaction zones. Possible triggers of cycle-to-cycle variations were determined in the velocity fluctuations in the cylinder axis direction and the flame formation in the gaps between the spray plume. The findings support the understanding of dual fuel combustion and serve as a basis for developing future combustion models.

Reaction Sequences in Flash Smelting and Converting Furnaces: An In-depth View

Flash smelting and flash converting are mature technologies in copper and nickel sulfide smelting. The sensitivity of operation concerning the furnace design is evident. It is obvious that when two unit operations are carried out in separate spaces in the same furnace, skills related to maintenance of suspension oxidation of fine minerals, fluxing, fluid as well as heat flows and the overall energy balance are required. Despite these fundamental features, the flow-sheet wide understanding of linking the suspension oxidation of sulfides with the subsequent smelting processes in the furnace as well as the chemistry of its off-gas train is largely absent in the scientific literature. This review gives a detailed outlook on the microscale phenomena in flash smelting and flash converting furnaces accumulated during the last decades. It connects their vital features and chemistries with the reaction tendencies and heat fluxes in the different parts and reaction zones of the furnace as well as in the off-gas train from the smelter to the acid plant. Graphic Abstract

DIRECT OBSERVATION OF HIGH-TEMPERATURE AREAS OF METAL MELT AT OXYGEN CONVERTER BLOWING WITH LOW VOLTAGE APPLICATION

Introduction. The process of oxygen conversion, despite the existing improvements, can be supplemented by physical methods of influence, including the unconventional method of applying low-voltage potential developed at the Iron and Steel Institute of the NAS of Ukraine.Problem Statement. The studies of the method of low-voltage potential application on 60, 160 and 250 ton converters have shown that the technology intensifies thermophysical and hydrodynamic processes in the gasslag-metal system and increases the converter process efficiency.Purpose. The purpose of this research is to study the features of the influence on the reaction zones of the low voltage potential application at four blowing options with the use of high-temperature physical model.Materials and Methods. A physical model that simulates the top, bottom and combined oxygen blowing under low-voltage potential application of different polarity on the lance has been used. An insert of a transparent quartz plate is made in one of the walls for visual observation and video recording. The top blowing is conductedwith two nozzle lance (nozzle diameter 1.7 mm with an angle of 30 ° to the lance). The bottom blowing is conducted with a bottom tuyere with a 1.5 mm diameter central nozzle. Combined blowing is realized by a combination ofthese options.Results. The visual observation of the reaction zones with different blowing options has shown that the highest temperature and the largest dimensions of the brightest parts of the bath correspond to the combined blowing, while the lowest ones are reported for the bottom blowing. While applying the low-voltage potential method it has been established that the reaction zone is longer at the positive polarity on the lance, during the period of silicon oxidation, and at the negative polarity on the lance, during the period of intense carbon oxidation. The video of gas bubbles flotation, probably CO, has shown that the bubbles are formed more intensively in thecase of negative polarity on the lance.Conclusions. The applied technique has allowed estimating the influence of low-voltage potential application on the geometric parameters of the reaction zone.

Modeling product distribution of top-lit updraft gasification

A kinetic model for predicting biochar, producer gas, and tar formations of top-lit updraft (TLUD) gasification was developed. The three main zones within the TLUD gasifier, the pyrolysis, incomplete combustion, and reduction reaction zones, were incorporated into the model and sequentially solved. Validated with experimental data, the model was found capable of predicting biochar yield on pine woodchips at varying airflow rates, biomass moisture contents, and biomass compactness. However, when the particle size was varied, the model underestimated biochar yield. The model also accurately predicted the higher heating value of the producer gas that varied from 3.45 to 3.98 MJ/m3 compared to 3.61 to 3.67 MJ/m3 for the experimental results. The model qualitatively predicted tar content in the producer gas at varying conditions. However, accurate quantification of tar generation in TLUD gasification was not achieved.