Biogas Potential Assessment of the Composite Mixture from Duckweed Biomass

The article presents the research results of anaerobic digestion processes in bioreactors of composite mixtures based on initial and residual biomass of Lemna minor duckweed and additives: inoculum (manure), food waste, and spent sorbents to determine biogas potential (biogas volume, methane content). Duckweed Lemna minor, which is widespread in freshwater reservoirs, is one of the promising aquatic vegetation species for energy use. Residual biomass is obtained by chemically extracting valuable components from the primary product. The purpose of the research was to evaluate the possibility of the energy potential of residual biomass of Lemna minor to reduce the consumption of fossil fuels and reduce greenhouse gas emissions. This is in line with the International Energy Agency (IEA) scenarios for the reduction of environmental impact. The obtained results confirm the feasibility of using this type of waste for biogas/biomethane production. The recommendations on the optimal composition of the mixture based on the residual biomass of Lemna minor, which will allow for an increase in biogas production, are given. The obtained data can be used in the design of bioreactors.

Influence of Steel Slag-Superfine Blast Furnace Slag Composite Mineral Admixture on the Properties of Mortar and Concrete

A composite mineral admixture was prepared by steel slag and superfine blast furnace slag. The influence of superfine blast furnace slag content of the composite mixture on the mortar and concrete was investigated. The results show that the composite mineral admixture may decrease the strength of concrete at the early age but improve the strength development over time. Increasing the content of superfine blast furnace slag can reduce the degradation of the early strength. The reduction of the autogenous shrinkage and adiabatic temperature rise is significant when the composite mineral admixture is added. The reduction is more obvious when the water-to-solid ratio (w/s) is low. The results show that with steel slag and superfine blast furnace slag playing as complementary parts in the composite mineral admixture, it can be used as an effective substitute of cement.

Disperse-and-Mix: Oil as an ‘Entrance Door’ of Carbon-Based Fillers to Rubber Composites

Oil was employed as an ‘entrance door’ for loading rubber with carbon-based fillers of different size and dimensionalities: 1D carbon nanotubes (CNTs), 2D graphene nanoplatelets (GNPs), and 3D graphite. This approach was explored, as a proof of concept, in the preparation of tire tread, where oil is commonly used to reduce the viscosity of the composite mixture. Rubber was loaded with carbon black (CB, always used) and one or more of the above fillers to enhance the thermal and mechanical properties of the composite. The CNT-loaded system showed the best enhancement in mechanical properties, followed by the CNT-GNP one. Rubber loaded with both graphite and GNP showed the best enhancement in thermal conductivity (58%). The overall enhancements in both mechanical and thermal properties of the various systems were analyzed through an overall relative efficiency index in which the total filler concentration in the system is also included. According to this index, the CNT-loaded system is the most efficient one. The oil as an ‘entrance door’ is an easy and effective novel approach for loading fillers that are in the nanoscale and provide high enhancement of properties at low filler concentrations.

Effective electrodynamical parameters and microwave heating of radially heterogeneous pellets containing EAF dust and biochar

In this work, we investigated the effect of microwave radiation with radially heterogeneous pellets consisting of electric arc furnace (EAF) dust and biochar. We reviewed the possible content of EAF dust in terms of permittivity and permeability of its components and calculated effective permittivity and permeability of EAF dust by an effective medium approach. Using obtained values we calculated dependencies of effective permittivity and permeability of EAF dust - biochar composite mixture on the volume fraction of EAF dust and conductivity of biochar. Taking into account these dependencies we simulated electromagnetic field and temperature distribution within pellet with a radial dependency of volume fraction of EAF dust and effective permittivity correspondingly.

Composite Drug Delivery System Based on Amorphous Calcium Phosphate–Chitosan: An Efficient Antimicrobial Platform for Extended Release of Tetracycline

One major warning emerging during the first worldwide combat against healthcare-associated infections concerns the key role of the surface in the storage and transfer of the virus. Our study is based on the laser coating of surfaces with an inorganic/organic composite mixture of amorphous calcium phosphate–chitosan–tetracycline that is able to fight against infectious agents, but also capable of preserving its activity for a prolonged time, up to several days. The extended release in simulated fluids of the composite mixture containing the drug (tetracycline) was demonstrated by mass loss and UV–VIS investigations. The drug release profile from our composite coatings proceeds via two stages: an initial burst release (during the first hours), followed by a slower evolution active for the next 72 h, and probably more. Optimized coatings strongly inhibit the growth of tested bacteria (Enterococcus faecalis and Escherichia coli), while the drug incorporation has no impact on the in vitro composite’s cytotoxicity, the coatings proving an excellent biocompatibility sustaining the normal development of MG63 bone-like cells. One may, therefore, consider that the proposed coatings’ composition can open the prospective of a new generation of antimicrobial coatings for implants, but also for nosocomial and other large area contamination prevention.

Non-Stationary Flooding Based on Application of a Thermoactive Polymer Composition at Offshore Fields

A high performance technology has been developed for unstable waterflooding of layered-heterogeneous producing reservoirs of oil fields with a thermal gradient. The technology is based on cyclic injection of a thermoactive low-viscosity oil-soluble liquid polymer composition into the formation, which passes into a high-viscosity phase in situ, blocking the produced formation water flow. Application of the technology results in the increase of area of stimulation, both along the strike and vertical sweep efficiency. Monitoring the reservoir filtration characteristics enables control of the profile of the mixture advance in the formation. The effect of unstable injection of the proposed thermoactive polymer composition on the residual resistance factor was studied in an experimental setup consisting of two parallel-connected linear reservoir models with different permeability. The composition contains a working agent, a dispersant and sea water. The optimal ratio of the components that make up the composite mixture was determined as a result of laboratory and experimental studies. The viscosity behavior of the composite mixture at different temperature values for reservoir conditions is determined. Monitoring techniques for reservoir filtration properties have been developed in order to control the flow profile of the mixture in the reservoir. The analysis of the obtained results showed the efficiency of this technology for layered-heterogeneous reservoirs with a thermal gradient and the availability of overflows. This technology enables aligning area of stimulation, both along the horizontal and vertically using smaller volumes of the agent and with a slight change in the injection pressure. Unstable injection of the composite system provides a significant additional removal of residual oil. Thermoactive polymer composition should be injected cyclically in order to increase the reservoir coverage, align the frontal advance and for enhanced oil recovery due to the involvement of low-permeability oil-saturated areas into the development. This method allows you to change the direction, flow rates, and create unsteady cyclic pressures. A redistribution of formation fluids, a decrease in capillary pressures and the flow of a working agent into oil-saturated low-permeability zones occurs under the positive and negative pressure drops in the formation. The proposed technology was implemented in the section V of the block of the «Neft Dashlary» field (X horizon) in April-June 2016 and in the section of the «Pirallahi» field (KSw) in February-March 2017. At the pilot site of the «Neft Dashlary» field, the impact effect continued until May 1, 2017. Additional oil production in the period from 01.05.2016 to 01.05.2017 made up 3201.4 tons. Additional oil production at the selected area of the Pirallahi field by the end of 2017 made up 170 tons.

Enhancement of concrete performance via mixed limestone and granite powders

The granite and limestone powders are commonly exploited as a replacement for cement; however, the effects of different mixing dosages of them on the mechanical properties and durability of concrete have not been scrutinized carefully. Under different environmental conditions, the compressive strength of the specimens is measured using cube compressive, splitting tensile, freeze-thaw cycles, and sulfate immersion tests. The phase composition of hydration products and microstructure is evaluated by SEM scanning analysis. The results indicate that the composite mixture of granite and limestone powders shows a complementary synergistic effect and improves the mechanical properties, freeze-thaw resistance, and sulfate erosion resistance of the concrete. The best values for the mechanical properties and freeze-thaw resistance are obtained when the dosages of granite and limestone powders in order are 10% and 5%. For the case of granite and limestone powders equal to 10% and 15%, respectively, the best sulfate erosion resistance is reported.