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The weed Solidago canadensis L. poses a global threat to the environment as it spreads uncontrollably on roadsides, in forests, fields, meadows, and farmland. Goldenrod emits toxic substances that suppress other plants on the site, displacing wild ones. Thus, goldenrod conquers huge areas very quickly. The use of herbicides and mechanical methods does not solve the problem of the spontaneous spread of goldenrod. On the other hand, many scientists consider goldenrod as a valuable source of biologically active substances: flavonoids, phenolic compounds, vitamins, etc. In this study, we consider Solidago plants as a promising, free (cheap), and renewable substrate for the production of methane gas. The goal of the study was to identify the main patterns of degradation of the Solidago canadensis L. plant by methane-producing and sulfate-reducing bacteria with methane gas production and simultaneous detoxification of toxic copper. The composition of the gas phase was monitored by gas chromatography. The pH and redox potential parameters were determined potentiometrically; metal concentrations were measured by photometry. The concentration of flavonoids, sugars and phenolic compounds in plant biomass was determined according to well-known protocols. As a result of the study, high efficiencies of methane degradation in the Solidago plant and copper detoxification were obtained. Methane yield has reached the value of 68.2 L kg−1 TS of Solidago canadensis L. biomass. The degradation coefficient (Kd) was also high at 21.4. The Cu(II) was effectively immobilized by methanogens and sulfate reducers during the goldenrod degradation at the initial concentrations of 500 mg L−1. Thus, a new method of beneficial application of invasive plants was presented. The result confirms the possibility of using methanogenic microorganisms to produce methane gas from invasive weeds and detoxification of toxic metals.

The use of fossil fuels (methane, oil, etc.) is undergoing an unprecedented crisis now. There is the urgent need to search for alternative energy sources. A wide range of degraded organic materials can be effectively used to provide energy together with environmental protection. Soapstock is a hazardous waste containing a high concentration of toxic organic compounds of man-made origin (fatty acids, surfactants, dyes, etc.). To prevent environmental contamination such substances require an effective treatment approach. The goal of the study was to isolate the adapted-to-fatty-acids methanogenic microbiome and investigate the patterns of sodium acetate and soapstock degradation with simultaneous biomethane synthesis. The effectiveness of the degradation of sodium acetate and soapstock by non-adapted and adapted microbiomes was evaluated by decreasing the concentration of dissolved organic compounds. The effectiveness of the fermentation process was determined by the biogas (mixture of CH4 and CO2) yield. The most effective degradation occurred in the variant with sodium acetate and adapted methanogens and amounted to 77.9%. In other variants, the patterns and the efficiency of purification were similar ranging from 60.6 to 68.0%. The biomethane was mostly synthesized by adapted methanogens on the soapstock and sodium acetate as substrates. Thus, the CH4 yield was 368.4 L/kg of dissolved organic compounds or 127.5 L/kg of soapstock. The results of this study demonstrated the potential of methanogenic microorganisms in the biodegradation of soapstock with simultaneous biogas synthesis. The results can serve as a basis to reduce the reliance on fossil fuels by generating biomethane via the fermentation of toxic organics.

The influence of static loadings of the foundations of structures in the process of soil compaction of the base on the subsidence of the soil surface and the bench outside the loaded contour is considered in the work. The studies were performed on models of rectangular massive foundations using the method of equivalent soil layer, based on the theory of compaction of linear-deforming half-space. Using this method, the values of the average sedimentation of the models of rectangular foundations were calculated, taking into account all components of normal stresses and lateral soil extension. On the basis of the method of angular points of the equivalent layer, the values of subsidence of the soil surface outside the contour of the foundation models are calculated, depending on the distance from the contour of the foundation, the value of the average subsidence of the foundation and its parameters. To determine the areas of the soil surface most sensitive to the perception of static loads, lines of equal settlements of the soil surface outside the contour of the foundation models are constructed. On the basis of theoretical studies, probable magnitudes of sedimentation of soil benchmarks are calculated, depending on the subsidence of the soil surface and the distance from the contour of the foundation. The probable minimum distance from the contour of the structure to the places of laying of initial soil benchmarks is established to ensure the required accuracy of geodetic observations. The results of the conducted researches may find application in the design of geodetic observations of the settlements and deformations of the foundations of engineering structures and the choice of the locations of local level points.

Environmental pollution by toxic metals is a common ecological problem. Chromium and copper compounds released into the environment as a result of human-made stress pose a serious threat to living organisms. Phytoremediation is a promising method of toxic metals removal from contaminated sites. The concentration of metals in grass biomass—in the roots and aerial parts—was determined by X-ray fluorescence analysis. The estimation of numbers of microorganisms was conducted by a tenfold dilution and spread-plating method. It was shown that lawn grass accumulated from 69.1 ± 13.2 to 497.7 ± 74.1 mg/kg Cu and Cr during the growth in the contaminated soil with 50, 100, and 200 mg/kg of metals. In general, there was a pattern of accumulation of copper in the aerial part of the grass and chromium in the roots. Thus, the total copper concentration in the aerial part ranged from 105.2 ± 23.8 to 497.7 ± 74.1 mg/kg of plant biomass. The total chromium concentration in the roots ranged from 156.4 ± 47.9 to 426.8 ± 62.5 mg/kg. The viability of the soil microbiome was not inhibited at such metal concentrations. The obtained data allow lawn grass to be considered as promising for the phytoremediation of contaminated areas.