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 usage of herbicides is increasingly spreading both in the world and in Ukraine. Constant monitoring of this type of the polluting substances is one of the areas for maintaining the ecological security. It is significant for diverse environmental objects, especially for the surface water sources. Contemporary herbicides have a wide range of various mechanisms of action. In this regard, applied methods have to ensure the high level of sensitivity and reasonable specificity for measuring the excessive concentrations of herbicides in the environment. Besides, it is considerable to choose appropriate test organisms. They have to satisfy the list of requirements, while the most important one is that it would be a hydrophyte that has full contact with water. Therefore, the Elodea canadensis Michx. has been chosen by us as a test object. This species is a cosmopolitan and is widely used for the bioassay procedure. The system of biochemical transformations is one of the most sensitive links for the maintenance of the cell homeostasis. Typically, enzymes react to the stress-induced variation in environmental situation by modification of their activity. Consequently, this fact is used for the stress assessment of the organism. We have offered to measure the enzymatic activity of superoxide dismutase (SOD) as the most remarkable system biomarker on the toxic impact of the herbicides. The main function of SOD is the prevention of the growing oxidative stress in the cell. Thus, it can serve as an integral index that acts on the influence of varied chemical substances. For this reason, the aim of the research paper is to indicate the specific changes in the SOD activity of the Elodea canadensis’ cells in conducting the bioassay of the herbicides of varied groups. The aim was achieved through the investigation of the dynamical changes in the SOD activity of Elodea canadensis. The water plant had contact with varied groups of the herbicides in different concentrations. As a result, we have discovered the high sensitivity of the SOD activity of Elodea canadensis while being immersed into water with different herbicides. Hence, this test can be recommended for use to determine the contamination of water with pesticides. We recommend using a one-day experiment for the most representative results to explore the dynamical changes in the enzyme activity of elodea in herbicide solution. The elaborated bioassay method has the following advantages: quickness, accessibility and sensitivity. The absence of the specificity in similar studies can refer to disadvantages. Howsoever, it can also refer to advantages if the screening is conducted for a wide range of contaminations.

The work shows that the Gause's principle of competitive population displacement can be violated, thus confirming the existence of competition with balancing. Competition with balancing can be analogous to the principle of sustainable development announced in the ideas of Jay Wright Forrester, Dennis L. Meadows and Jorgen Randers on global environmental systems. It is likely that competition with balancing cannot exist for a long time without external management.

Fossil carbon-containing fuel is currently one of the most common in industry and economy. The rapid depletion of reserves of this fuel makes it necessary to search for the alternative one. Landfills are a place where methane is spontaneously synthesized due to the decay of organic waste. Controlled and regulated fermentation of the landfill organics can provide biomethane as well as environmental bioremediation. The aim of the work was to study the patterns of methane fermentation of multi component organic waste and optimize the process to increase the efficiency of biomethane synthesis and waste decomposition. Colorimetric and potentiometric methods were used for pH and Eh measurement. Volumetric and chromatographic methods were applied to control volume and composition of synthesized gas. Fermentation parameters were calculated with the use of mathematical and statistical ones. The achievement of high efficiency of methane fermentation of organic waste due to the process regulation was shown. The modeling of unregulated fermentation of organic waste in landfills showed low efficiency of the process. It took 69 days. Weight of waste decreased only 5 times. Hydrogen yield was 5 L/kg of waste. Methane was not synthesized. The regular mass transfer, regulation of the process and waste grinding showed the greatest efficiency. Weight of waste decreased 20 times during only 14 days. Hydrogen yield was 27 L/kg, methane yield was 12 L/kg of waste. Thus, the absence of regulation caused long term decay of waste. The high efficiency is achieved due to regulation of the fermentation process. The results will serve as a basis for the development of industrial biotechnology for the utilization of organic waste to reduce the volume of existing landfills and produce methane energy. This will further allow bioremediation of contaminated areas, obtaining an alternative to fossil fuel biomethane.

Plants of the Ambrosia genus are invasive and cause many ecological problems, including the oppression of the growth of agricultural crops and native plants, land depletion, and the production of strong allergens. The use of weeds as a sustainable feedstock for biogas production, either methane or hydrogen, is a promising way to fulfill the energy needs of the current generation, eliminate the depletion of non-renewable carbon resources, and preserve the ecosystem degradation caused by invasive species impacts. A diversified microbial community was used as inoculum and Ambrosia artemisiifolia L. biomass as a substrate for anaerobic degradation and methane production. In this regard, the development of biotechnological approaches to ragweed degradation will promote the integration of new renewable energy systems. Herein, we have shown the high effectiveness of combining the processes of anaerobic degradation of plant biomass for methane production and detoxification of meal-containing model sewage by a diversified microbial community. Thus, the maximum methane yield was 56.0 L kg−1 TS. The presence of 500 mg L−1 Cu(II) slightly inhibited methane synthesis, and the methane yield was 38.4 L kg−1 TS. In contrast to a diversified microbial community, the natural microbiome of ragweed almost did not synthesize methane and did not degrade plant biomass (Kd = 2.3). Methanogens effectively immobilized Cr(IV), Cu(II), and Fe(III) during ragweed fermentation at initial concentrations of 100–200 mg L−1. The obtained results showed the high effectiveness of applying a diversified microbial community in a sewage treatment plant for the degradation of a noxious plant, Ambrosia artemisiifolia L.