This paper investigates the influence of a phosphogypsum dump on the surrounding environment (soil ecosystem) in the Sumy region (Ukraine). Analysis of the surrounding soils was performed to study the possible presence of compounds leaching from the dump. For physical chemical analysis of samples, X-ray fluorescence (XRF) analysis, X-ray diffraction (XRD) analysis, and Fourier transform infrared spectrophotometry (FTIR) were used. XRF analysis did not confirm the contamination of soils around the phosphogypsum dump, and the soil fluoride levels measured in this study were comparable to the average soil fluoride concentration of soils globally. The colonization of the surface of the phosphogypsum dump by living organisms after the reclamation process was also analyzed. Field research was carried out on the routes, which specify the boundaries of the contours of plant communities, for description of phytocenoses in the territory of the dump, where the pH value ranged from 2.5 to 5.3, depending on the age of phosphogypsum terraces. Annual and perennial herbaceous plants are dominant on the reclaimed dump slopes. On the third and fourth phosphogypsum terraces (20 and 25 years old, respectively), tree forms have begun to settle, represented mainly by Populus tgemula, Populus alba, Betula pendula, and Robinia pseudoacacia. The studied patterns of ecological groups of plants growing under natural change of species can be used for the complete reclamation of the dump.

Possibility of using phosphogypsum as a mineral substrate for the sewage sludge treatment in bio-sulfidogenic conditions has been investigated. Anaerobic microbiological degradation (AMD) on the way of sulfidogenesis was used to produce biogenic hydrogen sulfide. The ozonation of the sludge prior to the AMD under bio-sulfidogenic conditions led to higher efficiencies of hydrogen sulfide production and organic matter removal. After 20 days of digestion, the elimination of CODt and CODs varied between 78-84% and 83-87%, respectively, within advanced operation of anaerobic bioreactor. Technological applications of such system has been discussed. SOME ABBREVIATIONS USED IN THE TEXT TS-total solids, mg/dm 3 VS-volatile solids, mg/dm 3 TSS-total suspended solids, mg/dm 3 VSS-volatile suspended solids, mg/dm 3 VFA-volatile fatty acids, mg/dm 3 COD t-total chemical oxygen demand, mg/dm 3 COD s-soluble chemical oxygen demand, mg/dm 3 SRT-sludge retention time, day SRB-sulfate-reducing bacteria AMD-anaerobic microbiological degradation WWTP-wastewater treatment plants _________________________

The paper is focused on the research of biochemical treatment of sewage sludge and phosphogypsum under sulphate-reducing conditions with a phosphorus release process. The theoretical foundations of the work were based on the biochemical formalization using the principles of autocatalysis of natural systems. During the experimental research for the control of physicochemical parameters of the process spectroquantic, X-ray fluorescence analysis and other techniques were used. A schematic model of the dephosphatation process under anaerobic stabilization of sewage sludge and phosphogypsum was developed. The increase of phosphogypsum dosage had a close correlation with the release of phosphate ions. At the stimulating action of the phosphogypsum additive, a 2.5–5.0-fold increase in soluble phosphate concentration was observed. The rational dose of phosphogypsum was determined. Along with an increase the ratio of COD (Chemical Oxygen Demand)/phosphogypsum to 0.1, an increase in the phosphate ions in solution was observed. A further increase in the ratio of COD/phosphogypsum did not affect the concentration of phosphate ions in solution.

This article presents future trends in research using microbiological methods to intensify bioprocesses for biogas production. The pretreatment by combinations of physical and chemical methods, such as cavitation and electrolysis, is considered. The approach of the article involved reviewing the residual area on the intensification technologies of anaerobic digestion with current methods to improve the quality and quantity of biogas. The most valuable reported positive results of the pretreatment of biological raw materials in the cavitation process were reviewed and are presented here. A model of the effect of electrolysis on the species diversity of bacteria in anaerobic digestion was developed, and changes in the dominance of the ecological and trophic systems were revealed on the basis of previous studies. The stimulating effect on biogas yield, reduction in the stabilization period of the reactor, and inactivation of microorganisms at lower temperatures is associated with different pretreatment methods that intensify anaerobic digestion. More research is recommended to focus on the electrolysis treatment of different types of waste and their ratios with optimization of regime parameters, as well as in combination with other pretreatments to produce biomethane and biohydrogen in larger quantities and in better qualities.

This paper focuses on the study the possibility of phosphogypsum utilization in the biotechnological processes for hydrogen sulfide removal from biogas. The optimal parameters of the process of granulation dihydrate phosphogypsum were determined. The biochemical characteristics of granular carrier based on phosphogypsum was studied. The efficiency of the gas cleaning under immobilization of the thiobacillus on the surface support medium was analyzed. The main parameters of the gas cleaning process were determined. The degree of H 2 S removal from a gas stream was 98.22% at pH = 5.0 and optimum empty bed residence time of 10 h. The possibility of the phosphogypsum using as a new type of mineral support medium for the associations of sulfur-oxidizing microorganisms developing was determined in the process of biological gases purification from sulfur compounds. It was the first time both theoretically and experimentally proved that the mineral support on the basis of phosphogypsum has a sufficient micro and macro elements that necessary for the thiobacteria development. Thus it is eliminating the need to supply additional sources of feeding organisms to biofilter. The gas purification biotechnology with support medium using on the basis of phosphogypsum was developed. This technological solution which allows providing the high quality of gas stream purification with a high content of sulfur compounds, particularly hydrogen sulfide (more than 10% of the gas total volume).