The solid fraction, according to many researches, is an effective organic fertilizer, the activity of which is at the level of mineral fertilizers and even exceeds their effectiveness, while the use of the liquid fraction does not always give positive results. In the article the optimal concentration of the liquid fraction in water solution for fertilization during cultivation of onion for chives in soil was determined. Sediment from biogas production was obtained at the thermophilic fermentation (50ºC) of cattle manure in the laboratory institution which operated at the periodical regime of loading. Fermentation lasted 25 days. Seven variants of plant feeding were assessed: clean water (control), mineral fertilizers (solution of ammonium nitrate in water in the concentration of 1:25), unsolved liquid biofuel fraction and mixture of liquid fraction from the postferment with water in concentrations of 1:10, 1:50, 1:100, 1:500. It was determined that the highest efficiency was observed in case of fertilization of plants with the mixture of liquid fraction from postferment with concentration of 1:500. Along with the increase of liquid fraction concentration and fertilization of plants with water solution of mineral fertilizers, onion productivity dropped slightly. Fertilization of plants with the liquid fraction from postferment resulted in fractional dying of plants and reduction of efficiency. The crop control of nitrogen content proved that in case of every day watering of onion with clean water and mixture of liquid fraction with water concentration of 1:100-1:500 did not exceed the maximum admissible concentration which is 800 mg·kg−1. Thus, in case of onion cultivation for chives, taking into consideration the crop growth and low nitrogen content, it is recommended to use the mixture of liquid fraction with water of 1:500 concentration.

The aim of the work is to increase biogas output and generation of electricity in biogas plants due to the joint fermentation of cattle manure with winemaking waste. To achieve this goal, the following tasks were solved: the biogas yield from cattle manure with winemaking waste was determined during periodic loading of the digester; on the basis of the obtained experimental data, a mathematical model was calibrated to estimate the biogas yield during fermentation of cattle manure with the addition of winemaking waste. As a result of the studies, it was found that when manure is fermented with part of the water replaced in the substrate 2% of the winemaking waste, the fermentation dynamics in the substrate are similar to the fermentation of pure cattle manure. Biogas obtained by fermentation of manure with the addition of 2%, 6.5% and 13% of wastewater from wine production instead of water in the first day of fermentation either did not burn at all or burned poorly. The addition of winemaking waste to a substrate based on manure in an amount of 13% allows increasing the maximum biogas yield by a third to 1,372 l/(hr×kg dry organic matter). The significance of the research results lies in the fact that the use of winemaking waste as a substrate will allow a third increase in biogas output and power generation, and a reduction in the payback period of a 4,4 MW biogas plant using the green tariff to 6,5 years.

In agriculture of Ukraine, crop production is over 79%, of which more than half is accounted for by cereals, legumes and industrial crops. A significant amount of by-products is prioritized for use as organic fertilizers, a certain amount is burned in the fields, which harms the environment and reduces soil fertility, and only 2-3% is used for energy needs. At the same time, the use of crop by-products as organic fertilizers involves the application of nitrogen fertilizers to the soil, because in the process of biodegradation of plant residues a significant amount of nitrogen is removed from the soil. In addition, plant residues are not recommended to be deeply plowed to accelerate their biodegradation. However, from 30% (straw) to 40% (corn stalks) of these plant residues without compromising soil fertility can be used as biofuel, which, however, unlike wood, has a higher ash content and high chlorine and alkali metals, which can be significantly reduce due to prolonged storage of straw in the open air. In addition, straw has a low melting point, so it is recommended to burn it only in a grate. However, despite these shortcomings, the use of crop by-products as fuel can generate profits from the sale of thermal energy, fuel pellets or briquettes, as well as savings from replacing natural gas with biofuel when heating industrial, administrative and cultural facilities. For a farm with an area of approximately 2000 hectares, half of which is used for grain crops, savings and profits can amount to almost 7.5 million UAH/year.

The processing of livestock waste and agricultural production enables not only improving environ mental safety, but also obtaining energy resources.Problem Statement. Cow manure is used to produce biogas, but its yield is relatively low. One way to increase biogas yield is the joint fermentation of cow manure with substandard flour, which cannot be used as human food and as feed for farm animals. However, the flour content in the substrate, at which the biogas yield is maximum and there is no inhibition of the methane fermentation process, is not a solved issue.Purpose. Increase biogas yield by adding substandard flour to a cow manurebased substrate. Materials and Methods. Research of biogas yield during methane fermentation of substrate based on cow manure with the addition of substandard flour was carried out on a biogas plant consisting of a methane tank with a working volume of 30 l and wet gasholder at periodic substrate loading and fermentation temperature 35 °C. The portion of the substrate included 1.7 kg of manure, 2.5 kg of water and 50, 100, 250 or 500 g of flour.The composition of flour in the substrate was 1.2%, 2.3%, 5.6% and 10.6%. The dichotomy method was used to determine the optimal flour content in the substrate, provided the maximum biogas yield.Results. The maximum biomethane release is 14.3 l/kg dry organic matter (DOM), at 1.2% of the flour con tent in the substrate; 20.9 l/kg DOM, at 2.3%; 19.2 l/kg DOM, at 5.6%. At a content of 10.6% flour in the subst rate, the biogas did not burn, fermentation quickly stopped. The optimum flour content in the substrate based on cow manure, in which the biogas yield increases 1.5 times, is 3.7%.Conclusions. Based on the conducted experimental studies, a model of biogas yield with gradual loading of the substrate was built and the optimal flour content in the substrate was determined, at which the maximum biogas yield is provided. K e y w o r d s : biogas, methanetank, substandard flour, cattle manure, biogas plant, and methane fermentation.Currently, one of the most important and urgent problems is processing of animal waste and agricultural production, not only for environmental safety, but also for obtaining energy resources. Based on the use of biogas technologies, cow manure is used, as a rule,

The volume of ethanol production waste—molasses waste in Ukraine—reaches up to 4 million m3 per year. It is not easy to dispose of and is polluting the environment. Currently, the development of an effective technology for using molasses in biogas plants to obtain energy gas—biogas—is an urgent problem. The purpose of our work is to determine the rational volume of loading molasses bard into the methane tank in a quasi-continuous mode to obtain the maximum volume of biogas. To achieve this goal, the following experimental studies were carried out: mono-fermentation of molasses and combined fermentation of cattle manure and molasses on a laboratory biogas plant in a periodic mode; on the basis of the obtained laboratory studies, a special simulation model of biogas output during the quasi-continuous fermentation of substrates was established and the amount of molasses added to obtain the maximum biogas output was determined. The maximum output of biogas under the periodic system of loading the methane tank when adding 10.5% molasses to cattle manure is 1.462 l/(h kg DOM); when adding 26.1% molasses to cattle manure, it is 3.594 l/(h kg DOM). In order to increase the yield of biogas, it is advisable to add molasses in the amount of 30% of the volume of the substrate to the substrate based on cattle manure, which allows the discounted payback period of the biogas plant to be reduced to 1.2 years.

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The urgency of the study is due to the need to increase the productivity of biogas plants by intensifying the process of methane fermentation of cattle manure in mesophilic mode by adding to it the waste from biodiesel production: crude glycerine. To substantiate the rational amount of crude glycerine in the substrate, the following tasks were performed: determination of dry matter, dry organic matter, and moisture of the substrate from cattle manure with the addition of crude glycerine; conducting experimental studies on biogas yield during fermentation of cattle manure with the addition of crude glycerine with periodic loading of the substrate; and development of a biogas yield model and determination of the rational composition of crude glycerine with its gradual loading into biogas plants with cattle manure. The article presents the results of research on fermentation of substrates in a laboratory biogas plant with a useful volume of 30 L, which fermented different proportions of crude glycerine with cattle manure at a temperature of 30 °C, 35 °C, and 40 °C. The scientific novelty of the work is to determine the patterns of intensification of the process of methane fermentation of cattle manure with the addition of different portions of crude glycerine. A rapid increase in biogas yield is observed when the glycerol content is up to 0.75%. With the addition of more glycerine, the growth of biogas yield slows down. The digester of the biogas plant, where experimental studies were conducted on the fermentation of substrates based on cattle manure with the addition of co-substrates, is suitable for periodic loading of the substrate. As a rule, existing biogas plants use a gradual mode of loading the digester. Conducting experimental studies on biogas yield during fermentation of cattle manure with the addition of crude glycerine with periodic loading of the substrate makes it possible to build a mathematical model of biogas yield and determine the rational composition (up to 0.75%) of crude glycerine with its gradual loading in biogas plants. Adding 0.75% of crude glycerine to the substrate at a fermentation temperature of 30 °C allows to increase the biogas yield by 2.5 times and proportionally increase the production of heat and electricity. The practical application of this knowledge allows the design of an appropriate capacity of the biogas storage tank (gasholder).