Control of microbiological contamination and content of cations in wastewater of grain processing enterprises in Uzbekistan

. The microbiological contamination of wastewater leaving the grain washing equipment of the flour mill of JSC "Galla Alteg" has been studied, and the results of determining ions using the ion chromatographic method are also presented. The relationship between the hydrogeochemical characteristics of the grain growing environment and the chemical composition of wastewater has been studied. It has been established that the ratio of the total concentration of cations in wastewater is specific. This allows you to obtain information about the type of adsorbent that can be used in the future to purify this type of wastewater.


Introduction
Humidification and washing of grain are the processes of preparing grain for grinding, improving the degree of its food use.During moistening and subsequent defoliation, physical and biological changes occur in the grain, as a result of which the separation of the shells from the grain is facilitated with minor losses of endosperm; When washing, the surface of the grain is cleaned, heavy and light impurities and puny grains are released, and microorganisms are removed.To moisten and wash grain at flour mills, they use: machines in which grain is moistened with cold or warm water in order to change its physical properties during hydrothermal treatment; machines for moistening grain with steam before peeling or flattening when processing various crops into cereals; machines that separate impurities that differ from grain in hydrodynamic properties [1].The industry produces two types of humidifying machines: water-jet for adding water in a dripping state and water-spraying for adding water in a spray, as well as combined washing machines with a vertical squeezing column [2][3][4][5].The use of water jet machines in the flour milling industry makes it possible to accurately dose water in proportion to the amount of grain.However, uniform wetting of its surface is not achieved, and therefore devices are required that allow additional mixing of the moistened grain mixture.More uniform wetting of the grain surface is achieved in machines in which water is added to the grain in a sprayed state [6][7][8].Water consumption in water-jet humidifying machines ranges from 2 to 8 liters per 1 ton of grain, depending on the degree of moisture, and in water-spraying machines -25...50 liters per 1 ton of grain [9][10][11].

Materials and methods
In combined washing machines, water serves as a medium for separating impurities that are difficult to separate using the dry method of grain cleaning.Hydro separation is based on the difference in the falling speed of grain and impurities in water.It is advisable to feed grain into the washing bath in the zone of formation of upward flows of water, i.e., against the direction of rotation of the grain augers.When grain enters the downward flow zone, i.e. in the direction of rotation of the augers, a large amount of grain enters the destoning augers.To filter washing water in order to extract grain waste, separators are used, which are installed in the grain cleaning department of a flour mill directly above the press.The separator is fed with waste from several washing machines or humidifying-husking machines.Also, a screw press is used to squeeze water out of washing waste after processing it in the separator.In the press, waste from the outlet pipe through a rubber sleeve enters the receiving housing and onto the auger.The pre-squeezed water passes through a sieve into the pan and is discharged into the sewer [12].Washing waste, pressed to the required moisture content, is discharged through a pipe and is sent through gravity pipes for drying.To dispose of waste, it is necessary to dry it.At flour mills equipped with complete equipment, it is carried out on non-standardized installations created on the basis of commercially produced steam screw dryers.When designing food enterprises, in particular grain processing enterprises, the cost of water spent on production and household needs is one of the main factors determining the economic efficiency of the enterprise [13].An increase in tariffs for housing and communal services affects the retail sales price of food products.The consumption of cold and hot water by an enterprise is determined by the following parameters: daily, annual consumption and consumption per hour of maximum load.The calculation of these parameters is based on consumption rates, which are given per 1 ton of grain, and the results of technological calculations of the cost of hydrothermal treatment.Grain processing enterprises have established water consumption standards, which include all additional water costs for operating personnel, consumers, cleaning of premises and for other needs.This norm has been included in the current document without changes [5][6][7][8].Moreover, the justification for the standards is not given; moreover, over such a long period of time, not only prices, but the very attitude towards water consumption have changed significantly.Therefore, the calculation of the amount of consumption and its structure using the example of a specific enterprise is of undoubted theoretical and practical interest.

Results
The food industry is directly related to environmental problems, because recently there has been a lot of talk about the production of environmentally friendly products.Intensive processing and large volumes of processed products can have potential environmental impacts.As for the food industry, the focus is on environmental pollution with organic rather than toxic substances.Inadequate pollution control or effective pollution prevention measures can result in contamination of public infrastructure and adverse impacts on local ecosystems.The function of production loss control is to improve production yield and production efficiency while reducing waste and solving environmental pollution problems.Drinking water is of great importance for all life on the planet.In the food industry, a large amount of water is also used for technological purposes, for example, for pre-cleaning of raw materials, washing, decolorization, pasteurization, cleaning of process equipment and cooling of finished products.In particular, obtaining high-quality, environmentally friendly flour with minimal labor and energy costs at grain processing and flour production enterprises is the main task of mill enterprises.The production of flour and cereals is a complex technological process and has various technical means of mechanization.Nevertheless, the issues of grinding or preparing grain before planting, in particular washing grain with water, at small-scale enterprises have not been fully resolved.Currently, due to the complexity of technological processes and the high degree of contamination of raw materials, the water consumption for washing grain mass is on average 2-3 cubic meters per 1 ton of grain, most mills have switched to the dry method.method of cleaning grain mass.But this does not allow the surface of the grain to be completely cleaned and affects its technological properties.An undoubted advantage of washing grain with water is the cleaning of the outer layers of grain from dust and microorganisms, as well as the separation of impurities that differ from the grain in specific gravity.Microorganisms and heavy metal compounds are the main pollutants of mill effluents during grain water purification.The maximum permissible concentration of arsenic, antimony and indium in water is 0.05 mg/l, gallium -0.1 mg/l.Traditional technological schemes for treating wastewater from semiconductor production usually provide for the separation of arsenic compounds from them and do not take into account emissions of gallium, indium and antimony compounds, which correspond to the latter in toxicity.Waste technological solutions generated during the production of semiconductors, as well as containing arsenic and gallium compounds in concentrations of up to several tens of g/l, are neutralized using water treatment technology.The most widely used is the lime-phosphate version of the reagent method, which leads to the formation of an excess volume of sludge, high mineralization of the treated wastewater, and significant consumption of reagents, which subsequently overcomes the above.processes.flaws.Technical processes developed due to the lack of sufficient financial resources at enterprises, for example, due to the possibility of using existing equipment for chemical treatment and recycling of industrial waste, imposed stringent requirements for minimizing capital and operating costs during their implementation.Most wastewater is dangerous to human life, and there is a simple explanation for thispathogenic microorganisms.They can cause many gastrointestinal diseases, including such dangerous diseases as dysentery, cholera, typhoid fever and others.Therefore, to determine the level of danger of wastewater, analysis is used for qualitative and quantitative pollution of one type or another.In the course of our research at the Institute of Microbiology of the Academy of Sciences of the Republic of Uzbekistan, microbiological analyzes of wastewater coming out of the grain washing equipment of the Galla Alteg JSC flour mill were carried out.For microbiological analysis of water samples, methods generally accepted in soil and water microbiology were used.
To study the number of main physiological groups in water, samples were taken from benthic and plankton water layers.Microorganisms in the water under study include: ammonifying bacteria -GPA nutrient medium, phosphorus-decomposing bacteria -Pikovsky solid nutrient medium, oligonitrophils and free-living nitrogen-fixing bacteria -Ashby nutrient medium, Chapek micromycete -solid nutrient medium and actinomycetes -starch-ammonia nutrient medium.the environment is planted and studied.The suspension was prepared from water samples taken for microbiological analysis.To do this, 1 ml was taken from a water sample using a pipette and placed in 9 ml of water in a sterilized test tube.This process was continued serially, diluted to 1:100,000 and repeated.1 ml of liquid from a test tube was inoculated onto special solid selective nutrient media in a Petri dish in three replicates: meat-peptone medium with ammonifiers, Pikovsky medium with phosphorus-degrading bacteria, Ashby medium with oligonitrophils and free nitrogen-fixing bacteria, Czapek medium with micromycetes and actinomycetes were cultivated and studied on a starch-ammonia nutrient medium using the "dilution" principle (Table 1).As a result of the microbiological analysis, the number of ammonifying bacteria was 5.3x10 6 HBB cells/ml in 1 ml of water; species of Bacillus and Micrococcus bacteria were found in the GPA nutrient medium.It has been established that the total number of phosphorusdecomposing bacteria is 6x10 3 HBV cells/ml in 1 ml of water.The number of oligonitrophilic microorganisms growing in a nitrogen-free environment was 5.4x10 4 CBB cells/ml, and the number of free-living nitrogen-fixing bacteria was 9x10 1 CBB cells/ml.The total number of micromycetes was 2×10 2 KHB cells/ml.Actinomycetes and yeast bacteria were not detected., 03032 (2024) E3S Web of Conferences https://doi.org/10.1051/e3sconf/202449703032497 Thus, in this microbiologically analyzed water sample, almost all the main physiological groups of microorganisms (except for actinomycetes) were observed.Further studies determined the content of cations and anions using the ion chromatographic method.Controlling the content of ionic forms of toxic and biogenic components in natural water is important for environmental protection.Environmental monitoring is necessary because anthropogenic loads are increasing and the operational characteristics of known deposits are increasing, which leads to a deterioration in the quality of natural drinking water.It is important to establish general patterns of distribution of microcomponents depending on the content of matrix ions, as well as the dynamics of changes in the concentrations of toxic compounds and nutrients in underground drinking water from various deposits.The relevance of solving such problems is due, on the one hand, to environmental problems of water resources, industrial wastewater treatment and reuse, and on the other hand, to issues of compliance of drinking water brands with the model declared by the manufacturer.Conditions conducive to the formation of the chemical composition of wastewater used in the hydrothermal treatment of grain processing enterprises are distributed according to the latitudinal and vertical zoning of grain crops.Such processes are probabilistically determined, limited to a certain number of geochemical situations, and therefore they are predictable.Identifying the specific chemical composition of wastewater after use in a technological process and establishing the features of the natural functioning of mineral springs based on characteristic indicators is an important task when studying the possibilities of using it back in a technological process (Figure 1).In the studies, the content of cations was determined using the ion chromatographic method.The work was performed on an ion chromatograph with a conductometric detector, using Shodex IC YS-50 4.6x125 mm columns, with a mobile phase: 0.23 g of HNO3 per 1 liter, brought to the mark with water (filtered and degassed), with a flow rate: 1.0 ml/min, column temperature: room temperature, sample volume: 20 µl.The optimal ratio of ion concentrations, being one of the criteria for the physiological usefulness of the water itself used for washing grain and its content in the surface of the grain, requires purification before applying hydrothermal treatment to the return flow.The following water samples were analyzed: waste water coming out of the grain washing equipment of the Galla Alteg JSC flour mill.The sample was collected in a plastic container.Samples were not filtered.Chromatography was carried out immediately (on the day of selection or on the day of admission).Before analyzing the samples, calibration was carried out using a combined solution of six anion standards (Table 2).The software identifies and quantifies each analyte by integrating peak areas.

Conclusions
In conclusion, this study focused on investigating the microbiological contamination of wastewater discharged from the grain washing equipment at the flour mill of JSC "Galla Alteg."Additionally, the chemical composition of the wastewater was analyzed using the ion chromatographic method.The relationship between the hydrogeochemical characteristics of the grain growing environment and the wastewater's chemical composition was explored.The findings revealed a specific ratio of total cation concentrations in the wastewater, indicating the presence of distinctive chemical components.This observation holds significant potential for future wastewater treatment processes, as it provides valuable information regarding the selection of appropriate adsorbents for purification purposes.Understanding the microbiological contamination and chemical composition of the wastewater is crucial for ensuring effective treatment and minimizing environmental impacts.By identifying the specific cation concentrations, suitable adsorbents can be chosen to target and remove the contaminants efficiently.The results of this study contribute to the development of strategies for wastewater management and treatment in the grain industry.Implementing appropriate purification techniques based on the identified chemical components will aid in mitigating the environmental footprint associated with flour mill operations.Further research and experimentation should be conducted to optimize the purification process and evaluate the effectiveness of various adsorbents in removing the specific contaminants identified in the wastewater.By continuously improving wastewater treatment methods, the flour mill industry can enhance its sustainability and environmental stewardship while maintaining high product quality standards.

Table 1 .
Number of microorganisms of the main physiological group in water samples, in 1 ml of water.

Table 2 .
Number of microorganisms of the main physiological group in water samples, in 1 ml of Thus, in studies using the ion chromatographic method, the content of cations in the analyzed water sample was observed to be almost all types (except lithium).