ESTABLISHMENT OF THE LAWS OF FORMATION AND CHEMICAL COMPOSITION OF WASTEWATER OF A DAIRY PROCESSING PLANT IN THE WESTERN REGION OF UKRAINE
Authors: Bytsyura Leonid , Senyk Yurii , Barna Iryna 
Published: December 2023

The dairy industry has a wide range of processing end products, which can be conventionally divided into liquid, solid and dry products. The first group includes pasteurized milk, cream and fermented milk drinks (kefir, yoghurt, desserts), the second group includes butter and cheese, the third group includes dry milk (whole or skim), proteins of various composition and purity, casein and whey. The wastewater of a dairy factory is the result of various technological and production processes, which vary in time and, accordingly, their products are not discharged simultaneously, which determines the formation of effluents of different compositions and volumes. Industrial wastewater generated at dairy factories is divided into two types: polluted and partly polluted wastewater. Polluted wastewater is produced after cleaning equipment, industrial pipelines, automobile tanks, floors, industrial premise panels, etc. Partly polluted wastewater is produced as a result of the cooling processes of milk and equipment. Both types of wastewater form a common flow that is subject to cleaning, disinfection and discharge into drainage systems or surface water bodies (depending on the chemical composition).

The study of the wastewater composition of a dairy processing plant was divided into two stages. At the first stage, the analysis of mixed phases formed during the production process in each section of the factory was carried out.

The analysis was carried out for one day of production at a dairy factory that processed 496 tons of whole milk, of which 170 tons were used to make whole milk products and cottage cheese, and the rest were used to make butter and casein. At the same time, 1200 m3 of water was used for all production processes, and additional water consumption for auxiliary processes and services amounted to 643 m3, so the total discharge per day was 2000.47 m3.

The next step was to directly analyse the wastewater indicators of the dairy processing plant. To offset the impact of the production process on the composition of dairy wastewater and the volume of manufactured products, we organized sampling every two hours for four days. As a result, 48 points of analysis were obtained, which allowed us to form an objective assessment of the factory’s discharge.

As a result of the research, the regularities and sources of formation of wastewater were established, and the chemical composition of wastewater from a dairy processing plant in the Western region of Ukraine was experimentally determined. The results obtained allowed us to draw the following conclusions. The formation of the total runoff is caused by both technological and related processes, which include sudden emissions of highly polluted wastewater with a high concentration of major pollutants, the use of different volumes of water for technological processes, and different volumes and composition of wastewater during the day. Therefore, to correctly assess the composition of a dairy factory's discharge, a systematic and long-term study is required, rather than a spot analysis.

The chemical composition of wastewater was experimentally studied according to the main indicators regulated by the legislation of Ukraine regarding the discharge of wastewater into the sewage system and municipal biological treatment facilities. The data obtained indicates that the chemical composition of the total wastewater from the dairy processing plant does not meet the requirements. The main pollutants are: organic components, which are expressed in exceeding the chemical oxygen demand on average by three times, and at the peak load - by 10 times; phosphates in terms of total phosphorus - by 8-22 times and chlorides - by 2-7 times.

A comparative characterization of individual technological stages shows that the most polluted wastewater is generated in the process of acid casein production. These waters are characterized by high values of COD, chlorides and phosphates, and their contribution to the overall value of these indicators is determinant. The production of whole milk products is characterized by a slight excess of COD.

As a result, in order to prevent the death of activated sludge in municipal biological treatment facilities, pretreatment of wastewater is necessary to bring the above indicators to the norms.

Key words: dairy industry, dairy processing plant, wastewater, wastewater chemical composition, the Western region of Ukraine.