ВЛИЯНИЕ ТУРБИДНЫХ ВЗВЕШЕННЫХ НАЛОЖЕНИЙ НА РЕЖИМ РАБОТЫ И ЭФФЕКТИВНОСТЬ ОЧИСТКИ ВОДООЧИСТИТЕЛЬНОГО СТАНДАРТА

УДК 691.327.333

Abstract

Currently, nearly 40% of the world’s population lives in regions experiencing a shortage of clean drinking water. According to international statistical organizations, by 2025, six out of every ten people, or approximately 5.5 billion individuals, will suffer from a lack of safe drinking water.

This article analyzes the operating regime of the Taxiatosh water treatment plant, the stages of water purification, and the results of field and laboratory studies conducted based on seasonal variations in incoming water quality. The research shows that the turbidity level of incoming water significantly increases due to climatic factors, particularly during periods of precipitation and snowmelt. The turbidity of water samples taken at the inlet ranged from 310 to 1900 mg/dm³, while after treatment, this value decreased to 1.0–3 mg/dm³. At the same time, pH and total dissolved solids did not show significant differences between inlet and outlet points. The results indicate that the existing four-stage treatment system (mechanical treatment, coagulation–flocculation, sedimentation, and filtration) operates effectively under normal conditions. However, during periods of extremely high turbidity, the system experiences difficulties due to increased load. The study concludes that improving treatment processes, optimizing hydraulic parameters, and modernizing the facility are necessary. These findings are of significant scientific and practical importance for ensuring stable drinking water supply.

Аннотация

В настоящее время почти 40% населения Земли проживает в регионах, испытывающих дефицит чистой питьевой воды. По данным международных статистических организаций, к 2025 году шесть из десяти человек, или около 5,5 миллиарда человек, будут страдать от нехватки безопасной питьевой воды. В данной статье анализируется режим работы Тахиаташского водоочистного сооружения, этапы очистки воды, а также результаты полевых и лабораторных исследований, проведенных на основе сезонных изменений качества поступающей воды. Исследования показывают, что уровень мутности поступающей воды значительно возрастает из-за климатических факторов, особенно в периоды осадков и таяния снега. Мутность проб воды, взятых на входе, составляла от 310 до 1900 мг/дм³, а после обработки эта величина снизилась до 1,0–3 мг/дм³. При этом рН и общее количество растворенных твердых веществ не показали существенных различий между точками входа и выхода. Результаты показывают, что существующая четырехступенчатая система очистки (механическая очистка, коагуляция-флокуляция, седиментация и фильтрация) эффективно работает в нормальных условиях. Однако в периоды чрезвычайно высокой мутности система испытывает трудности из-за увеличенной нагрузки. В исследовании делается вывод о необходимости совершенствования процессов очистки, оптимизации гидравлических параметров и модернизации объекта. Эти результаты имеют важное научно-практическое значение для обеспечения стабильного питьевого водоснабжения.

Keywords: water, water treatment, plant, sedimentation tanks, total dissolved solids, water composition, turbidity level.

Ключевые слова: вода, водоочистка, завод, седиментационные резервуары, общее количество растворенных твердых веществ, состав воды, уровень мутности.

Introduction

Efficient and rational use of water resources is one of the most pressing global issues today. Population growth, along with the rapid development of industry and agriculture, is increasing the demand for water. At the same time, pollution of existing water sources complicates treatment processes. Suspended sediments in natural water sources are among the main indicators of water quality. These particles, consisting of mineral and organic matter, negatively affect the physical, chemical, and biological properties of water, reducing its clarity and deteriorating sanitary conditions. High turbidity directly affects treatment processes: mechanical filters clog faster, chemical reagent consumption increases, and sedimentation and filtration efficiency decreases. Moreover, suspended particles can protect microorganisms, making disinfection more difficult. Therefore, it is important to scientifically analyze the operating regimes of water treatment plants and optimize their hydraulic and technological parameters. The aim of this study is to identify factors affecting treatment processes and develop scientifically based recommendations to improve efficiency.

Materials and Methods

The Taxiatosh water treatment plant is located in the Taxiatosh district of the Republic of Karakalpakstan and uses water from the Amu Darya River, specifically through the Taxiatosh hydraulic structure. At this facility, the water treatment process is carried out in four sequential main technological stages. At the first stage, water undergoes preliminary mechanical treatment. Before entering the radial settling tank (radial clarifier), the water is passed through coarse and fine screens to remove large and small solid debris. At this stage, aluminum sulfate is added as a coagulant [8]. During the coagulation process, fine dispersed particles adhere to each other, forming larger flocs. As a result, the settling velocity of suspended particles increases, creating favorable conditions for the subsequent stage [9]. The second stage takes place in horizontal settling tanks. During this process, the larger particles formed during coagulation settle under the influence of gravity, and the water is purified from the main suspended impurities. The sedimentation process significantly improves water quality and enhances the efficiency of the subsequent filtration stage [10]. At the third stage, the water undergoes filtration. Filtration is mainly carried out using quartz sand filters, which remove the remaining fine mechanical particles and some colloidal substances. This stage further improves the clarity and physicochemical properties of the water [18]. At the fourth stage, the treated water is supplied to consumers through pumping stations [19]. In addition, the system includes special backwash pumps designed for cleaning the filters, ensuring their efficient operation. At the final stage, water samples are analyzed in the plant laboratory through chemical and bacteriological tests. The obtained results are evaluated in accordance with the requirements of the national standard O‘zDSt [21,22]. The design capacity of the Taxiatosh water reservoir is 60,000 m³. However, the actual useful capacity is insufficient to fully meet the demand for clean drinking water. This discrepancy is mainly caused by the high level of sediment accumulation in the settling tanks of the treatment plant, as well as the continuously increasing demand for water. The transfer of water from the Taxiatosh hydraulic structure to the Taxiatosh water treatment plant is carried out through natural flow and hydraulic structures. During water movement, its quantitative and qualitative parameters are monitored, and within the framework of experimental studies, hydraulic regimes and physicochemical properties of water are analyzed [11]. Initially, the process of water intake from the Suenli canal, as well as the mechanical treatment stage using screens, is presented in Figure 1. This figure illustrates the movement of water from the source to the treatment plant and the main technological processes involved.

Figure 1. Stage of removing small and solid impurities during water intake to the treatment facility

After passing through the initial mechanical treatment stage, the water is conveyed to the radial sedimentation tank using three Flygt pumps. The total water delivery capacity of the pumps is 1500 m³ per hour. This corresponds to 72,000 m³ per day and approximately 26.28 million m³ per year. In the radial sedimentation tank, aluminum sulfate is added to the water as a coagulant and thoroughly mixed. During the coagulation process, aluminum sulfate attracts fine dispersed suspended particles in the water, causing them to aggregate into larger flocs. As a result, the settling velocity of the particles increases, and they are effectively settled in the radial sedimentation tank in Figure 2.

Figure 2. Operation process of the radial sedimentation tank and sampling

At the second stage, the water is passed through a horizontal sedimentation tank, where the majority of suspended (turbid) particles are settled. In this process, the turbidity of the water must be reduced to the required standard limits. To ensure the efficient operation of the sedimentation tank, the facility must be regularly cleaned of accumulated sludge deposits [12,13]. In the horizontal sedimentation tank, coarse and medium-sized particles are retained, and the clarified water is then transferred to the next stage — the filtration process in Figure 3.

Figure 3. Operation process of the horizontal sedimentation tank

At the filtration stage, fine dispersed particles that have not settled, as well as colloidal substances and other impurities, are removed using quartz sand filters [14-16].To evaluate the quality of the filtered water, chemical analyses are carried out. After that, the water is treated with a sufficient amount of chlorine for disinfection. As a result, the drinking water is brought to hygienic standards and assessed in accordance with the established norms (Table 1). The treated and disinfected water is then supplied to consumers through a pumping station (Figure 4). At this stage, continuous and stable water delivery is ensured.

Figure 4. Filter units of the Taxiatosh water treatment facility

In addition, the water that has undergone mechanical treatment is conveyed by pumps (Figure 5) to subsequent technological stages, including storage basins intended for chemical treatment processes.

Figure 5. Pumping station of the Taxiatosh water treatment facility

The main requirements for drinking water quality indicators are established in accordance with the State Standard of the Republic of Uzbekistan — O‘zDSt 950:2011 in Table 1  [21].

Table 1. Requirements for drinking water according to O‘zDSt 950:2011

Taxiatosh water treatment facility receives water from a supply canal, and water samples were taken to determine quality indicators. Laboratory studies were conducted at the Department of Hydraulics and Hydroinformatics in Figures 6. During the analysis, modern laboratory equipment such as a spectrophotometer and a pH meter was used. The spectrophotometer was used to determine the turbidity of the water and assess its optical properties, while the pH meter was used to measure the hydrogen index (pH) of the water. The obtained results serve as a basis for evaluating the initial water quality condition and for determining the efficiency of subsequent water treatment stages [17].

Figure 6. Measurement of water turbidity using a spectrophotometer and determination of water acidity/alkalinity using a pH meter

Conclusion

Based on field studies and laboratory analyses conducted at the Taxiatosh Water Treatment Plant, the following conclusions were drawn. The research shows that the turbidity level of incoming water to the plant varies significantly throughout the year, mainly due to climatic factors. In particular, during the winter and early spring months, the turbidity level of water is relatively low, ranging approximately between 70–300 mg/dm³. However, during periods of increased precipitation, especially in the spring season and during snowmelt, a sharp increase in turbidity was observed due to intensified erosion processes. To bring such highly turbid water to drinking water standards, a four-stage treatment process is applied at the plant. This process includes mechanical particle removal, coagulation-flocculation, sedimentation (clarification), and final filtration stages. During the study, it was also found that under extreme conditions—such as heavy rainfall—the incoming water load increases sharply, which limits the operational capacity of the existing technological system. This leads to a decrease in treatment efficiency. The identified issues indicate that the hydraulic and technical capacities of the plant are not fully aligned with the quality and quantity of incoming water. Therefore, to ensure a stable and high-quality drinking water supply, it is necessary to continuously monitor the operational regime of the plant, develop automated control systems, and consider hydraulic processes during modernization. Particular attention should be given to adapting hydraulic parameters to real operational conditions. The study shows that achieving a stable drinking water supply requires not only reliance on existing technologies but also systematic modernization and scientifically based management.

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