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Modern technological schemes in water supply for clarifying surface water include using reagents as coagulants, flocculants, etc. To mix them with the source water on plants usually use different types of mixing devices. Tubular mixer is one of such devices. Our research work involves the study of a tubular mixer with improved design, which can mix several reagents with source water. The paper presents theoretical and experimental studies of the tubular mixer with improved design for mixing several reagents with natural water. It is theoretically and experimentally substantiated the feasibility of using this tubular mixer for mixing several reagents with natural water over a short mixing time. The improved design of tubular mixer can mix several reagents with natural water in a short mixing time, intensify the mixing process and improve quality of water after treatment.

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Underground infrastructural objects such as sewage and water supply networks, which mainly consist of pipes or collectors, are exposed to solid corrosion of concrete and metal, significantly reducing their service life. Today, laser 3D scanning, which allows you to create a three-dimensional map of the pipe's inner surface, is considered one of the promising methods of monitoring sewer networks. Specialists use wheeled robots or aerial platforms with stereo cameras and lasers as devices for laser scanning. The main advantage is that 3D maps can easily detect and quantify structural defects on the pipe's inner surface. Creating a three-dimensional model and its subsequent analysis makes it possible to examine the drainage network in the shortest possible time to find cracks and sealing violations. This model helps to determine the nature of the flow of waste liquids; establish the presence of deposits; assess the degree of wear and corrosion of pipes; insulation condition; integrity and quality of the network after construction or repair. Laser scanning will prevent negative environmental impact, preserve ecology, and not harm the life and health of workers.

In this work, the technological parameters that can significantly effect on a quality of clarification low-concentration suspension by dissolved air flotation were considered. These parameters are: particle size, air bubble size, water rise velocity and air concentration in water. The size of solid particles influences on the probability of their collision with bubbles. The water rises velocity change time of contact between solid particles and bubbles in the working area, which also effects on the probability. Increasing the air concentration in a tank improves the quality of water clarification, because more bubbles are formed there. These factors will be taken into account in further studies to find the optimal dimensions of flotation tank for better cleaning low-concentration suspension.