From an aesthetic point of view, wastewater treatment plants are not glamorous, and often serve up unappealing odors. Nevertheless, high-quality treatment of waste water in cities and communities is an essential part of our basic water supply.
In order to make sure that the water inlet to wastewater treatment plants operates efficiently, products and technologies are used to monitor the waste water route at several points. Due to potentially induced flammable substances, there might be explosive atmospheres. This risk requires components that are suitable for use in explosion-hazardous areas.
Pepperl+Fuchs offers various solutions: Remote I/O systems for signal transmission to PROFIBUS DP, the fieldbus infrastructure FieldConnex® for consistent digital data transfer with PROFIBUS PA, and the modules of the multi-functional K-system, including numerous signal conditioners and isolated barriers. All of these products meet the requirements for safe and reliable water treatment in wastewater treatment plants.
In many regions, natural slope helps transport the waste water of homes and industries to treatment plants. Wherever this is not possible, pumps lift the water to a higher level, and then forward it to the plant. This procedure can be interrupted if the rules of proper water and waste disposal are not followed. Foreign particles, such as wet wipes, for instance, quickly become a problem when blocking the inflow pumps. To avoid this kind of disruption, the inflow pumps are monitored. A frequency converter works as a rotational speed monitor in this case. If there is any blockage, the constant monitoring allows a quick reaction, so that a blocked pump will not lead to troubles inside the treatment plant.
Apart from waste water, rainwater can also be conducted to the treatment plant. Rainwater is collected in a retention basin as a first step, in order to prevent subsequent stages from overloading. At the same time, the basin must not overflow. Ultrasonic sensors detect the fill level inside the basin, transmitted to the control room by transmitter power supplies or field barriers.
The measuring values serve as a basis to control the pumps that conduct rainwater to the plant. Those pumps are equipped with rotational speed monitors as well, enabling switching to reserve pumps. This ensures that there is always enough water flowing into the plant and that there are no disturbances, such as a burst pipe, for instance.
To avoid high salt loads, lyes, and acids from reaching the biological treatment step, conductivity and pH values are measured when the water is entering the plant. Excessive amounts of these agents would interfere with the decay of organic materials and must not enter this stage of the treatment plant. A fieldbus or transmitter power supplies with adjustable limit values transmit the measured values of the water entering the control room.
The world’s largest wastewater treatment plant is located in the Mexican Tula Valley of Hidalgo. About 60 km away from the capital Mexico City, the Atotonilco plant treats up to 60 % of the waste water from the city. The project particularly focuses on sustainability: resulting biogas is used for energy production, and the treated waste water irrigates up to 80,000 ha of land.