FOCUS
Overcoming chemical dosing challenges in wastewater treatment
By Adeel Hassan , product manager, Watson-Marlow Fluid Technology Solutions
Sustainability is driving the use of higher concentration chemicals to minimise transport costs and emissions, as well as reduce the size of dosing systems. However, high concentration chemicals, such as sulfuric acid used in neutralisation, can be hazardous if not contained after a pump failure. Therefore, it is important that plant managers select a pump that is compatible with high concentration chemicals and prevents chemical exposure to the operator. High concentration chemicals require an accurate and repeatable pump to maintain process capability. Peristaltic pumps with low pulsation and no ball valves result in parts per million (ppm) concentrations with low standard deviations, minimising chemical usage and maximising process quality.
Around 359 billion m 3 of wastewater is produced globally each year. 1 Along with municipal wastewater, a range of industrial processes produce wastewater, such as chemical manufacturing, food processing and powerplants. If the effluent water is going to be discharged back into the environment, it must be treated to comply with regulatory requirements and prevent damage to ecosystems and human health. Alternatively, many industrial companies want to reuse their wastewater to minimise their environmental impact, reduce costs and overcome water shortages. For this purpose, the wastewater must be treated so that it is suitable for its new purpose, such as industrial cooling water. Wastewater treatment providers are facing the challenge of handling
a variety of treatment chemicals, as well as external factors such as increasing demand and the drive for sustainability. Wastewater treatment providers can overcome different process challenges by upgrading their pumping technology.
COAGULANTS AND FLOCCULANTS
Regulations around preventing eutrophication are driving the removal of phosphates from wastewater. Ferric chloride, commonly used in this process, reacts aggressively with metal pumps. By selecting a pump with a plastic case, wastewater treatment providers can ensure their equipment is compatible with ferric chloride systems. Furthermore, in diaphragm pumps, ferric chloride can pose a threat of solid content becoming stuck under the ball valves that are keeping the
DISINFECTION AND NEUTRALISATION
Chemical disinfection involves the use of oxidising chemicals, such as sodium hypochlorite. However, oxidising chemicals off-gas, causing gas to be present in the fluid. This gas can block a diaphragm pump by preventing correct operation of the ball valves. Wastewater treatment providers can overcome this by selecting peristaltic pumps, which push any gas present in the fluid through the pump without causing any maintenance issues.
42 Water & Wastewater Asia | September-October 2024
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