Peristaltic pumps are a type of positive displacement pump used to move fluids through a system. A peristaltic pump operates on a simple principle involving the compression and relaxation of a flexible tube or hose. Here's how it works:
The pump consists of a flexible tube or hose made of materials like silicone, rubber, or other elastomers. This tube is positioned inside a casing or housing. Inside the pump casing, there are rollers or shoes mounted on a rotor. The rotor is usually driven by an electric motor.
The image above shows a range of peristaltic pumps manufactured by Blue-White.
As the rotor turns, the rollers or shoes rotate, pressing against the flexible tube. This action creates a squeezing or compressing effect on the tube, which decreases its internal volume. This compression moves along the length of the tube in a wave-like motion, much like the way a hand would squeeze toothpaste from a tube. As the tube is compressed, it creates a vacuum behind the point of compression. This vacuum draws fluid into the tube from the inlet side. As the compression moves along the tube, the fluid is propelled forward towards the outlet side. The flexible nature of the tube prevents fluid from flowing backward, ensuring one-way flow.
The process of compression and relaxation repeats continuously as the rotor turns, resulting in a steady flow of fluid through the pump. As with all PD pumps, flow rate of the peristaltic pump can be adjusted by controlling the speed of the rotor. Slowing down the rotor decreases the frequency of compression cycles, reducing the flow rate, while increasing the rotor speed increases the flow rate.
One of the advantages of peristaltic pumps is that the fluid only comes into contact with the interior surface of the flexible tube, minimizing the risk of contamination or damage to the pump components.
In wastewater treatment, peristaltic pumps are commonly used for various applications due to their ability to handle abrasive, viscous, and corrosive fluids without contaminating the pump itself. They have a variety of uses, some of which are listed below:
Peristaltic pumps are often used to accurately meter chemicals such as coagulants, flocculants, disinfectants, and pH adjusters into wastewater treatment processes. Their precise flow control ensures the correct dosing of chemicals, which is crucial for effective treatment.
These types of pumps can be used for sampling wastewater at different points in the treatment process. They can collect representative samples without contaminating the sample or the pump itself, making them ideal for quality control and monitoring purposes.
They can also handle thick, abrasive sludge and transfer it from one stage of treatment to another, such as from settling tanks to digesters or dewatering equipment.
Aeration Control: Peristaltic pumps can be employed to control the flow of air or oxygen into aeration tanks in biological wastewater treatment processes. By precisely regulating the air flow, peristaltic pumps help maintain the ideal environment for aerobic bacteria to break down organic matter in the wastewater.
Apart from metering chemicals, peristaltic pumps can also be used for transferring chemicals between different treatment stages or storage tanks. Their ability to handle a wide range of chemicals without contamination makes them versatile in various wastewater treatment applications.
Peristaltic pumps are valued for their simplicity, reliability, and versatility in various applications where precise and gentle fluid handling is required.
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