Pumps for Coagulants and Flocculants in Wastewater Treatment 

Wastewater treatment is a critical process that ensures the safe disposal of contaminates, and reuse of leftover water in a number of industries such as mining, agriculture, food production and the petrochemical industry.    

For the effective treatment of wastewater, there are a number of steps that the process has to undergo, one of which is the addition of coagulants and flocculants to the fluid, which facilitate the removal of suspended solids.  

North Ridge Pumps, with decades of expertise in industrial pumping solutions, offers a comprehensive range of pumps designed specifically for this application. Our pumps are tailored to meet the unique demands of coagulation and flocculation, ensuring efficient and reliable operation in wastewater treatment plants. 

Understanding Coagulation and Flocculation 

Coagulation 

Coagulation involves the addition of chemicals, such as aluminium sulfate or ferric chloride, to destabilise fine particles that may be suspended in water. These coagulants cause the particles to group together into larger clusters, making it easier to separate solids from the liquid. 

Flocculation 

Following coagulation, flocculants are added to the fluid to encourage the grouped particles to bind together into larger, heavier clusters. These clusters, or flocs, sink to the bottom of the treatment tank, forming a sludge layer that can be separated from the water. 

Challenges in Coagulation and Flocculation 

The integrity of the chemicals used in this process relies on precise dosing and gentle handling.  Any damage to flocculants can significantly reduce their efficacy and cause contaminates to remain within the water.   

Wastewater treatment plants often experience varying process demands, such as seasonal changes or fluctuations in water quality, which require adaptable pumping solutions. 

Selecting the Right Pump for Coagulation and Flocculation Processes 

1. Shear Sensitivity 

Flocculants are particularly sensitive to shear forces, which can damage their structure and reduce their effectiveness. Pumps should operate with a slow and gentle pumping motion, ensuring that the flocculants remain intact during dosing or transfer. 

2. Accurate Dosing 

Precision is critical in the addition of coagulants and flocculants. Pumps should provide dosing accuracy greater than 99%, ensuring consistent treatment outcomes while minimising chemical waste. Other things to consider are; 

• Metering Method – Timed metering can be set to alter how the pump meters from amounts dosed over a set amount of time. Volume proportioning is beneficial where chemical concentration can fluctuate, and the volume of coagulants or flocculants need to be managed.  In this process, an external probe or sensor would be connected directly to the pump which would automatically adjust the volume of chemicals required for PH correction.  

• Operation – Start and Stop can be controlled remotely via an external input such as a float switch on a tank, a control signal from process, or 4-20ma analogue control directly connected to the unit. Accelerated maximum metering can be achieved by the pressing of a single button should an external sensor malfunction. 
  

3. Variable Speed Drives (VSD) 

Wastewater treatment demands can vary significantly due to factors such as seasonal algae blooms or changes in water quality. Variable-speed pumps allow operators to dynamically adjust dosing rates, ensuring consistent optimal performance. Additionally, pumps can be designed for continuous 24/7 operation, keeping flocculants in suspension within a closed-loop system when not actively dosing. 

4. Chemical compatibility 

Coagulants and flocculants used in wastewater treatment often contain chemicals that can be corrosive, abrasive, or reactive with certain materials. This means that; 

• Pumps must be constructed with materials that resist corrosion and degradation when exposed to the chemicals being transferred. Common materials include stainless steel, polypropylene, PVDF, or PTFE. 

• Seals and gaskets must also be compatible with the chemical composition of the coagulants and flocculants to prevent leaks and ensure longevity. Options such as Viton, EPDM, or PTFE are often recommended. 

• Pumps may be lined or coated with special materials to provide an additional layer of protection against chemical wear, especially for highly acidic or alkaline substances. 

5. Flow Rates 

The flow rate of a pump determines how much liquid can be transferred within a specific timeframe, which is a crucial factor in wastewater treatment where demand can vary.  Pumps should be selected based on their ability to handle peak flow demands while maintaining efficiency during lower demand periods. 

6. Reduced Engineering & External Accessories 

Using a pump specially designed for this application can streamline your process and reduce engineering requirements for process skids and eliminate the need for external accessories.  

This will ensure that non-return or pressure loading valves are unnecessary, and that the predictive flow can eliminate the requirement for an external flowmeter.   

Additionally, the need for a control panel can also be eliminated due to a superior remote interface.   This means that should any problems arise on site, visits by expensive on-site engineers to remote or difficult to access locations can often be avoided.  The unit can be accessed and controlled remotely, with onsite personnel guided over the phone or via on screen prompts on how to undertake maintenance of the one wearing part.  
 
7. Quality Control and Ease of Use 

• Access & Control: This type of pump offers flexible access options, with menu functions that can be restricted by passcode or hidden altogether. Remote access is fully supported, enabling seamless operation from any location. It is compatible with industry-leading process control systems, including PROFIBUS®, Profinet, and CANbus, and is fully IoT-capable for enhanced connectivity and integration. 

• Built In User Interface: The need for separate Human Interface (HMI) is eliminated and the locally attached display enables full control of the pump via intuitive touchscreen.  This displays essential performance information such as current flow, operating pressure, warnings in case of hose rupture, as well as stopping the pump prior to pump leakage. Should maintenance be required the interface visually guides users on how to replace the hose. 

Applications in Wastewater Treatment 

Specialised pumps are designed to meet the diverse needs of wastewater treatment plants, including: 

• Coagulant Dosing: Precise addition of coagulants to destabilise particles 

• Flocculant Transfer: Gentle handling to maintain chemical efficacy 

• Sludge Removal: Efficient pumping of settled sludge for further processing 

Explore Our Range 

North Ridge Pumps supplies a comprehensive range of pumps for varying industrial applications - view pumps for flocculation and coagulation applications here.