Chemical management and precise chemical dosing for different water treatment processes have never been smarter and easier. As populations and economies on the African continent grow, so does urbanisation and industrialisation, bringing increased investment in water infrastructure and the necessity for smart water treatment processes. For instance, as water-borne diseases become a worldwide concern, engineers begin to focus on reducing the risk of biological contamination in their water treatment systems.
Grundfos supports the industry with intelligent solutions that mitigate bacteria growth, keep water quality under control and ultimately reduce clean water costs. Everybody immediately recognises the value of clean and safe water, thus chemical management and costs are vital as water treatment requires extremely accurate dosing of chemicals. Maintaining proper water quality and avoiding interference with overall plant efficiency is critical, but manual chemical preparation and dosing are fraught with human error and high costs from chemical overdosing.
Digital dosing technology took a quantum leap when the Grundfos DDI-60 and 150 “Digital dosing pumps” were released in 2006/7. The accuracy of the dosing pumps became best in the industry with a turndown ratio of 800:1 including several new features. In 2010, the next generation of “Grundfos SMART Digital” pumps was launched, with even more features. Turn down ratios of 1000:1 and up to 3000:1 on certain models was part of this generation. The range was expanded from 30l/hr up to 200l/hr with the release of the “Grundfos SMART Digital XL” range in 2017.
The main advantage of SMART digital dosing pumps is the exceptionally wide dosing range of dosing rates, whilst maintaining high accuracy. Thus, concentrated chemicals can now be dosed without the need to dilute chemicals into day tanks. This reduces chemical handling equipment and tasks on site. A further advantage of SMART digital dosing system is that the pumps are available with onboard intelligence so that the pumps can communicate with PLC systems via digital, analogue or industrial data networks. No need for electric starters, VSD’s or servo motor control systems resulting in cost savings, says Albert de Vos, Aquatechnica.
Modern digital dosing pumps, such as those incorporated in systems can deliver the needed amount of chemicals with high precision. The integrated AutoFlowAdapt makes additional monitoring and control devices redundant. One such system involved our Water Treatment Partner, Aquatechnica; the contractor, PCI SA; the Nooitgedacht Water Treatment Works of Nelson Mandela Bay; and required accurate polymer dosing to remove the content in one example of a water treatment process. A prerequisite was fast and simple integration into the existing process and PLC, along with intuitive user-friendliness of the product.
The tender for the extension of the Nooitgedacht Water Treatment Works was based on conventional cam-operated dosing pumps with manual adjustment. This type of pump has a turndown ration of only 10:1. If operated in conjunction with a VSD (i.e. variable speed control of the electric motor) a turndown ratio of around 100:1 can be achieved. Aquatechnica offered a solution by using the new Grundfos SMART Digital DDA60-10 FCM dosing pump as an alternative to what was described in the original tender enquiry.
The solution was 16 x DDA60-10 FCM SMART Digital Dosing pumps installed in duty standby arrangement into 8 x plug-and-pump dosing systems that were expertly designed, aptly equipped and easily wall mountable. The Grundfos SMART digital dosing pump technology of the stepper motor provided smooth continuous dosing flow. An integrated flow monitor controls this flow and provides feedback about the actual flow in comparison to the set point. In addition, the Grundfos SMART Digital Dosing range provided modular pumps for easy integration into the existing process
The solution also included 16 x Grundfos CIU (Communication Interface Unit), these innovative units made for easier system integration and communication between the PLC and pumps via Modbus TCP. CIU’s provide a plug-and-pump concept by allowing for communication via many different protocols. With our AutoFlowAdapt, dosing process malfunctions are detected, and environmental changes are compensated, so that the required target flow rate, smart chemical management and proper water quality are achieved. In general, the AutoFlowAdapt function compensates for fluctuating system pressure, automatically and continuously to ensure dosing accuracy is maintained.
After three months of discussion, the approval was given to proceed with the latest Grundfos technology. The equipment was supplied as pre-mounted systems including the auxiliary equipment as required for the specific application. The advantage of the pre-mounted systems is that they are factory tested (and inspected), reducing installation time and risk. The customer was impressed with the clear display menu structure providing the needed information that eases the lives of system operators in their daily work.