Wednesday, March 20, 2013

Verder Chemical Dosing in the Spotlight

Verder Chemical Dosing in the Spotlight

In this article Philip Brown, Project Manager for pumping solutions at Verder UK, explains the chemical dosing process, and how dosing techniques are commonly applied by Verder to the popular chemical dosing functions of pH buffering and phosphate removal.

Chemical Dosing

Chemical dosing is the controlled delivery of a chemical into contaminated water, sewage or sludge–like fluid, usually as a pre-processing method. It is frequently used during sewage treatment, and as part of the anaerobic digestion process for making energy from waste. Chemical dosing is also used when treating industrial effluents to remove contaminants, before it can be returned to a natural watercourse.

The Dosing Process

A set of chemical dosing equipment mounted on a "skid" (a relocatable metal frame) is the most effective way build a chemical dosing system to dispense chemicals. Most skid mounted assemblies use at least two peristaltic or reciprocating dosing pumps. These are attached to pipe manifolds and the whole unit is usually protected within a cabinet. 

In such arrangements one pump acts as a duty standby component to ensure the dosing process is uninterrupted in the event that a wearable component fails, and the system needs to be serviced. 

Normally, chemical dosing systems are set up with pumps and valves to accurately and automatically control the dosing process to inject a chemical into a pipe or vessel at a predetermined rate.

pH Buffering

Chemicals such as sodium hydroxide or lime are dosed in conjunction with pH measurement - a process known as pH buffering to ensure that the process runs in the optimum pH range for the reactions of the chemical process to take place. 

For sewage works systems the amount of buffering will vary according to the time of day; for example at a high rate in the morning when people use the toilet or bathroom, at a lower flow rate during the day, and back at a high  dosing rate in the evening when they finish work. As a result, dosing pumps need to increase the amount delivered at these peak demand times and reduce it during the hours of sleep, producing a diurnal, cyclical flow. 

Removing Phosphates Using a Unique Product Developed by Naiad Aquatic Water Services

Introduction of an iron-based chemical solution like ferrous or ferric sulphate or chloride can very effectively remove phosphates which are pricipitated out during a settlement stage. Alternatively ferrous sulphate can take the form of copperas crystal, a by-product of the pigment industry, which can be mixed in a tank with water in a unique patented process available from Verder, and provided in conjunction with Naiad Aquatic Water Services. 

Working in an exclusive collaboration with Verder UK, Naiad Aquatic Water Services, has developed a range of chemical dosing systems including the Naiad Copperas Saturator. 

The latter was developed in partnership with Thames Water’s R&D section to provide a cost-effective alternative to liquid dosing. Naiad chemical dosing systems incorporate feed-back and load profile control options, and enable process optimisation for phosphate removal and septicity control. When used to dose chemicals into sewage for phosphate removal, Verder's equipment ensures that phosphate residuals in the final effluent consistently meet targets, and odours are minimised. 

Verder takes pride in delivering pumping solutions that are designed around the needs of the customer, not off-the-shelf packages which are made-to-fit all, but which seldom fit any site's needs perfectly. Verder points out that their customer feedback regularly shows that the quality and robust nature of the company's end-product is superior to their competitors off-the-shelf solutions.

Verder has found by experience that the best outcomes come from their practice of involvement with engineers face-to-face, and by setting-up meetings to discuss their client's requirements in detail. Whether the setting is a boardroom, or on-site in "boiler suits", they place a high priority to always providing a professional service built upon courtesy and respect between contractor and customer. 

Philip Brown points out that ultimately, it all boils down to Verder's passion for saving water utilities as much money as possible, while at the same time always providing them with the most reliable and robust equipment.

Visit Verder's website for more information at

Author: Verder
Phone Number: +44(0)1924 221 001

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