Clarification / Sedimentation
Clarification discharge
Sedimentation has been the mainstay process for solid-liquid separation in the water and wastewater industry since its inception, based upon the simple fact that because solids are heavier than water, they will settle in a quiescent basin. This belies some of the complexities of the detailed design of settlement basins, be they clarifiers or thickeners, and the mechanisms required to ensure that they function correctly and reliably in the given application. Ovivo’s expertise and offering in this field is second to none. Our application experience covers: circular, rectangular, conical and flat bottom tanks. Various clarifier (scraper) bridges are available together with innovative designs to encourage settlement and mixing of coagulants when used.
Further Details
A simple Stokes Law approach is often unsuitable, due to:
- The impact of fats, oils and greases on grit and primary settlement
- Coagulation and flocculation of colloidal particles
- The essential requirement for rapid sludge removal after biological nutrient removal
Coupled with this, the actual areas of a clarifier or settlement tank have to be designed to optimize their function for overall effective operation, such as:
- The inlet and feedwell configuration, to ensure effective distribution and to avoid short circuiting
- The dewatering zone, the bottom slope and sludge removal configuration, to maximize sludge concentration, but avoid rat holing
- Launder and weir design, which should ensure effective collection of clear water and to avoid sludge carry over
Tank Design
All of these issues have been addressed in those areas of the world that have been treating their water and sewage for many years, and certain customs, traditions and design norms have developed to capture this plethora of detailed design options; for example:
- Rectangular or circular design bridge and drive design, center or peripheral
- Echelon, logarithmic spiral or simple rake design
- Inlet configuration: concrete feedwell, center column, peripheral pipe
Our Expertise
In recent years, many optimizations have been introduced to enhance the performance of sedimentation systems, some of which have been successful, and some not. With the increased use of membrane separation, many people believe that the sedimentation tank has had its day, but Ovivo believe that it will remain a key option for designers of water and wastewater treatment systems.
As a consequence of the perceived simplicity of the sedimentation tank, many sedimentation units are purchased and installed that are less than optimal. At Ovivo, our experts will evaluate a client’s requirements in order to design an optimized solution to match the identified need.
Drive Design
Convenient, economical service is a priority for Ovivo, and we are proud of our reputation for delivering drives that are economical and simple to maintain.
Our sedimentation drives are designed and built for long service, and in strict compliance with applicable standards. Each component within every one of our drives is engineered to exceed the requirements for 20 years’ continuous duty, and it is widely recognized that just routine maintenance has enabled many of our drives to still be operational after 30 or 40 years of continuous service – with their original gears and bearings.
Ovivo Solutions
Ovivo have the experience and the knowledge to offer optimal design solutions - we are serious about sedimentation. Our heritage brands represent the largest installed base of sedimentation tanks across the world, featuring rectangular and circular shaped tanks centre and peripheral drive designs.
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