Coagulation Equipment Information
Coagulation equipment promotes the destabilization and initial aggregation (flocculation) of finely divided, suspended solids by the application of a magnetic field, the addition of a coagulant, or a biological process.
The process of coagulation causes suspended colloidal particles in the liquid to group together and form colloids, resulting in thickening or curdling. Milk and blood are common examples of solutions that coagulate due to biological factors, such as the presence of bacteria and tissue. Coagulation equipment for environmental, industrial, and medical applications does not normally implement a biological process but instead induces coagulation through chemicals or electric charge.
Coagulation equipment has two main areas of use, the medical industry and the wastewater treatment industry. In the wastewater treatment industry, coagulation is induced to remove contaminants from water. This process is carried out either by electrocoagulation or through chemical means.
Electrocoagulation uses electricity to induce coagulation. Electric charge is dispersed through a solution and reduces colloid charge, causing the particles to become suspended in the water. Electrocoagulators are becoming more common due to decreasing energy costs and ever-present wastewater treatment needs. They treat wastewater containing foodstuff, oil, dyes, pulp and paper, mining and metal processing, mechanical polishing, and organic matter from landfill leachates.
Chemical coagulation uses aluminum sulfate or poly aluminum chloride to neutralize charges in a solution and encourage flocculation (clumping or binding together of particles). Coagulants are added and stirred vigorously into the solution. The equipment that distributes and mixes coagulants vary based on the type of application and scale of the system.
In the medical field coagulators encourage blood clotting and also destroy harmful tissue.
Coagulation analyzers provide physicians with hemostasis (the process of stopping bleeding) test results from patients. They are used as point-of-care testing devices in cardiothoracic surgical suites and cardiac catheterization laboratories. Clinicians use results from coagulation analyzer tests to monitor the effectiveness of heparin therapy, an anticoagulation therapy used during cardiopulmonary bypass surgery, angioplasty, hemodialysis, and other clinical procedures.
Electrocautery equipment is used by surgeons to stop bleeding and provide hemostasis. An example of a hemostasis instrument is the hemostatic scalpel blade, which is a type of cutting and coagulating thermal scalpel blade. This type of coagulation equipment maintains the clean cutting characteristics of a traditional steel scalpel while simultaneously sealing blood vessels. Another example is a hemostasis valve, is used for catheters and comprises an elastomeric partition valve secured in a housing.
Selecting a coagulator depends largely on the type of process and application for which it is being used. In treating wastewater, a coagulator must be fit to the size of the system it is treating and must also use techniques (either electrocoagulation or chemical coagulants) that are both cost-effective and treatment-effective for the process. An analysis of the chemistry in the wastewater will determine the type of materials necessary for designing the equipment as well as those needed as coagulants. For medical processes, tools and equipment are specific to the type of medical procedure being implemented.
Video credit: Analytican Biotechnologies/CC BY 3.0
- Channels (performance): The number of channels in coagulation equipment vary from one up to four channels. The number of channels means the number of testing channels for different parameter analysis at the same time. Example would be a 4 channel coagulation analyzer can perform 4 different analysis at the same time.
- Configuration: Bench-top or portable
- Display: LCD, LED, Graphic
- Test types (parameters): PT, aPATT, TT, FIB, FAC, D-DIMER, APTT
- Assays performed: clotting, chromogenic, immunologic, and immunoturbidimetric
- Coagulation works in automatic or semi-automatic operation
Factors affecting coagulation operations are temperature, sequence of chemical addition, and residual aluminum.
- Temperature significantly affects coagulation operations, particularly for low turbidity waters, by shifting the optimum pH.
- Sequence of chemical addition is traditionally is to first add chemicals for pH correction, then add the metal coagulant, then add the flocculant aid. However, there are instances when other sequences are more effective. The best sequence for a particular application can be determined by jar test experiments.
- Residual aluminum, if the aluminum is in particulate form, indicates improvements to filter retention or whether it is soluble, which would require improving the chemistry of coagulation, particularly the pH before filtration.
Factors affecting the efficiency of the coagulation-flocculation process include the following.
- Type of coagulant used
- Coagulant dosage
- Final pH
- Coagulant feed concentration
- Intensity and duration of mixing at rapid mix stage
- Flocculator retention time
- Type of dosage of chemical additives other than primary coagulant (e.g. polymers)
- Flocculator geometry
- Type of stirring device used
- Sequence of chemical addition and time lag between dosings
- Velocity gradients applied during flocculation stage