HMGA Water Project
  • Home
  • Project Overview
    • Project Description
    • Project Team
    • Collaborative Projects
    • FAQ
  • Publications
    • Blog
    • Factsheets
    • News Articles
  • Events
  • Gallery
  • Dedirting
  • Contact

Clarifying the Solid Removal Process

3/28/2016

4 Comments

 
Picture
Figure 1: Examples of creaming in settling tanks
When working with small particle removal, experience has shown that the addition of chemical coagulants or flocculants is usually a necessity. The question is what is the best method of applying this system?

First, all the applicable terms need to be defined:
  1. Clarification: this term can be used to describe the overall process of removing fine particles from water
  2. Coagulation: is the act of neutralizing the charges of particles that allow them to repel each other.
  3. Flocculation: occurs when neutralized (coagulated) particles are brought together to form larger compounds called ‘flocs’
  4. Sedimentation: separating solids from water through settling
  5. Creaming/Flotation: separating solids from water by floating them to the surface
  6. Dewatering: separating solids from water through filtration

The first stage in the clarification of water is coagulation. When small particles are involved, coagulation usually has to be achieved through the addition of chemical aids. The next stage is flocculation and whether or not another chemical is required here is dependent on the particles and the desired speed of floc formation. The final stage is separating the flocs from the water.
Picture
Figure 2: Coagulation, flocculation, creaming, sedimentation, and dewatering
Floc separation can occur three different ways: sedimentation, creaming, or dewatering. The method chosen will depend on the type of flocs as some will naturally sink and others will prefer to float. It is important to match the coagulant and flocculant chemicals, floc behaviour, and method of separation to make a clarification system operate properly and efficiently.
Each separation method has its own challenges including infrastructure needs. Sedimentation is most commonly completed using a settling tank. The separated solids will need to be scooped out regularly so the tank has sufficient room to collect solids. Creaming is associated with air flotation where solids either naturally float or are aided with dissolved air carrying solids upwards. The solids are then skimmed off the water surface. Dewatering uses filters to collect the solids behind a membrane. The membrane will require regular cleaning or replacement when the solids clog the pores. Water used to clean the membranes will also need to be considered for further treatment.
References
  • Tramfloc, Inc. (2014). Selecting Polymers, Jar Testing Procedures. In Flocculants. Retrieved March 14, 2016, from http://tramfloc.com/polymers-selection-jar-testing-procedures/
  • GE Power & Water. (2012). Chapter 05 - Clarification. In Handbook of Industrial Water Treatment. Retrieved March 14, 2016, from http://www.gewater.com/handbook/ext_treatment/ch_5_clarification.jsp
4 Comments

Dissolved Air Flotation

3/14/2016

1 Comment

 
Dissolved Air Flotation, referred to by its acronym of DAF, is a method of removing contaminants from wastewater that have a tendency to float, such as fine solids. Pressurized air is injected into a water stream which is commonly sourced from post-treatment clarified water. That water is mixed with the incoming untreated water where the dissolved air is no longer pressurized and comes out of the solution in tiny bubble form. These bubbles attach to the contaminants and together they rise to the surface. The contaminants can then be skimmed off and disposed. Clarified water exits through the bottom of the tank to ensure the floating contaminants do not continue past the unit.
Picture
Figure 1: Diagram of a DAF unit (Komline-Sanderson, 2015)
The solids to be removed may be too fine to be caught by the rising bubbles. In these cases, coagulants and/or flocculants are used to aggregate them into larger clusters. The coagulants and flocculants are added either in a preceding tank or piping system.
​
DAF systems will have a smaller footprint than a settling system as there is more active movement in a DAF system. It is an indoor system as it should not freeze. The timing of any chemical additions for aggregation of soils must be carefully considered as it will take time to properly bind the solids. If they are added too close to the DAF, full flocculation will not occur and that chemical will be wasted.

​References
  • Mundi, G. S. (2013). Assessment of Effective Solids Removal Technologies to Determine Potential for Vegetable Washwater Reuse (Master's thesis). NovemberRetrieved from https://atrium.lib.uoguelph.ca/xmlui/bitstream/handle/10214/7737/Mundi_Gurvinder_201312_Msc.pdf?sequence=3
  • Komline-Sanderson. (2015). Applications. In Dissolved air flotation. Retrieved December 14, 2015, from http://www.komline.com/images/tab_DAF_app.png
1 Comment

    Project Updates

    Find articles on project-related topics here

    Archives

    December 2016
    October 2016
    September 2016
    July 2016
    June 2016
    May 2016
    April 2016
    March 2016
    February 2016
    January 2016
    December 2015
    November 2015
    October 2015
    September 2015
    August 2015
    July 2015
    June 2015
    May 2015
    April 2015
    March 2015
    February 2015
    January 2015
    December 2014
    November 2014
    October 2014
    September 2014

    Topics

    All
    Aerators
    Coagulation & Flocculation
    Deionization
    Discharge Characterization
    Drum Filter
    Filter Bags
    General Information
    Hydrocyclone
    Lake Simcoe
    Lesson Learned
    Muck
    Nottawasaga Valley
    Pre Treatment
    Pre-Treatment
    Sampling
    Settling Ponds/Tanks
    South-Eastern Georgian Bay
    System Evaluation
    Treatment Technologies
    Ultrafiltration
    Washing Process
    Water Quality Parameters
    Watershed

    RSS Feed

    Article Titles

    Introduction to
      Watersheds

    Lake Simcoe Watershed
    Nottawasaga Valley
      Watershed
    South-Eastern Georgian
      Bay Watershed
    Water, Water,
      Everywhere?
    The Trouble with Muck:
      Size
    Lesson Learned: Bottom-
      up Aerator to Treat
      Washwater in Settling
      Tanks
    Phosphorus, the
      Environment, and
      Farming
    Nitrogen’s Impact on Air,
      Land, and Water
    Water-borne Pathogens
      and Food Safety
    Defining Dissolved
      Oxygen
    Filter Bags
      Demonstration Site
    Organic Matter
      Breakdown &
      Biochemical Oxygen
      Demand
    Dealing with Cloudy
      Water
    Hydrocyclone
      Demonstration Test
    What IS Muck?
    Demystifying Oxidation-
      Reduction Potential
    News Release
      "Technology
      Investigation: Filter
      Bags"
    Drum Filter
      Demonstration Site
    Decomposing With(out)
      Oxygen
    Flow monitoring
    Lesson Learned: Drum
      Filter Optimization
    Polders & the Holland
      Marsh
    Vegetable Washing
      Process
    ​Dry Soil Removal
    Ultrafiltration &
      Deionization
      Demonstration Site
    News Release
      "Technology
      Investigation:
      Ultrafiltration &
      Capacitive Deionization"
    Progressive Passive
      Filtration
    ​Dissolved Air Flotation
    Clarifying the Solid
      Removal Process
    Factsheet Reading Order
    News Release:
      "Technology
      Investigation:
      Coagulation &
      Flocculation"
    Self-Indexing Filter
    Monitoring Discharge
    ​  Flows
    Settling Soil
    Mass Loading
      Calculations
    Lesson Learned:
      Technology Selection
    Electrocoagulation
    Auto-Samplers
Powered by Create your own unique website with customizable templates.