Difference between revisions of "Flocculation"

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{{Infobox technology|Name=Flocculation|Category=Separation technologies}}
{{Infobox technology|Name=Flocculation|Category=[[Pre-processing]] ([[Pre-processing#Separation_technologies|Separation technologies]]), [[Post-processing]] ([[Post-processing#Separation_technologies|Separation technologies]])|Product=Solid phase (flocs) and liquid phase|Feedstock=Liquid phase with solid particles and, if applicable, flocculant}}
<onlyinclude>'''Flocculation''' refers to the "reversible aggregation of colloidal particles to larger particles that can be filtered"<ref>{{Cite book|author=Peter W. Atkins, Loretta Jones|year=2006|book_title=Chemie - einfach alles|publisher=Wiley-VCH|place=Weinheim|ISBN=978-3-527-31579-6}}</ref>. The IUPAC Gold Book uses coagulation and flocculation as synonyms of agglomeration and defines agglomeration as a "process of contact and adhesion whereby dispersed particles are held together by weak physical interactions ultimately leading to phase separation by the formation of precipitates of larger than colloidal size."<ref>{{Cite web|Author=The International Union of Pure and Applied Chemistry (IUPAC)|title=IUPAC - agglomeration (except in polymer science) (A00182)|url=https://goldbook.iupac.org/terms/view/A00182|year=|e-pub date=|date accessed=January 31, 2022}}</ref>
<onlyinclude>'''Flocculation''' refers to the "reversible aggregation of colloidal particles to larger particles that can be filtered"<ref>{{Cite book|author=Peter W. Atkins, Loretta Jones|year=2006|book_title=Chemie - einfach alles|publisher=Wiley-VCH|place=Weinheim|ISBN=978-3-527-31579-6}}</ref> or separated by sedimentation. The IUPAC Gold Book uses coagulation and flocculation as synonyms of agglomeration and defines agglomeration as a "process of contact and adhesion whereby dispersed particles are held together by weak physical interactions ultimately leading to phase separation by the formation of precipitates of larger than colloidal size."<ref>{{Cite web|Author=The International Union of Pure and Applied Chemistry (IUPAC)|title=IUPAC - agglomeration (except in polymer science) (A00182)|url=https://goldbook.iupac.org/terms/view/A00182|year=|e-pub date=|date accessed=January 31, 2022}}</ref>


Flocculation can be purposefully induced by adding ''flocculants''. "Flocculants are agents that make fine and subfine solids or colloids suspended in the solution form large loose flocs through bridging, thus achieving solid-liquid separation."<ref>{{Cite book|author=Shuying Wang, Jinyang Fu, Cong Zhang, Junsheng Yang|year=2021|section_title=Chapter 9 – Muck conditioning for EPB shield tunnelling and muck recycling – 9.3.1.5 Flocculants|book_title=Shield Tunnel Engineering : From Theory to Practice|publisher=Elsevier|place=Amsterdam, Netherlands|ISBN=9780128239926}}</ref></onlyinclude>
Flocculation can be purposefully induced by adding ''flocculants''. "Flocculants are agents that make fine and subfine solids or colloids suspended in the solution form large loose flocs through bridging, thus achieving solid-liquid separation."<ref>{{Cite book|author=Shuying Wang, Jinyang Fu, Cong Zhang, Junsheng Yang|year=2021|section_title=Chapter 9 – Muck conditioning for EPB shield tunnelling and muck recycling – 9.3.1.5 Flocculants|book_title=Shield Tunnel Engineering : From Theory to Practice|publisher=Elsevier|place=Amsterdam, Netherlands|ISBN=9780128239926}}</ref> Cells, for example, can be aggregated by adding multivalent cations, metal salts or polymers (for example, polyaluminum chloride).</onlyinclude>


==Feedstock==
==Feedstock==


=== Origin and composition ===
=== Origin and composition ===
The feedstock would usually be the feed that shall be separated by flocculation and (if used) the chosen flocculant.


=== Pre-treatment ===
=== Pre-treatment ===
The flocculant can be stored in powder form or in a solution. "Most commercial flocculants are synthetic water soluble polymers with average molecular weights in the region 1000 to 30 × 10<sup>6</sup>. They are generally supplied as powders that have a limited storage life, particularly when made up into solution."<ref>{{Cite book|author=E. S. Tarleton, R.J. Wakeman|year=2007|section_title=3 – Pretreatment of suspensions|book_title=Solid/liquid separation : equipment selection and process design|publisher=Butterworth-Heinemann|place=Oxford|ISBN=9781856174213}}</ref>


==Process and technologies==
==Process and technologies==
The choice of the flocculants strongly depends on the desired outcome and the particles that shall be flocculated.
The choice of the flocculant strongly depends on the desired outcome and the particles that shall be flocculated.


For the flocculation of micro algae in wastewater, biopolymer flocculants can be used, as described in ''Microalgae-Based Biofuels and Bioproducts'', 2017: "Polymer flocculants are polymers with charged functional groups. Polymer flocculants can induce flocculation by neutralizing the surface charge of particles or by forming bridges between individual particles. The functional groups should ideally be positively charged to allow for interactions with the negatively charged microalgal cells. Polymers are generally very effective at low dosages. In wastewater treatment, polyacrylamide-based flocculants are commonly used. Because they can contain potentially toxic acrylamide residues, flocculants based on natural biopolymers are preferred over synthetic polymers. An effective biopolymer flocculant for harvesting microalgae is chitosan, which is prepared by deacetylation of chitin. However, the cost of chitosan is relatively high due to its use in medical applications. Cheaper alternatives are cationic starch or tanfloc, which are, respectively, starch and tannins functionalized with quaternary ammonium groups."<ref>{{Cite book|author=K. Muylaert, L. Bastiaens, D. Vandamme, L. Gouveia|year=2017|section_title=5 – Harvesting of microalgae: Overview of process options and their strengths and drawbacks – 5.3.5 Biopolymer flocculants|editor=Cristina Gonzalez-Fernandez, Raúl Muñoz|book_title=Microalgae-based biofuels and bioproducts : from feedstock cultivation to end-products|publisher=Woodhead Publishing|place=Kindlington, United Kingdom|ISBN=9780081010235}}</ref>
=== Flocculation of microalgae ===
[[File:Floculación.png|alt=Schematic graphic: Flocculation of microalgae|thumb|Flocculation of microalgae]]
For the flocculation of microalgae in wastewater, biopolymer flocculants can be used, as described in ''Microalgae-Based Biofuels and Bioproducts'', 2017: "Polymer flocculants are polymers with charged functional groups. Polymer flocculants can induce flocculation by neutralizing the surface charge of particles or by forming bridges between individual particles. The functional groups should ideally be positively charged to allow for interactions with the negatively charged microalgal cells. Polymers are generally very effective at low dosages. In wastewater treatment, polyacrylamide-based flocculants are commonly used. Because they can contain potentially toxic acrylamide residues, flocculants based on natural biopolymers are preferred over synthetic polymers. An effective biopolymer flocculant for harvesting microalgae is chitosan, which is prepared by deacetylation of chitin. However, the cost of chitosan is relatively high due to its use in medical applications. Cheaper alternatives are cationic starch or tanfloc, which are, respectively, starch and tannins functionalized with quaternary ammonium groups."<ref>{{Cite book|author=K. Muylaert, L. Bastiaens, D. Vandamme, L. Gouveia|year=2017|section_title=5 – Harvesting of microalgae: Overview of process options and their strengths and drawbacks – 5.3.5 Biopolymer flocculants|editor=Cristina Gonzalez-Fernandez, Raúl Muñoz|book_title=Microalgae-based biofuels and bioproducts : from feedstock cultivation to end-products|publisher=Woodhead Publishing|place=Kindlington, United Kingdom|ISBN=9780081010235}}</ref>


Exemplary applications: Flocculation is used in biotechnology applications in conjunction with microfiltration to improve the efficiency of biological feeds. The addition of synthetic flocculants to the bioreactor can increase the average particle size making microfiltration more efficient. When flocculants are not added, cakes can form and accumulate causing low cell viability. Positively charged flocculants work better than negatively charged ones since the cells are generally negatively charged.
=== Exemplary applications ===


In the brewing industry flocculation is a very important process in fermentation during the production of beer where cells form macroscopic flocs. These flocs cause the yeast to sediment or rise to the top of a fermentation at the end of the fermentation. Subsequently, the yeast can be collected (cropped) from the top (ale fermentation) or the bottom (lager fermentation) of the fermenter in order to be reused for the next fermentation.
==== Improving fermentation feeds ====
Flocculation is used in biotechnology applications in conjunction with microfiltration to improve the efficiency of biological feeds. The addition of synthetic flocculants to the bioreactor can increase the average particle size making microfiltration more efficient. When flocculants are not added, cakes can form and accumulate causing low cell viability. Positively charged flocculants usually work better than negatively charged ones since the cells are generally negatively charged.


Yeast flocculation is primarily determined by the calcium concentration, often in the 50-100ppm range. Calcium salts can be added to cause flocculation, or the process can be reversed by removing calcium by adding phosphate to form insolubable calcium phosphate, adding excess sulfate to form insoluble calcium sulfate, or adding EDTA to chelate the calcium ions. While it appears similar to sedimentation in colloidal dispersions, the mechanisms are different.
==== Yeast flocculation ====
In the brewing industry flocculation is a very important process during the production of beer by fermentation where cells form macroscopic flocs. These flocs cause the yeast to sediment or rise to the top of a fermentation at the end of the fermentation. Subsequently, the yeast can be collected (cropped) from the top (ale fermentation) or the bottom (lager fermentation) of the fermenter in order to be reused for the next fermentation.
 
Yeast flocculation is primarily determined by the calcium concentration, often in the 50–100 ppm range. Calcium salts can be added to cause flocculation, or the process can be reversed by removing calcium by adding phosphate to form insolubable calcium phosphate, adding excess sulfate to form insoluble calcium sulfate, or adding EDTA to chelate the calcium ions. While it appears similar to sedimentation in colloidal dispersions, the mechanisms are different.


==Products==
==Products==


=== Post-treatment ===
=== Post-treatment ===
After the flocculation process, usually the flocs are separated from the liquid phase. This separation can simply be the sedimentation of the flocs, but they can also be separated by other techniques like [[sieving]], [[membrane filtration]], collection of the flocs at the top layer etc.


==Technology providers==
==Technology providers==
===Company name===
{| class="wikitable sortable mw-collapsible"
{{Infobox provider-flocculation}}
|+'''Technology comparison'''
The company description goes here.
! class="cd-text-darkgreen" style="vertical-align:{{{va|bottom}}}"| Company name
! class="cd-text-darkgreen" style="vertical-align:{{{va|bottom}}}"| Country
! class="cd-text-darkgreen" style="vertical-align:{{{va|bottom}}}"| Technology subcategory
! class="cd-text-darkgreen" style="vertical-align:{{{va|bottom}}}"| Technology name
! class="cd-text-darkgreen" style="vertical-align:{{{va|bottom}}}"| TRL
! class="cd-text-darkgreen" style="vertical-align:{{{va|bottom}}}"| Capacity [kg/h]
! class="cd-text-darkgreen" style="vertical-align:{{{va|bottom}}}"| Processable volume [L]
! class="cd-text-darkgreen" style="{{writing-mode|s2}};vertical-align:{{{va|bottom}}}"| Feedstock: Food waste
! class="cd-text-darkgreen" style="{{writing-mode|s2}};vertical-align:{{{va|bottom}}}"| Feedstock: Garden & park waste
|-
! style="height:1.8em;"|
!
!
!
!
!
!
!
!
|-
| [[Flocculation#Dewlink|Dewlink]]
| United Kingdom
| -
| Tubox® & Swingmill®
| 9
| -
| -
| class="cd-background-lightgreen cd-text-darkgreen" style="text-align:center" |●
| class="cd-background-lightgreen cd-text-darkgreen" style="text-align:center" |●
|-
| [[Flocculation#MVest_Water|MVest Water]]
| Norway
| -
| NORWAFLOC® / NORWAPOL
| 9
| -
| -
| class="cd-background-lightgreen cd-text-darkgreen" style="text-align:center" |●
| class="cd-background-lightgreen cd-text-darkgreen" style="text-align:center" |●
|}
 
=== Dewlink ===
{{Infobox provider-flocculation|Company=Dewlink Sludge Treatment Ltd.|Webpage=https://dewlink.com|Country=United Kingdom|Contact=info@dewlink.com|TRL=9|Technology name=Tubox® (Mixing tank with high speed mixing tube, creating a collision effect leading to faster flocculation) & Swingmill®|Feedstock=Sludge (Waste Activated Sludge, DAF Sludge, Chemical Sludge, Digested Sludge, Raw Sludge)|Product=Sludge / dewatered sludge and water|Agitator=High-speed mixing blade|Separation type=Flocculation|Image=Dewlink logo.png}}
Founded in Telford UK, '''DEWLINK SLUDGE TREATMENT LTD''' provides a simple and cost effective method of dewatering sludge and wastewater from many industrials.
 
The three main stages of sludge dewatering process (polymer dissolution, flocculation and dewatering) are indispensable.
 
We have used these processes as the main focus for our dewatering products. With our attention to details and the drive for perfection, we have developed a new system which is more efficient, stable, economical, intelligent, secure, convenient and environmentally friendly. This is a technical innovation in the solid-liquid separation industry and we believe this will change the pattern of the industry, promoting further development of technologies.
 
===MVest Water===
{{Infobox provider-flocculation|Company=MVest Water|Webpage=https://mvestwater.com|Contact=info@mvestwater.com|Country=Norway|Technology name=NORWAFLOC® (Natural & biodegradable flocculant/coagulant, combined into one product) / NORWAPOL (Polishing filtration process)|TRL=9|Feedstock=Wastewater from aquaculture, from fish slaughterhouse, sludge, wastewater from agriculture, from food & beverage industry|Separation type=Flocculation, filtration|Product=Potable water|Image=Mvest-Water-logo.png}}
'''M Vest Water''' is a leader in the development of high performance and environmentally responsible “green” water and wastewater treatment products and processes. The company was incorporated in 2017 by Norwegian Water Technologies AS and M Vest Invest AS. We have a singular and clear-cut mission: to realize a zero-discharge future. With our disruptive technology, we are already making significant strides towards achieving this goal.
 
NORWAFLOC<sup>®</sup>, a natural polymer flocculant, is our flagship product. Its combination of both natural polysaccharide-based flocculants and a highly charged coagulant in a single product means that it can be applied in just one dosing step. The combination of a biodegradable, natural polymer with a highly charged coagulant leads to a completely natural product that achieves even better results compared to traditional synthetic polymers or other biopolymers.
 
== Open access pilot and demo facility providers ==
== Open access pilot and demo facility providers ==
[https://biopilots4u.eu/database?field_technology_area_data_target_id=106&field_technology_area_target_id%5B81%5D=81&field_contact_address_value_country_code=All&field_scale_value=All&combine=&combine_1= Pilots4U Database]
[https://biopilots4u.eu/database?field_technology_area_data_target_id=106&field_technology_area_target_id%5B81%5D=81&field_contact_address_value_country_code=All&field_scale_value=All&combine=&combine_1= Pilots4U Database]
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==References==
==References==


[[Category:Hybrid processing]]
[[Category:Pre-processing]]
[[Category:Post-processing]]
[[Category:Technologies]]

Latest revision as of 10:47, 7 March 2023

Technology
21-04-27 Tech4Biowaste rect-p.png
Technology details
Name: Flocculation
Category: Pre-processing (Separation technologies), Post-processing (Separation technologies)
Feedstock: Liquid phase with solid particles and, if applicable, flocculant
Product: Solid phase (flocs) and liquid phase

Flocculation refers to the "reversible aggregation of colloidal particles to larger particles that can be filtered"[1] or separated by sedimentation. The IUPAC Gold Book uses coagulation and flocculation as synonyms of agglomeration and defines agglomeration as a "process of contact and adhesion whereby dispersed particles are held together by weak physical interactions ultimately leading to phase separation by the formation of precipitates of larger than colloidal size."[2]

Flocculation can be purposefully induced by adding flocculants. "Flocculants are agents that make fine and subfine solids or colloids suspended in the solution form large loose flocs through bridging, thus achieving solid-liquid separation."[3] Cells, for example, can be aggregated by adding multivalent cations, metal salts or polymers (for example, polyaluminum chloride).

Feedstock

Origin and composition

The feedstock would usually be the feed that shall be separated by flocculation and (if used) the chosen flocculant.

Pre-treatment

The flocculant can be stored in powder form or in a solution. "Most commercial flocculants are synthetic water soluble polymers with average molecular weights in the region 1000 to 30 × 106. They are generally supplied as powders that have a limited storage life, particularly when made up into solution."[4]

Process and technologies

The choice of the flocculant strongly depends on the desired outcome and the particles that shall be flocculated.

Flocculation of microalgae

Schematic graphic: Flocculation of microalgae
Flocculation of microalgae

For the flocculation of microalgae in wastewater, biopolymer flocculants can be used, as described in Microalgae-Based Biofuels and Bioproducts, 2017: "Polymer flocculants are polymers with charged functional groups. Polymer flocculants can induce flocculation by neutralizing the surface charge of particles or by forming bridges between individual particles. The functional groups should ideally be positively charged to allow for interactions with the negatively charged microalgal cells. Polymers are generally very effective at low dosages. In wastewater treatment, polyacrylamide-based flocculants are commonly used. Because they can contain potentially toxic acrylamide residues, flocculants based on natural biopolymers are preferred over synthetic polymers. An effective biopolymer flocculant for harvesting microalgae is chitosan, which is prepared by deacetylation of chitin. However, the cost of chitosan is relatively high due to its use in medical applications. Cheaper alternatives are cationic starch or tanfloc, which are, respectively, starch and tannins functionalized with quaternary ammonium groups."[5]

Exemplary applications

Improving fermentation feeds

Flocculation is used in biotechnology applications in conjunction with microfiltration to improve the efficiency of biological feeds. The addition of synthetic flocculants to the bioreactor can increase the average particle size making microfiltration more efficient. When flocculants are not added, cakes can form and accumulate causing low cell viability. Positively charged flocculants usually work better than negatively charged ones since the cells are generally negatively charged.

Yeast flocculation

In the brewing industry flocculation is a very important process during the production of beer by fermentation where cells form macroscopic flocs. These flocs cause the yeast to sediment or rise to the top of a fermentation at the end of the fermentation. Subsequently, the yeast can be collected (cropped) from the top (ale fermentation) or the bottom (lager fermentation) of the fermenter in order to be reused for the next fermentation.

Yeast flocculation is primarily determined by the calcium concentration, often in the 50–100 ppm range. Calcium salts can be added to cause flocculation, or the process can be reversed by removing calcium by adding phosphate to form insolubable calcium phosphate, adding excess sulfate to form insoluble calcium sulfate, or adding EDTA to chelate the calcium ions. While it appears similar to sedimentation in colloidal dispersions, the mechanisms are different.

Products

Post-treatment

After the flocculation process, usually the flocs are separated from the liquid phase. This separation can simply be the sedimentation of the flocs, but they can also be separated by other techniques like sieving, membrane filtration, collection of the flocs at the top layer etc.

Technology providers

Technology comparison
Company name Country Technology subcategory Technology name TRL Capacity [kg/h] Processable volume [L] Feedstock: Food waste Feedstock: Garden & park waste
Dewlink United Kingdom - Tubox® & Swingmill® 9 - - ● ●
MVest Water Norway - NORWAFLOC® / NORWAPOL 9 - - ● ●

Dewlink

Flocculation provider
General information
Company: Dewlink Sludge Treatment Ltd. Dewlink logo.png
Country: United Kingdom
Contact: info@dewlink.com
Webpage: https://dewlink.com
Technology and process details
Technology name: Tubox® (Mixing tank with high speed mixing tube, creating a collision effect leading to faster flocculation) & Swingmill® Technology category: Pre-processing (Separation technologies), Post-processing (Separation technologies)
TRL: 9 Capacity: kg·h-1
Agitator: High-speed mixing blade Processable volume: L
Reactor: Separation type: Flocculation
Other:
Feedstock and product details
Feedstock: Sludge (Waste Activated Sludge, DAF Sludge, Chemical Sludge, Digested Sludge, Raw Sludge) Product: Sludge / dewatered sludge and water

Founded in Telford UK, DEWLINK SLUDGE TREATMENT LTD provides a simple and cost effective method of dewatering sludge and wastewater from many industrials.

The three main stages of sludge dewatering process (polymer dissolution, flocculation and dewatering) are indispensable.

We have used these processes as the main focus for our dewatering products. With our attention to details and the drive for perfection, we have developed a new system which is more efficient, stable, economical, intelligent, secure, convenient and environmentally friendly. This is a technical innovation in the solid-liquid separation industry and we believe this will change the pattern of the industry, promoting further development of technologies.

MVest Water

Flocculation provider
General information
Company: MVest Water Mvest-Water-logo.png
Country: Norway
Contact: info@mvestwater.com
Webpage: https://mvestwater.com
Technology and process details
Technology name: NORWAFLOC® (Natural & biodegradable flocculant/coagulant, combined into one product) / NORWAPOL (Polishing filtration process) Technology category: Pre-processing (Separation technologies), Post-processing (Separation technologies)
TRL: 9 Capacity: kg·h-1
Agitator: Processable volume: L
Reactor: Separation type: Flocculation, filtration
Other:
Feedstock and product details
Feedstock: Wastewater from aquaculture, from fish slaughterhouse, sludge, wastewater from agriculture, from food & beverage industry Product: Potable water

M Vest Water is a leader in the development of high performance and environmentally responsible “green” water and wastewater treatment products and processes. The company was incorporated in 2017 by Norwegian Water Technologies AS and M Vest Invest AS. We have a singular and clear-cut mission: to realize a zero-discharge future. With our disruptive technology, we are already making significant strides towards achieving this goal.

NORWAFLOC®, a natural polymer flocculant, is our flagship product. Its combination of both natural polysaccharide-based flocculants and a highly charged coagulant in a single product means that it can be applied in just one dosing step. The combination of a biodegradable, natural polymer with a highly charged coagulant leads to a completely natural product that achieves even better results compared to traditional synthetic polymers or other biopolymers.

Open access pilot and demo facility providers

Pilots4U Database

Patents

Currently no patents have been identified.

References

  1. ↑ Peter W. Atkins, Loretta Jones, 2006: Chemie - einfach alles. Wiley-VCH, Weinheim.
  2. ↑ The International Union of Pure and Applied Chemistry (IUPAC), : IUPAC - agglomeration (except in polymer science) (A00182) , Last access January 31, 2022. https://goldbook.iupac.org/terms/view/A00182
  3. ↑ Shuying Wang, Jinyang Fu, Cong Zhang, Junsheng Yang, 2021: Chapter 9 – Muck conditioning for EPB shield tunnelling and muck recycling – 9.3.1.5 Flocculants. Shield Tunnel Engineering : From Theory to Practice. {{{editor}}} (Ed.). Elsevier, Amsterdam, Netherlands.
  4. ↑ E. S. Tarleton, R.J. Wakeman, 2007: 3 – Pretreatment of suspensions. Solid/liquid separation : equipment selection and process design. {{{editor}}} (Ed.). Butterworth-Heinemann, Oxford.
  5. ↑ K. Muylaert, L. Bastiaens, D. Vandamme, L. Gouveia, 2017: 5 – Harvesting of microalgae: Overview of process options and their strengths and drawbacks – 5.3.5 Biopolymer flocculants. Microalgae-based biofuels and bioproducts : from feedstock cultivation to end-products. Cristina Gonzalez-Fernandez, Raúl Muñoz (Ed.). Woodhead Publishing, Kindlington, United Kingdom.
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