Difference between revisions of "Flocculation"

==Process and technologies==

==Process and technologies==

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>

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>