Method for removing
View Patent ↗A method for stabilizing and removing Cryptosporidium oocysts or Giardia cysts from water. The method comprises adding chitosan, a salt or solution of chitosan to water containing Cryptosporidium oocysts or Giardia cysts and a halogenating agent. The method may also include adding a secondary polyelectrolyte flocculant to the water. The resulting flocs are filtered to remove the Cryptosporidium oocysts or Giardia cysts.
1. A method for removing Cryptosporidium oocysts or Giardia cysts from recreational water containing a halogenating agent, comprising:
adding chitosan to the water comprising Cryptosporidium oocysts or Giardia cysts and a halogenating agent, wherein the Cryptosporidium oocysts or Giardia cysts have been exposed to the halogenating agent for a period of time effective to oxidize at least a portion of the Cryptosporidium oocysts or Giardia cysts, before adding the chitosan to the water;
allowing the Cryptosporidium oocysts or Giardia cysts and the chitosan to form stabilized flocs in the water; and
filtering the flocs of the Cryptosporidium oocysts or Giardia cysts and chitosan to remove the Cryptosporidium oocysts or Giardia cysts from the water.
2. The method of claim 1 , wherein the chitosan is in solution.
3. The method of claim 2 , wherein the solution comprises acetic acid.
4. The method of claim 1 , further comprising adding an anionic or cationic polyelectrolyte flocculant to the water before, during or after adding the chitosan.
5. The method of claim 4 , wherein the polyelectrolyte flocculant comprises at least one of alginate, hexametaphosphate, carboxymethylcellulose, pectin, polyaluminum hydroxychioride, polyaluminum silicate sulfate, polyaluminum sulfate or polyacrylamide.
6. The method of claim 4 , wherein said polyelectrolyte flocculant is about 5 ppb to about 100 ppm by weight in water.
7. The method of claim 1 , wherein the water is in a swimming pool, spa, water park, hot tub, or bath.
8. The method of claim 1 , comprising filtering the floes in at least one of a sand, cartridge or diatomaceous earth filter.
9. The method of claim 1 , further comprising adding an inorganic aluminum coagulant.
10. The method of claim 9 , wherein said inorganic aluminum coagulant is aluminum sulfate or polyaluminum chloride.
11. The method of claim 9 , wherein the inorganic aluminum coagulant is about 50 ppb to about 100 ppm by weight in water.
12. The method of claim 1 , further comprising adding a ferric salt coagulant.
13. The method of claim 12 , wherein said ferric salt coagulant is ferric sulfate or ferric chloride.
14. The method of claim 12 , wherein said ferric salt coagulant is about 50 ppb to about 100 ppm by weight in water.
15. The method of claim 1 , wherein said chitosan is about 5 ppb to about 100 ppm by weight in water.
16. The method of claim 1 , wherein the halogenating agent comprises at least one of sodium hypochlorite, calcium hypochlorite, chlorine, hypochlorous acid, bromine, hypobromous acid, N-chlorosuccinimide, sodium hypobromite, pyridinium bromide perbromide, N-bromosuccinimide, chloramine-T, chlorhexadine, biguanides, dichlorodimethylhydantoin, bromochlorodimethylhydantoin dibromodimethylhydantoin, dichloroisocyanurate, or trichloroisocyanurate.
17. The method of claim 1 , wherein said halogenating agent is about 1 ppm to about 50 ppm by weight in water.
18. The method of claim 1 , wherein said halogenating agent is about 2 ppm to about 20 ppm by weight in water.
19. The method of claim 1 , comprising adding a halogenating agent to the water before adding chitosan.