Algaecides that kill algal blooms without effecting other aquatic animals.

1. West Bengal university of animal and fishery sciences
Faculty of Fishery
Sciences
Submitted to
Prof. T .J . Abraham
Department of AAH
Submitted by
Shrija Majumder
F/2021/30

2. An Assignment on-

3. Table of contents
01
04
02
05
03
06
Introduction Types of Algaecides Algae Matters
Methods of
application
General
Effectiveness
Considerations

4. INTRODUCTION
• Algaecide is a biocide used for killing and preventing the
growth of algae, often defined in a loose sense that, beyond
the biological definition, also includes cyanobacteria ("blue-
green algae").
• An algaecide may be used for controlled bodies of water
(reservoirs, golf ponds, swimming pools), but may also be
used on land for locations such as turfgrass.

5.  Algae blooms can clog filters and otherwise
increase treatment costs and efforts. Historically,
copper sulfate and other algaecides have been used
to destroy this excessive biomass before it enters
the drinking water treatment plant.
 Other methods involving metals (Al, Fe, Cu, Ag,
Ca), photosensitizers (hydrogen peroxide, cyanines,
TiO2), herbicides, and chemicals derived from
natural compounds have proven effective in
managing harmful algal blooms (HABs) as well.
Chemical methods have a higher likelihood of
toxicity and non-target response than other
available methods.

6. TYPES OF ALGAECIDES
Natural
Algaecides
Natural
Alagaecides
Synthetic
Alagaecides

7. Natural
Algaecides
Natural algaecides are allelopathic chemicals (i.e., chemicals that inhibit the
growth of a plant that are naturally released by a different plant). The efficacy
for natural algaecides is typically more gradual than other types of algaecides,
allowing the system to accommodate increased oxygen demand associated with
algal mortality upon application.
Example :- Barley straw.

9. Synthetic Algaecides
 Copper has been a known biocide of marine and
freshwater organisms for hundreds, even thousands, of
years.
Ex: copper sulphate, chelated copper compounds.
 Synthetic organic algaecides are absorbed by algae and
contain “membrane active” chemicals that disrupt algae
metabolism.
 Oxidizer algaecides kill algae by rupturing the cell
membranes; however, oxidizers can also disrupt other
cellular functions.
Ex: sodium carbonate peroxyhydrate.

11. Algae matters
 Algaecides are used to control many species of planktonic, filamentous,
and branched algae. The most common causes of taste and odour
problems in drinking water are due to algae byproducts.
 Cyanobacteria produce toxins as secondary metabolites. There are three
primary classes of cyanotoxins:1) Hepatotoxins 2) Neurotoxins and 3)
Dermatotoxins .
 Filter run times in water treatment facilities can be directly affected by
the level of primary production in water bodies. The clogging of
treatment plant filters increases the cost of treatment.

12.  Extensive algal growth can affect water quality and aquatic
habitats. Algal blooms may reduce water clarity.
 Algae blooms can reduce aesthetic appeal of reservoirs, lakes, and
rivers.
Continues,

13. Methods of Application
Algaecides should be applied in a uniform manner.
 Surface application: Spraying a diluted mixture of algaecide from the shore or
a boat evenly across the surface of the water.
 Subsurface application: In deeper water, the algaecide is applied through a
weighted hose or other sub-surface delivery system to concentrate application
where the greatest concentration of algae is present.
 Polymer application: A polymer may be added to certain algaecides to
improve sinking and deposition and minimize loss (e.g., due to spraying).
 Aircraft application: Algaecide is applied as a spray from aircraft (e.g., plane
or helicopter).
 Drip system application: For application of algaecide in irrigation conveyance
systems and other moving water.

15.  Algaecides can be effective for controlling or reducing the growth
of unwanted algae.
 Algae are difficult to control long term.
 Algaecides will eliminate all algae or their spores.
 The efficacy of algaecides is short-lived in water.
 The efficacy of copper-containing algaecides can be impacted
under certain environmental conditions.
 Copper is less effective in waters with high alkalinity and pH.
General Effectiveness

16. Consideration
 Cell lysis: 1. Algaecides must be used with particular caution
2. Algaecides should be used when cell numbers are low.
 Chemicals and water quality standards:1. Chemicals used for algaecides must not
be applied in doses.
2.Chemicals in algaecides do not degrade,
and once applied, may persist in water bodies indefinitely.
 Non-target organisms: Algaecides can be toxic to non-target organisms.
 Short- vs. long-term management: Algaecides are generally a short-term solution to
a pending bloom..
 Permitted algaecides: Only use U.S. EPA- and State-approved algaecides.

17.  Water body characteristics: Determine current pH, alkalinity, and
DOC.
 Drinking water supply treatment: Treatment should be triggered
by changes in water quality.
 Monitoring: For all algaecides, monitor for effects on target and
non-target organisms.
Continues,

18. Effects of Chemical Algaecides
 Copper, silver compounds:
 Advantages: Extremely low price.
 Disadvantages: Toxicity against non-target species, accumulation in the environment
and release of toxins from algal cells after treatment .
 Hydrogen peroxide :
 Advantages: Low price, low toxicity for non-target species, fast degradability,
selective towards cyanobacteria.
 Disadvantages: Risky manipulation with concentrated hydrogen peroxide, fast
degradability (short time of action), risk of release of toxins from algal cells after
treatment.

19.  Phthalocyanines:
 Advantages: High toxicity towards photoautotrophs, biodegradable.
 Disadvantages: Insufficient knowledge about toxicity towards fish and
macrophytes, blue/green coloration, risk of release of toxins from algal cells
after treatment.
 Titanium dioxide and other insoluble photosensitizers:
 Advantages: Toxicity towards photoautotrophs via ROS production.
 Disadvantages: Insoluble in water.

20.  Herbicides (diuron, endothall, atrazine, simazine and others):
 Advantages: Low price, toxicity towards photoautotrophs.
 Disadvantages: Toxicity against non-target species, accumulation in the
environment, toxic residues, release of toxins from algal cells after the
treatment.
 Chemicals derived from natural compounds:
 Advantages: Effective in low concentrations, biodegradable, natural
products.
 Disadvantages: Preparation of extracts or isolation of alkaloids in high
amounts. Unknown toxicity towards other non-target species, price for
extraction/synthesis, risk of release of toxins from algal cells after treatment.

21. Thank
You