Algae

11.8 ALGAE

You do not have to be a water or wastewater operator to understand that algae can be a nuisance. Many ponds and lakes in the U.S. are currently undergoing eutrophication, the enrichment of an environment with inorganic substances (e.g., phosphorus and nitrogen), causing excessive algae growth and premature aging of the water body. The average person may not know what eutrophication means,but when it occurs and especially when filamentous algae like Caldophora break loose in a pond or lake and washes ashore, algae makes its stinking, noxious presence known.Algae are a form of aquatic plants and are classified by color (e.g., green algae, blue-green algae, goldenbrown algae, etc.). Algae come in many shapes and sizes (see Figure 11.6). Although they are not pathogenic, algae do cause problems with water and wastewater treatment plant operations. They grow easily on the walls of troughs and basins, and heavy growth can plug intakes and screens. Additionally, some algae release chemicals that give off undesirable tastes and odors.

Algae are also commonly classified based on their cellular properties or characteristics. Several characteristics are used to classify algae including:
1. Cellular organization and cell wall structure
2. Nature of the chlorophyll(s)
3. Type of motility, if any
4. Carbon polymers that are produced and stored
5. Reproductive structures and methods

Many algae (in mass) are easily seen by the naked eye, while others are microscopic. They occur in fresh and polluted water, as well as in salt water. Since they are plants,they are capable of using energy from the sun in photosynthesis. They usually grow near the surface of the water because light cannot penetrate very far through the water. Algae are controlled in raw waters with chlorine and potassium permanganate. Algae blooms in raw water reservoirs are often controlled with copper sulfate. Note: By producing oxygen, which is utilized by other organisms including animals, algae play an important role in the balance of nature.

Algae bloom
a phenomenon whereby excessive nutrients within a river, stream, or lake causes an explosion of plant life that results in the depletion of the oxygen in the water needed by fish and other aquatic life. Algae bloom is usually the result of urban runoff (of lawn fertilizers, etc.). The potential tragedy is that of a “fish kill,” where the stream life dies in one mass execution. Algal bloom sudden spurts of algal growth that can affect water quality adversely and indicate potentially hazardous changes in local water chemistry.

Algae
simple plants, many microscopic, containing chlorophyll. Freshwater algae are diverse in shape, color, size, and habitat. They are the basic link in the conversion of inorganic constituents in water into organic constituents.

Excess algae can interfere with the simple pleasure of looking at a lake for its beauty. Unsightly scum is usually caused either by tangled masses of filamentous algae or by "blooms" of certain planktonic algae that float on the lake surface forming scums. The regular occurrence of visible algae blooms often indicates that nutrient levels, especially phosphorus, are too high.

Low Rainfall and high temperatures are often times a contributor to increased algae in ponds. Rain can tend to be a good dilution factor for pollutants. If there is no rain and high temperatures and high levels of evaporation, what normally is not considered polluted or high BOD becomes more concentrated and thereby, increases chances for algae growth.

10.6.7.3 Salts
When acids and bases chemically interact, they neutralize each other. The compound (other than water) that forms from the neutralization of acids and bases is called a salt.
Salts constitute, by far, the largest group of inorganic compounds. A common salt used in waterworks operations, copper sulfate, is utilized to kill algae in water.

Solutions for Algae Control

Traditional solutions
· Herbicides and Algaecides, Copper Sulfate and Bleach are traditional chemical methods that have been used in the past.
· Fountains and Aeration help increase mixing and aeration and increase normal biological activity, thereby lessening the chance for algae to grow.
· Mechanical cutting and removal of aquatic weeds or harvesting of duckweed is common, but high on manpower
· Mechanical spraying or brushing of clarifiers, weirs and surface areas will significantly help with treatment plants and algae removal
· Physical covers of clarifiers

· Bacteria- The use of non-toxic, environmentally friendly biological products in lakes and ponds has become very popular recently because it is natural and involves no use of herbicides or algaecides. Bacteria out-compete with the algae for nutrients and carbon. If the proper environmental conditions are there, bacteria can grow quicker and more efficiently. The pond is cleaner and no toxic chemicals or residuals result. Bacteria are then added on a maintenance dosage to keep the algae from growing.
· Surface-growing plants such as duckweed can provide natural cover. Duckweed, if kept from the effluent by inserting surface baffles in front of the effluent weir, is very effective toward reducing algae in the lagoon. Water Hyacinths also help with BOD reduction.