«Relationship of Algae to Water Pollution and Waste Water Treatment Bulent Sen, Mehmet Tahir Alp, Feray Sonmez, Mehmet Ali Turan Kocer and Ozgur ...»
Relationship of Algae to Water Pollution and
Waste Water Treatment
Bulent Sen, Mehmet Tahir Alp, Feray Sonmez,
Mehmet Ali Turan Kocer and Ozgur Canpolat
Additional information is available at the end of the chapter
Pollution of surface water has become one of the most important environmental problems.
Two types of large and long-lasting pollution threats can be recognized at the global level:
on the one hand, organic pollution leading to high organic content in aquatic ecosystems and, in the long term, to eutrophication. It is a well-known fact that polluted water can reduce water quality thus restricting use of water bodies for many purposes.
Organic pollution occurs when large quantities of organic compounds from many sources are released into the receiving running waters, lakes and also seas. Organic pollutants originate from domestic sewage (raw or treated), or urban run off, industrial effluents and farm water. Organic pollution could negatively affect the water quality in many ways.
During the decomposition process of organic water dissolved oxygen in the water may be used up greater rate than it can be replenished thus, giving rise to oxygen depletion which causes severe consequences on the aquatic biota. Organic effluents also frequently contain large quantities of suspended solid which reduce the light available to photosynthetic organisms mainly algae. In addition organic wastes from people and animals may also rich in disease causing (pathogenic) organisms [1,2,3].
2. Algae and water pollution Algae are the main the primary producers in all kinds of water bodies and they are involved in water pollution in a number of significant ways. Firstly, enrichments of the algal nutrients in water through organic effluents may selectively stimulate the growth of algal species producing massive surface growths or ‘blooms’ that in turn reduce the water quality and affect its use. However, certain algae flourished in water polluted with organic wastes play an important part in “self-purification of water bodies”. Some pollution algae may © 2013 Tahir Alp et al., licensee InTech. This is an open access chapter distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
336 Water Treatment frequently are toxic to fish and also mankind and animals using polluted water. In fact, algae can play significant part of food chain of aquatic life, thus whatever alters the number and kinds of algae strongly affects all organisms in the chain including fish.
Algae are also known to be causes of tastes and odors in water . In fact, a large number of algae are associated with tastes and odors that vary in type. Certain diatoms, blue-green algae and coloured flagellates (particularly Chrysophyta and Euglenophyta) are the best known algae to pose such problems in water supplies, but green algae may also be involved.
Some algae produce an aromatic odor resembling to that of particular flowers or vegetables.
In addition, a spicy, a fishy odor and a grassy odor can also be produced by odor algae [5,6].
3. Algae as bioindicators Bioindicator organisms can be used to identify and qualify the effects of pollutants on the environment. Bioindicators can tell us about the cumulative effects of different pollutants in the ecosystem and about how long a problem may persist. Although indicator organisms can be any biological species that defines a trait or characteristics of the environment, algae are known to be good indicators of pollution of many types for the following reasons.
algae have wide temporal and spatial distribution.
many algal species are avaliable all the year.
response quickly to the charges in the environment due to pollution.
Algae are diverse group of organisms found in large quantities.
easier to detect and sample.
The presence of some algae are well correlated with particular type of pollution particularly to organic pollution Algae of many kinds are really good indicators of water quality and many lakes are characterized based on their dominant phytoplankton groups. Many desmids are known to be present in oligotrophic waters whilst a few species frequently occurs in eutrophic bodies of water . Similarly, many blue-green algae occurs in nutrient-poor waters, while some grow well in organically polluted waters . The ecosystem approach to water quality assessment also include diatom species and accociations used as indicators of organic pollution. Five algal species were selected as indicators of the degree of pollution in rivers in England. Stigeoclonium tenue is present at the down stream margin of the heavily polluted part of a river, Nitzschia palea and Gomphonema parvulum always appear to be dominant in the mild pollution zone whilst Cocconeis and Chamaesiphon are reported to occur in unpolluted parts of the stream or in repurified zone . Navicula accomoda is stressed to be a good indicator of sewage/organic pollution as the species comfortably occur in the most heavily polluted zones in which other species can not occur. The same hold true for species and varietes of Gomphonema  which is commonly found in highly organically polluted water. Amphora ovalis and Gyrosigma attenuatum are also introduced as good examples of diatoms to be affected by high organic content of water .
A list of more than 850 algal taxa was published based on the reports of considerable number of authors. According to this list, many algal genera have species that grow well in water containing a high concentration of organic wastes. Green algae Chlamydomonas, Relationship of Algae to Water Pollution and Waste Water Treatment 337 Euglena, diatoms, Navicula, Synedra and blue- green algae Oscillatoria and Phormidium are emphasized to tolerate organic pollution . At species level, Euglena viridis (Euglenophyta), Nitzschia palea (Bacillariophyta), Oscillatoria limosa, O.tenuis, O.princeps and Phormidium uncinatum (Cyanophyta) are reported to be present than any other species in Plate 1. 1.Stephanodiscus hantzschii Grunow 2.Cyclotella comta (Ehrenberg) Kützing 3.Thalassiosira weissflogii (Grunow) G.Fryxel & Hasle 4.Aulacoseira distans (Ehrenberg) Simonsen 5.Cyclotella ocellata Pantocsek 6. C. kützingiana Thwaites 7.Cocconeis pediculus Ehrenberg 8.C.placentula Ehrenberg 9. Meridion circulare (Greville) C. Agardh 10. Diatoma vulgaris var. lineare Grunow 11. D.
tenuis C.Agardh 12. Surirella ovalis Brébisson 13. S. ovata var. apiculata W. Smith 14. S. linearis W.
Smith 15. S.
minuta Brébisson 16. Cymatopleura solea (Brébisson) W. Smith .
338 Water Treatment organically polluted waters . Some diatom taxa in a stream polluted with the waste water of a slaugher house are given in Plate 1-4 .
Plate 2. 1.
Pinnularia viridis (Nitzsch) Ehrenberg 2. P. biceps W. Gregory 3. Stauroneis phoenicenteron (Nitzsch) Ehrenberg 4. Pinnularia brebissonii (Kützing) Rabenhorst 5. Craticula ambigua (Ehrenberg) D. G.
Mann 6. Pinnularia mesolepta (Ehrenberg) W.
Relationship of Algae to Water Pollution and Waste Water Treatment 339 Plate 3. 1. Rhopalodia gibba (Ehrenberg) Otto Müller 2-3. Eucocconeis flexella (Kützing) Meister 4.
Achnanthidium minutisimum (Kützing) Czarnecki 5. Eucocconeis quadratarea (Østrup) Lange-Bertalot 6.
Achnanthes marginulata Grunow 7. Ulnaria delicatissima var. angustissima (Grunow) M. Aboal & P. C.
Silva 8. U.
acus (Kützing) M. Aboal 9. U. amphirhyncus (Ehrenberg) Compère & Bukhtiyarova 10. U.
danica (Kützing) Compère & Bukhtiyarova 11. U. biceps (Kützing) P. Compère .
340 Water Treatment Plate 4. 1.Fragilaria capucina var. vaucheriae (Kützing) Lange-Bertalot 2.Pseudostaurosira brevistrita (Grunow) D.M.Williams & Round 3.Staurosirella pinnata (Ehrenberg) D.M.Williams & Round
4.Gomphonema truncatum Ehrenberg 5.Rhoicosphenia abbreviata (C. Agardh) Lange-Bertalot 6.Gomphonema olivaceum (Hornemann) Brébisson 7.Nitzschia sublinearis Hustedt 8.N. umbonata (Ehrenberg) LangeBertalot 9. N. hantzschiana Rabenhorst 10. Tryblionella angustata W. Smith 11. Nitzschia linearis (C.
Agardh) W. Smith12. N. constricta (Kützing) Ralfs. .
Relationship of Algae to Water Pollution and Waste Water Treatment 341 Algae are also good indicators of clean water since many species occur insistently and predominately in the clean water zone of the streams. However it is more satisfactory to emphasize the presence or absence of several species of clean water algae rather than of any one species to define the clean water zone. Approximately 46 taxa has been announced as representatives of the clean water algae including many diatoms, several flagellates and certain green and blue-green algae . However it is emphasized that minute flagellates are better indicators of clean water than many larger algae. A few of the clean water algae are planktonic whilst many are benthic, attached to substrata at the bottom or sides of the running waters.
There are many studies by various authors emphasizing the relationships of algae to clean water. A community composed of the diatom Cocconeis and the blue-green alga Chamaesiphon is claimed to be present in the portion of the stream which has returned to normal following purification of a polluted condition . Kolkwitz listed 61 diatoms, 42 green algae, 41 pigmented flagellates, 23 blue-green algae, and 5 red algae as organisms of oligosaprobic and /or unpolluted zones and Lackey found 77 species of planktonic algae in the clean water portion of a small stream, 40 of which were absent in the polluted area[15,16]. The flagellates Chromulina rosanoffi, Mallomonas caudata, the green algae Ulothrix zonata and Microspora amoena are also reported as oligosaprobic zone organisms . Two groups of algae, Cryptophyta and Chrysophyta, are reported to be indicators of clean and/or unpolluted water as the members of these algal groups tend to occur in abundance, oppositely reacting adversely to pollution . The absence of blue-green algae was also accepted an indication of clean water .
4. Use of algae in saprobien system The classic scheme for the interpretation of streams ecological conditions based on the biota was first introduced by Kolkwitz and Marsson . They defined five zones based on the degree of pollution and proposed the use of aquatic organisms as indicators of different pollution and/or recovery zones of rivers which were polluted with organic matter such as sewage. However more recently Werner proposed nine different zones in the saprobic system in a stream organically polluted . Survey of the saprobic zones and the corresponding communities are given Table 1. Pollution zones proposed in that saprobient system were basically termed “Coprozoic” “Polysaprobic”, “Mesosaprobic”, “Oligosaprobic” and “Katharobic”. Each zone was different in chemical and physical characteristics and containing characteristic species. He listed indicator species of these zones except the last one which is infact clean water.
Polysaprobic zone was characterized by almost complete absence of algae except for bluegreen alga Arthrospira (Spirulina) jenneri and green alga Euglena viridis. Bacteria and Protozoa were the most common groups in this zone. The preponderance of blue-green algae (Cyanophyta) was characteristic of alfa-mesosaprobic zone while diatoms (Bacillariophyta) and green algae (Chlorophyta) were dominant organisms in beta-mesosaprobic zone.
Peridiniales (Dinophyta) and Charales (Charophyta) occurred in any quantity only in the 342 Water Treatment oligosaprobic zone. In the same zone, the bacterial count was low but there was a great variety of plants and animals (including fish) in considerable numbers.
5. Use of algae in wastewater treatment Recently, algae have become significant organisms for biological purification of wastewater since they are able to accumulate plant nutrients, heavy metals, pesticides, organic and inorganic toxic substances and radioactive matters in their cells/bodies [22-25]. Biological wastewater treatment systems with micro algae have particularly gained importance in last 50 years and it is now widely accepted that algal wastewater treatment systems are as effective as conventional treatment systems. These spesific features have made algal wastewaters treatment systems an significant low-cost alternatives to complex expensive treatment systems particularly for purification of municipal wastewaters.
In addition, algae harvested from treatment ponds are widely used as nitrogen and phophorus suplement for agricultural purpose and can be subjected to fermentation in order to obtain energy from metane. Algae are also able to accumulate highly toxic substances such as selenium, zinc and arsenic in their cells and/or bodies thus eliminating such substances from aquatic enviroments. Radiation is also an important type of pollution as some water contain naturally radioactive materials, and others become radioactive through contamination. Many algae can take up and accumulate many radioactive minerals in their cells even from greater concentrations in the water . MacKenthun emphasized that Spirogyra can accumulate radio-phosphorus by a factor 850.000 times that of water .
Considering all these abilities of algae to purify the polluted waters of many types, it is worth to emphasize that algal technology in wastewater treatment systems are expected to get even more common in future years.