Introduction to Environmental Introduction to Environmental EngineeringEngineering

Dr. Kagan ERYURUKDr. Kagan ERYURUK

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Microbial GroupsMicrobial Groups

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Importance of Microbiology Importance of Microbiology in Environmental in Environmental EngineeringEngineering

• Microbiology; a branch of biology devoted to Microbiology; a branch of biology devoted to the study of microorganisms (microbes).the study of microorganisms (microbes).

• The objects of this science; the engineering The objects of this science; the engineering systems of water, wastewater, solid wastes, systems of water, wastewater, solid wastes, soil and gas biotreatment.soil and gas biotreatment.

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1. Bacteria1. Bacteria

• As decomposers – indispensable As decomposers – indispensable ecological role by decaying ecological role by decaying organic matterorganic matter

• Natural processes are enhanced Natural processes are enhanced and accelerated in stabilizing and accelerated in stabilizing organic wastes in treatment plantsorganic wastes in treatment plants

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Reproduction and SporesReproduction and Spores• Bacterial reproduction; Bacterial reproduction;

by binary fission – From by binary fission – From one cell 2 new cells. one cell 2 new cells.

• Each then divide again. Each then divide again. Approx. every 15 – 30 Approx. every 15 – 30 mins. mins. (doubling time)(doubling time)

• Survival mechanism -Survival mechanism -Some species form Some species form spores with tough spores with tough coatings that are coatings that are resistant to heat, lack resistant to heat, lack of moisture, and loss of of moisture, and loss of food supply.food supply. www.anselm.edu/.../ genbio/mitosisnot.htmlwww.anselm.edu/.../ genbio/mitosisnot.html

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Coliform Coliform BacteriaBacteria• A commonly used  bacterial indicator of

sanitary quality of foods and water.

• Total coliform bacteria - commonly found Total coliform bacteria - commonly found in the environment (e.g., soil or in the environment (e.g., soil or vegetation). Generally harmless. They vegetation). Generally harmless. They indicate the presence of organic indicate the presence of organic material.material.

• Fecal coliform bacteria- a sub-group of Fecal coliform bacteria- a sub-group of the total coliform group.  Present in the total coliform group.  Present in large quantities in the intestines and large quantities in the intestines and feces of humans and other and animalsfeces of humans and other and animals..

• Escherichia coliEscherichia coli - a sub-group of the fecal - a sub-group of the fecal coliform group.  Most coliform group.  Most E. coliE. coli are harmless are harmless and are found in large quantities in the and are found in large quantities in the intestines of humans and warm-blooded intestines of humans and warm-blooded animals.  Some strains, however, may animals.  Some strains, however, may cause illness. (E.g. E. coli O157:H7)cause illness. (E.g. E. coli O157:H7)

• All are used as a common indicator of the All are used as a common indicator of the bacteriological quality of water.bacteriological quality of water.

www.ericsecho.org/ whatisec.htm

wqm.igsb.uiowa.edu/.../ faqsbeachenvironprof.htm

E. coli

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Heterotrophic and Autotrophic Heterotrophic and Autotrophic BacteriaBacteria

Bacteria can be classified into Bacteria can be classified into 2 main groups2 main groups depending on their source of nutrients:depending on their source of nutrients:

• HeterotrophsHeterotrophs use organic matter as both an use organic matter as both an energy and a carbon source for synthesis. They energy and a carbon source for synthesis. They are further sub-divided into 3 groups depending are further sub-divided into 3 groups depending on their action toward free oxygenon their action toward free oxygen– AerobesAerobes– AnaerobesAnaerobes– FacultativeFacultative

• AutotrophsAutotrophs oxidize inorganic compounds for oxidize inorganic compounds for energy and use carbon dioxide as a carbon energy and use carbon dioxide as a carbon sourcesource

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HeterotrophsHeterotrophs• Aerobes require free dissolved oxygen in Aerobes require free dissolved oxygen in

decomposing organic matter to gain energy for decomposing organic matter to gain energy for growth and multiplication. Found in activated growth and multiplication. Found in activated sludge and trickling filters in wastewater sludge and trickling filters in wastewater treatment.treatment.

• Anaerobes oxidize organics in the complete Anaerobes oxidize organics in the complete absence of dissolved oxygen by using oxygen absence of dissolved oxygen by using oxygen bound in other compounds (such as nitrate and bound in other compounds (such as nitrate and sulfate). They predominate in sludge sulfate). They predominate in sludge digestion .digestion .

• Facultative bacteria compose a group that uses Facultative bacteria compose a group that uses free dissolved oxygen when available but can free dissolved oxygen when available but can also live in its absence by gaining energy from also live in its absence by gaining energy from anaerobic reaction. They are active in both anaerobic reaction. They are active in both aerobic and anaerobic treatment units.aerobic and anaerobic treatment units.

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AutotrophsAutotrophs• Oxidize inorganic compounds for energy and use Oxidize inorganic compounds for energy and use

carbon dioxide as a carbon source.carbon dioxide as a carbon source.

• Nitrifying, sulfur, and iron bacteria are of greatest Nitrifying, sulfur, and iron bacteria are of greatest significance.significance.

• Nitrifying bacteria oxidize ammonium nitrogen to Nitrifying bacteria oxidize ammonium nitrogen to nitrate. Nitrification can occur in biological nitrate. Nitrification can occur in biological secondary treatment under the conditions of low secondary treatment under the conditions of low organic loading and warm temperatures (often organic loading and warm temperatures (often avoided to reduce oxygen consumption in treatment avoided to reduce oxygen consumption in treatment and to prevent floating sludge on the final clarifier).and to prevent floating sludge on the final clarifier).

• Iron bacteria can flourish in some pipes (more of a Iron bacteria can flourish in some pipes (more of a problem for water delivery pipes).problem for water delivery pipes).

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2. FUNGI2. FUNGI• Microscopic non photosynthetic Microscopic non photosynthetic

plants including yeasts and moldsplants including yeasts and molds

• Molds are aerobic and grow best Molds are aerobic and grow best in acid solutions high in sugar in acid solutions high in sugar contentcontent

• Fungi are found in wastewater in Fungi are found in wastewater in small numbers but if there is small numbers but if there is large increase in fungi large increase in fungi concentration it is an indication of concentration it is an indication of a change in pH of the activated a change in pH of the activated sludge. sludge. 

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Protozoa and Protozoa and Multicellular AnimalsMulticellular Animals

• Protozoa- single-celled aquatic animals that Protozoa- single-celled aquatic animals that multiply by binary fission. They have complex multiply by binary fission. They have complex digestive systems and use solid organic matter digestive systems and use solid organic matter as food.as food.

• Protozoa are aerobic organisms found in Protozoa are aerobic organisms found in activated sludge, trickling filters, and oxidation activated sludge, trickling filters, and oxidation ponds treating wastewater.ponds treating wastewater.

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VirusesViruses

• Viruses are obligate, intracellular Viruses are obligate, intracellular parasites that replicate in living hosts’ parasites that replicate in living hosts’ cells (i.e. not involved in the digestion of cells (i.e. not involved in the digestion of wastewater)wastewater)

• They may be involved in infecting They may be involved in infecting bacterium, but their real relevance to bacterium, but their real relevance to wastewater treatment is in terms of wastewater treatment is in terms of infection of humans infection of humans

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AlgaeAlgae• Algae are microscopic photosynthetic plants Algae are microscopic photosynthetic plants

of the simplest form.of the simplest form.

• Their relevance to most wastewater Their relevance to most wastewater processes is in terms of their control in the processes is in terms of their control in the processes and at the end of the pipe.processes and at the end of the pipe.

• Wastewater stabilization ponds support Wastewater stabilization ponds support luxurious blooms of algae to the point where luxurious blooms of algae to the point where the suspension becomes self-shading.the suspension becomes self-shading.

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Bacterial Growth Bacterial Growth RequirementsRequirements1.1. Terminal electron acceptorTerminal electron acceptor2.2. MacronutrientsMacronutrients

a. carbona. carbonb. nitrogenb. nitrogenc. phosphorusc. phosphorus

3.3. MicronutrientsMicronutrientsa. trace metalsa. trace metalsb. vitaminsb. vitamins

4.4. EnvironmentEnvironmenta. moisturea. moistureb. temperatureb. temperaturec. pHc. pH

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Growth in Pure CulturesGrowth in Pure Cultures

• During lag phase, bacteria adapt themselves to During lag phase, bacteria adapt themselves to growth conditions. It is the period where the individual growth conditions. It is the period where the individual bacteria are maturing and not yet able to divide.bacteria are maturing and not yet able to divide.

• The log phase is a period characterized by cell The log phase is a period characterized by cell doubling. The number of new bacteria appearing per doubling. The number of new bacteria appearing per unit time is proportional to the present population. unit time is proportional to the present population.

• The stationary phase is often due to a growth-limiting The stationary phase is often due to a growth-limiting factor such as the depletion of an essential nutrient, factor such as the depletion of an essential nutrient, and/or the formation of an inhibitory product such as and/or the formation of an inhibitory product such as an organic acid. an organic acid.

• At death phase (decline phase), bacteria die. This At death phase (decline phase), bacteria die. This could be due to lack of nutrients, a temperature which could be due to lack of nutrients, a temperature which is too high or low, or the wrong living conditions.is too high or low, or the wrong living conditions.

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Mathematics of GrowthMathematics of Growth

• log growth phaselog growth phase

nPP )2(0

2logloglog 0 nPP

....222222 0000 PPPPP

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ExampleExample

• Bread yeast cells divide and form 2 cells Bread yeast cells divide and form 2 cells every 5 minutes. If you place 10every 5 minutes. If you place 1055 cells in cells in a suitable environment, how many cells a suitable environment, how many cells will you have in 30 minutes?will you have in 30 minutes?

sgeneration 6nerationminutes/ge 5

minutes 30n

cells 10 x 4.6210 665 P

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Mixed CulturesMixed Cultures

• Pure cultures do not exist in naturePure cultures do not exist in nature

• Log growth may occur when one Log growth may occur when one organism or group has few external organism or group has few external limitslimits

• Most organisms interact with other Most organisms interact with other organisms:organisms:– competition for food and other competition for food and other

resourcesresources– inhibitorinhibitor