인간의 삶과 역사 속의 미생물

1. 인간의 삶과 역사 속의 미생물 강의자료ppt-11 2012-1학기

2. 미생물은어떤 존재인가?

3. 환경 지킴이로서의미생물

4. 미생물과오수 처리

5. Wastewater and sewage treatment • Wastewater • Domestic sewage or liquid industrial waste • Wastewater treatment • Relies on industrial-scale use of microbes for bioconversion • Following treatment, the discharged treated wastewater (effluent water) is suitable for • Release into surface waters • Release to drinking water purification facilities • Wastewater treatment processes • Similar to self-purification processes observed in rivers and streams except are controlled and intensified

6. Wastewater and sewage treatment • Wastewater treatment facility • Its goal is to reduce organic and inorganic materials in wastewater to a level that no longer supports microbial growth and to eliminate other potentially toxic materials • The efficiency of treatment is expressed in terms of a reduction in the biochemical oxygen demand (= biological oxygen demand, BOD) • The relative amount of dissolved oxygen consumed by microbes to completely oxidize all organic and inorganic matter in a water sample

7. Wastewater and sewage treatment • Wastewater treatment is a multistep operation employing both physical and biological processes • Primary, secondary, and sometimes tertiary treatments are used

8. Wastewater treatment processes

10. Wastewater and sewage treatment • Primary treatment • Uses physical separation methods to separate solid and particulate organic and inorganic materials from wastewater

11. Primary treatment of wastewater

12. Wastewater and sewage treatment • Secondary Treatment • Anoxic secondary treatment involves a series of digestive and fermentative reactions carried out by various microbes under anoxic conditions • The process is carried out in large enclosed tanks (sludge digesters or bioreactors)

13. Sludge digester for anoxic secondary wastewater treatment

14. Wastewater and sewage treatment • Secondary treatment(cont’d) • Aerobic secondary treatment uses digestive reactions carried out by microbes under aerobic conditions to treat wastewater with low levels of organic materials • The trickling filter(살수여상법[撒水濾床法]) and activated sludge(활성오니법[活性汚泥]) are the most common decomposition processes

15. Aerobic secondary wastewater treatment processes Trickling filter in a treatment facility

16. Aerobic secondary wastewater treatment processes Aeration tank of an activated sludge installation

17. Aerobic secondary wastewater treatment processes Wastewater flow through an activated sludge installation

18. Wastewater and sewage treatment • In the activated sludge process, wastewater is mixed and aerated in large tanks and slime-forming bacteria (e.g., Zoogloearamigera) grow and form flocks • Most treatment plants chlorinate the effluent after secondary treatment to further reduce the possibility of biological contamination

19. Wastewater and sewage treatment • Tertiary Treatment • Any physiochemical or biological process employing precipitation, filtration, or chlorination procedures similar to those used for purification of drinking water • Reduces the levels of inorganic nutrients (e.g., phosphate, nitrate, nitrite) • Most complete method of treating sewage but it has not been widely adopted due to costs

21. Hone septic tank system • Frequently fail to work properly, contributing to groundwater contamination

22. 미생물과생물학적 환경정화 (bioremediation) * 생물학적 환경복원

23. Microbialbioremediation • Mercury and heavy metal transformations • Petroleum biodegradation (생물학적분해) • Biodegradation of xenobiotics * Xenobiotics: A completely synthetic chemical compound not naturally occurring on Earth

24. Microbialbioremediation: Mercury and heavy metal transformations • Mercury is of environmental importance because of its tendency to concentrate in living tissues and its high toxicity • The major form of mercury in the atmosphere is elemental mercury (Hgo) which is volatile and nontoxic and oxidized to mercuric ion (Hg2+) photochemically • Most mercury enters aquatic environments as Hg2+ which is more toxic than Hgo

25. Microbialbioremediation: Mercury and heavy metal transformations • Hg2+ readily absorbs to particulate matter where it can be metabolized by microbes • Some microbes form methylmercury (CH3Hg+), an extremely soluble and toxic compound (100 times more toxic than Hg2+) • Several bacteria can also transform toxic mercury to nontoxic forms - Transform CH3Hg+ to Hg2+ and Hg2+ to Hg0

26. Microbialbioremediation: Petroleum biodegradation • Prokaryotes have been used in bioremediation of several major crude oil spills

27. Environmental consequences of large oil spills Contaminated Beach in Alaska containing oil from the Exxon Valdez spill of 1989

28. Environmental consequences of large oil spills Oil spilled into the Mediterranean Sea from a power plant

29. Environmental consequences of large oil spills Center rectangular plot (arrow) was treated with inorganic nutrients to stimulate bioremediation

30. Taeanoil spills

31. Taeanoil spills

32. Taeanoil spills

33. Taeanoil spills

34. Microbialbioremediation: Petroleum biodegradation • Diverse bacteria, fungi, and some cyanobacteria and green algae can oxidize petroleum products aerobically • Oil-oxidizing activity is best if temperature and inorganic nutrient concentrations are optimal • Hydrocarbon-degrading bacteria attach to oil droplets and decompose the oil and dispense the slick

35. Hydrocarbon-oxidizing bacteria in association with oil

36. Microbialbioremediation: Petroleum biodegradation • Gasoline and crude oil storage tanks are potential habitats for hydrocarbon-oxidizing microbes - If sufficient sulfate is present, sulfate-reducing bacteria can grow and consume hydrocarbons

37. Microbialbioremediation: Biodegradationof xenobiotics • Xenobiotic compound • Synthetic chemicals that are not naturally occurring • e.g., pesticides, polychlorinated biphenyls, munitions, dyes, and chlorinated solvents • Many degrade extremely slowly

38. Microbialbioremediation: Biodegradationof xenobiotics • Pesticides • Common components of toxic wastes • Include herbicides, insecticides, and fungicides • Represent a wide variety of chemistries • Some of which can be used as carbon sources and electron donors by microbes

39. Examples of xenobiotic compounds

40. Persistence of herbicides and insecticides in soils

41. Persistence of herbicides and insecticides in soils

42. Microbialbioremediation: Biodegradationof xenobiotics • Plastics of various types are xenobiotics that are not readily degraded by microbes

43. Chemistry of synthetic polymers