Download presentation
Presentation is loading. Please wait.
1
강의자료 ppt-11 인간의 삶과 역사 속의 미생물 2012-1학기
2
미생물은 어떤 존재인가?
3
환경 지킴이로서의 미생물
4
미생물과 오수 처리
5
Wastewater and sewage treatment
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., Zoogloea ramigera) 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
20
modern conventional sewage treatment plant
21
Hone septic tank system
Frequently fail to work properly, contributing to groundwater contamination This system combines an anaerobic waste liquefaction unit (the septic tank) with an aerobic leach field. Biological oxidation of the liquefied waste takes place in the leach field, unless the soil becomes flooded.
22
미생물과 생물학적 환경정화 (bioremediation)
* 생물학적 환경복원
23
Microbial bioremediation
Mercury and heavy metal transformations Petroleum biodegradation (생물학적분해) Biodegradation of xenobiotics * Xenobiotics: A completely synthetic chemical compound not naturally occurring on Earth
24
Microbial bioremediation: 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
Microbial bioremediation: 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
Microbial bioremediation:
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
Taean oil spills
31
Taean oil spills
32
Taean oil spills
33
Taean oil spills
34
Microbial bioremediation: 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
Microbial bioremediation: 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
Microbial bioremediation: Biodegradation of 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
Microbial bioremediation: Biodegradation of 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
Microbial bioremediation: Biodegradation of xenobiotics
Plastics of various types are xenobiotics that are not readily degraded by microbes
43
Chemistry of synthetic polymers
Similar presentations
© 2024 SlidePlayer.com Inc.
All rights reserved.