role of micor-org

8/3/2019 Role of Micor-Org

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2k10-MSc-Str-08


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MICRO-ORGANISM

Prokaryote

Eukaryote

Phylogenetic tree of life


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CELL STRUCTURE

Internal structure of microbial cells.

(a) Diagram of a prokaryote.

(b) Diagram of a eukaryote.


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Some microorganisms found in natural waters,wastewaters, and wastewater treatment processes

Bacteria

Algae

ProtozoaArchaea

FungiVirus


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Algae and Cyanobacteria aretiny organisms that occurnaturally in saltwater andfreshwater.

Individual organisms can oftenonly be seen under amicroscope, although withsome species, individuals canjoin together to form coloniesvisible to the naked eye.


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Algae belong to a large group oforganisms called eukaryotes - a Latinword meaning true nucleus.

They store their genetic material in atiny, membrane-bound structurecalled a nucleus.

Algae are divided into groups thatreflect the color most commonlyexhibited by members, although notall will be the definitive color.

For example most green algae aregreen, but some are brown, red,

orange, or yellow.Although there are many types ofalgae, only some groups areimportant in terms of the impact theycan have on freshwater supplies.


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TABLE 1GROUPS OF ALGAE COMMONLY OCCURRING IN FRESHWATER SYSTEMS:

SCIENTIFIC NAME COMMON NAME

CHLOROPHYTES GREEN ALGAE

CRYPTOPHYTES CRYPTOMONADS

DINOPHYTES DINOFLAGELLATES

EUGLENOPHYTES EUGLENOIDS

BACILLARIOPHYTES DIATOMSCHRYSOPHYTES YELLOW-GREEN ALGAE


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Cyanobacteria are members of a group known as eubacteria ortrue bacteria.

For a long time they were not recognized as bacteria, more oftenbeing referred to as blue-green algae.

All bacteria belong to a group of organisms known asprokaryotes, a Latin word meaning before nucleus.

Bacteria have no organized nucleus.

Cyanobacteria are classified as bacteria, not algae, since theirgenetic material is not organized in a membrane-bound nucleus.

Unlike other bacteria, they have chlorophyll and use the sun as

an energy source.They are often referred to as blue-greens, since the first

cyanobacteria identified were blueish-green in color.

However, not all members are this color.

Some are olive or dark green, and others are even purplish incolor.


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As mentioned, bothalgae and

cyanobacteria occur

naturally in surfacewaters.

Although their sizeis usually

microscopic, whenconditions areideal, both can

undergo aphenomenon

known as bloom.

This results whenthe algae reproduce

rapidly and theindividuals formclumps visible tothe naked eye.

Heavy blooms canovertake water

bodies, and evenchoke out portions

of streams orrivers.

WHY ARE

THEY

IMPORTANT?


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Large blooms of algae and cyanobacteria can clogintake pipes and filter lines, and are aesthetically

unappealing.

When blooms of algae or cyanobacteria die anddecay, the dead cells often produce objectionableodors as a result of oxygen depletion in the

surrounding water.

When a bloom dies in a pond or shallow lake,severe oxygen depletion can even cause fish kills.

Algae do not produce substances that are toxic tohumans or animals.

In contrast, some cyanobacteria producesubstances that are extremely toxic, and are

capable of causing serious illness or even death if

consumed.

These substances are called cyanotoxins.

There are currently over 70 different cyanotoxins,which are grouped by their method of toxicity (Table

2).

One cannot tell if a cyanobacterial bloom isproducing toxins simply by looking at the bloom.

Instead, you should assume toxins are present andavoid using the water.


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TABLE 2

CYANOTOXINS AND THEIR OCCURRENCE IN

FRESHWATER

SCIENTIFIC

NAME TYPE OF TOXINOCCURRENCE

IN FRESHWATER

SAXITOXIN/

NEOSAXITOXINNEUROTOXIN NOT COMMON

ANATOXIN-A/

ANATOXIN-A(S)NEUROTOXIN NOT COMMON

MICROCYSTIN HEPATOXIN COMMON

NODULARIN HEPATOXIN NOT COMMON


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Natural process in which surface waters receive inputs ofnitrates and phosphates resulting in over nourishment ofaquatic ecosystems (Algae bloom, anaerobic surface water)


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Phosphorus is a keyof nutrient

responsible foreutrophication.

The bright green colourresults from blue-greenalgae (Cyanobacteria),which are growing on

phosphorus added to thenear side of the curtain.


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The following test canbe used to distinguish

between the two forms:

Scoop a handful of thebloom with your

fingers spread slightlyapart.

Let the water drainthrough your fingersand examine what

remains in your hand.

If long, stringy masses areleft dangling from yourfingers, it is a filamentous

form, and most likely abloom of green algae.

If after straining throughyour fingers all thats leftare a few bits sticking to

your skin, its a planktonicform and most likely acyanobacterial bloom.

Wash your hands withsoap and hot waterfollowing the test.


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The first treatment step should always bebloom prevention.

Natural surface water will occasionally bloomregardless of the best efforts at prevention, butthe frequency and severity of the bloom can bereduced by using good management practices.

Runoff should be controlled to minimizefertilizer and/or waste inputs, and livestockshould not be permitted to water directly fromsurface water sources.

Water should be kept as nutrient-free as

possible.

Treatment

Options


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Aeration can also be a valuable tool in combatingblooms.

Good aeration keeps the water moving and maintains

a more constant temperature from top to bottom.This helps to prevent extremely warm layers of water

from forming at the surface during the hot summermonths.

Aeration also prevents severe oxygen depletioninitiated by the death and decay of an algal bloom.

Although algae may still bloom with aeration,cyanobacteria do not thrive in moving water.

Cyanobacteria tend to bloom under warm, calmconditions.

Proper aeration helps to prevent these conditions fromoccurring.


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TREATMENT DEPENDING ON SIZE OF BLOOM

If a bloom begins to form in a surface water source, determinethe size and type of the bloom.

If it is a filamentous bloom, there are a few options.

Small filamentous algal blooms close to shore can be removedwith a rake or hoe and placed away from the watershed area to

prevent re-entry of the dead bloom into the water.

Filamentous algae decompose easily, and can be used forcompost if combined with other materials to increase air

circulation.

Large blooms of planktonic or filamentous organisms are moredifficult to handle.

If the situation is severe, there are a number of chemicaloptions available for treating surface water.


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CHEMICAL TREATMENT

Chemical treatmentoptions commonlyinclude one of thefollowing fourcompounds:

Copper sulphate

Lime (as quicklime, or calcium

hydroxide)Alum (as aluminum sulphate)

Ferric chloride


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Advantages &

Disadvantagesof ChemicalTreatment

Following treatment, thedead cells settle to thebottom.

There are advantages anddisadvantages to each

method of chemical control.If the dugout to be treated

contains fish, great careshould be taken whenapplying any chemical.


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What is biological treatment of water?

Biological water treatment involves the use of naturallyoccurring micro-organisms in the surface water to improve waterquality.

Under the optimum conditions, including enough oxygen, theorganisms break down material in the water such as dissolved

organic carbon (DOC) and thus improve water quality.

Sand or carbon filters are used to provide a place on which thesemicro-organisms grow.


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Biological watertreatment processes areideally suited to treatwater that is highly

colored and has high DOCand nutrient levels.

Research showed that

the biological treatmentsystem, including a slowsand filter and

biological activatedcarbon (BAC) filter,

effectively reduce DOC,turbidity and color in

surface water,improving the quality of

water.


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Thebiologicaltreatmentsystem hasthree parts:

A slow sand filter where water flows by gravity; it is designed to removesuspended matter.

A biological activated carbon (BAC) filter to reduce dissolved organicmatter.

A 1000 L storage tank to meet peak household demands.

The system was designed to operate continuously, providing highquality non-potable water to the entire household by filteringparticulate matter and biodegrading organic matter

For drinking, a reverse osmosis (RO) membrane was installed asan additional protective barrier.


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The biologicaltreatment system

successfully reducedthe levels of DOC,color, turbidity and

chlorophyll (algae) inthe water to within

specified guidelines ineach trial.

The BAC filter improved thewater quality by removing:

75% to 92% of DOC.More than 80% of the color

73% to 96% of the turbidity.

More than 90% of the chlorophyll.

The results of the

sampling conductedon one of threesurface water

systems are shown inTable 1.


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PARAMETER GOAL

BEFORE

SAND

FILTER

AFTER

SAND

FILTER

AFTER BAC

FILTER

AFTER

RO

Dissolved Organic

Carbon, DOC (mg/L)


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