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Unformatted text preview: MICROBIOLOGY
OF
WASTE
TREATMENT
 A.  Treatment
process
 1.  Common
characteris?c
‐
complex
interac?ons,
mul?‐substrate,
mul?‐species
 interac?ons.
 
‐
Aerobic
treatment
systems
are
less
well
understood
than
the
less
widely

 
used
anaerobic
treatment
systems,
which
are
microbiologically
beKer

 
understood.
 2.  Most
(80%)
are
small
treatment
facili?es
(<1
MGD),
and
most
(>85%)
have
at

 
least
secondary
treatment
.
 3.  Wastewater
treatment
in
U.S.
began
in
beginning
of
the
last
century.

 Filtra?on
along
with
chlorina?on
was
the
major
reason
for
decline
of
 mortality
by
bacterial
pathogens
such
as
typhoid,
cholera
and
other
 waterborne
diseases.


 MICROBIOLOGY
OF
WASTE
TREATMENT
 • 

In
the
U.S.
in
the
1800s,
popula?on
increased
from
5M
to
75M
(currently
 
300M)
 • 

By
the
early
1900s
many
ci?es
had
sewer
systems
to
collect
wastewater
and

 
‘treatment’
was
limited
to
dilu?on,
removal
from
source,
irriga?on
for
 agriculture.
 • 

Driving
force
for
centralized

 


control
and
treatment
was

 


public
health,
cholera,

 


typhoid,
etc.

 • 

First
biological
treatment,

 trickling
filter
in
Madison,
WI
 in
1901.
 • 

First
ac?vated
sludge
plant,
 1916,
San
Marcos,
TX

 Defini?ons
 BOD
‐
Biochemical
Oxygen
Demand,
defines
strength
of
an
organic
wastewater.

 BOD
‐
measures
the
waste
loading
to
treatment
plants
and
determines
 effec?veness
of
treatment
in
the
plant.
 

 
 
O 2 
 
 
 
 














O2
 
organics


‐‐‐‐‐‐‐‐>


CO2

+

bacterial
cells


‐‐‐‐‐‐‐>


CO2

+

protozoa
 Defini?on:

The
quan?ty
of
oxygen
used
by
a
mixed
heterogeneous
popula?on
of
 organisms
in
the
aerobic
oxida?on
of
organic
maKer
in
the
sample
at
20°C
for
5
 days.

Procedure
is
standardized
with
respect
to
inorganic
nutrients,
temp.
of
 incuba?on,
methodology.
 Nitrifica?on
oxygen
demand
 O2
 O2
 ‐













NO ‐
 NH3













NO2 3 BOD
 mg/L
 Carbonaceous
oxygen
demand
 5 
 
 
10 
 
 
 
15
 Time
(days)
 Defini?ons:
 COD
‐
Chemical
Oxygen
Demand,
used
to
determine
the
total
organic
carbon
in
a
 wastewater
of
sample.


 Defined
as
the
amount
of
oxygen
needed
to
oxidize
the
organic
carbon
in
the
 sample
completely
to
CO2
and
H2O
in
the
presence
of
potassium
dichromate:

 organics

+

oxygen

+

K2Cr2O7


to


CO2

+

H2O

+

Cr3+
 Total
solids
‐
includes
both
organic
and
inorganic
material
which
results
from
the
 mass
remaining
from
a
water
or
wastewater
sample
amer
drying
in
an
oven
at
low
 temp.

[Biomass]
 Suspended
solids
‐
that
por?on
which
is
retained
on
a
glass
fiber
filter
and
dried.
 Dissolved
solids
‐
that
por?on
which
goes
through
the
glass
fiber
filter
and
dried.
 Vola?le
solids
‐
that
por?on
of
total
solids
which
are
lost
on
burning
at
500°C
 [organic
frac?on]
 Table
7.2.

Typical
characteris?cs
of
domes?c
wastewater
(mg/L)
 

 
 Parameter 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 







Concentra?on
 
strong 
 
medium 



220 




500 






15 






25 






40

 
 
8 




720 




220 
 
 
 
 
 
 
 
 
 
 



weak




 
 
 
 
 
 
 
 
 
110
 
250
 




8
 


12
 


20
 




4
 
350
 
100
 
 

 BOD5 
 
 
 
 COD 
 
 
 
 Organic
N 
 
 
 NH3‐N 
 
 
 
 Total
N 
 
 
 
 Total
P 
 
 
 
 Total
solids
[biomass] 
 Suspended
solids 
 

 
 
 
 
 



400 
 
1,000 
 





35 
 





50 
 





85 
 





15 
 
1,200 
 



350 
 
 
 
 
 
 Table
7.3

COD,
BOD5,
BOD5/COD
ra?os
of
selected
wastewaters
 
 
 
 
 
 
 
 
 
 
 
 
 Domes?c
sewage
 
Raw 
 
 
 
 
Amer
biological
treatment Slaughterhouse
wastewater 
 Dis?llery
vinasse 
 
 
 Dairy
wastewater 
 
 
 Rubber
factory
waste 


 
 Tannery
wastewater 
 
 Tex?le
dyeing

 
Raw 
 
 
 
 
Amer
biological
treatment Dram
mill
effluent
 
Raw 
 
 
 
 
Biologically
stabilized 
 
 
 
 
 
 
 BOD:


degrad.
organics 
 O2
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
COD 
mg/L 
500 
 


50 
 




3,500 
 


60,000 
 





1,800 
 





5,000 
 



13,000 
 
 
 
 
 
BOD5 
mg/L 
300 
 


10 
 





2,000 
 



30,000 
 
 
900 
 





3,300 
 





1,270 
 
660 
 




5 
 
226 
 


30 
 
 
 O2
 
 
BOD5/COD
 
 
 
 
 
 
0.60
 
0.20
 








0.57 
 








0.50
 








0.50
 








0.66
 








0.10 

 
0.48
 
0.04
 
0.36
 
0.12
 
 
 

 

 






1,360 
 
 

116
 
 
 
 
620 
 
250 
 
 
 
 
 
 
 
 
 
 
 
 
 

 
CO2

+

bact.
cells 
 
 O2
 
 
CO2

+

protozoa
 COD:




all
organics

+

K
dichromate
 
CO2

+

H2O
 Major
objec?ves
of
waste
treatment
 1.  To
remove
pathogen
and
parasites.
 2.  To
reduce
the
BOD
(organic
content)
of
wastewater.


 3.  To
reduce
levels
of
major
nutrients,
N
&
P
which
can
adversely
affect
 receiving
waters. 

 wastewater
 effluent
 Primary
 clarifier
 Aera?on
tank
 Final

 clarifier
 recycle
 Excess
 solids
 wastewater
 effluent
 Primary
 clarifier
 Aera?on
tank
 Final

 clarifier
 recycle
 Excess
 solids
 Aerobic
treatment
 (general
scheme)
 Ac?vated
Sludge
unit
process
 

 


 • 

There
are
2
main
goals
of
the
aerobic
ac?vated
sludge
process
 
1. 
biological
oxida?on
of
the
readily
degradable
organic
frac?on
 
2. 
floccula?on
and
seKlement
of
the
biomass
(sludge)
from
the
treated

 
 
effluent.
 
3.

Equa?on
describing
ac?vated
sludge
process
‐
simplest
descrip?on
 
 
 
 
C10H19O3N

+

9O2


‐‐‐‐‐‐‐‐‐>


C5H7O2N

+

5CO2

+

H2O
 
This
describes
"waste
stabiliza?on",
e.g.
conversion
to
CO2
 
It
is
‘stabilized’
because
it
no
longer
exerts
an
‘oxygen
demand’
 4.

Opera?on
of
process
‐
defines
a
set
of
condi?ons
for
the
successful

 
 
organisms.

e.g.
there
is
considerable
selec?ve
pressures
opera?ng. 

 
 
a.

heterogeneous
waste
‐
complex
polymers,
proteins,
carbohydrates,
lipids
 
 
b.

short
deten?on
?me,
rapid
dilu?on
rate
 
 
c.

rapid
seKling
ability
 5.

Hence,
organism
popula?on
should
 
 
a.

be
nutri?onally
versa?le
and
be
heterogeneous
popula?on
 
 
b.

rapid
growers,
short
genera?on
?me
 
 
c.

form
flocs
and
aKach

[prevents
washout
and
lessens
preda?on]
 6.  Microbial
numbers
are
high
both
in
numbers
and
diversity.

Meaningfulness
of
census
 data
is
limited
given
the
limited
detec?on
methods,
table
8.1.
 7.  Protozoa
 
 
a.

important
for
effec?ve
opera?on
of
the
unit
process
 
 
b.

not
just
a
consequence
of
the
system,
but
a
desired
result.

They
func?on
as

 
 
 
"polishers"
 
 
c.
e.g.

presence
of
high
numbers
of
ro?fers
associated
with
low
BOD.
 
 
d.

Table 
 
 
 
With
protozoa 
Without
protozoa 

 
 
 
 
BOD


(mg.L) 
 
15 
 
 
60
 
 
 
 
COD 
 
 
130 
 
 
220
 
 
 
 
org
N 
 
 
8 
 
 
17
 
 
 
 
susp.
solids 
 
30 
 
 
100
 
 
 
 
bact.
numbers 
5 
 
 
130

(x
106/ml)
 Table
8.1


Distribu?on
of
aerobic
heterotrophic
bacteria
in
standard
ac?vated
sludge
 
 
 
 
 
 Group
(Proteobacteria) 
 
 
 
 
 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
percent
of
total
isolates
 
 
 
 
 
 
 
 
 
 
 
 
 






50.0 
 
 
5.8
 
 
1.9
 







11.5
 
 
1.9
 
 
1.9
 







13.5
 
 
1.9
 
 
1.9
 
 
5.8
 
 
1.9
 
 
1.9
 
 
 
 

 Comomonas
–
Pseudomonas 
 
 Alcaligenes 
 
 
 
 
 Pseudomonas 
 
 
 
 
 Paracoccus 
 
 
 
 
 Uniden?fied
Gram‐nega?ve
rods 
 Aeromonas 
 
 
 
 
 Flavobacterium
–
Cytophaga 
 
 Bacillus 
 
 
 
 
 
 Micrococcus 
 
 
 
 
 Coryneform 
 
 
 
 
 Arthobacter 
 
 
 
 
 Aureobacterium
–
Microbacterium 
 
 
 
 
 
 
 
 
 
 

 Floccula?on
and
seKling
 • 

Flocs
are
loose
aggregates
of
microorganisms,
protozoa,
inorganic
maKer
in
a
matrix
of
 extracellular
polymers.
 • 

Good
floccula?on
and
seKling
are
important
for
2
reasons
 
1. 
effluent
quality

‐

suspended
solids
removal,
BOD
removal,
90
‐
99%
reduc?on
in

 
 
bacterial
numbers.
 
2. 
high
substrate
removal
‐
in
aera?on
unit
because
it
is
recirculated
into
the
 

 
 
unit,
this
maintains
an
ac?ve
popula?on.
 • 

Poor
seKling
‐
the
most
frequent
problem
encountered
in
waste
treatment
plants.
 • 

Causes
of
poor
seKling
 
1.
 

Poor
floc
forma?on
–

Dispersed
growth,
no
floc
forma?on,
no
seKling
of

 
 
microbes;

 
 
‐
waste
is
too
concentrated
or
deten?on
?me
is
too
short.
 
2. 

Pin‐point
flocs
‐
flocs
too
small,remain
in
suspension.

Can
be
caused
by

 
 
temperature
fluctua?ons.
 
3. 
Density
problem

‐

rising
sludge
 
 
Solids
rise
to
surface
in
seKling
tank,
get
washed
out
causing
poor
effluent
quality.
 
 
‐
nitrifica?on
in
aera?on
tank:

NH3

‐‐‐>

NO2‐

‐‐‐>

NO3‐



 
 
‐
with
denitrifica?on
in
seKling
basin:

NO3‐

‐‐‐>

N2O

‐‐‐>

N2


 
 
‐
remove
sludge
before
denitrifica?on
can
occur
 
 
‐

manage
cell
concentra?on
and
dissolved
oxygen
in
aera?on
tank
 
 
‐
anaerobic
sludge
‐

if
lem
too
long,
anaerobiosis
will
take
place
in
the
seKling

 
 
basin
with
produc?on
of
CO2,
CH4,
H2S.
 Bulking
sludge
‐
Major
opera?onal
problem
with
the
others
being
rela?vely
minor
 problems.


 • 

Very
different
from
'rising
sludge',
bulking
sludge
is
a
problem
of
poor
compactability
 
 
 
SVI
ml/g

=

SV
x
1000 

 
 
 
 
 







MLSS
 
SVI
=
sludge
volume
index,
SV
=
vol
amer
30
min
seKling
of
1
L
MLSS
=
mixed
liquor

 
suspended
solids,
dry
weight
of
1L
 
 
 
normal
SVI
=
50‐150
ml/g
 
 
 
bulking
SVI
=
200‐2000ml/g
 • 


Bulking
is
frequently
associated
with
high
numbers
of
filamentous
organisms
that
are
 normal
inhabitants
of
ac?vated
sludge,
but
the
cause
and
effect
is
difficult
to
establish.

On
 the
one
hand,
you
see
lots
of
filaments
in
bulking
sludge.

On
the
otherhand,
do
the
 organisms
create
the
condi?on
or
do
the
condi?ons
select
for
the
organisms?
 • 



 • No
single
cause
but
rather
tends
to
be
associated
with
the
following
condi?ons.

What
 causes
it
and
therefore
what
can
cure
it
is
not
understood
very
well.

Certain
observa?ons
 correlate
well,
but
there
is
no
simple
cause
and
effect,
hence
there
is
no
simple
control
for
 the
problem.
 
a.

influx
of
industrial
waste
[brewery,
food
processing]
 
 
‐

poor
nutri?onal
balance
‐
very
high
C:N
ra?o

[sugar
from
waste
from
illegal
 
 

dis?llery
during
prohibi?on]
 
b.


low
substrate
loadings?

filamentous
bacteria
have
lower
Ks
than
normal
 
 

 
ac?vated
sludge
bacteria.
 
c.

low
N
or
P
levels,
favor
fungi,
C10H17O6N,
vs.
bact.
C5H7O3N
 
d.

low
pH,
tends
to
favor
fungi

 
e.

high
sulfide,
favors
sulfur
oxidizing
filamentous
heterotrophs,
Beggiatoa
and

 
 
Thiothrix
 
e.

low
DO,
favors
filamentous
bacteria,
e.g.
Sphaero?lus.
 • 

Foaming
 
a.

Different
from
poor
seKling,
causes
poor
BOD
in
effluent,
also
increases
aerosol
 dispersal
of
treatment
plant
organisms.

Poten?ally
a
pathogen
risk,
but
also
a
general
 increased
risk
of
aerosol
inhala?on.

 
b.

Organisms
associated
with
foaming
tend
to
be
ac?nomycetes,
Nocardia,
etc,
which
 have
high
levels
of
hydrophobic
and
waxy
compounds
in
their
cell
walls.

These
serve
as
 surfactants
which
stabilize
the
foam.
 Table
9.2


Comparison
of
physiological
characteris?cs
of
floc‐formers
and
filamentous
 organisms
 
 
 
 
 
 
 
 
 
 
 
Bacteria
 Characteris?cs 
 
 
 
 
 
floc
former 
filamentous
 Maximum
substrate
uptake
rate 
 
 
high
 
 Maximum
specific
growth
rate 
 
 
high
 
 Endogenous
decay
rate 
 
 
 
 
high
 
 Decrease
in
specific
growth
rate
from 
 
significant 

low
substrate
conc.
 Resistance
to
starva?on 
 
 
 
 
low 
 
 Decrease
in
specific
growth
rate
due 
 
significant 

to
low
DO
 Poten?al
to
sorb
organics
under
excess 
high
 
 Ability
to
use
nitrate
as
electron
acceptor 
yes 
 
 Exhibits
abundant
uptake
of
P 
 
 
yes 
 
 
 
 
 
 
 
 
 
 
 
 
 
low
 
low
 
low
 
moderate
 
high
 
moderate
 
low
 
no
 
no
 
 
 
 

 • 

Removal
of
pathogens,
parasites,
viruses
=
99
to
99.9%
 
3
major
mechanisms
 
 
1.

they
do
not
compete
or
grow
well
under
the
given
condi?ons
 
 
2.

they
are
consumed
by
protozoa
 
 
3.

they
flocculate
and
seKle
out
 • 

Current
wastewater
quality
issues

 
pharmaceu?cals
and
personal
care
products
 
 
‐
an?bio?cs,
hormones,
surfactants,
enzymes,
 
treatment
plants
were
not
designed
for
these
products
 
 
‐
extremely
low
concentra?ons,
are
they
seen
as
substrates?
 March
10,
2008
 Drug
Traces
Common
in
Tap
Water
 By
THE
ASSOCIATED
PRESS
 
Filed
at
12:09
p.m.
ET
 A
vast
array
of
pharmaceu?cals
‐‐
including
an?bio?cs,
an?‐convulsants,
mood
stabilizers
and
sex
hormones
‐‐
have
 been
found
in
the
drinking
water
supplies
of
at
least
41
million
Americans,
an
Associated
Press
inves?ga?on
shows.
 To
be
sure,
the
concentra?ons
of
these
pharmaceu?cals
are
?ny,
measured
in
quan??es
of
parts
per
billion
or
trillion,
 far
below
the
levels
of
a
medical
dose.
Also,
u?li?es
insist
their
water
is
safe.
 But
the
presence
of
so
many
prescrip?on
drugs
‐‐
and
over‐the‐counter
medicines
like
acetaminophen
and
ibuprofen
 ‐‐
in
so
much
of
our
drinking
water
is
heightening
worries
among
scien?sts
of
long‐term
consequences
to
human
 health.
 In
the
course
of
a
five‐month
inquiry,
the
AP
discovered
that
drugs
have
been
detected
in
the
drinking
water
supplies
 of
24
major
metropolitan
areas
‐‐
from
Southern
California
to
Northern
New
Jersey,
from
Detroit
to
Louisville,
Ky.
 Water
providers
rarely
disclose
results
of
pharmaceu?cal
screenings,
unless
pressed,
the
AP
found.
For
example,
the
 head
of
a
group
represen?ng
major
California
suppliers
said
the
public
''doesn't
know
how
to
interpret
the
 informa?on''
and
might
be
unduly
alarmed.
 How
do
the
drugs
get
into
the
water?
 People
take
pills.
Their
bodies
absorb
some
of
the
medica?on,
but
the
rest
of
it
passes
through
and
is
flushed
down
 the
toilet.
The
wastewater
is
treated
before
it
is
discharged
into
reservoirs,
rivers
or
lakes.
Then,
some
of
the
water
 is
cleansed
again
at
drinking
water
treatment
plants
and
piped
to
consumers.
But
most
treatments
do
not
remove
 all
drug
residue.
 And
while
researchers
do
not
yet
understand
the
exact
risks
from
decades
of
persistent
exposure
to
random
 combina?ons
of
low
levels
of
pharmaceu?cals,
recent
studies
‐‐
which
have
gone
virtually
unno?ced
by
the
general
 public
‐‐
have
found
alarming
effects
on
human
cells
and
wildlife.
 ''We
recognize
it
is
a
growing
concern
and
we're
taking
it
very
seriously,''
said
Benjamin
H.
Grumbles,
assistant
 administrator
for
water
at
the
U.S.
Environmental
Protec?on
Agency.
 Members
of
the
AP
Na?onal
Inves?ga?ve
Team
reviewed
hundreds
of
scien?fic
reports,
analyzed
federal
drinking
 water
databases,
visited
environmental
study
sites
and
treatment
plants
and
interviewed
more
than
230
officials,
 academics
and
scien?sts.
They
also
surveyed
the
na?on's
50
largest
ci?es
and
a
dozen
other
major
water
providers,
 as
well
as
smaller
community
water
providers
in
all
50
states.
 Con?nued.
 ...
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This note was uploaded on 10/25/2011 for the course ENVSCI 411 taught by Professor Young during the Spring '11 term at Rutgers.

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