i“
'm‘J
the case of zinc from the photoengraving laboratories of Seattle newspapers,
) "
faced with removing the zinc or changing their engraving process, the news - "
3f
'
;
papers elected the latter [8].
'. _'—;.'
.
Choosing to divert wastes to the Sound to alleviate the eutrophicatiom
.
Lake Washington means that Seattle must now carefully monitor 1ndustnal *'
efuents to catch toxic wastes before they build up
to dangerous levels as well
»
_
““
as conünuously study the effect of the sewage on the receiving waters and Î ï
.
their aquatic life. The diversion of sewage from one body of water to another
' '
%“
can only delay solving the ultimate problem of nding ecologically
ways of disposing of wastes and raise further questions about our overall
nl
waste treatment strategy.
'
;
…
Treatment Strategy
_'
There are three types of sewage treatment in use today—primary, secondary,
.
and tertiary. Primary and seconda1y treatments, however, are the major types
:“
……
and shall be discussed here.
_
ï '
’
.
;
Primary Treatment. Primary treatment, the most elementary, is a phys—
‘
_
ical process in Which sewage is piped to open tanks where the solid wastesæe
allowed to settle. Particles that oat to the surface may be skimmed off, but
’
_
the remainder of the sewage is discharged directly into the stream. Bactena
,
,
'
'
‘
and fungi proliferate at sewage outfalls since they utilize sewage as well as
plant and animal remains for food. These microorganisms are responsible fOr'ËÏ
the decomposition of the waste matter, securing energy from the organic
““““““““““"“
'
,
stances (compounds containing carbon) and releasing> the inorganic sub- '
stances, including nitrogen and phosphorus, into the stream again. While this
'
'
'
_
activity, from an ecological point of view, is important in retuming nutr16ts .'
,
;
the food cycle for utilization by higher plants and animals, bacteria must
Ê
'
& great deal of oxygen in order to make use of the available
'
-
;“
…
î ' …È: ï : Î Ï 5€Ér f î …; %‘ ï “ ÿf ' Ÿ
*7
Just below
sewage outfall oxygen may be depleted completely. Here;
:
'anaerobicf bacteria (bacteria which can live without oxygen) carry out the
;
composition process. These bacteria release foul—smelling methane and hy- }
drogensulde, imteà‘d Of the carbon dioxide released by oxygen bacteria. At
græterdtanœs_Qm the point of eluent release, oxygen content increases
,
more diluted.
…
'
“
in water with low oxygen Content
and is anmdlcat0rofmgamc pollution. These worms can tolerate
,
05 ppm. Much higher concentrations of.- oxygen,
‘
howeVer, arenecessæyfœa
ecosystem. For a diversled
'
Warm—water ShPOPIa“1ŒWVhldmCÏU(Ï€SSllch sh as bass and sunshathe
ÎË.ÏÊÏÎÂÎËZ°ËËÊÎ…“°‘Q‘°“*P"f°‘ W°“°.“ Y“““ '°WY9
_
‘_
_9 ,_ÊlUË9°WŒmspopulqtuonsm the lake MlChlgdl‘l Bas… are shown
'" ““ 'Ï“°P'
…
_
x
—
—
_
iî‘fü:i"«fä”,»@s“‘f
Î ‘ …
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…… …
…… …“ “ …“ … ……
…
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'
…… …“ …………“…‘ ………‘ ……………”… …… …… …… …… …“ …‘ …… …
\
l …“ … \ ll“l…ll“l “… …“…
'm‘J
the case of zinc from the photoengraving laboratories of Seattle newspapers,
) "
faced with removing the zinc or changing their engraving process, the news - "
3f
'
;
papers elected the latter [8].
'. _'—;.'
.
Choosing to divert wastes to the Sound to alleviate the eutrophicatiom
.
Lake Washington means that Seattle must now carefully monitor 1ndustnal *'
efuents to catch toxic wastes before they build up
to dangerous levels as well
»
_
““
as conünuously study the effect of the sewage on the receiving waters and Î ï
.
their aquatic life. The diversion of sewage from one body of water to another
' '
%“
can only delay solving the ultimate problem of nding ecologically
ways of disposing of wastes and raise further questions about our overall
nl
waste treatment strategy.
'
;
…
Treatment Strategy
_'
There are three types of sewage treatment in use today—primary, secondary,
.
and tertiary. Primary and seconda1y treatments, however, are the major types
:“
……
and shall be discussed here.
_
ï '
’
.
;
Primary Treatment. Primary treatment, the most elementary, is a phys—
‘
_
ical process in Which sewage is piped to open tanks where the solid wastesæe
allowed to settle. Particles that oat to the surface may be skimmed off, but
’
_
the remainder of the sewage is discharged directly into the stream. Bactena
,
,
'
'
‘
and fungi proliferate at sewage outfalls since they utilize sewage as well as
plant and animal remains for food. These microorganisms are responsible fOr'ËÏ
the decomposition of the waste matter, securing energy from the organic
““““““““““"“
'
,
stances (compounds containing carbon) and releasing> the inorganic sub- '
stances, including nitrogen and phosphorus, into the stream again. While this
'
'
'
_
activity, from an ecological point of view, is important in retuming nutr16ts .'
,
;
the food cycle for utilization by higher plants and animals, bacteria must
Ê
'
& great deal of oxygen in order to make use of the available
'
-
;“
…
î ' …È: ï : Î Ï 5€Ér f î …; %‘ ï “ ÿf ' Ÿ
*7
Just below
sewage outfall oxygen may be depleted completely. Here;
:
'anaerobicf bacteria (bacteria which can live without oxygen) carry out the
;
composition process. These bacteria release foul—smelling methane and hy- }
drogensulde, imteà‘d Of the carbon dioxide released by oxygen bacteria. At
græterdtanœs_Qm the point of eluent release, oxygen content increases
,
more diluted.
…
'
“
in water with low oxygen Content
and is anmdlcat0rofmgamc pollution. These worms can tolerate
,
05 ppm. Much higher concentrations of.- oxygen,
‘
howeVer, arenecessæyfœa
ecosystem. For a diversled
'
Warm—water ShPOPIa“1ŒWVhldmCÏU(Ï€SSllch sh as bass and sunshathe
ÎË.ÏÊÏÎÂÎËZ°ËËÊÎ…“°‘Q‘°“*P"f°‘ W°“°.“ Y“““ '°WY9
_
‘_
_9 ,_ÊlUË9°WŒmspopulqtuonsm the lake MlChlgdl‘l Bas… are shown
'" ““ 'Ï“°P'
…
_
x
—
—
_
iî‘fü:i"«fä”,»@s“‘f
Î ‘ …
”
…… …
…… …“ “ …“ … ……
…
‘
…
'
…… …“ …………“…‘ ………‘ ……………”… …… …… …… …… …“ …‘ …… …
\
l …“ … \ ll“l…ll“l “… …“…