Convenüonal “industrial waste treatment equipment tends to borrow
heavily from sanitary waste treatment methods such as mechanical screening, ..
settling, and skimming common to primary treatment; biological
employing trickling lters or activated sludge to reduce BOB, as is done in ?
secondary treatment; and application of various chemicals such as alum or
lime to remove small waste particles by coagulation and subsequent sedimen—
tation, as is done in municipal tertiary treatment for inorganic phosphates.
Industrial organic matter that resistS”biological degradation can sometimes be '
reduced by adso1ption (adherence due to surface attraction) on granulated or
carbon, an approach also used in advanced municipal waste treat—
;;*
ment and in drinking water purication. Methodsto separate liquid materials
of different weights by gravity or by centrifuge to obtain the desired product
and isolate the waste have their origin in commonly applied scientic prin—
ciples. Other forms of advanced waste treatment include the use of special resins to remove inorganic ions, electrodialysis to remove salts, advanced mechanical lters in combination with water soluble compounds to control the
consistency of the material being ltered, and a process called ammonia
stripping which allows nitrogen—containing ammonia gas to escape from wa—
ter into the atmosphere and thus reduces the amount of nitrogen in wastes
that otherwise might be incorporated in nitrates—inorganic nutrients that
also may be a health threat in drinking water. These processes are used in
_
both municipal and industrial waste treatment, but generally have been applied most often in industry.
Some waste treatment processes have been tailor—made for specic in—
dustries: the removal of suldes in tannery wastes by the use of ue gases con—
_taining carbon dioxide; the
of cyanides with ferrouS compounds
'
to render the cyanides insoluble; extracting phenols with solvents; distilling
j 5
liquors; the removal of salts by forcing water to reverse its nor—
malosmüt1c passage (reverse osmosis) through membranes that are not persalts; and pmcipitating metals With Chemicals. These
techruques gare=generally expensive,however, and industry, by and large, has
lehedmsteadupon the broad—scale treatment methods developed to reduce
theBO
1n domestic sewage. Thus, despite sharply rising investments in
WaStecontrol equipment, cOmpanies frequently have been unable even to
As we have seen, this situation has”
to pump their waste streams into the mu—
v
n101paltreatmentsysæm, passing on the problem to the community as a
,.
Th18practicehasmsp1red aheatedcontrov‘ersy. Theargument that heavy
"
à
mdustnalusegfmumŒPal facilities represents
subsidy for industry is
!
counteredhytheargumemthat Such centralized treatment is more efficient
»
th"mÜnSltËtre9îm€tWhichentailshlghercosts that Would be passed on to
prices. Furthermore, the …
Plant'wasœCharæœnmcsarem0fethaadeqæœ to cover
Ï
res“““““gfromthedischalges
…
.
108
Thî rSfyTechn0|09y
_
heavily from sanitary waste treatment methods such as mechanical screening, ..
settling, and skimming common to primary treatment; biological
employing trickling lters or activated sludge to reduce BOB, as is done in ?
secondary treatment; and application of various chemicals such as alum or
lime to remove small waste particles by coagulation and subsequent sedimen—
tation, as is done in municipal tertiary treatment for inorganic phosphates.
Industrial organic matter that resistS”biological degradation can sometimes be '
reduced by adso1ption (adherence due to surface attraction) on granulated or
carbon, an approach also used in advanced municipal waste treat—
;;*
ment and in drinking water purication. Methodsto separate liquid materials
of different weights by gravity or by centrifuge to obtain the desired product
and isolate the waste have their origin in commonly applied scientic prin—
ciples. Other forms of advanced waste treatment include the use of special resins to remove inorganic ions, electrodialysis to remove salts, advanced mechanical lters in combination with water soluble compounds to control the
consistency of the material being ltered, and a process called ammonia
stripping which allows nitrogen—containing ammonia gas to escape from wa—
ter into the atmosphere and thus reduces the amount of nitrogen in wastes
that otherwise might be incorporated in nitrates—inorganic nutrients that
also may be a health threat in drinking water. These processes are used in
_
both municipal and industrial waste treatment, but generally have been applied most often in industry.
Some waste treatment processes have been tailor—made for specic in—
dustries: the removal of suldes in tannery wastes by the use of ue gases con—
_taining carbon dioxide; the
of cyanides with ferrouS compounds
'
to render the cyanides insoluble; extracting phenols with solvents; distilling
j 5
liquors; the removal of salts by forcing water to reverse its nor—
malosmüt1c passage (reverse osmosis) through membranes that are not persalts; and pmcipitating metals With Chemicals. These
techruques gare=generally expensive,however, and industry, by and large, has
lehedmsteadupon the broad—scale treatment methods developed to reduce
theBO
1n domestic sewage. Thus, despite sharply rising investments in
WaStecontrol equipment, cOmpanies frequently have been unable even to
As we have seen, this situation has”
to pump their waste streams into the mu—
v
n101paltreatmentsysæm, passing on the problem to the community as a
,.
Th18practicehasmsp1red aheatedcontrov‘ersy. Theargument that heavy
"
à
mdustnalusegfmumŒPal facilities represents
subsidy for industry is
!
counteredhytheargumemthat Such centralized treatment is more efficient
»
th"mÜnSltËtre9îm€tWhichentailshlghercosts that Would be passed on to
prices. Furthermore, the …
Plant'wasœCharæœnmcsarem0fethaadeqæœ to cover
Ï
res“““““gfromthedischalges
…
.
108
Thî rSfyTechn0|09y
_