of waste streams, with untreated storm drainage piped into the rivers. The
awkward part of this method is that storm waters carry a great deal of pollu—
tion which, if discharged untreated, as suggested, can counteract the im—
provements
in stream quality that the advanced treatment plants at the end
of the sewage
stream are designed to produce.
Urban pollutants which enter the storm waters include street litter, salt
and other de—icing chemicals, pesticides, fertilizers, feces and urine from pets,
household and commercial refuse, and waste waters from air—scrubbing oper—
ations that convert air pollutants into water pollutants. One survey in Chi—
cago
indicates that soluble dust and dirt in the streets of a large city contain a
BOD potential equivalent to five percent of that in the secondary treatment
eluent from the municipal plant serving people in the city [45]. Much of the
dirt and dust is from human activities such as construction, tire shredding, and
road surfacing material, rather than from natural sources. In less densely populated urban regions, the BOD load of storm sewer water actually may equal
the BOD load in the local secondary wastewater efHuent [46]. Lead and hy—
drocarbon wastes from vehicle exhaust and other air pollution fallout also are
prominent contaminants of storm water [47]. The contribution from pets
should not be underestimated. Some one—half million dogs in New York City
leave 5000—20,000 tons of feces and 600,000—1 million gallons of urine in the
city streets each year. In Baltimore, the gures for 100,000 dogs are
4000—13,000 tons of feces and 120,000—200,000 gallons of urine per year [48].
These organic wastes present some human health hazard as well as add a sig—
nificant BOD load to waste water.
Alternative Waste Treatment Methods
Sanitary waste treatment is, of course, essential to human health. Lacking,
however, has been a thorough study of alternative methods too achieve sani—
tary treatment with the fewest possible environmental side effects. One ex—
ploration of comprehensive systems for sanitary waste treatment was recently
completed by the US. Army Corps of Engineers [49]. Three different treat—
ment systems and appropriate sewer networks were assessed for the 2500
square—mile Chicago—Northwest Indiana region which has 13,500 industries
and will have an estimated nine million persons by 1990. Each alternative
system was investigated at a different level of application, but the most com—
plete would involve, by 1990, treatment of an average of some 3.3 billion gal—
lons per day of municipal, industrial, stormwater, and agricultural wastes.
This total, incidentally, is based on the assumption that industries will greatly
reduce water use by 1990 through extensive in-plant water recycling.
One alternative studied was advanced biological treatment as an adjunct
t0 Secondary
treatment facilities already in existence. A second alternative,
spec1ahzed physical-chemical techniques, required the replacement of all ex—
isting facrl1ties. The third was a land treatment plan that called for the trans—
P0Tt Of WaStes
via a tunnel system to a 700—square mile site some 25 miles
SOUth Of Chicago, There, the raw wastes would be treated biologically, then
'I 14
Thirsty Technology
awkward part of this method is that storm waters carry a great deal of pollu—
tion which, if discharged untreated, as suggested, can counteract the im—
provements
in stream quality that the advanced treatment plants at the end
of the sewage
stream are designed to produce.
Urban pollutants which enter the storm waters include street litter, salt
and other de—icing chemicals, pesticides, fertilizers, feces and urine from pets,
household and commercial refuse, and waste waters from air—scrubbing oper—
ations that convert air pollutants into water pollutants. One survey in Chi—
cago
indicates that soluble dust and dirt in the streets of a large city contain a
BOD potential equivalent to five percent of that in the secondary treatment
eluent from the municipal plant serving people in the city [45]. Much of the
dirt and dust is from human activities such as construction, tire shredding, and
road surfacing material, rather than from natural sources. In less densely populated urban regions, the BOD load of storm sewer water actually may equal
the BOD load in the local secondary wastewater efHuent [46]. Lead and hy—
drocarbon wastes from vehicle exhaust and other air pollution fallout also are
prominent contaminants of storm water [47]. The contribution from pets
should not be underestimated. Some one—half million dogs in New York City
leave 5000—20,000 tons of feces and 600,000—1 million gallons of urine in the
city streets each year. In Baltimore, the gures for 100,000 dogs are
4000—13,000 tons of feces and 120,000—200,000 gallons of urine per year [48].
These organic wastes present some human health hazard as well as add a sig—
nificant BOD load to waste water.
Alternative Waste Treatment Methods
Sanitary waste treatment is, of course, essential to human health. Lacking,
however, has been a thorough study of alternative methods too achieve sani—
tary treatment with the fewest possible environmental side effects. One ex—
ploration of comprehensive systems for sanitary waste treatment was recently
completed by the US. Army Corps of Engineers [49]. Three different treat—
ment systems and appropriate sewer networks were assessed for the 2500
square—mile Chicago—Northwest Indiana region which has 13,500 industries
and will have an estimated nine million persons by 1990. Each alternative
system was investigated at a different level of application, but the most com—
plete would involve, by 1990, treatment of an average of some 3.3 billion gal—
lons per day of municipal, industrial, stormwater, and agricultural wastes.
This total, incidentally, is based on the assumption that industries will greatly
reduce water use by 1990 through extensive in-plant water recycling.
One alternative studied was advanced biological treatment as an adjunct
t0 Secondary
treatment facilities already in existence. A second alternative,
spec1ahzed physical-chemical techniques, required the replacement of all ex—
isting facrl1ties. The third was a land treatment plan that called for the trans—
P0Tt Of WaStes
via a tunnel system to a 700—square mile site some 25 miles
SOUth Of Chicago, There, the raw wastes would be treated biologically, then
'I 14
Thirsty Technology