by Spike Carlsen
.   What
after the
                     KITCHEN WASTE
                     WATER INLET
                                             "Out of sight, out of
                                             mina" is the attitude
                                             most of us have when
                                             it comes to flushing
                                             the toilet, popping the
                                             bathtub drain or run-
                                             ning the dishwasher
                                             But all that waste-
                                             water goes some-
                                             where. And that
                                             "somewhere" is
                                             usually a wastewater
                                             treatment facility, or
                                              an on-site septic
                Recycled/Recyclable • Printed on Recycled Paper (20% Postconsumar)
Reprinted by the U S Environmental Protection Agency with permission from THE FAMILY HANDYMAN Magazine, Home Service Publications. Inc . an
  affiliate of Reader's Digest Association Inc. 7900 International Drive, suite 950. Minneapolis. MN 55425 Copynght 1997 All Rights Reserved

                                                           GRIT REMOVAL
                                                          , CHAMBER
              A T IEATMENT
     PLANT runs wastewater
     through a chain of basins and
     tanks, progressively removing
     solids, dissolved solids and
     harmful pathogens By the time
     the water is released, it has
     spent 8 to 16 hours in the
     facility and is at least as clean
     as the body of water it's
     released into.
                 TANKS ,
                                                                     NO SLUDGE
   Sanitary disposal hasn'r
 alwavs been the norm, l.'p until
 the rnni- LSI UK it was common
 practice to simply dump chain
 her pots and garbage into street-
 side gutters, ditches and Ces-spl!s.
 When Louis Pasteur discovered
 that microorganisms in raw
 sewage made people sick, cities
 began developing st-wer systems
 to usher wastes out or town. Still,
 even  MI vcars ago, it was com-
  mon lor ulies   even those
       with a population of
         more than .1 million -
         untreated waste into
         rivers and Likes  I;
        "wasn't until the l^~0s,
         when the Clean Water
       Act mandated that all
      wastewaier be cleaned
   before being returned to
 rivers and lakes, that the United
 States really began cleaning up
 its act.
   Here's the poop.

 In outlying areas, where
 installing sewer pipes between
 distant houses and treatment
 facilities are prohibitively expen-
 sive, septic systems (Fig. A| are
 used.  About one quarter < >t the
 U.S. population (up to 50 per-
   cent of the population in
   some states) relies on these
   on-site wastewater treatment
    The process is quite simple.
 Wastewater enters the tank,
where solids drop  to the bottom
ot the tank to create sludge, and
grease and oils rise to the top :o
Create scum. The sludge and
scum  should be pumped .-n;
everyone !o two \ eai
wastewater between the two la\ •
ersflows to a distribution
which sends it out  to ,1 series oi
     1O8  MARCH 1997  THi FAMILY


absorption or leach trenches. From
here the wastewater is absorbed by
the surrounding gravel and soil; a
small amount is wicked up to the
surface to evaporate or be con-
sumed by vegetation.
   The sludge on the tank bottom
decomposes with the help ot bacte-
ria. Lots ot'grease can slow or even
wipe out the bacterial action ot'a
septic tank, and if the grease is
allowed to flow into the leach field,
it can coat and clog the rock and
soil and prevent absorption.
Because of this, garbage disposals
are not recommended for homes
with septic tanks unless a grease
trap  is incorporated into the sys-
tem. The grease trap,  located
between the kitchen sink and septic
tank, has special baffles to trap
grease before it enters the septic
system. The grease in the trap must
be pumped out regularly.
   Septic system owners may not
get nailed with monthly sewer
fees—but those who neglect pump-
ing their tank, or are careless with
what thev dispose of, will get nailed
with a clogged drainfield and even-
tually a bill for a new septic system.
Paints, varnishes, waste oil and pes-
ticides can destrov  the bacterial
      Use  less  water; treat less water
      Regardless of whether your house is connected to a septic system
      or wastewater treatment facility, the less water you use, the less
      wastewater needs to be processed.
        Following are a few water-saving tips:
      • When it's time to remodel, install a low-flush toilet. Older toilets
      use 5 gallons per flush, but those made within  the past 10 years
      use 3.5 gallons, and many built today use 1.6 gallons. If we all
      converted to low-flush toilets, the United States would save 3 bil-
      lion gallons of water PER DAY.
      • Fix drippy faucets. A faucet dripping twice a  second wastes 50
      gallons of water—and treatment—per week.
      • Don't leave the water running. Keep a jug of  water in the fridge
      so you don't have to run water to get  a cold drink. Turn off the
      water when it's not needed while shaving,  brushing your teeth or
      washing your car.
action of a system. These chemicals
may also migrate into the drinking
water supply if there's a well on the
property. Likewise, plastics, diapers,
condoms, coffee grounds, tampons
and cai litter can contribute to the
premature demise of a septic-
   Septic systems and drainage
tields are carefully designed, based
on soil conditions and the number
of people living in a house. Life-
spans of 20 years or more are tradi-
tionally projected, but with careful
planning and maintenance, systems
can last indefinitely.

Wastewater treatment simulates
nature's purification process—but
at a much accelerated pace. While-
water released from a treatment
facility isn't "drinking water" clean,
it is likely to match or exceed the
purity of the body of water it's

FIG. C  SLUDGE, produced at the annual rate of about 500 Ibs. per household, is disposed of in increasingly
environmentally sound ways  After it's dewatered, it can be burned for heat, composted to create soil amendments, even
incinerated and the ash turned into building materials.

released into.
   Treatment if\g. B) can be
broken down into five basic
steps, though processes may be
combined and vary greatly
from plant to plant.
   In preliminary treatment,
wastewater is delivered to the
facility via sewer pipes, some as
large as 12 ft. in diameter. At
this stage, less than 0.5 percent
of the wastewater is solids; the
rest is water and dissolved mat-
ter. The wastewater flows
through bar screens to remove
trash and debris, then slowly
moves through a grit tank
where sand and heavy particles
settle and are removed.
   During primary treatment,
water moves on to sedimenta-
tion tanks where it's undis-
turbed tor a few hours. Solids
that sink are scraped from the
bottom of the tank and
removed. Grease and oils that
float to the top are removed
with large rotating skimmers.
About 15 percent of U.S. treat-
ment plants discharge water
after this stage.
   Secondary treatment begins
with the wastewater wending its
way through a chain of concrete
basins. The water is mixed and
oxygen is introduced, to begin
the aeration process. This sets
up an environment where the
active bacteria, called activated
sludge, feed on the incoming
waste solids and dissolved
organic matter, thus speeding
up the treatment process. The
water then flows into clarifying
tanks where the heavy, activat-
ed sludge microorganisms set-
tie out. As odd as it seems, some
of this sludge is recirculated
back into the aeration tanks to
provide active microorganisms
to keep the bacterial treatment
process alive.
   During disinfection, harm-
ful bacteria and other microor-
ganisms in the water are killed
by adding chlorine, or running
the water past banks of high-
intensity ultraviolet lights. This
is to prevent the discharge of
harmful organisms or
pathogens into the receiving
body of water. At this point the
wastewater has been in the
plant for 8 to 16 hours,
   In some plants, water moves
on to advanced treatment, most
often to remove phosphorus
and nitrogen, which stimulate
algae growth and eventually
deplete the oxygen levels of
lakes or rivers. Some forms of
advanced treatment are so
thorough, the water is used to
water yards and parks. In most
cases though, it's discharged
into streams, rivers, lakes or
   Each household generates
about 500 Ibs. per year of the
solids or sludge removed dur-
ing treatment (Fig. C). Often
the sludge is simply buried, but
increasingly it's being recycled.
In some cases the sludge is
dewatered and then combined
with other ingredients to create
fertilizers and soil amend-
ments. Sludge may also be
incinerated, and the ashes used
as a soil conditioner or in con-
struction materials. Sludge can
also be composted or
processed to produce methane
gas, which can in turn be
burned to supply heat for a
portion of the facility. 0
An Direction • MIKE SMITH
llluiirationi • DON MANNES
Contultinl • DENNIS LINDEKE.
                              THE FAMILY HANDYMAN   MARCH 1997  113