The Durham daily globe., 1892-09-27
SEWAGE OF LONDON.
1T is TAKEN OUT TO SEA AND SCAT
TERED OVER THE WAVES.

Method of Separating the sIudge from
the EfIuent-CIean Ships.
"Oh, how unpleasant! The idea Of go
ing 10 sea with sludge" On the con-
trary. you know nothing of it. The
deck Of the sludge ship is broad and
clean: the deck house or ''saloon" small
but comfortable; on the bridge fresh
breeze j. blowing; the sunlight sparkles
brightly on the ruffled surface of the
river, and you scarce can realize that
this fine steamer is carrying a thousand
tons Of London sludge out to sea. Yet
such is the fact The idea that the
mud barges" Of the county council,
which take out the precipitated portion
of London sewage to the Barrow deep,
are simply dirty dredges is quite mis-
take. They are powerful twin screw
steamships, worked by two sets of triple
expansion engines, and fitted with three
large tanks, kept covered, and abso-
lately free from nuisance to anybody,
even to the seamen on board. They can
make two trips out to sea in every
twenty-five hours, steaming about ten
knots. aud, as a matter~-Sf fact, they
thus dispose Of II 900 tons of sludge in
2 week.
The sludge is precipitated by treat
ing the sewage with lime and sulphate
Of iron. First, six huge cages catch
debris, such as sticks and dead rats and
ecls, etc, in the great rushing sewers
which drain London. This rubbish is
burned III Instructors at the rate Of
something like hundred tons week;
then the black river Of sewage is stirred
III tanks with lime-or, more correctly,
lime water-in the proportion of about
81 grains to the gallon. The effect Of
the lime IS to precipitate matter in sus-
pension and solution and also to deOdOr-
ize. You may take a smelling bottle
with you if you like, but with plenty of
lime about you will hardly need it. But
walking on along the top of the twenty
seven feet wide sewer, which is probably
to become a beautiful boulevard for
Barking, one comes to the sulphate of
iron "shOp," where $50 tons at a time
are received, and where, after being dis
solved in the proper proportion as di-
reCted by the chemist in charge, it, too,
finds its way to the swift river of sew
age
EUt then comes pause in the rivers
mad career. ltiS admitted through the
PenstOck chamber-that is, a building
with a number Of iron gates-to a set of
covered precipitating channels, where it
can leisurely mediate after it's wild
rushings from London. Here in its
quiet bed the lime and iron, III casting
down the solid portions, can take full
effect, and the clear portion Of the liquid
a. the tOp-nOw called the effiuent---
Is let off over the head Of II wall at the
end Of the chamber to channel at the
other side; whence, gathering speed
again. it rushes to "a reservoir, from
which at ebb tide it Joins the Thames.
Iue aIudSo passes through pipes from
the bottoms Of the precipitating cham
DeTs TO another reservoir. whence it is
pumped to the tanks in the sludge
ships and conveyed to sea.
The effect on the river is most salts
factory. On the testimony of the har-
Dor master it l. "aner now than it has
been FOR some years, while Mr.. Thudi-
Chum. the chemist 1T the Barking "out-
tali' wOrL:S, loyfully maintains it has
30 per cent, OF oxygen, which it has not
reloiced Iii for some summers past. But
The clean io:csnJr4 ana the scent Of sea-
weed ut DlEkiug, ana the much prrer
looking .@tPr iii the Thames itself, are
prvo!- 10 the Eniniti&tci Of the success
Of tie "new" system.
That system is only now getting into
fuI! working order The county coun-
eli have added TWO more ships TO the
fee. !na!,Ing now five in all; and they
are conveying some Al, 600 tons of sludge
UaI 10 sea every week. Four ships are
constantly ut work day and night, and
one takes Its turn of a rest week for
painting. repairs, etc, and affOrding a
hrhtcr tim" for the men. These are
sailors, and sleep on board, regular
watches being kept, except one twenty
four hours III every seven days, when
they are. allowed off duty.
The diScharging ground of the steam
crs Is the BarrOw deep, some miles be-
yond the More light. The deep is an
unused channel, the north bound vessels
taking a course considerably to the left
and sonthward ships far to the right.
The channel has been buoyed by the
council. and no captain may commence
dlscharSing until lie has passed the
North Knot buoy. The discharge is
quickly effected by opening valves in the
Vessels bottom: the principle being
much the same as that used on the self
emptying which, indeed, is but
an adaptation Of the law that water finds
its own level, the bottom of the tanks
being built on level with the sea. The
valves are easily opened from the deck,
and 50 quick is their action that the
who.e thousand tons can be discharged
IN seven minutes. Generally the time
occupied. however, Is longer, the vessel
perhaps steaming ten miles while empty
ing her strange cargo. The white wake
of the ship is discolored, gulls hover
over it, and then among the tumbling
waves and the fresh breezes the sludge
Is gone.
The mind can hardly grasp the fact
thar 4 hundred million gallons of sewage
pour down the huge drain to Barking
every tyentV-fOur hulrS But If We