Improvements in Apparatus for Treating Sewage and other Impure Liquids by Electrolysis.
Year: 1888

page_text: Date of Application, 11th Jan., 1888
Complete Specification Left, 8th Oct., 1888
Complete Specification Accepted, 16th Nov., 1888
Improvements in Apparatus for Treating Sewage and other Impure
Liquids by Electrolysis.
I, WILLIAM WEBSTER Junr., of 50 Lee Park, Blackheath, in the County of Kent,
Electrician and Chemist, do hereby declare the nature of this invention to be as
follows:-
In the Specification to my application for Letters Patent dated January 27th 1887
No. 1333 described a method of and apparatus for purifying sewage and other
impure liquids by the action of electric currents, by bringing the liquid while flowing
through tanks or reservoirs in contact with electrodes having very extended surfaces,
the negative electrodes being made of iron while the positive electrodes were made
either also of iron or of carbon, or other suitable material, resulting in the production
of nascent ammonia and hydrogen at the negative electrode and of nascent oxygen
and chlorine at the positive electrode which when this is of iron causes the production
of proto-chloride of iron. The combined action of these elements and compounds on the
sewage resulted in the precipitation of the solid suspended matter thereof and also in the
chemical conversion and precipitation of the dissolved impurities therein so as to
render the liquid perfectly innocuous.
I have found that it is necessary for the economic working of this process, when
constructing the tanks or reservoirs for containing the sewage under. treatment, of
brickwork or cement, to prevent all absorption of the liquid by the said materials, as
even if such absorption takes place only to such an extent as to render the walls damp,
a conducting action is set up through them whereby a portion of the electric current
is lost; and according to my present invention I prevent such absorption by coating
the tank or reservoir with a suitable waterproof insulating material such as asphalt,
tar or the like. According to another improvement, also with a view to working the
process economically, I employ for carrying the same out a number of tanks, which,
during the time that the purifying process is being carried on, have no conducting
connection with each other through the liquid, whereby I am enabled to connect the
electrodes of the several tanks or reservoirs in series on the same electrical circuit and
Dc;1

page_text: thus, owing to the large amount of surface presented by the electrodes and con-
sequently the very small resistance offered by them, I am enabled to operate effectually
upon the contents of a number of tanks with the same strength of electrical current
as is required for acting upon a single tank; whereas, if the contents of the severa!
tanks are in conducting connection with each other, a considerably greater strength of
current is required, involving either larger electrodes or greater horse power for
producing the necessary current.
As all the tanks or a number thereof are necessarily supplied with the sewage from
one and the same conduit or from branches thereon, electrical connection would be
set up between them through the body of liquid in the conduit, and consequently, in
order to enable the operation in series as above described to be carried out, it is
necessary to first supply each tank with its charge and then to close the connection
with the supply conduit by a sluice valve, so that the enclosed body of liquid is
subjected to the electrolytic action until the purification is effected, instead of causing
such action to take place while the liquid is flowing through the tank.
With such an arrangement, the enclosed body of sewage may with advantage he
agitated or an artificial circulation set up therein in order to effectually bring about
a uniform action of the electric currents upon the whole mass, and this may be con-
veniently effected by forcing currents of cold or heated air or of air and steam
through the same, either by means of perforated pipes or channels on the bottom of
the tank or reservoir or by other suitable means.
With the above described arrangement, as also with the arrangements where the
sewage is made to flow through the tank or reservoir, I in some cases arrange the
positive and negative electrodes in groups at certain distances apart, instead of
arranging them as parallel walls, as described in my said prior application; by this
means I am enabled to place the positive and negative electrodes of each group very
close together, and thus to reduce the resistance offered to the electric current to a
corresponding extent.
My electrolytic process may also be employed in combination with the use of lime
water added to the sewage, whereby a certain saving in the strength of electrical
current required, proportionate to the amount of lime added may be effected, but in
this case only a very small proportion of the organic matter in solution would be acted
upon in addition to the precipitation.

page_text: COMPLETE SPECIFICATION.
Improvements in Apparatus for Treating Sewage and other Impure
Liquids by Electrolysis.
I, WILLIAM WEBSTER Junr. of 50 Lee Park, Blackheath, in the County of Kent,
Electrician and Chemist do hereby declare the nature of this invention and in what
manner the same is to be performed to be particularly described and ascertained in and
by the following statement :-
In the Specification to my Letters Patent dated January 27th 1887 No. 1333 I
described a method of and apparatus for purifying sewage and other impure liquids
by the action of electric currents by bringing the liquid while flowing through tanks
or reservoirs in contact with electrodes having very extended surfaces, the positive and
negative electrodes being made of iron, resulting in the production of nascent
ammonia and hydrogen at the negative electrode and of nascent oxygen and chlorine
at the positive electrode, which causes the production of hypochlorite of iron. The
combined action of these elements and compounds on the sewage resulted in the
precipitation of the solid suspended matter thereof and also in the chemical conversion
and precipitation of the dissolved impurities therein so as to render the liquid
perfectly innocuous.
I have found that it is necessary for the economic working of this process when
constructing the tanks or reservoirs for containing the sewage under treatment, of
brickwork or cement, to prevent all absorption of the liquid by the said materials, as
even if such absorption takes place only to such an extent as to render the walls damp,
a conducting action is set up through them whereby a portion of the electric current
is lost; and according to my present Invention I prevent such absorption by coating
the tank or reservoir with a suitable waterpoof insulating material such as asphalt,
tar or the like.
According to another improvement, also with a view to working the process
economically, I employ for carrying the same out a number of tanks, which, during
the time that the purifying process is being carried on, have no conducting connection
with each other through the liquid, whereby I am enabled to connect the electrodes of
the several tanks or reservoirs in series on the same electrical circuit and thus, owing
to the large amount of surface presented by the electrodes and consequently the very
small resistance offered by them, I am enabled to operate effectually upon the contents
of a number of tanks with the same quantity of electrical current as is required for
acting upon a single tank; whereas if the contents of the several tanks are in
conducting connection with each other a considerably greater quantity of current
is required, involving either larger electrodes or greater horse power for producing
the necessary current.
As all the tanks or a number thereof are necessarily supplied with sewage from one
and the same conduit or from branches thereon, electrical connection would be set up
between them through the body of liquid in the conduit, and consequently, in order to
enable the operation in series as above described to he carried out, it is convenient to
first supply each tank with its charge and then to close the connection with the supply

page_text: conduit by a sluice valve so that the enclosed body of liquid is subjected to the
electrolytic action until the purification is effected, instead of causing such action to
take place while the liquid is flowing through the tank. In dealing with large
quantities of sewage however this is of no great importance.
With such an arrangement the enclosed body of sewage may with advantage be
agitated or an artificial circulation set up therein in order to effectually bring about a
uniform action of the electric currents upon the whole mass, and this may be con-
veniently effected by forcing currents of cold or heated air or of air and steam through
the same, either by means of perforated pipes or channels on the bottom of the tank or
reservoir or by other suitable means.
With the above described arrangement as also with the arrangements where the
sewage is made to flow through the tank or reservoir, I in some cases arrange the
positive and negative electrodes in groups at certain distances apart, instead of
arranging them as parallel walls, as described in my said prior patent, by this means
I am enabled to place the positive and negative electrodes of each group very close
together, and thus to reduce the resistance offered to the electric current to a
corresponding extent.
My electrolytic process may also be employed in combination with the use of lime
water added to the sewage, whereby a certain saving in the strength of electrical
current required, proportionate to the amount of lime added, may be effected.
Fig. 1 of the accompanying drawings shews a plan of a set of electrolytic tanks
arranged according to my above described invention. Fig. 2 shews a part plan to an
enlarged scale, and Fig. 3 shews an enlarged cross section, A A A are a number of
tanks arranged side by side, constructed of brickwork rendered waterproof by a
coating of asphalt or other suitable material. These tanks are each separately
supplied with the sewage to be treated by a pipe B having branches B¹ provided, with
sluice cocks so that when each tank is filled, its communication with the pipe can be
cut off. These tanks all communicate with a channel C through sluices D D', and
this channel communicates firstly by a sluice E with a reservoir F and secondly
by a sluice E and passage G with a second reservoir F¹. The reservoir F is also
provided either with a sluice H. communicating with the passage G or with a sluice H¹
communicating with the tank F', these sluices being at such a height as to allow the
supernatent liquid to flow off from F after the solid matter has setiled therein. Thus
when the tanks, or any of them, have been filled with sewage and this has been
subjected to the electrolytic treatment by an arrangement of electrolytic apparatus
which may either be similar to that described in my Patent No. 1333-87 or may be
arranged as presently to be described, the whole of the solid suspended matter will first
rise to the top owing to the quantity of gas bubbles mixed therewith, so that the
comparatively clear liquid can then be discharged through the sluices D channel C and
the sluice E into the tank F. When by this means the supernatent sludge has sunk
to the level of the sluices D the sluice E is closed and the sluice E is opened, so as to
allow the sludge to pass into the reservoir F, where it is allowed to settle, after which
the supernatent liquid can be run through sluice H or H¹ into F. The sludge in F
may then be removed and treated in any desired manner while the clear liquid in Fi
may either be run off into a river or tidal water or it may be run over land or
otherwise disposed of, and in some cases it may first be passed through electrolytic
filtering apparatus such as described in my patent No. 13337 or in the l'rovisional
Specification to my application No. 1105 of 1888.
In some cases I dispense with the separation of the sludge from the supernatent
liquid as it flows from the tanks A. A, and allow both to flow together into the
reservoir where the solid matter is allowed to subside, after which the supernatant
liquid is allowed to flow from F into F through the sluice H¹.
The arrangement of the electrolytic apparatus is as follows.
An electric current generated by a suitable dynamo electric machine at I passes
from the positive pole first to a conductor J extending along the side of the first
tank A. From this conductor branch conductors K extend across the tank and are
connected to positive electrodes L consisting of thick iron, plates secured at their upper

page_text: ends to beams M laid over the top of the tank. Between these electrodes are placed
the negative electrodes L of thin iron plates the upper ends of which are also secured
to the beams M and are electrically connected to negative conductors K¹
branching from the main negative conductor J₁ running along the other side of
the tank.
The end of this is connected to the conductor J2, to which is also connected the
positive conductor J to the next tank, and so on, along the whole row, the negative
conductor J¹ of the last tank being connected by a lead to the negative pole of the
dynamo machine. Thus it will be seen that the current passes in series from tank to
tank while it branches off in parallel to each row of electrodes in the tank. The
positive and negative electrodes being placed very close together in each row or group,
the resistance is greatly diminished. The conductor J2 is carried along the end of
all the tanks with a break J³ at each tank, so that by connecting any one or more
of these breaks by a contact switch, the electrical current may be made to pass by
the corresponding tank or tanks. Fig. 4 shews a plan of a modified arrangement
in which the sewage is raised from the sewer N by a pump O into a shoot P,
running along the top of the tanks, into each of which the sewage is admitted by
a sluice.
The sewage after treatment is discharged by the channel C into the reservoirs F F¹
as before.
Instead of treating the sewage in tanks as described, it may be made to flow along
a long shoot P in which are arranged groups of electrodes as indicated in the part
enlarged plan at Fig. 5.
The positive and negative electrodes L L are arranged in parallel groups along the
whole length of the shoot and are coupled to the sectional conductors JJ' by the
positive and negative branch conductors K K', the conductor J at the one end being
connected to the positive pole of the dynamo, while that at the other end is
connected to the negative pole. Thus it will be seen that the current flows through
each group of two sets of electrodes in parallel, and in series through the several
groups.
The sewage, while flowing along the shoot towards the reservoirs is brought into
repeated intimate contact with all the electrodes so that by the time it flows at Q into
the reservoirs it will have been effectually purified.
Having now particularly described and ascertained the nature of this inven-
tion and in what manner the same is to be performed I declare that what I
claim is :-
1. Arranging a number of separate electrolytic tanks for treating sewage with
their electrodes connected in series with the main conductor, so that, the current
passes in series through the several tanks substantially as and for the purpose herein
described.
2. Arranging the electrodes in groups in the tanks or conduits for the electrolytic
treatment of sewage, the electrodes in each group being connected in parallel,
while the several groups of electrodes are connected in series, substantially as herein
described.
1
1
L 1.
1000
ABEL & IMRAY,
Agents for the Applicant.