FIELD OF THE INVENTION
The present system relates to a dosing system for bioreactors and the like and ,in
particular, to a carbon dosing system adapted to effectively discharge metered quantity of
dissolved organic carbon into the bio-reactor against the pressure created by the height of
the water column. The dosing system of the present invention is favourably adapted to be
effective for long term efficient operation of bio-reactors such as those using carbon
consuming sulfate reducing bacteria to achieve desired sulfide precipitation of heavy metal
and reduction of dissolved sulfate in traditional bio-reactors such as chemo-bioreactor to
treat Acid mine drainage/ coal mine drainage/ wastewater. The dosing system is further
adapted for applications where high amount of nutrient is always required for the microbial
activities e.g. dosing of nutrient/buffer/other liquid in any fermentation process or dosing
of sugar/ nutrient for production of bread or alcohol and the like, making such system
capable of wide industrial application.
BACKGROUND ART
It has been a common experience in the traditional bio-reactors for treatment of effluent
for treatment of the acid mine drainage with sulfate reducing bacteria or the like, the lime
based hydroxide precipitation system usually suffer from lack of sulfide precipitation,
which reduces the efficiency of the system due to reduction in the availability of the
dissolved organic carbon. A carbon supplement to the precipitation system is thus
necessary all over the world for thousands of such bio-reactors that suffer from problems
relating to carbon depletion. It is known in the art, that a good amount of dissolved
organic carbon source is required for the decomposition of sulfate into metallic and
hydrogen sulfide in presence of sulfate reducing bacteria. In all such experimental set-up
where decomposition using bacterial treatment has been applied, supply of organic carbon
is done only once. Such bio-rector process suffer from a phenomenon called carbon
draught after within 2-3 months of operation of the reactor column and the carbon
concentration of dissolved organic carbon is -educed and thus decreasing the efficiency of
the reactor column. This necessitates supply of carbon from an external source in the form
of addition of nutrient.

There has been therefore a persistent need in the art to develop a system for carbon
dosing in the bio-rector for sulfide precipitation with enhanced efficiency through periodic
dosing of the dissolved organic carbon from external source, in measured quantity right at
the place of reduction environment at the bottom of the rector below the water column
overcoming the pressure of column such that the sulfate reducing bacteria gets nutrient to
maintain favored higher reduction efficiency of the reactor column for long run operation.
In the existing practice of sulfate reduction using dissolved organic carbon as the nutrient
addition for supplementing depleted carbon for improving reduction efficiency of bacterial
treatment some literatures (such as by T.K. Tsukamoto and G.C. Miller, 1999) which
suggest that carbon source is required for the sulfide precipitation of the heavy metal but
effective carbon dosing system has been reported yet.
US 7093594 states about a 'Dosing device' wherein a dispenser for dispensing a dose
material and a dose actuation mechanism comprising links and hinged joints to effect
desired dosing.
US 5184761 speaks about a 'Dispensing apparatus' comprising a pressurized dispensing
container having a tubular valve stem biassed into an extended position and valve means
operable to dispense fluid through the stem when the stem is depressed, the housing
defining an airway extending from an inlet means open to the atmosphere to an outlet
defined by a mouthpiece whereby inhalation of a user results in an air flow through the
airway and a flow sensor arranged in the airway and operable to actuate another valve
means in response to a flow of air being sensed in the airway.
US 6523723 speaks about a 'Dosing Feeder For Liquids' wherein a dosing arm which
defines an upwardly-open dosing cup and a dosing head having a fitting, which defines a
passageway in which said dosing arm can extend and a first duct which extends through
said fitting to said passageway; selective screw threading means and an adapter allow said
dosing cup to dispense of bonding liquid from a container.
US 7299800 speaks about a 'Fluid product dispensing device' comprising a fluid dispenser
device including a reservoir containing the fluid and a propellant; a metering valve
mounted on the reservoir and including a metering chamber, and a valve member that is

movable between a rest position and a dispensing position; and an automatic trigger
system, including an actuator element to displace one of the valve member and the
reservoir relative to the other so as to bring the valve member into its dispensing position.
Thus while the above systems relates to devices for dispensing of liquids for various
applications, none of the above devices aims to solve dispensing liquids at the points of its
application with periodic intervals in a accurately controlled metered quantity involving
intricate electronic control based on requirement of carbon replenishment for specific
application in bio-reactors.
There has been thus a persistent need to developing a carbon dosing system which can
effectively discharge the dissolved carbon in the bio-reactor against the pressure created
by the height of the water column at the exact location of reducing environment where
carbon draught phenomenon has occurred in an operating bio-reactor column, needing
fresh infusion of liquid/dissolved carbon as nutrient supplement for the sulfate reducing
anaerobic bacteria to retain the desired reduction efficiency of the reactor bed/column. The
system would be capable of periodic dosing of dissolved organic carbon from an external
source in controlled quantity at the reducing reaction site itself in a consistent manner,
thus ensuring reliable and efficient operation of the bio-reactor for sulfate reduction and
sulfide precipitation system by providing required nutrient for anaerobic bacteria involved
in the reduction process, improving longterm operational life of the bio-reactors.
OBJECTS OF THE INVENTION
It is thus the basic object of the present invention is directed to avoid the problem
associated with traditional bioreactors about carbon depletion, which involves introducing
organic carbon from outside into the bioreactor when the carbon source in the bioreactor is
totally exhausted by the sulfate reducing bacteria.
Another object of the present invention to provide a dosing systems such as a carbon
dosing system for bio-reactors for sulfate reduction and/or in other filed such as where
high amount of nutrient is always require for microbial activities adapted for metered
dosing of required reaction actives at desired locations and thereby would favour better
control and efficacy of such bio reactions.

A further object of the present invention is directed to a dosing systems such as a carbon
dosing system for bio-reactors which would favour achieving higher rate of sulphate
reduction.
A further object of the present invention is directed to a carbon dosing system for bio-
rectors for sulfate reduction, adapted for periodic dosing of dissolved organic carbon
capable of discharging liquid carbon from external reservoir by injecting at high pressure
against the pressure of the water column in the reactor.
A still further object of the present invention is directed to a carbon dosing system for
periodic dosing of dissolved organic carbon in bio-rectors for sulfate reduction in accurately
controlled quantity for replenishment of carbon requirement involving simple and effective
solid-state control.
A still further object of the present invention is directed to a carbon dosing system for
periodic metered dosing of dissolved organic carbon in bio-rectors which would be simple
to operate and user friendly.
SUMMARY OF THE INVENTION
Thus according to the basic aspect of the present invention there is provided a dosing
system for bioreactors and the like comprising:
a reactor vessel;
a dosing unit operatively connected to said reactor vessel;
a vessel containing the liquid to be dosed operatively connected to said dosing unit;
means to selectively allow desired amount of the liquid to be dosed into the reactor first
into said dosing unit and thereafter further down into the reactor vessel.

Another aspect of the present invention is directed to said carbon dosing system for
bioreactors and the like comprising:
a reactor vessel;
a dosing unit operatively connected to said reactor vessel;
a vessel containing the dissolved carbon to be dosed operatively connected to said dosing
unit;
means to selectively allow desired amount of the dissolved carbon to be dosed into the
reactor first into said dosing unit and thereafter further down into the reactor vessel; and
a controller means adapted to selectively operate said valve means to allow selectively and
measured quantity of dosing of the liquid in the reactor.
A further aspect of the present invention is directed to a dosing system for bioreactors
wherein said valve means comprises a first solenoid valve adapted to allow measured
quantity of the liquid to be reacted into said dosing unit from said vessel containing the
same and a second solenoid valve at the outlet of the liquid to be purged to the reactor
and operatively connected with a discharge metallic pipe.
A still further aspect of the present invention is directed to a dosing system for bioreactors
wherein said discharge metallic pipe comprise a cylindro-spiral dispenser at the end away
from its operative connection to the second solenoid valve at its top end.
A still further aspect of the present invention is directed to a dosing system for bioreactors
a dosing system for bioreactors wherein said first solenoid valve is fitted on the sidewall of

the tube working as the inlet of the liquid into the dosing unit and operatively connected to
said vessel containing the liquid to be dosed.
A still further aspect of the present invention is directed to a dosing system for bioreactors
wherein said controller comprises a solid state controller.
A still further aspect of the present invention is directed to a dosing system for bioreactors
wherein said dosing unit comprises a open ended tubular construction wherein tow wires
are inserted from the top of said tubular dosing unit ,one of said wires adapted to measure
the quantity of the liquid to be dosed and other wire adapted to work to discharge the
liquid by opening the second solenoid valve at the bottom of the dosing unit.
A still further aspect of the present invention is directed to a dosing system for bioreactors
wherein said controller means is housed in a metallic box.
The present invention and its objects and advantages are described in greater details with
reference to the accompanying non-limiting illustrative figure.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
Figure l:is the schematic illustration of the carbon dosing/injection system according to
the present invention for dissolved organic carbon in bio-reactors for sulfate
reduction/sulfide precipitation.

DETAILED DESCRIPTION OF THE INVENTION WITH REFERENCE TO THE
ACCOMPANYING DRAWINGS
The present invention is directed to a carbon dosing system adapted to discharge accurate
predetermined quantity of dissolved organic carbon, right at the bacterial residence site of
the reducing environment at the bottom of the reactor as additive nutrient for the sulfate
reducing bacteria below the water column in order to replenish the deficient carbon
concentration in the system and thus increasing the reduction efficiency of the system for
longer period in the same reactor column.
Reference is first invited to the accompanying Figure 1, that schematically illustrate the
carbon dosing system for the bio-reactor for the present invention adapted to discharge
measured quantity of dissolved organic carbon from an external reservoir at the bottom of
reactor whenever the carbon concentration has been substantially reduced by way of
sulfide precipitation of heavy metals, reduction of dissolved sulfate, and providing
nutrients to the sulfate reducing bacteria to restore and retain desired reduction
environment at the reactor bed below the water column. The Carbon dosing system of the
present invention is thus capable to assess the carbon draught situation and inject
predetermined dose of dissolved organic carbon from an external reservoir, automatically
at periodic intervals and thus ensuring long term reduction efficiency of the rector column.
It is clearly apparent from the accompanying Figure 1, that this carbon dosing system is
used to purge liquid at a measured quantity :o the reactor. The system comprise:
1) The main body is made of acrylic tube.
2) The tube is filled with 2Nos. Solenoid Valve.
One Solenoid Valve is fitted on the sidewall of the tube working as inlet of the liquid to be
purged for reaction, being connected to the vessel containing the liquid to be purged.
The other Solenoid valve is fitted at the outlet of the liquid to be purged to the reactor and
connected with a discharge metallic pipe with a cylindro-spiral dispensing ring at the
bottom which will go down inside the reactor.

Two wires are inserted from the top of the tube wherein one of the wire is to be adjusted
to measure the quantity of the liquid to be purged in to the reactor and the other wire is
working to discharge the liquid by opening the solenoid valve fitted at bottom.
These, two wires and the two solenoid valves are connected to a solid-state controller
housed in a metallic Box.
The present system thus can act as periodic dosing system with the attachment of the
electronic instrumentation/controller. It is able to introduce the carbon into the bioreactor
in a long range depending upon the requirement.
The performance and reliability of the system is tested for different parameters under
variable operating conditions and dosing fluid characteristics.
An initial dosing rate is selected for discharging the liquid dissolved carbon. One solenoid
valve is adjusted according to the scale of discharge. As the control panel is switched on,
the liquid dose is first discharged from the vessel (A) containing the dissolved organic
carbon /liquid carbon to the dosing unit (B) by the solenoid valve(Sl). As the fixed amount
of dose is provided to the dosing unit(B), the second solenoid valve (S2) is opened on the
opening of a switch in the control panel, discharging the liquid to the reactor vessel
through a cylindro-spiral dispenser at the bottom of the reactor column at the bacterial
residence site.
Testing of the carbon dosing system of the present invention has been carried out
comprising the following different steps at different stages of implementation of the
system:
1. Design of the construction parameters including lengths, diameters, materials for
the containers and connecting passages etc. are selected for desired performance
and reliability to meet the requirement of accurate quantity of periodic dosing.
2. Selection of the discharge parameters are determined based on the rate of
discharge, time, quantity etc.
3. Measuring strength, leakage, capacity etc. : elaborate tests are carried out once
the system is constructed for checking leakages from the system, over or under
capacity dosage, repeatability, accurac/ etc are measured.
4. Measurement of the carbon dosing performance according to the height of water
column by measuring and correlating the calculated dosing rate to the actual dosing

rate, under variable water column heights in bio-reactor.This data are compiled and
presented in the accompanying Table 1 below.
5. Performance testing of the electronic instrumentation comprising testing of
functioning of solenoid valves and the solid-state controller for accuracy and
consistency at the desired level.
6. Endurance test of the set up was carried out for ascertaining for how many times
the system can perform reliably without any disturbance under variable operating
conditions such as the variations in viscosity, temperature, density of the dose
material etc.
7. Selection of concentric tubular dose discharge system which is first of its kind, not
reported earlier.
Table 1:
TEST DATA INDICATING ACCURACY AND RELIABILITY OF THE DOSING SYSTEM.

The above test data and observations clearly indicate the accuracy and reliability of the
carbon dosing system according to the invention in terms of designed and actual dosing of
dissolved organic carbon, using the present system and thus ensuring efficient
performance of the bio-reactors for sulfate reduction using sulfate reducing bacteria,

subjected to carbon depletion after lapse of certain time during operation, while equipped
with the present carbon dosing system according to the invention.
It is thus possible by way of the present invention to achieve the following advantages
over the existing systems used for the same purpose:
-the rate of sulfate reduction becomes higher than usual reactors.
-both the reactive anions and carbon radicals are present to complement each other that
speed up the reaction rate higher than each of them working independently.
-the dosing system of the invention can control carbon dosing rate as per requirement
which is an unique novel feature of the system.
-the system is capable of delivering sufficient pressure discharge for carbon dosing against
the load of the water column.
Such a dosing system described above is also suitable for application in other field where
high amount of nutrient is always required for the microbial activities, comprising the
areas like:
a. Organic carbon/ nutrient /lime dosing/addition into bioreactor /test cell/chemo-
bioreactor to treat Acid mine drainage/ coal mine drainage/ wastewater;
b. Addition/dosing of sugar/ nutrient for production of bread or alcohol;
c. Addition/dosing of nutrient/buffer/other liquid in any fermentation process;
d. Addition/dosing of inorganic chemical into chemical synthesis/transformation reactor.
The carbon dosing system of the present invention is thus an user friendly and reliable
device adapted to ensure its functional benefits including accuracy of discharging, time and
periodicity, enhancing the operational efficiency of the reactors/treatment columns,
extendable to a wide range of application area with equal reliability and consistency and
thus having the potential for economic advantages in various industrial applications.

WE CLAIM:
1.A dosing system for bioreactors and the like comprising:
a reactor vessel;
a dosing unit operatively connected to said reactor vessel;
a vessel containing the liquid to be dosed operatively connected to said dosing unit;
means to selectively allow desired amount of the liquid to be dosed into the reactor first
into said dosing unit and thereafter further clown into the reactor vessel.
2. A carbon dosing system for bioreactors and the like comprising:
a reactor vessel;
a dosing unit operatively connected to said reactor vessel;
a vessel containing the dissolved carbon to be dosed operatively connected to said dosing
unit;
means to selectively allow desired amount of the dissolved carbon to be dosed into the
reactor first into said dosing unit and thereafter further down into the reactor vessel; and
a controller means adapted to selectively operate said valve means to allow selectively and
measured quantity of dosing of the liquid in :he reactor.
3. A dosing system for bioreactors as claimed in anyone of claims 1 or 2. wherein said
valve means comprises a first solenoid valve adapted to allow measured quantity of the
liquid to be reacted into said dosing unit from said vessel containing the same and a
second solenoid valve at the outlet of the liquid to be purged to the reactor and
operatively connected with a discharge metallic pipe.
4. A dosing system for bioreactors as claimed in claim 3 wherein said discharge metallic
pipe comprise a cylindro-spiral dispenser at the end away from its operative connection to
the second solenoid valve at its top end.

5. A dosing system for bioreactors as claimed in anyone of claims 1 to 4 wherein said first
solenoid valve is fitted on the sidewall of the tube working as the inlet of the liquid into the
dosing unit and operatively connected to said vessel containing the liquid to be dosed.
6. A dosing system for bioreactors as claimed in anyone of claims 1 to 5 wherein said
controller comprises a solid state controller.
7. A dosing system for bioreactors as claimed claim 6 wherein said dosing unit comprises a
open ended tubular construction wherein tow wires are inserted from the top of said
tubular dosing unit ,one of said wires adapted to measure the quantity of the liquid to be
dosed and other wire adapted to work to discharge the liquid by opening the second
solenoid valve at the bottom of the dosing unit.
8. A dosing system for bioreactors as claimed in anyone of claims 6 or 7 wherein said
controller means is housed in a metallic box.
9. A bioreactor comprising a dosing system as claimed in anyone of claims 1 to 8.
10. A dosing system for bioreactors and a bioreactor having the same substantially as
hereindescribed and illustrated with reference to the accompanying figures.

A carbon dosing system for bioreactors adapted to effectively discharge metered quantity
of dissolved organic carbon in the bio-reactor against the pressure of the water column.
The carbon dosing system is adapted to discharge exact amount of carbon at the actual
site of reduction environment through a cylindro-spiral dispenser in presence of sulfate
reducing bacteria at the bottom of rector. The carbon supplement is ensured at desired
controlled rate, dispensed from an outside reservoir, operatively through selectively
disposed solenoid valves actuated by an solid-state electronic controller, as addition when
the carbon source is totally exhausted by the sulfate reducing anaerobic bacteria at the
reaction site. The system is on one hand effective for long term efficient operation of bio-reactors and the like making such system capable of wide industrial application.