Bioreactor and method of measuring contaminants in an aqueous environment

A method and apparatus are provided for measuring the concentration of contaminants in an aqueous water system, wherein the contaminants are measured with the bioreactor containing a biofilm or microbial community which acts on the water to be analyzed to provide a measure of the amount of the dissolved organic carbon which is biodegradable. A bed for facilitating regulation of water flow through the bioreactor is provided, and an autosampling mechanism enables the measurement of total organic carbon, inorganic carbon and oxygen, between sample inflow and sample outflow at specified time intervals.

BACKGROUND OF INVENTION 
1. Field of Invention 
The present invention relates to the field of water contaminant and 
treatment measurements. 
2. Brief Description of the Prior Art 
Analyzing contaminants in a water supply can often take significant time to 
complete, and furthermore is often difficult to carry out. Present 
techniques and apparatus generally require much time to obtain 
measurements or readings of water supply contaminants. Water utilities are 
confronted with the task of maintaining contaminants at reduced levels, 
while, at the same time, controlling the levels of treatment compounds to 
maintain a safe concentration for consumption by users or ultimate 
discharge of the water into the ecosystem. Often strict government 
regulations must be met so as to have a minimum acceptable level of 
contaminants and maximum acceptable levels of treatment chemicals. 
Coliform bacteria and other contaminants must be carefully monitored and 
treated. In addition to the treatment compounds themselves added to water, 
byproducts are often formed from the reaction of these compounds with the 
contaminants. Therefore, it is not possible to simply add a given amount 
of treatment chemical to a water supply, rather, the water must be 
monitored before, as well as after, and even during the treatment process. 
Thus the need for accurate, timely analysis of contaminants, treatment 
chemicals and byproducts in a water system remains important to the 
ability to provide adequate treatment and management of a water supply. 
Dissolved organic matter is an important component in a water system that 
must be carefully monitored and controlled due to its relationship with 
the contaminants. The greater the presence of dissolved organic matter in 
a water system the greater the potential for water contaminants, such as, 
for example, bacteria and other organisms to proliferate and further 
contribute to the degree of contamination of a water supply. The effect is 
more pronounced over time if bacteria and other organisms are allowed to 
build up. Therefore, measurement of biodegradable organic matter in a 
water system provides information which can be used to determine the 
extent and success of disinfectant or treatment to be administered to a 
water supply. 
Biodegradable organic carbon has been measured by a number of different 
assays as a way of determining the concentrations of biodegradable 
dissolved organic matter present in the aqueous system. The assays, 
however, are known to take substantial time. Reliability and rapidness of 
measurement are desired when monitoring the concentrations of 
biodegradable organic contaminants at a water utility during the 
purification or disinfecting treatment process. 
SUMMARY OF THE INVENTION 
The present invention provides a method and apparatus for measuring 
concentrations of contaminants in aquatic systems, such as, for example, 
those present in water utility systems. Biodegradable dissolved organic 
matter is determined by the present invention. A method and apparatus are 
provided for measuring levels of organic carbon and inorganic carbon in a 
water system and utilizing a differential analysis to determine the level 
of biodegradable organic carbon contained in a water system. The apparatus 
of the invention provides a bioreactor which is inoculated with microbes 
to form a biofilm which acts upon the biodegradable organic carbon present 
in the water to be analyzed. The microbes generally comprise the natural 
flora and organisms indigenous to the water supply or system to be 
analyzed. The apparatus includes at least one chromatography column which 
is packed with a material on which microbes can proliferate. Water flow is 
directed through the column with a pump. The apparatus and method also 
facilitate control and regulation of the water passage through the column 
length. A bed is provided through which the water to be analyzed passes as 
it enters the column. A microbial inoculum is introduced to the bioreactor 
and resides on the packing material within the column. The bed provides an 
even flow of water to the microbes within the column and facilitates 
uniform water residence time as the water flows through the column. 
The microbial community establishes itself within the column, and 
thereafter can be utilized to measure biological activity with respect to 
water samples which flow through the bioreactor. A sample of the inflow 
water is taken and a sample of water is taken at the outflow. The 
biodegradable dissolved organic carbon (BDOC) present in the water sample 
is acted upon by the microbes wherein the biodegradable dissolved organic 
carbon concentration is ascertained by the difference between the readings 
of DOC concentrations between the inflow and the outflow. The present 
invention provides a novel sampling apparatus and method wherein 
continuous and automated readings of DOC concentrations at the inflow and 
outflow points of the bioreactor are obtained. The apparatus and method 
also provide means for determining inorganic carbon and organic carbon 
concentrations, and the concentration of dissolved oxygen in a water 
sample. 
It is an object of the present invention to provide a method and apparatus 
for determining the concentration of biodegradable organic matter in a 
water system as a way to measure biodegradable dissolved organic matter in 
the water system. 
It is another object of the present invention to accomplish the above 
object with a bioreactor. 
It is an object of the present invention to provide a novel bioreactor 
apparatus which can measure concentrations of material affected by the 
microbial community or biofilm present in the bioreactor. 
It is another object of the present invention to provide a bioreactor which 
can be used to provide accurate readings of biodegradable dissolved 
organic carbon in an aquatic environment, such as, for example, a drinking 
water utility processing plant. 
It is another object of the present invention to provide a novel method and 
apparatus for measuring contaminants in an aquatic environment, wherein 
the measurement can be determined within minutes of taking a sample. 
It is another object of the present invention to accomplish the above 
objects by providing water flow regulating means for regulating the 
passage of water as it enters and/or exits the bioreactor columns. 
It is another object of the present invention to improve the reliability 
and accuracy of measuring contaminants in an aqueous environment with a 
bioreactor by maintaining a uniform flow of water to be analyzed as the 
water sample travels through the column of the reactor. 
Another object of the present invention is to decrease the measurement time 
of ascertaining the concentration of contaminants in an aqueous 
environment, namely where the contaminants comprise biodegradable 
dissolved organic matter.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Referring to FIG. 1, a bioreactor 20 according to the present invention is 
shown comprising a water input line 21, a water output line 22, means for 
moving the water through the reactor, which is shown comprising an inflow 
pump 23, which preferably may comprise a peristaltic pump, and first and 
second columns 25 and 27, respectively. A sample source reservoir 24 is 
provided in which the water input line 21 extends so that the inflow pump 
23 can draw a flow of water from the sample source 24 and move the water 
along the input flow line 21 for delivery to the first column 25. The 
sample source, while shown represented as a reservoir 24, is preferably 
provided as a direct line (not shown) from the water source to be 
analyzed, such as, for example, any drinking water sources, including, 
without limitation, reservoirs, streams, wells or springs. The direct line 
may include one or more filtration steps, as necessary, to remove debris, 
and/or other components from the water source. Preferably filters used, 
while not shown, are comprised of materials which do not interfere with 
organic molecules and microbes, and which permit microbes to pass through 
into the filtrate. Generally, large particles which might otherwise 
interfere with the columns or water flow through the bioreactor 20 are 
desired to be removed. 
The inflow pump 23 directs the water through the first column 25, out of 
the first column 25 through a transition line 26 and into a second column 
27. The water inflow represented by arrow "a" may be diverted by an inflow 
valve 29 shown disposed in line and downstream from the pump 23. The 
inflow valve 29 is located before the first column 25 and can divert 
sample flow to the sampling tube 30 in the direction of arrow "b". The 
sampling tube 30 may be used for collecting spot samples or can be 
connected in-line for direct delivery of inflow sample to an analyzer, 
such as that shown in FIG. 2. 
The first and second columns 25, 27 are provided with means for regulating 
and controlling the flow of water through a column. Preferably, as shown 
in FIG. 1, and in the enlarged view of FIGS. 3 and 3a, is a bed 32 
comprising a plurality of apertures 33 through which the water entering 
the first column 25, for example, is forced. The bed 32 is generally 
comprised of an end fitting 34a, a bed support 34b, and an o-ring or 
gasket member 34c. The bed support 34b is placed on the end of the end 
fitting 34a and is secured with the gasket 34c. The end fitting 34a is 
then placed onto the end of the column 25. An end cap 35 is placed over 
the end fitting 34a to secure the bed 32 in place on the end of the column 
25. Suitable attachment means is provided for attachment of the bed 32 to 
the end of the column 25. As shown, the attachment means may, for example, 
comprise first threads 25a on the outer circumference of the column and 
matingly associated second threads 35a on the rim of the end cap 35. 
Preferably, the bed 32 comprises materials which do not interfere with the 
organic molecules and microorganisms and which do not leach molecules into 
the system. PTFE is an example of a compound that can be used to comprise 
the components of the bed 32, as can any other suitable inert material, 
which will not react, by adsorption, absorption, or otherwise, with the 
sample water, the microbes or the contaminants in the sample water, and 
which also will not leach material therefrom. The bed 32 facilitates even 
dispersion of the sample water through the column 25 represented by the 
arrows "c", so that water residence time and flow is generally equalized 
between various vertical zones of travel through the column 25. Since the 
beds 32 can be the same for each column inflow and outflow, they are 
generally designated by the numeral 32. Similarly, water flow through 
second column 27 is shown passing through the bed 32 in the direction of 
arrows "d". Optionally, while not shown, a water jacketed column can also 
be used as a way to maintain the temperature of the column. 
The first and second columns 25,27 are filled with a packing material, 
generally 36, which preferably comprises a suitable base on which the 
microbes (not shown) can proliferate to establish a biofilm or community. 
The packing material 36 preferably comprises a material which will not 
react with the water stream, the microbes, or any of the byproducts or 
contaminants being analyzed. For example, the packing material 36 may 
comprise a borosilicate glass. Preferably, an open-pored sintered glass 
material is used, and particularly preferably, open-pored sintered glass 
having a sphere diameter of about 1 to 2 mm, and a pore diameter of from 
about 60 to 300 .mu.m, such as that commercially available in the 
industry. 
The bioreactor 20 is prepared by assembling the components shown in FIG. 1, 
and then packing the first and second columns 25,27 with the packing 
material 36. The first column 25 is filled about half-way with the source 
water, and the packing material 36 is added to fill a couple of 
centimeters of vertical height of the first column 25, and tapped to 
settle the packing material 36 within the column. This step is repeated 
until the first column 25 is fully packed. The bed 32 is placed onto the 
top of the column 25 as described above (FIGS. 3 and 3a). 
Source water is then pumped through the first column 25, through the 
connecting tube 26 and then through the second column 27, until the second 
column 27 is about half full. The second column 27 is packed in the same 
manner as described above in relation to the first column 25, and is then 
closed with a bed 32. 
An output flow valve 37 is provided on the output flow line 22 for 
diverting output flow from the second column 27 to a waste flow line 40 or 
to a sample output flow line 41. The sample output flow line 41 may in 
turn be connected to a sample analyzer for monitoring of the water 
outflow, such as that shown in FIG. 2. 
Preferably, the first and second columns 25,27 are comprised of a non 
reactive material, such as, for example, borosilicate glass. The flexible 
tubing utilized to comprise the flow lines can comprise any suitable 
non-reactive composition, and preferably a polytetrafluoroethylene 
material is used. 
The bioreactor 20 must be inoculated with microbes in order to commence 
operation. The microbes utilized are those indigenous to the water source 
to be measured, such as for example a stream (not shown). The inflow of 
source water 38 into the reactor columns 25,27 introduces the microbes to 
the bioreactor 20 where they reside on the surfaces of the packing 
material 36. Generally, the source water 38 is permitted to continuously 
flow through the bioreactor 20, at a predetermined rate, so that the 
microbial community or biofilm can be sustained within the bioreactor 20. 
The bioreactor 20 must undergo a period of up to about four to six months, 
or sometimes greater, for the microbial community to become established on 
the packing material 36 surfaces. 
Establishment of the microbial community in the bioreactor 20 can be 
ascertained by repeating a measurement of a water sample containing a 
known concentration of contaminants until consistent results are obtained. 
Generally, the biodegradable dissolved organic carbon expressed as a 
percent of dissolved organic carbon (DOC) which is removed from the water 
inflow by the action of the microbes in the bioreactor 20 steadily 
increases from the initial inoculation of the bioreactor 20 with the water 
containing the microbes until the biofilm has been established, at which 
time the rate of DOC removal levels off. The biofilm establishment time 
depends on the type of contaminants and organisms present, as well as 
other factors which might have an effect on the microbial metabolism rate 
such as, for example, temperature and season of year. 
Measurement of the DOC concentration can be performed by taking a reading 
of the inflow and the outflow and determining the difference in the 
concentration of DOC. The microbes in the bioreactor 20 will consume DOC. 
Therefore, if the total concentration of organic carbon of the inflow is 
known, the difference in the organic carbon reading from the outflow 
provides a measure of the concentration of biodegradable dissolved organic 
carbon (BDOC). The measurement obtained is a net measurement because the 
microbes, while consuming organic molecules, excrete some organic 
molecules, as well, such as for example, waste products. Therefore, the 
measurement of BDOC which appears to be consumed actually represents some 
organic matter which is consumed by the microbes and some organic matter 
which the microbes have produced as byproducts of metabolism. 
Once established, the bioreactor 20 can be utilized to ascertain the 
concentration of biodegradable organic matter present in the water system. 
The water sample 38, or stream, to be analyzed is pumped through the 
columns 25,27 and samples taken at the inflow and at the outflow to 
measure the concentrations of contaminants present in the form of organic 
carbon molecules. Inorganic carbon (IC) can also be determined as a check 
on the microbe activity. The net change in organic carbon between the 
concentration of the inflow versus the concentration of the outflow is 
representative of biodegradable dissolved organic matter, which has been 
metabolized (although a minor amount of the organic carbon may actually 
have been a byproduct of microbial metabolism the reading obtained is 
generally accepted as an underestimate of BDOC contaminant). 
A preferred sampling and measuring apparatus is shown in FIG. 2. A 
bioreactor 100 with autosampling capabilities is shown in partial 
schematic view. The water supply source for sampling is generally 
represented by the reservoir 101, but can comprise a direct line from a 
stream, well or other water supply to be analyzed. An inflow line 102 
extends from the sample reservoir 101 or stream to a sample inflow pump 
103 which operates to draw water from the sample source 101 and moves the 
water through the reactor first and second columns 105,106. The first and 
second columns 105,106 are preferably provided with the flow regulation 
means described above in relation to FIGS. 3 and 3a, and shown comprising 
the bed 32. The flow regulation means facilitates an even flow of sample 
water through the first and second columns 105,106 to provide uniform 
residence time for sample contact with the biofilm established within the 
first and second columns 105,106. The bed 160 can be provided to be of the 
same construction as the bed 32 described above and shown in FIGS. 3 and 
3a. 
Sample water flows into the first column 105, and then through a transition 
tube 109 connecting the columns 105,106 and through the second column 
outflow tube 107. The transition tube 109 makes it possible for there to 
be an additional sampling point between the columns 105,106. The second 
column outflow line 107 flows into an output flow diverter valve 108 which 
can be operated to divert the flow exiting the second column 106. As shown 
in FIG. 2, three paths of travel are possible from the diverter valve 108. 
The output flow diverter valve 108 may be manually operated or can be 
automatically operated in conjunction with a timer or other mechanical or 
electronic means. A waste line 111 is connected to the output flow 
diverter valve 108 to provide a further path of travel. A flow line 112 is 
also provided as a further path of travel for the sample flow coming out 
of the second column 106, which flow line 112 leads to a TOC analyzer 113. 
The third path of travel shown from the diverter valve 108 connects to an 
oxygen flow cell valve 114 which regulates passage through an oxygen flow 
cell 115. 
The dissolved organic carbon (DOC) concentration of the water samples to be 
analyzed with the bioreactor 100, is ascertained with the use of a DOC 
analyzer 113. The analyzer 113 receives sample and through the use of UV 
radiation and a chemical oxidizing reagent, such as, for example, ammonium 
persulfate, measures the amount of formed carbon dioxide resulting from 
the oxidation of the carbon containing compounds present in the sample. 
Such analyzers are commercially available, such as, for example, a Sievers 
model 800 TOC analyzer. The concentration of the organic compounds present 
in the water sample is measured by the TOC analyzer 113. 
Since the calculation is determined by taking the difference between the 
total carbon and the inorganic carbon to ascertain the total organic 
carbon, if high levels of inorganic carbon are present in the water 
samples, then the total organic carbon measurement is overestimated. An 
inorganic carbon (IC) removal module 116 is provided to remove the 
inorganic carbon from the sample. The removal module 116 may comprise a 
vacuum degassing module which has the capability of removing approximately 
99% of the inorganic carbon in the sample. Unamended sample flows into the 
IC removal module 116 and is degassed and the sample is then sent to the 
TOC analyzer 113 where it is acidified and analyzed for dissolved organic 
carbon. The IC removal module 116 can be commercially purchased as a 
Sievers ICR Module 800 (Inorganic Carbon Removal Module). 
Readings are taken of total organic carbon (TOC) and inorganic carbon (IC) 
for each sample. A timer 1 17 is provided to control the flow path of the 
water sample to be analyzed by selecting between two flow paths. The timer 
117 preferably comprises a digital two channel timer which can be set to 
regulate the flow of the sample to pass through the IC removal module 116 
for a reading of TOC or to bypass the removal module 116 for reading of 
IC. The first channel of the timer 117 changes between selection of flow 
from the inflow line 118 and flow through the outflow line 112 of the 
bioreactor 100. The second channel selects whether the TOC is measured 
with IC present or after IC removal has taken place. This permits 
selection between measurements of TOC and IC, as well. The selection of 
channels is time-based and can be preset. A selection valve 120, which 
preferably comprises an electrically controlled two-way position valve 
switcher, connects the TOC analyzer 113 with the IC removal module 116. 
The selection valve 120 is switched to permit the flow of sample through 
the IC removal module 116 for the TOC measurement. For the IC measurement, 
the removal module 116 is bypassed and the module 116 is switched off. The 
preferred time of operation for TOC and IC measurement is one hour. The 
timer 117 can therefore be set to alternate between uninterrupted flow to 
the analyzer 113 and flow through the IC removal module 116, prior to the 
flow to the analyzer 113. 
The second channel regulates timed selection between sample inflow and 
sample outflow through an inflow/outflow valve 121. For example, the 
second channel of the timer 117 can be set to change between inflow and 
outflow every two hours, so that for two hours the inflow is sampled and 
for the next two hours the outflow is sampled. Other times can be used 
depending on the TOC concentration, column size and the residence time 
required for the microbes in the bioreactor 100 to act on the 
biodegradable dissolved organic carbon. 
In addition, while the IC reading operates as a check on biofilm activity, 
the IC readings can be done less frequently than the TOC readings, with 
the timer 117 adjusted accordingly. 
As shown in FIG. 2, an oxygen monitoring system, generally 130, is 
provided. The oxygen monitoring system 130 can be provided in line with 
the bioreactor flow paths to receive sample inflow and sample outflow for 
analysis of oxygen content. The sample may flow through the analyzer 
inflow line 118 wherein inflow sample is drawn through the inflow/outflow 
valve 121 for measurement with the TOC analyzer 113, as discussed above. 
Sample may also be moved through the column inflow line 132 with the 
inflow pump 103. Sample can be drawn through the column inflow line 132 
with the inflow pump 103 and then moved through the first column 105, 
through the connecting tube 109 and through the second column 106. The 
inflow pump 103 can be preset to a desired flow rate to provide adequate 
residence time of the sample water in the columns 105,106 so that the 
microbes can act on the molecules in the sample. In addition, while not 
shown, an inflow selection valve may be provided to permit one or more of 
the analyzer inflow line 118 and/or the oxygen analyzer flow line 133 to 
receive a flow at the same time, in addition to the flow to the column 105 
through the column inflow line 132, which must be continuously maintained. 
An oxygen analyzer flow line 133 is connected to a oxygen monitoring 
system inflow pump 134 which sends an inflow sample through the oxygen 
monitoring system 130. 
A pulse damper 135 is provided to receive the flow from the oxygen 
monitoring system inflow pump 134, whereupon the flow is directed next 
through a temperature control means, shown in FIG. 2 comprising an inflow 
water jacket 136 and an outflow water jacket 138. The oxygen monitoring 
system includes an inflow cell 137 and an outflow cell 115. Water inflow 
sample enters the inflow cell 137 after passing through the water jacket 
136 as shown in FIG. 2. An outflow cell 115 receives sample outflow from 
the second column 106 through the oxygen flow cell valve 114. The oxygen 
monitoring system inflow pump 134 supplies an oxygen inflow cell 137 with 
sample water. The inflow cell 137 and the outflow cell 115 each contain an 
electrode which is used to give rise to an electrical potential which is 
in turn is detected by an amplifier 149. The amplifier 149 can be any of 
those commercially available for reading the potential from the flow cell 
electrodes, such as for example the Instech Dual Oxygen Electrode 
Amplifier Model 203. A pulse damper 135 is provided in the flow path 
before the inflow cell 137. The damper 135 facilitates an even response by 
minimizing strong flow variations and variations in the measurement 
response. 
FIG. 4 shows the damper unit 135 in an enlarged view comprising 
compensation tubing 141 and a resistance unit 142 shown after the pump 
134. The resistance unit preferably comprises an adjustable clamp or other 
suitable narrowing element which constricts the flow through the line 143. 
The material comprising the damper components generally must not react 
with the molecules to be measured or affect the biofilm or leach any 
material into the system. 
The second electrode 115 is connected alternatively with the outflow 
through the outflow oxygen monitoring line 145 or directly with the first 
electrode 137 of the inflow. This arrangement provides for the calibration 
of both electrodes 137,115 at the same time. The first electrode of the 
inflow cell 137 has an outlet line 147a through which the sample passes, 
which in turn is connected to an interrupt valve 146 which can be set in 
one of two positions as shown, to dispense the sample to a waste line 147b 
or to permit sample flow to the second electrode 115 through the 
transition line 147c. The oxygen flow cell valve 114 located before the 
second electrode of the outflow cell 115 can be operated to permit the 
sample flow from the inflow cell 137 to enter the outflow cell 115. 
The amplifier 149 measures the response from the first and second 
electrodes, 137 and 115, respectively. The electrodes 137, 115 are in line 
oxygen electrodes and are provided to measure in real time with the system 
flow. The response or signal detected by the amplifier 149 can be further 
integrated by a recording device (not shown) to calculate a reading 
corresponding to the oxygen content of the sample. 
It is often necessary to calibrate the first and second electrodes 137, 
115, which is done by bypassing the bioreactor columns 105,106 with the 
oxygen monitoring system calibration valve 148 set to close the inflow 
line 133 and draw calibration standard 151 from the calibration flow line 
150. Also, the oxygen flow cell valve 114 is closed to prevent outflow 
from entering the oxygen monitoring system 130. Preferably, the 
calibration standard 151 comprises oxygen saturated water. 
The measurement of TOC was obtained by taking the data stored on the TOC 
analyzer 113 and processing it to obtain concentration values over time 
for the sample. The activity and metabolism of the bacteria is observed 
over time, and the concentration of BDOC can be ascertained to evaluate 
the contaminant level present in the water supply being analyzed. 
The bioreactor 100 is prepared for operation by first introducing a flow of 
water from the source, such as for example, a stream, which is to be 
analyzed. Conditions for preparation and operation of the bioreactor 100 
require darkness, so as to prevent light from activating any algae which 
might be present in the water source or in the column. Also, any water to 
enter the bioreactor which contains disinfectant, such as chlorine or the 
like, must first be neutralized to prevent destruction of the biofilm. The 
water from the source is then pumped through the reactor columns. 
Preferably, this is done at a flow rate of about 2 to 4 ml/min. This can 
be done by attaching a direct supply line from the stream to the pump 103 
or can be achieved by providing a line from a sample reservoir 101 
containing the source water. The water must be maintained at a continuous 
rate of flow through the reactor in order to allow the bacteria and other 
organisms in the water to inhabit the packing material 110 of the columns 
105,106. This generally takes approximately four to six months, after 
which time, the bioreactor 100 is ready for use. The flow of source water 
must also be continuously maintained through the bioreactor 100 even when 
no measurements are to be taken, in order to enable the biofilm to 
maintain a state of equilibrium. 
The measurement of contaminants in a water supply is an ongoing task. The 
inoculated bioreactor 100 is provided with a flow of sample from the 
reservoir 101 or water source which was used to provide the inoculum for 
the bioreactor 100. For example, in instances where treatment chemical 
disinfectant has been added to the water supply, the bioreactor 100 can be 
used to determine the BDOC level. The water from the reservoir 101 is made 
to flow through the bioreactor 100 by the use of the pump 103. Preferred 
flow rates of from about 2 to 4 ml/min. are generally used for a 
bioreactor in which the columns 105,106 are about 2 to 3 cm in diameter 
and 40 to 70 cm in height. Columns with different size dimensions can also 
be employed, and other flow rates, both greater and slower can be used. 
For example, a single column can also be used. The flow rate can be 
determined by the volume of the column and can be regulated with the pump 
to achieve uniform flow rates if different column sizes and numbers are 
used. 
Water to be measured is permitted to flow through the bioreactor columns 
105,106. The diverter valve 108 is operated to permit sample outflow from 
the second column 106 to enter the inflow/outflow control valve 121. The 
control valve 121 accepts the outflow sample and permits the sample to 
further pass to the DOC analyzer 113, whereupon the sample is run through 
a subchannel flow path which leads to the IC/DOC valve 120. The IC/DOC 
valve 120 is operated with the timer 117 to control the flow to one of two 
possible paths, one which IC removal takes place and another which IC is 
not removed. As noted above the timer 117 has two channels and generally 
the second channel regulates the flow through the IC removal module 116 to 
either send the sample to the IC removal module 116 for removal of IC or 
to bypass IC removal and permit the sample to flow directly to the 
analyzer 113. If the sample is directed through the IC removal path, the 
sample is then analyzed after the IC removal. Generally, the timer channel 
regulating the IC module flow is switched on an hourly basis to provide an 
hour of IC removed sample analysis and an hour of IC present sample 
analysis. 
The above described sampling procedure with respect to the IC removal 
described in connection with sample outflow is also done with respect to 
the inflow sample. In that case inflow sample from the DOC inflow line 118 
is moved to the inflow/outflow valve 121 with the use of the pump 152. The 
inflow undergoes the same sampling procedures as described above in 
relation to the outflow sampling analysis and the IC removal module. 116. 
The inflow sample is measured by the DOC analyzer 113 to provide readings 
of carbon concentration for sample inflow with and without removal of 
inorganic carbon. 
EXAMPLE 1 
The following data was generated with water from White Clay Creek, located 
in southeastern Pennsylvania. The flow rate was maintained at 4 ml/min. 
The columns used were two borosilicate glass tubes each having an internal 
diameter of 2.5 cm and a length of 60 cm, sold under the name 
Chromaflex.TM. by Kontes. The packing material comprised open pored 
sintered glass of 1-2 mm sphere diameter, 60-300 .mu.m pore diameter, 
unmodified, which is sold under the name Siran.RTM. by Schott. PTFE tubing 
used to connect the pumps, valves and columns in the arrangement described 
above and shown in FIG. 2. The bioreactor was inoculated by pumping water 
from the White Clay Creek through a filter system including a first 25 
.mu.m filter in line with a second 0.3 .mu.m filter, and then through the 
columns. This was done in the absence of light and for a period of four 
months after which time the bioreactor was colonized. When the reactor was 
inoculated and the biofilm formed, a sample of the White Clay Creek water 
was drawn into the bioreactor with the inflow pump and pumped through the 
columns at a rate of 4 ml/min. The readings were taken and recorded in 
Table 1 below, and the total organic carbon (TOC) in mgC/l, ascertained by 
taking the difference between (i) the average of the first six values of 
TOCin and (ii) the average of the next six TOCout values to obtain the 
first point "A" on Graph 1 (FIG. 5). Subsequent readings in the same 
manner, listed in Table 1, produced points "B","C", and "D". The readings 
represent sample from which the IC was removed by the IC removal module. 
TABLE 1 
______________________________________ 
Data Used to Calculate Stream water BDOC Concentration 
TOC (mg C/L) 
Date Time In Out 
______________________________________ 
5/30/96 18:35 2.725 
18:41 2.706 
18:47 2.665 
18:53 2.673 
18:59 2.671 
19:05 2.679 
20:29 1.869 
20:35 1.858 
20:41 1.859 
20:47 1.864 
20:53 1.865 
20:59 1.854 
22:29 2.608 
22:35 2.622 
22:41 2.631 
22:47 2.630 
22:53 2.630 
22:59 2.622 
5/31/96 00:38 1.858 
00:44 1.853 
00:50 1.847 
00:56 1.850 
01:02 1.853 
02:32 2.594 
02:38 2.608 
02:44 2.612 
02:50 2.625 
02:56 2.613 
03:02 2.621 
04:33 1.859 
04:39 1.856 
04:45 1.860 
04:51 1.861 
04:57 1.910 
05:03 2.588 
06:33 2.600 
06:39 2.606 
06:51 2.613 
06:57 2.615 
07:03 2.623 
08:21 1.862 
08:27 1.853 
08:33 1.852 
______________________________________ 
While not shown, alternately, several TOCin readings with IC present (that 
is, water from the inflow) can be taken at six minute intervals over the 
course of an hour and an average value of .mu.g C/l can be obtained for 
ICin. During the next hour, several TOCout readings with the IC present 
(that is water from the outflow) can be taken in about six minute 
intervals and an average value of .mu.g C/l can be obtained for ICout. As 
pointed out above, the IC concentration can be used as a check on the 
biological activity of the biofdim. 
EXAMPLE 2 
Dissolved oxygen can also be measured by the bioreactor apparatus. The 
oxygen monitoring system described above was utilized by first calibrating 
the electrodes by bypassing the reactor, closing off valve 148, and using 
O.sub.2 saturated water 151 from the calibration line 150. For optimal 
results, a calibration check was performed on the electrodes after each 
reading. The electrode used was a Clark-style polarographic electrode 
(Ag/AgCl). The flow rate, temperature, and pressure are kept constant, 
then more accurate results can be obtained. The values of dissolved oxygen 
concentrations are indicated in mm Hg and the following formula is used to 
convert the result to mg/l: 
##EQU1## 
The amplifier takes the reading from the electrode and provides a 
measurement of the oxygen level in the sample. A valve is provided and is 
switched to permit inflow and outflow readings to be made. 
Other modifications consistent with the scope of the invention described 
herein may also be made. For example, while not shown, it is understood 
that filters may be used to remove large particles of debris from the 
water flow to the columns. The filtration may be done in line before the 
entry to the column or analyzers or can be done in the line feeding the 
stream water to the reactor. In addition while two columns are shown, the 
apparatus may comprise additional columns, as well, or a single column may 
be used. The valves can be manually or electronically operated and can 
also be controlled with a timer.