Automated nutrient monitoring for water and wastewater
By R.Keir, Mohamed Aboul Eish, Ph.D., D. L.Davis and R. H. Clifford, Ph.D.
Hourly/daily nutrient trend
Nutrient pollution of waterways
is a very serious issue
experienced all over the
world. Adverse human activities
increase the nutrients beyond the
normal levels through point and nonpoint
sources, such as deforestation
and urbanization, use of fertilizers,
inadequate treatment of human
sewage, increased animal waste, industrial
wastewater and aquaculture operations.
Resulting nutrients enter into
water systems, rivers and lakes, and
lead to both enrichment and toxic
problems.
Other problems caused by an
increase in nutrient levels include acidification
due to runoff from agricultural
lands. Additionally, the runoff may
lead to an increase in levels of ammonia
and nitrate, which are harmful to
humans and aquatic life.
Canada has a total area of
9,984,670 sq km that constitutes
9,093,507 sq km of land and 891,163
sq km of water. About 7,200 sq km is
irrigated land and, as a result, fertilizers
and animal waste that are either
used or present on the land are washed
as runoff into the surrounding rivers,
lakes, and eventually major oceans and
bodies of waters, such as the Arctic,
Pacific, Atlantic and Hudson Bay.
Reports have suggested that nonpoint
sources, such as the use of fertilizers
and manure, can contribute
293,000 tons of nitrogen and 56,000
tons of phosphorus annually to the
total nutrient levels in the Canadian
environment. On the other hand, pointsource
pollution results mainly from
municipal sewage, and contributes
80,000 tons of nitrogen and 5,600 tons
of phosphorus annually. As municipalities
enhance their wastewater treatment
facilities, the level of the nutrients
discharged is lowered, but the bigger
concern is with utilities that still
use primary treatment and communities
that do not use any treatment.
Certain regulations have been
developed to control the nutrients’
input into the environment. Although
the regulations have not eliminated the
problem completely, they have somewhat
controlled the infiltration of the
nutrients and decreased the effect of
the nutrients in some areas. Two of the
major issues limiting the ability to
decrease the effect of the nutrients’
pollution are insufficient monitoring
data from industries that are not discharging
their waste through wastewater
treatment plants, and inconsistency
of the data collected about nutrients
loading from certain wastewater
treatment plants. In addition, more
data is needed to be generated about
the effect of the nutrients on the
Canadian ecosystem in order to find an
effective solution. Continuous efforts
are made to find better monitoring/
processing control techniques that
would help provide more information
about the nutrients discharge and, as a
result, reduce the nutrients discharged
and their effect on the environment.
A new on-line TNPC-4110C
Shimadzu analyzer, capable of analyzing/
monitoring total nitrogen (TN),
total phosphorus (TP), and total organic
carbon (TOC), has been recently
introduced. The analyzer can be used
for both monitoring processes and
process control. It automatically performs
the sampling, pretreatment
(physical and chemical), digestion, and
analysis. So, in addition to helping
meet current and future regulations
regarding levels of nutrients being discharged,
the analyzer will save on
labour and cost.
A study was performed in which
this analyzer was installed in a wastewater
reclamation plant that is responsible
for treating and discharging about
18 million gallons of water per day.
Throughout the study, the instrument
was not only used to demonstrate its
ability to upgrade the technology being
used, but also to automate the monitoring
and process control system within
the plant to provide maximum efficiency.
The analyzer was installed between
the primary clarifier and the biological
nutrient reactor. It was used to monitor
the levels of nitrogen, phosphorus, and
total organic carbon in the influent, and
accordingly adjust the fermentate
added for better treatment. Previous to
installation of the TNPC-4110C analyzer,
manual techniques were used for
monitoring, which resulted in increased labour, wasted time, and increased cost.
As a result, monitoring was performed
biweekly. Biweekly monitoring was
constrained not only by availability of
labour but also by availability of time
to sample, digest, and analyze.
Consequently, the reporting frequency
was not consistent. Inconsistency
caused over treatment or under treatment
of water and, as a result, a discharge
that would either introduce
more chemicals or nutrients into the
environment.
After installation of the analyzer,
the automation capability not only
reduced the involved labour and time,
but also enabled an increase in the frequency
of monitoring and consistency
of analysis. Increasing the frequency
of monitoring was possible from
biweekly, to daily or hourly, and as a
result provided a tool which would
allow a faster response to sudden
changes, and accordingly a better
treated discharge. Automation of the
whole monitoring process also meant
that less error was involved in the sample
handling and analysis, which
ensured more consistent data.
With such an analyzer, a trend can
be developed or obtained about the
nutrient levels within the stream,
which can help in improving the efficiency
of the treatment. Increasing the
frequency of monitoring also meant
developing a database of information
about the nutrient levels not only within
a specific stream, but also information
that would help in relating the
nutrient levels to other factors such as
seasonal changes, industrial discharges,
or sudden input of nutrients
into the system.
In conclusion, using the TNPC-
4110C analyzer, in monitoring/analysis/
process control of one of the major point-source pollution problems, can
help in achieving one of the initiatives
of the Canadian Council of Ministers
of the Environment, which is Pollution
Prevention. This analyzer through its
automated monitoring/analyses process
will provide the wastewater treatment
plant with an advanced technology that
will help accelerate the reduction in
pollutants discharged and accordingly
minimize the health risk involved. Not
only that but the TNPC-4110C analyzer
automation capability, reduces the
energy, resources, and materials used in
the process.
Richard Keir is with Mandel
Scientific, Guelph, Ontario,
e-mail: rkeir@mandel.ca.
Mohamed Aboul Eish, Daniel Davis and Robert
Clifford are with Shimadzu Scientific
Instruments, Maryland.
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