Cozy Environment for Bacteria
dTRANS pH 02 for a reliable, uninterrupted cleaning process
in wastewater treatment plants
By way of introduction, the
pH-value is one of the most
important parameters in
a wastewater treatment
plant for the subsequent
biological treatment of
the wastewater and must
therefore be continuously
recorded and monitored.
Measured values can be read very clearly as digital numeric values, bar graphs, or graphical
trend curves on the high-contrast LCD graphic display with background lighting .
Wastewater is treated in wastewater treatment plants.
activated sludge, or is conveyed to the digesters as surplus
Biological and chemical processes are used in this process
activated sludge. The purpose of the digester is to stabilize
as well as mechanical ones. The screening system is the first
the sludge. Stabilization in this context means the most ad-
station of the mechanical purification stage. The purpose of
vanced anaerobic degradation of organic compounds with the
this process is to remove coarse materials from the wastewa-
aid of specific bacteria. These bacteria convert the organic
ter. Materials trapped in this manner are referred to as sieved
components of the anaerobic digested sludge into biogas.
or screening materials. The grit chamber is used to separate
heavy solids. Water flows very slowly in this section so that
Combination of pH-electrodes and transmitter
these particles can sink to the bottom. The last mechanical
To ensure optimum degradation capability, the bacteria
purification of the wastewater is in the primary settlement
require a pH-value in the range from 6.5 to 8.5. Most bacte-
tank. All the lighter materials that are still in the wastewater
ria are damaged or inactive outside of this tolerance range.
and which have not been removed in the grit chamber settle
Monitoring of the pH value and neutralization if necessary
to the floor of this tank to form so-called raw sludge. It is con-
are therefore essential to ensure a problem-free purification
veyed into digesters while the pre-treated water is directed
process in wastewater treatment plants. JUMO has developed
on to the aeration tank.
JUMO tecLine pH-electrodes in combination with the JUMO
The biological purification starts here. The wastewater is first
dTRANS pH 02 transmitter/controller for this application.
mixed with activated sludge. The sludge contains numerous
In principle a wastewater treatment plant poses no great
micro-organisms, such as bacteria, that are able to break
challenge for a pH-electrode. However, the intake of these
down the colloidal, organic contaminants dissolved in the
plants often includes oils and greases, which can have a neg-
wastewater – compounds of carbon, nitrogen, and phospho-
ative effect on the pH-measurement. High amounts of salt
rous. The activated sludge settles in the secondary settle-
after snow removal or dirt and bio-growth can also clog the
ment tank and collects at the bottom. The collected sludge is
pH-electrode.
then removed and taken back to the aeration tank as return
pH-measurements without risk
Sewer system
Screening system
Grit chamber
-- Liquid level
-- Indicator
-- pH-value
-- Conductivity
Primary
settlement tank
Aeration tank
Secondary settlement tank
-- Dissolved oxygen -- pH-value
-- pH-value
-- Temperature
-- Temperature
-- Indicator
-- Indicator
-- Controller
Digester
-- Liquid level
-- Pressure
-- Temperature
-- pH-value
-- Indicator
To prevent measurement errors due to this type of con-
figuration with a PC. You can use it to create and edit data
tamination, JUMO tecLine pH electrodes with a PTFE ring
records, transfer them to the device, and export them from
diaphragm are used in many wastewater treatment plants.
it. Data can be stored and printed. The device can also be in-
The advantage: due to the smooth surfaces, dirt particles
tegrated into a data network by means of an RS422/485 or
do not adhere and accumulate. The “self-cleaning” effect of
Profibus DP interface.
the PTFE material and the large ring-shaped surface of this
diaphragm make it especially suitable for media containing
grease and oil.
In addition to all the usual options, JUMO has for the first
time implemented a series of special functions not usually
found in compact devices for this liquid analysis controller/
transmitter:
pH transmitter/controller with extras
In addition to pH-electrodes, transmitters and control devices
• Flow-rate measurement: the device is able to record flow
are also used. The new JUMO dTRANS pH 02 transmitter/
rate quantities in parallel to the pH-value via a standard
controller makes the current pH-value available to the control
signal or binary input (pulse counter, for example for
room of the wastewater treatment plant. It is a compact,
impeller sensors). This flow-rate measurement can be
modular device with mounting dimensions 96 mm x 48 mm x
used as a disturbance variable for a control system. Flow
90 mm (W x H x D).
rate quantities can also be used as display values with
daily or total values. Alarm or switching functions can be
In addition to the pH-value, the device has a second mea-
triggered by measured values.
surement input for the temperature which is then used for
temperature compensation of the main parameters. This can
• Data logger: makes it possible to record and document
be recorded and if necessary also monitored by a Pt100 or
processes and supports analysis of the processes. Up to
Pt1000, NTC/PTC. Standard signals 0(4) to 20 mA or 0 to 10 V
43,500 data records can be saved (ring buffer). Depending
can also be connected.
on the resolution, this is equivalent to a storage time of
from about ten hours to 150 days. Data can be read by
In addition to the main input (pH/redox) and the secondary
means of the setup program and then further processed
input (temperature compensation), the basic device alone has
with a Microsoft Office product.
two binary inputs, two relays, one power supply for external
sensors and a setup interface. The device comes standard
• Math module: with the math module users can use free
equipped with two relays with changeover contacts. Functions
math combinations and evaluate measurement signals
can be assigned to them and the functions can be configured
with the JUMO dTRANS pH 02 – addition, subtraction,
in turn by parameters. P, PI, PD, and PID structures are freely
multiplication, division, square root, logarithm, exponen-
programmable as control functions.
tial function, and more.
Plain text operation together with the LC graphic display with
background lighting makes it almost possible to operate the
device without the operating manual. The plain text display
Author:
Dr. Öznur Brandt
provides information to technical personnel as needed about
Product Manager, Water and Wastewater
the status of the connected electrodes. A setup program is
Jumo GmbH & Co. KG 36039 Fulda, Germany
available in English, German, and French for convenient con-
Photo/Graphics:JUMO www.jumo.net
www.jumo.net