Wireless Sludge Level Monitoring based on Bluetooth Sensing Nodes

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I. INTRODUCTION
Sedimentation (settling) is the separation of suspended
particles that are heavier than water. The sedimentation of
particles is based on the gravity force from the differences in
density between particles and the fluid. Secondary
sedimentation tanks are fundamental facilities in activated
wastewater treatment processes. Usually a secondary
sedimentation tank is a cylindrical concrete building with a
conic bottom, and a rotary scraper is installed over the tank to
clear away the settled sludge in the bottom of the tank. In
order to ensure the effluent water’s quality and the back-flow
sludge’s density, the sludge level of the secondary
sedimentation tank is measured using a sludge level meter,
thus the settling sludge level status could be acquired and the
back-flow and drained sludge’s quantity could be controlled
further according to this value.


SYSTEM DESCRIPTION
The sludge level monitoring system based on smart
sensing channel uses a Bluetooth wireless technology
solution for data communication between the sensing
nodes and a host computer. Advanced data processing,
data logging are also included as software components of
the distributed measuring system. The topology, hardware
and software utilized for our system is detailed below.


RELATED WORK
In our early work, a transparent serial data transfer
system was designed and implemented using ADAM-series
modules, which is shown partly in Figure 1 [1]. The system
has four sludge level data transmitting component, each one
is composed of an ADAM4012 and an ADAM4550; and one
data receiving component composed of an ADAM4550 and
an ADAM4520 which obtains four sludge level data and then
sends them to a host PC.


IV. RESULTS
A. Transmission
With the MAXIM microprocessor sampling at 125Hz
and each sample being sent in a three byte packet, the
microprocessor sends 3,000 bytes per second to the
Bluetooth module. The serial line is configured with one start
bit, no parity, and one stop bit yielding a 30kbps data
transmission rate. This utilizes 26% of the available
bandwidth of the 115.2kbps serial line.