Environmental Research

1
Environmental Research
Development of Autonomous Sensor Platform for
Environmental Monitoring
Kate DeMello and Alicia Saucier Department of
Biology University of Massachusetts Dartmouth
Chen-Lu Yang Advanced Technology and
Manufacturing Center University of Massachusetts
Dartmouth
Introduction YSI Environmental 6-Series
multi-parameter sondes are currently designed for
long term unattended water quality monitoring in
a set location. Recently, YSI has partnered with
OceanServer to develop an autonomous underwater
vehicle (AUV) equipped with YSI sensors, opening
a new realm of possibilities for environmental
applications. The collection of data as the AUV
moves through a large body of water allows
mapping trends in multiple parameters
simultaneously with minimal attention or exertion
on the part of the researcher. However, the
transition to logging data in a dynamic setting
presents several complications.
(Autonomous underwater vehicle)

• Goals
• What effect does speed have on the measured value
  for a given parameter?
• How fast does each sensor equilibrate in moving
  water?
• What is the maximum AUV speed possible while
  maintaining the integrity of localized
  measurements?

(YSI sensors)

• Methods
• A two-tank circulation system was engineered to
  simulate dynamic water conditions.
• Prepared solutions are pumped over the sensor set
  at various speeds while a second sonde monitors
  static conditions inside the tank.
• Data is logged and analyzed to determine the
  equilibrated solution value and time lag.

(Autonomous sensor platform)

• Results to Date
• The specific conductivity probe equilibrates
  within 2 seconds of immersion in all solutions
  ranging from freshwater to brackish to marine
  simulations (Fig. 1).
• It takes 40 seconds for the two-tank circulation
  system to stabilize (Fig. 2).
• Once stabilized, the difference in equilibrated
  values between static and dynamic measurements is
  consistently within the probe's tolerance limits
  (Fig. 3).
• Fig. 4 shows the measurements with the sensor
  sets in static-vertical, static-horizontal, and
  dynamic-horizontal positions. The result shows
  good precision and accuracy on the two systems
  and three positions.
• Chlorophyll and pH probes demonstrate similar
  accuracy and precision as the conductivity probe.
  Temperature, dissolve oxygen and turbidity probes
  are currently under evaluation.

(Two-tank circulation system)
(Hydrographic data gathering)
Fig. 1
Fig. 3
Fig. 4
Fig. 2
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_at_ ATMC
Wachusett Missions Fig 5 illustrates the
results of a survey on Wachusett Reservoir in
central Massachusetts. These diagrams are the
result of 44,000 survey points gathered in two
4-hour missions. The mission data consists of
waypoints with command parameters such as depth
from surface or height from the bottom along with
vehicle speed and other mission requirements.
Waypoint data as well as collected sensor data is
stored in folders in an onboard hard drive on the
AUV. Digital maps from NOAA, USGS or satellite
imagery can be utilized within the mission
planning software for designing the survey path.
The focus of this task is to verify the
effectiveness of the newly developed autonomous
sensor platform with particular attention to all
of the physical and chemical parameters. With a
selection of environmental sensors,
geo-referenced information for depth, pH,
temperature, turbidity, dissolved oxygen,
vegetation coverage, ORP, turbidity, lake bottom
structure, and sediment can be gathered and
presented like those shown in the figure.
Fig. 5
Characteristics and Treatability of Oil-Bearing
Wastes from Aluminum Alloy Machining Operations
Luke Chen and Chueh-Chen Hsieh Department of
Water Resources Environmental
Engineering Tamkang University (Taiwan)
John Wetherbee and Chen-Lu Yang Advanced
Technology and Manufacturing Center University of
Massachusetts Dartmouth
Introduction Enomoto Industry Co., exclusively
uses water-based cutting fluid in its aluminum
alloy machining operation. After spraying onto
the work pieces, the cutting fluid is collected
together with aluminum chips, coarse particles,
fine particles, sludge and others. The chips are
settled on a conveyer at the bottom of a
collecting pan, and are carried out of the
cutting fluid mechanically, while coarse
particles are removed by drum filter.
However, fine particles remain suspended in the
emulsion. Even when recycling options are
used, the cutting fluids have a finite useful
life. The disposal of cutting fluids
involves the evaluation of corrosion, dermal
irritation, reduced tool life, color and odor.
The disposability of the spent cutting
fluids is becoming a major criterion for cutting
fluid selection, since the cost of disposal
can be much greater than the cost of purchase.

• Objectives
• Characterize spent cutting fluid from Enomotos
  facility.
• Evaluate pretreatment methods, centrifugation,
  chemical coagulation, and electrochemical
  coagulation, for the feasibility of on site
  disposal into local sewage systems.

(Aluminum machining)
3
University of Massachusetts Dartmouth Chapter of
Sigma Xi, the Scientific Research Society 14th
Annual UMass Dartmouth Research Exhibition

• Analytical Methods
• Metal content atomic absorption spectrometry and
  UV-Vis spectrometry.
• Total suspended solid (TSS) gravimetric method.
• Turbidity UV-Vis spectrometry.
• Oil and grease (OG) methylene chloride
  extraction.

• Experimental
• Chemical analysis/physical examination (Tables 1
  and 2).
• Emulsion stability test.
• Centrifugation.
• Chemical coagulation.
• Electrochemical coagulation.

Table 1
Table 2

• Results
• Fig. 1 is the flow diagram of the electrochemical
  system.
• Fig. 2 shows the stability of synthetic oil-water
  emulsion and cutting fluid.
• Fig. 3 shows the effectiveness of centrifugation
  for demulsification.
• Fig. 4 shows the effectiveness of chemical
  coagulation for oily water demulsification.
• Fig. 5 is the reaction profile of the
  electrochemical treatment.
• Fig. 6 shows the effectiveness of electrochemical
  treatment for emulsion removal.

Fig. 1
Fig. 2
Fig. 4
Fig. 3
(Electrochemical reactor)
Fig. 6
Fig. 5

• Conclusions
• Metal contents remaining in spent cutting fluids
  are well within the discharge limits.
• TSS and OG are way beyond allowable discharge
  limits.
• TSS and OG are the major contributors to
  turbidity.
• Chemical coagulants are effective in breaking
  down emulsions by neutralizing the negative
  charge on micells, thus destabilize the oil-water
  system.
• Electrochemical coagulation reduces turbidity
  from 3,261 to 60 FAU in three minutes, and the
  turbidity continued to decrease to lower than 14
  FAU.

(Test system)