WP - Measuring Oil in Water - Final
WP - Measuring Oil in Water - Final
WP - Measuring Oil in Water - Final
Background
Oil in water analysis is a global issue that crosses many industries, analytical
methods, and regulatory agencies. Due to the negative effects of oil on the
environment, there are strict limits on the amounts of oil allowed in water. Failure to
meet these limits can lead to heavy fines. While any industry that discharges produced
water needs to test for oil in water, their specific needs can differ from industry to
industry. The petroleum industry is most concerned with measuring Total Oils and
Grease (TOG) in both their upstream and downstream wastewater. For industrial
pretreatment of wastewater, public water treatment plants, and most other nonpetroleum industries discharging produced water, it is most important to test for Fats,
Oils and Grease (FOG) in their effluent. FOG differs from TOG in that it tends to contain
large amounts of animal and vegetable components in the oil. FOG can be especially
concerning in effluent streams because it can lead to clogged sewer lines which
causes Sanitary Sewer Overflows (SSOs).
The people responsible for conducting oil in water measurements understand that
the measurement can be quite challenging. Wastewater from different sources can
contain many different types of hydrocarbons, each with different chemical make-ups.
On top of the lack of chemical uniformity in different oils, there has been a large
variety of methods developed to quantify the oil in the wastewater. While none of the
following methods is perfect, each will have its own advantages and disadvantages
for oil in water analysis.
www.brown.edu/Research/Evchem/facilities/shared
G A S CHROMATOGRAPHY
F L A ME ION IZATION DETECTION (GC-F ID)
Agilent GC-FID
ADVANTAGES
ADVANTAGES
Provides details on
different hydrocarbons
present
Follows ISO 9377-2
Precise
U V F L UORESCEN CE
ADVANTAGES
Advanced Sensors
UV Fluorescence
Analyzer
Requires no solvent
UV Fluorescence is a common field technique for oil in water
Can be setup as an
analysis which typically uses either a UV lamp or a Laser Induced
online system
Fluorescence (LIF) as a light source. Because it does not require
Inexpensive
a solvent extraction, the technology is ideal for online analysis of
Ideal for field use
a wastewater stream. UV fluorescence works by illuminating an
DISADVANTAGES
oil in water sample with UV light. The aromatic hydrocarbons in
Only detects aromatic
hydrocarbons
the sample emit fluorescent light that the instrument can detect.
Does not follow any
The amount of oil in water in the sample is based on the intensity
international method
of the light emitted. Instruments that contain a UV lamp typically
use a by-pass stream for analysis, however LIF instruments can
use probes that are fitted in-line with the produced water stream so that a by-pass stream is
not required. While UV fluorescence is a great technology for detecting aromatic hydrocarbons,
it will not detect any aliphatic compounds. Since typical oil in water samples are mainly
aliphatic, any change in the ratio of aliphatic to aromatic hydrocarbons can drastically affect
the results.
Q U A NTUM CASCADE
L A S E R IN F RARED (QCL -IR)
ADVANTAGES
ADVANTAGES
Summary
There are several methods available for both laboratory and field analysis of oil in water. The
choice of methods depends on budget, location of testing, time, and other factors. The most
important thing is to consistently test for the amount of oil in water in your wastewater stream
in order to avoid any regulatory fines and prevent potential damage to environment.
Resources
ASTM International D7066-07: Standard Test Method for dimer/trimer of chlorotrifluoroethylene (S-316) Recoverable Oil and Grease
and Nonpolar Material by Infrared Determination
EPA Method 1664, revision A (1999): N-Hexane Extractable Material (HEM; Oil and Grease) and Silica Gel Treated N-Hexane
Extractable Material (SGT-HEM; Non-polar material) by Extraction and Gravimetry
ISO ISO 9377-2:2000 (2000) Water quality determination of hydrocarbon oil index Part 2: Method using solvent extraction and
gas chromatography