Environmental Engineering Reference
In-Depth Information
Make sure that the correct phase is collected (discarded) in the L-L extraction.
Diethylether, benzene, petroleum ether, and hexane are lighter than water, whereas
chloroform, ethylene dichloride, methylene chloride, and tetrachloromethane are
heavier than water. Always perform extraction under the hood and minimize any
exposure to (inhalation of) solvents.
6.3 ANALYTICAL PRINCIPLES FOR COMMON WET
CHEMICAL METHODS
Discussed in this section are some of the most common wet chemistry methods
perhaps routinely employed in many environmental laboratories (Sanyer et al.,
1994; Smith, 1997; Williams, 2001). We focus here on the underlying chemistry and
operational principles for the measurement of these selected parameters summarized
in Table 6.3. Details of these methods can be found in EPA 100-400 or APHA 2000,
4000, and 5000 series methods.
6.3.1 Moisture in Solid and Biological Samples
The moisture content of solid (soil, sludge, sediment) and biological samples must
be measured so that contaminant concentration can be reported on a dry basis. This
determination involves weighing a portion of the sample in a tarred crucible, drying
to a constant weight at 1041 C and then calculating the percent moisture by:
wet weight dry weight
wet weight
%Moisture ¼
100
ð6
:
concentration on wet basis
100%moisture
Concentration ðdry weight basisÞ¼
ð6
:
6.3.2 Solids in Water, Wastewater, and Sludge
(TS, TSS, TDS, VS)
Solids are the matter suspended or dissolved in water or wastewater. Waters with
high dissolved solids (minerals) are unsuitable for drinking as well as for industrial
uses. Solids suspended in surface water and wastewater effluent are esthetically
unsatisfactory and undesirable from a water quality standpoint. Solids (sludge) in
wastewater are related to the biomass in the biological process and therefore are an
important process control parameter. As described below, there are various types of
solids that can be measured gravimetrically and volumetrically.
Total Solids (TS)
''Total solids'' is the term applied to the material residue left in the vessel after
evaporation of a sample and its subsequent drying in an oven at a defined
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