Alkaline Hydrolysis Treatability Study for Nitroaromatic

25 Pages·2009·0.96 MB·English

by  Licensed User

D
7
0
0
2
6
0
M
2
0
Alkaline Hydrolysis Treatability Study
for Nitroaromatic Compounds
Contaminated Soil
Steven T. Downey, PE, PMP
Lingke Zeng
Shaw Environmental & Infrastructure Group
Doug Mullendore, USACE
D
7
0
0
2
6
0
M
2
0
Agenda
• Introduction
• Technology Description
• Study Setup and Method
• Results
• Summary and Recommendations
D
7
0
0
2
6
0
M
2
0
Introduction
• The former Plum Brook Ordnance Works
(PBOW) was used to manufacture TNT from
1941 to 1945
• PBOW is located near Sandusky, OH
• Facility included 3 TNT manufacturing areas
• TNT production resulted in soil and
groundwater contamination
• Complete decontamination was not achieved,
so portions are still contaminated with
nitroaromatic and other contaminants
D
7
0
0
2
6
0
M
2
0
Introduction
• The primary chemicals of concern in soil are
trinitrotoluene (TNT), dinitrotoluene (DNT)
isomers, amino-DNT isomers, poly aromatic
hydrocarbon (PAH), poly chlorinated benzene
(PCB), and lead
• TNT and DNTs exhibit the most elevated
levels as high as 0.5 and 1 percent of soil
mass
• Alkaline hydrolysis was selected as a
preferred alternative for treating soil with high
concentrations of nitroaromatics
D
7
0
0
2
6
0
M
2
0
Introduction
• As a precursor to full-scale remediation, an alkaline
hydrolysis bench-scale treatability study was
conducted to:
– Determine the most effective reagent
– Establish treatment duration
– Determine the most effective neutralizing chemical
– Examine effects on contaminants other than nitroaromatics
• Treatability study was conducted at Shaw’s
Technology Development Laboratory (TDL) in
Knoxville, TN
D
7
0
0
2
6
0
M
2
0
Plum Brook Ordnance Works
D
7
0
0
2
6
0
M
2
0
Technology Description
• Hydroxide ion (OH-) is a strong nucleophile
• It has been shown to react with TNT, DNT isomers, and their
reduction products (e.g., amino-DNTs) under basic
conditions
• This provides an energy source for indigenous
microorganisms
• Nucleophilic substitutions of the nitro and methyl groups of
TNT by hydroxide ion are the initial steps in the degradation
process that result in a variety of potential reaction products
• Reaction products from alkaline hydrolysis of nitroaromatic
compounds include nitrite, nitrate, ammonia, carbonate,
acetate, and formate
• Following soil neutralization, the reaction products will be
D
7
0 decomposed via multiple pathways including biodegradation
0
2
6
0
M
2
0
Initial Alkaline Hydrolysis Products
D
7
0
0
2
6
0
M
2
0
Study Setup and Method
• The most effective alkaline hydrolysis reagent is dependent
on site-specific soil conditions
• Soil samples were collected from areas of known
contamination at TNT Area C of PBOW
• Another important factor in reagent selection is cost
• Alkaline reagents used in the study included:
– Caustic soda
– Calcium oxide
– Sodium carbonate
– Portland cement
– Lime kiln dust
D
7
0
0 – Bed ash
2
6
0
M
2
0