Reduction of Contaminants in Soil and Water By Direct Electric Current - Electrokinetics for Petroleum and Environmental Engineers - page 60

material, a potentially inexpensive source of calcium for
cement production. The fresh N-viro soil gives out ammo-
nia (NH 3 (g)) as a by-product of the process, which needs to
be mitigated prior to handling the material. Electrokinetic
extraction was proposed to reduce the excess ammonia in
N-Viro Soil™. The visual and textural observation of the
granular material indicated fine sand to silt size mixture
with little plasticity. The leachate was a brown colored liq-
uid. Upon arrival, the leachate was acidified to arrest NH 4 +
in the liquid, thereby preserving its original concentration.
The test specimens were prepared by mixing the N-Viro soil
with the leachate at the reported liquid content of 65%. Two
tests were conducted at constant potential of 30 V applied
across the electrodes for the 200-hr duration of treatment
for each. The voltage gradient measured in the samples
remained at approximately 0.3 V/cm. At the termination of
each test, the soil was sampled at three points along its length
and analyzed for moisture content, pH and NH 4 + concentra-
tion distribution. Figure 2.17 shows the post-electrokinetic
distribution of the measured concentration of NH 4 + and the
pH along the soil sample and the anode and cathode liquid
chambers. Overall, the concentration of ammonia in the soil
samples were reduced from about 150 mg/kg to less than 6
mg/kg in both samples tested.
The mass balance determination showed that for more
than 50% of the ammonia was unaccounted. Larger

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0

14

12

10

8

SOIL SAMPLE 6

4

2

0

Anode
water

0.25 0.50

Section along sample

0.75 1.00 Cathode

water

Sample EK1 Sample EK2 pH-EK1 pH-EK2

Figure 2.17 Post Electrokinetic Distribution of NH 4 in Processed Municipal Sludge Soil
(Pamukcu and Huang, 2001)