Environmental Engineering Reference
In-Depth Information
The viability of bacteria was checked with increasing concentrations of AgNO
3
in the
culture media, and it was observed that these strains could sustain the concentrations of
AgNO
3
up to 20,000 mg/l. Absorbance of AgNPs was taken on a UV-Vis spectrophotome-
ter at regular intervals from 1 to 72 h. After 72 h of incubation and on a shaker, the biomass
was centrifuged at 10,000 rpm on a REMI Deep Freeze Shaker for 15 min. The supernatant
was iltered out and the iltrate was washed three to ive times with distilled water and was
then dried in hot air oven at 200°C.
37.2.2 Chemical Characteristics of Landfill Leachate
The landill leachate used in the experiment was collected from the Gohagoda open dump
site, situated in the World Heritage city, Kandy. The collected leachate samples were char-
acterized for pH, temperature, conductivity, alkalinity, total dissolved solids, and dissolved
oxygen at ield conditions, and immediately transferred into the laboratory under 4°C condi-
tions for other experiments such as analysis of nutrients, COD, Cl
−
, solids, total organic car-
bon, dissolved organic carbon, and metals. The methods of analysis are given in Table 37.2.
TABLE 37.2
Summary of Major Chemical Constituents of Leachate from Gohagoda Open Landill, Kandy;
Methods of Analysis and Comparison with Literature
Gohagoda
Leachates
Acetogenic
Leachates
Methanogenic
Leachates
Constituents
Method/Reference
pH
ROSS sure-low
combination epoxy
body electrode
8.0-8.60
5.5-7
7.5-8.5
EC
Conductivity meter
(Orion 5-Star series)
8.96-29.6
7-30
<1
BOD
5
Winkler method [58]
21.6-1458
4000-30,000
<500-1000
COD
Spectrophotometer
(HACH DRB 200)
70-69,700
10,000-50,000
2000-6000
TOC
TOC analyzer
(Analytikjena Multi
N/C 2100)
3514.9
3000-20,000
<10-300
Alkalinity
Titrimetric method [58]
6200-19,320
2000-10,000
10,000-30,000
Ammonia-nitrogen
Iron-selective electrode
6.12-576.8
750-2000
1500-3000
Nitrate-nitrogen
Cadmium reduction
method
0.4-172.2
<1
<1
Nitrite-nitrogen
Diazotization method
0.04-112.7
< 0.1
<0.1
Phosphate
Ascorbic acid method
7.65-172.2
5-20
1000-3000
Zinc
Atomic adsorption
spectrophotometer
(GBC 933 Australia)
0.2-1.15
5-20
<0.01-0.05
Cadmium
0.004-0.062
<0.1-<0.2
<0.02-0.01
Nickel
0.133-0.532
<0.1-<1
<0.05-0.1
Chromium
0.021-0.323
0.1-<0.5
0.02-5
Copper
0.048-0.257
<0.1-0.1
<0.3-2
Lead
0.015-0.416
<0.1-<0.5
<0.05-0.2
Iron
1.49-15.25
100-800
0.1-0.5
Manganese
0.155-1.203
10-50
5-50
Source:
H. Robinson,
Commun. Waste Resour. Manage
. 8, 19, 2007.
Note:
All values are in mg/l except pH and EC (mS/cm).
