Environmental Engineering Reference
In-Depth Information
Table 1
Comparison of physicochemical characteristics of sewage sludge from different countries
Properties
Thailand
a
Spain
b
India
c
pH
6.82
8.6
7.0
Electrical Conductivity (ms cm
−1
)
2.28
Organic Carbon (%)
19.82
43.4
5.52
Total Nitrogen (%)
3.43
2.5
1.73
Total Phosphorus (%)
-
1.06
-
Exchangeable K (mg kg
−1
)
870
-
208.96
Exchangeable Ca (mg kg
−1
)
8,332
-
154.13
Total Fe(mg kg
−1
)
6,059
Total Ni (mg kg
−1
)
47.17
Total Mn (mg kg
−1
)
186.2
Total Zn (mg kg
−1
)
801
174
785.3
Total Pb (mg kg
−1
)
1.22
1.00
60.0
Total Cr (mg kg
−1
)
1,326
445
35.5
Total Cd (mg kg
−1
)
2,621
-
154.5
a
Parkpain et al. (
1998
),
b
Martinez et al. (
2002
),
c
Singh and Agrawal (
2009
)
Use of
Pesticides and
Fertilizers
Industrial effluents
Waste water
irrigation
Heavy metals
(waste water/
sewage sludge)
Household
waste, Coal
burning
Atmospheric
depositions
Petroleum
combustion and
electroplating
industries
Metal smelting
and refining, fossil
fuel burning
Fig. 1
Sources of heavy metals
P constituted the majority of the total N and P in the characterized sludge,
respectively (Sommers et al.
1976
). The analyzed sewage sludge contained approx-
imately 50% organic matter and 1-4% inorganic carbon. Relatively constant con-
centrations of organic and inorganic C, organic N, and inorganic P, Ca, and Mg were
present in a given sludge type, throughout the sampling period. The levels of inorganic
N, organic P, K, and all other metals were somewhat inconsistent during the entire
period of the study (Sommers et al.
1976
). The major deviations found were for trace
elements and heavy metals, such as Cd, Zn, Cu, Ni, and Pb (Sommers et al.
1976
).
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