Environmental Engineering Reference
In-Depth Information
TABLE 37.1
Composition of Acetogenic and Methanogenic Landill Leachates
Values from Literature
Acetogenic Leachate
Methanogenic Leachate
Parameter
a
Al-Wabel [1]
Robinson [16]
Hunce [18]
Robinson [16]
pH
5.9-6.3
5.5-7.0
7.9
7.5-8.5
Conductivity
6.3-42.5
7-30
37.2
<1-<1
BOD
-
4000-30,000
4250
<500-1000
COD
13,900-22,350
10,000-50,000
8038
2000-6000
Alkalinity
-
2000-10,000
13,200
10,000-30,000
Ammonium-nitrogen
-
750-2000
1430
1500-3000
Nitrate-nitrogen
-
<1-<1
-
<0.1-<0.1
Phosphate
-
5-20
22.8
1000-3000
Chloride
1000-2000
7000
2000-4000
Zinc
0.108-0.226
5-20
1.767
<0.01-0.05
Cadmium
<0.002
<0.1-<0.2
<0.005
<0.02-0.1
Nickel
0.384-0.718
<0.1-<1
0.597
<0.05-0.1
Chromium
0.21-0.336
1-<0.5
0.354
0.02-5
Copper
0.124-0.246
<0.1-0.1
0.145
<0.3-2
Lead
<0.04
<0.1-<0.5
<0.05
<0.05-0.2
a
All values are in mg/l except pH and EC (mS/cm).
(such as
NO
3
−
,
NO
2
−
,
NH
4
+
,
SO
3−
,
PO
3−
, and Cl
−
) and xenobiotic organic compounds (such
as phenols, halogenated hydrocarbons, chlorinated aliphatics, and aromatic hydrocarbons)
are reported in the landill leachate, which may cause serious biological effects [11,19].
Mainly, landill leachate can be classiied as acetogenic (acetate production by anaerobic
bacteria) and methanogenic (methane production by anaerobic bacteria) leachate accord-
ing to their characteristics
(Table 37.1).
The recorded chemical oxygen demand (COD), biological oxygen demand (BOD), and
other solids, such as total suspended solids, volatile suspended solids, and total solids for
acetogenic leachate, are considerably high compared with methanogenic leachate [16].
However, landill leachate characteristics can be different from temperate to tropical coun-
tries owing to the climatic differences and variation in consumer patterns [6]. In addition,
solid waste composition and age of the landill signiicantly inluence the determination of
the composition of landill leachate [6]. Although many characterization studies and exten-
sive review of the composition of landill leachates are available, these are restricted to the
developed nations. Only a few studies are reported on the landill leachate, its transport,
and its fate in the tropics, especially from the Asian region [19,20,21]. Therefore, charac-
terization of leachate plays a signiicant role on deciding appropriate treatment practices.
37.1.3 Common Treatment Practices for Landfill Leachate
Leachate treatment technologies fall into two basic types, biological and physical/chemical.
In larger systems and depending on the treatment goals, integrated systems that combine
the two are often used. The most common biological treatment is activated sludge, which
is a suspended-growth process that uses aerobic microorganisms to biodegrade organic
contaminants in leachate. With conventional activated sludge treatment, the leachate is
aerated in an open tank with diffusers or mechanical aerators. Air stripping, adsorption,
