Treatment of Landfill Leachate Using Activated Sludge Technology: A Review

Table 1

Characteristics of landfill leachate with different periods.

Leachate type	Early	Medium-term	Old
Landfill useful life (years)	<5	5–10	>10
pH (−)	6.5–7.5 (7.0)	7.0–8.0 (7.5)	7.5–8.5 (8)
COD (g/L)	10–30 (15)	3–10 (5)	<3 (2)
BOD/COD (−)	0.5–0.7 (0.6)	0.3–0.5 (0.4)	<0.3 (0.2)
NH4^+-N (mg/L)	500–1000 (700)	800–2000 (1000)	1000–3000 (2000)
COD/NH4^+-N	5–10 (6)	3-4 (3)	<3 (1.5)

The values in parentheses are typical values.