. 2015 Jan 25;13:4. doi: 10.1186/s40201-015-0155-5

Table 1.

The main characteristics of the five wastewater treatment plants

Wastewater treatment plants	Population served	Primary treatment	Secondary treatment	Tertiary treatment and disinfection	Biochemical parameter			Water turbidity*		Use of treated water
Wastewater treatment plants	Population served	Primary treatment	Secondary treatment	Tertiary treatment and disinfection	Flow rate (m ³ /s)	BOD* (mg/L)**	TSS** (mg/L)**	influent	effluent	Use of treated water
WWTP1	100000	Screening and grit removal	Activated sludge and A2/O*****	Sand filtration followed by chlorination	0.46	<6	<30	High	Moderate	Discharged into creek
WWTP2	85000	Screening and grit removal	Conventional activated sludge	Chlorination	0.27	<30	<30	High	Moderate	Discharged to the highway surface water channel
WWTP3	2100000	Screening, grit removal and sedimentation	Trickling filter followed by activated sludge	Chlorination and UV radiation	5.2	28	28	High	Moderate	Agriculture irrigation
SWWTP4	ND**	Sedimentation	Activated sludge and oxidation with O₂	Chlorination	ND	ND	ND	High	Moderate	Agriculture irrigation
SWWTP5	ND	Sedimentation	Activated sludge and oxidation with O₂	Chlorination	ND	ND	ND	High	Moderate	Agriculture irrigation

*Low = <1 NTU; moderate = 1–10 NTU; high = >10 NTU; **ND = Not data; ***BOD = Biochemical oxygen demand; ****TSS = Total suspended solids; *****A2/O = Anaerobic/anoxic/oxic.