Greywater Management in Low and Middle-Income Countries - SSWM

chambers amounts to 40% and 50%, respectively. The organic loading rate of the
subsequent dosing chamber is pumped (submersible pump, 0.6 kW) onto an aerobic
stored in a 500-litre plastic tank and used for irrigation of non-edible crops.
Overall analysis of the greywater from 25 families in Biet-Diko and Bilien revealed
very high COD and BOD 5 concentrations of 1,270 mg/l and 590 mg/l, respectively.
The treated greywater properties of Bilien village are given in Table 5-9. The removal
rate for both COD and BOD 5 in these household treatment systems ranges between
75% and 95%.
Household 1 Household 2 Household 3 Household 4
standards
10 persons 6 persons 7 persons 14 persons
–
Clear + bad
smell
Clear + no
smell
Clear + no
smell
Grey + turbid +
slight smell
–
pH – 7.2 7.2 7.3 7.0 6–9 1
EC 2,700 2,200 1,900 2,000 1,400 2
Chloride mg/l 330 295 268 286 400 1
mg/l 248 192 175 191 230 1
mg/l 1,500 1,200 1,100 1,100 –
mg/l 145 80 85 284 100 1
5
mg/l 65 27 28 130 30 1
mg/l 70 54 78 97 50 1
3
mg/l 23 16 10 22 30 1
4
mg/l 47 13 27 48 30 1
irrigation (Ministry of the Environment, 2003)
The bar screen is cleaned twice a week. The septic tank is desludged every
every three years. The system has been in operation since 2000.
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Examples of Greywater Management Systems