Greywater Management in Low and Middle-Income Countries - SSWM

System performance was generally satisfactory. Table 5-3 summarises the data
treatment step was equivalent to some of Monteverde’s most pristine streams. Fish
Inlet drum
(SP 1)
st
nd
polishing pond
(SP 4)
standards
mg/l 167 8.4 2.0 2.4 1
mg/l 8.4 9.5 10.0 28 30 2
mg/l 342 284 213 128 –
NTU 96 7.5 2.0 3.8 –
NH 4
-N mg/l 8.4 1.0 0.1 0.4 –
4
mg/l 7.6 5.2 2.3 1.2 –
mg/l 1.6 3.6 1.5 – –
cfu/100 ml 1.5 x 10 8 17,000 69 122 1
°C 21 20 20 21 –
pH 6.3 5.9 6.8 7.0 5.0–9.0
mg/l 1.0 1.0 6.9 6.2 –
1: Costa Rican guidelines for wastewater reuse (recreational reuse) (MdS, 1997), 2: Mexican standard for wastewater reuse
(Comisión Nacional del Agua, 1997)
and frogs have colonised the pond and are assumed to be responsible for the lack
of mosquito larvae.
Manual desludging of the settling tank has been reported as a necessary
maintenance activity. It is carried out annually by the owner’s son at a cost of USD 7
and requires about three hours. The removed sludge is buried in the owner’s garden.
houses connected to one main settling tank eases maintenance.
pruning of overhanging branches, removing of leaves and rubbish from the pond,
and thinning of aquatic plants, all of which are relatively straightforward and not very
time-consuming tasks.
64
Costs
Examples of Greywater Management Systems