Biofilter

Removal efficiencies (%)

COD

BOD₅

SS

Sand 1 - 2mm

67.35^a

78.04^a

87.10^a

Sand 2 - 4 mm

33.05^ab

63.62^a

87.53^a

Lateritic gravel 2 - 4 mm

13.26^bc

30.12^ab

65.53^ab

Lateritic gravel 4 - 6 mm

−2.23^c

18.16^b

45.82^bc

Granitic gravel 1 - 2 mm

55.67^a

72.48^a

81.26^a

Granitic gravel 2 - 4 mm

15.25^bc

41.36^ab

65.77^ab

Granitic gravel 4 - 6 mm

2.03^c

27.33^ab

34.97^c