Land treatment of wastewater 443
a) the required volume of the wastewater storage pond,
b) whether flooding will occur from this wastewater application or not?
c) possible environmental impacts to be resulted from the RI application.
Note: the following RI application procedures is recommended
Wastewater application = 4 days
Resting period = 10 days
8.8. A municipality in Southeast Asia plans to use part of its wastewater to
irrigate a 1-ha land for growing corns. The following information are
given:
Applied N concentration = 30 mg/L
N uptake of corns = 200 kg/(ha-year)
Denitrification, as % of applied N loading = 20
Precipitation (Pp) – evapotranspiration (ET) = 30 cm/year
Runoff = 0
a) To prevent excessive N contamination of the groundwater, the percolate
N of this wastewater irrigation should be equal to or less than 10 mg/L.
Determine the amount of wastewater (in m^3 /year) that should be applied
to this 1-ha land to support corn growth.
b) If, due to a severe drought in a particular year, the Pp – ET is -30 cm/yr,
but the municipality still applies the same amount of wastewater as in a)
to this 1-ha land for corn growth. Determine the concentration of
percolate N in this particular year and the environmental impacts to be
resulted from this practice.
8.9 A municipality in Southeast Asia produces wastewater with the
following characteristics:
Flow rate = 2,000 m^3 /day
BOD 5 = 100 g/m^3
NH 4 -N = 20 g/m^3
Fecal coliforms = 10^3 no./100 mLa) You are to design an overland flow (OF) unit to treat this wastewater to
produce an effluent having BOD 5 and NH 4 -N concentrations of less
than 20 and 5 g/m^3 , respectively. Give dimension (length × width) and