Organic Waste Recycling

382 Organic waste recycling: technology and management

Determine whether the effluent BOD 5 and fecal coliform

concentrations of the FWS construct wetlands will meet the

required standards or not and why?

7.9 A small municipality in Southeast Asia produces wastewater with the
following characteristics:

Flow rate = 100 m^3 /day

BOD 5 = 200 g/m^3

NH 4 -N = 20 g/m^3

Fecal coliforms = 10^4 no./100 mL

The municipality plans to construct a water hyacinth-based pond to treat this
wastewater and reuse the treated wastewater for fish production.

a) Determine the dimension of the water hyacinth-based pond to treat this

wastewater that should produce an effluent having BOD 5 and NH 4 -N

concentrations of less than 20 and 5 g/m^3 , respectively. Indicate whether

the treated wastewater is suitable to be applied to fish ponds.

b) If the area doubling time of the water hyacinth plants is 20 days and

density of the water hyacinth plants growing in this pond is 4 kg (wet

weight) per m^2 , determine: (1) the monthly quantity of water hyacinth

plants that needs to be harvested to maintain optimum pond performance

and (2) the annual productivity of the water hyacinth plants.

For BOD 5 removal in water hyacinth-based ponds: recommended BOD 5 loading
rate = 100 kg/(ha-day) and the BOD 5 removal follows the data given in Figure
7.15.

For NH 4 -N removal in water hyacinth-based ponds: NH 4 -N removal follows
Equation 7.10.