442 Organic waste reuse and recycling: technology and management
e) Helminth ova
f) Toxic organic compounds (e.g. trichloroethylene)8.4 A wastewater is generated at a flow rate of 1000 m^3 /day. An irrigation
(slow-rate) system is to be designed to treat this wastewater with an
application rate of 5 cm/week. What is the required land area if the
system is operated all year round? What is the required land area if the
system is designed for 40 weeks/yr?A sprinkler system is chosen for application of the wastewater. The
sprinklers are spaced in a square grid pattern of 20 m x 20 m, and each
sprinkler discharges at a rate of 1.6 L/s. How many sprinklers are needed
for the year-round operation? What is the application rate in cm/h? How
many hours should the system be operated each week to achieve the
application rate of 5 cm/week?8.5 A rapid infiltration system is designed for an application rate of 30 m/yr.
The system is run throughout the year by applying the wastewater every
Monday of a week followed by 6 days of resting. The wastewater
contains 50 mg/L of BOD 5. What are the average BOD 5 loading rates
annually, weekly and on Monday? Over the 7-day cycle, what is the
average BOD 5 loading rate in kg/(ha-day)? What is the BOD 5 loading on
Monday in kg/(ha-day)? If the wastewater flow is 2500 m^3 /day, with
respect to the above application cycle, calculate the land area required.8.6 A design equation for the overland flow process is given in Equation
8.13:a) Discuss the merits and drawbacks of this equation in predicting the
wastewater treatment efficiency;
b) Discuss whether equation 8.13 can be applied to predict fecal
coliform removal in the overland flow process;
c) Discuss whether equation 8.13 can be applied to predict wastewater
treatment efficiency for the slow-rate and rapid infiltration
processes.8.7 The soil of a municipality located in Southeast Asia is found to have an
infiltration capacity of 50 cm/day. It is planned to employ the rapid
infiltration (RI) system to treat this municipal wastewater whose flow
rate is 2000 m^3 /day. If only 1 ha of land is available for construction of
the RI system, determine: