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IIDesign Application Period <br /> Design application periods of 8 to 12 hr/day are recommended to allow <br /> japplication periods to be increased during harvest or repair periods without <br /> affecting process performance. For instance, if the design application period <br /> I� is 8 hr/day, wastewater normally would be applied to one-third of the total land <br /> I� area at any given time assuming a 24 hr/day system operation. If one-third of <br /> the system were shut down for harvest, the application period could be increased <br /> to 12 hr/day on the remaining two portions of the system, and the entire flow <br /> could be applied without increasing the application rate. <br /> Systems generally are designed to operate on a 24 hour basis to minimize <br /> land requirements. For small systems it may be more convenient or cost <br /> I <br /> I effective to operate only during one working shift. In this case the entire area <br /> I,. would receive the design daily flow during the 8 hour application period. Storage <br /> facilities would be required to hold wastewater during the 16 hour non-operating <br /> i <br /> period. <br /> p Design Example <br /> The following numerical example is presented to illustrate the design <br /> procedure just described. <br /> Assume the following information is known: <br /> 1. Applied wastewater - screened raw <br /> 2. Flow (Q) = 3,000 m3/day <br /> 3. Influent BODS (Co) = 150 mg/L <br />�l 4. Required effluent BODS (C) = 20 mg/L <br /> The necessary design calculations are: <br /> 1. Compute the required removal ratio C-5/Co <br /> C-5 20-5 = 0. 10 <br /> i Co 150 - <br /> -64- <br />