The characteristics of a settled wastewater (primary effluent) are as follows:This wastewa...

The characteristics of a settled wastewater (primary effluent) are as follows:

This wastewater is processed in a diffused-air activated-sludge system at an F/M loading of 10g of BOD applied per day for each 3.0 g of MLSS in the aeration basin. The final clarifiers are appropriately sized.

(a) During conventional operation, what are the estimated effluent BOD. SS. and P concentrations in milligrams per liter? Calculate the average waste organic solids production in milligrams per liter of wastewater treated. (For oP removal in waste-activated sludge, refer to Figure 14.7.)

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(b) Alum is then added to the aeration tanks at a dosage equivalent to an Al/P ratio (aluminum added to phosphorus in the applied wastewater) of 2.0:1.0. With this chemical addition, the effluent BOD, SS, and P decrease to 10,15, and 0.5 mg/l, respectively. No aluminum appears in the effluent. Calculate the average amounts of chemical precipitates and waste organic solids produced per liter of wastewater processed. How do these reactions affect the ionic character of the wastewater? (For help, refer to Figure 14.8 and Example 14.3.)

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(c) Assume that granular-media filtration is added as a tertiary step following the biologi­cal-chemical phosphorus removal. What are the estimated BOD, SS, and P concentrations in the effluent? Estimate the additional waste solids removed by tertiary filtration.