Question

A wastewater treatment plant, which serves a population of 300,000 people, receives an average daily volume of 24 million gallons per day (MGD) at an average influent 5-day biochemical oxygen demand concentration of 200 mgBOD5/L and an average influent total suspended solids concentration of 220 mgTSS/L. The plant operates a primary sedimentation process that remove 65% of the incoming TSS and 35% of the incoming BOD5%. This process is followed by a secondary treatment process before discharge to the local waters.

9. What is plant average BOD5 loading? (answer will be given in the unit of !#. /01!") ,"-

10. Knowing the primary treatment BOD5 removal efficiency and the plant combined primary and secondary BOD5 removal efficiency. How much BOD5 is removed during secondary

    treatment every day? (answer will be given in !#. /01!") ,"-

11. The biomass is quantified in terms of volatile suspended solids concentration (VSS) . For example, if the content of a biological reactor has a VSS concentration of 2000 mgVSS/L, it is estimated that there is 2,000 mg of biomass per Liter of reactor.
    With that said, what will be the expected secondary treatment biomass production if the

    net biomass yield is 0.3 lb VSS/lb of BOD5 removed)? (answer will be given in !#. 633") ,"-

1. What is the flow contributed by each habitant? (answer will be given in the unit of ! !"# ")

$%&'() . ,"-

2. What is the plant BOD5 mass loading contributed by each habitant? (answer will be given in the unit of ! #. /01! ")

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3. What is the plant TSS mass loading contributed by each habitant? (answer will be given

in the unit of ! #. 233 ") $%&'() . ,"-

4. What is the average influent total dissolved solids (TDS) concentration if the average influent total solids (TS) concentration is measured at 650 mg/L? (answer will be given in

the unit of !4! 213")) 5

5. Is it expected that the primary sedimentation process removes the solids that are measured as TDS? (answer will be given as yes or no)

6. What is the expected primary sedimentation process average effluent TSS concentration? (answer will be given in the unit of !4! 233")

5

7. What is the expected primary sedimentation process average effluent BOD5

concentration? (answer will be given in the unit of !4! /01!") 5

8. What is the plant combined primary and secondary treatment process average BOD5 removal efficiency if the final effluent discharged in the local waters has a concentration of 12 mgBOD5/L? (answer will be given in % removal)

Answer 1