Lagoon System Math - Division of Water Quality

Lagoon System Math - Practice ProblemsAnswer KeyThe Division ofWater Qualitymakes no claim as the accuracy ofany answers provided herein.

WB Chapter 13 • WASTE TREATMENT PONDS 223PRACTICE PROBLEMS 13.1~ BOD Loading1. Calculate the BOD loading (lbs/day) on a pondifthe influent flow is 390,000 gpd witha BOD of 245 mg/L.Lom,~ = C6 . ~y

224 WB Chapter 13 • WASTE TREATMENI' PONDS4. The BOD concentration of the influent wastewater to a waste treatment pond is 190mg/L. Ifthe flow to the pond is 125 gpni. how maliY pounds ofBOD are applied to thepond daily?

WB Chapter 13 •WASTE TREATMENI' PONDS 225PRACTICE PROBLEMS 13.2: Organic Loading Rate1. A 7.S-acre pond receives a flow of 200,000 gpd. H the influent flow has a BODcontent of 190 mg/L. what is the organic loading rate in lbslday/ac on the pond?\-ex.--d.. :­Lo-J ,.,J,. =

226 WB Chapter 13 • WASTE TREATMENI' PONDS4. The maximum desired organic loading rate for a IS-acre pond is 20 lbs BOD/day/ac.If the influent flow to the pond has a BOD concentration of 187 mg/L, what is themaximum desirable MOD flow to the pond? (Round to the nearest hundredth.)0... rc,,", '= IS 0

WB Chopur 13· WASTE TREATMENT PONDS 227PRACTICE PROBLEMS 13.3: BOD Removal Efficlency1. The BOD entering a waste treatment pond is 2JJ7 mg/L.lfthe BOD in the pondeffluent is 39 mg/L, what is the BOD removal efficiency of the pond?,"'-ov+~ q \(, 1r:::. ..... V~/ ..:: ,..... • 100%e ~\ LIOI"'I(..'/ -::ANS IL. \00= 10'- 1I"2.. """'::;1 '­

228 WB Chapter 13· WASTE TREATMENt PONDS4. The BOD entering a waste treatment pond is 140 mg/L. Ifthe BOD in the pondeffluent is 56 mg/L, what is the BOD removal efficiency of the pond?'Ir\ _O'J+ %. \00II-->I l.-l 0 ""C-} I L - S v WI '" I L ~/__....L. ..J~_. '00 701L.l0 VY\:1'L(,0 %ANS (PC) %\.

WB Chllpter 13· WASTETREATMENr PONDS 229PRACTICE PROBLEMS 13.4: Hydraulic Loading Rate1. A 20-acre pond receives a flow of 3.3 acre-feet/day. What is the hydraulic loading rateon the pond in inJday?QI ,,""CC\ ::;l.-O CI.(...rcFlow ~.6=c..c... ~ /c:I..""jHLQ -=\-\LR.::­~\ovJc..... .... c· c....>. o~'_'21cJ" I""Lo Co. '""~ I'"\-\LQ. =- o .l-=t ''-. {'... L.O cJ..", I~/ ANSHLI'l ::: "2-,0 '''"l~I2. A IS-acre pond receives a flow of Sacre-feet/day. What is the hydraulic loading rateon the pond in inJday1= \S VI c.. t'" c::1= loUJ = S.Cle.· ~ ( dGA Io..f"Cc.•.\4LR =~\ovJ._--­CAr~C--\..,....I-+L..R.:S c..c..' ?/c/'.· /I 5Go

230 WB Chapter 13· WASI'ETREATMENI' PONDS4. A waste treatment pond receives a flow of 1,680,000 gpd. If the surface area of thepond is 14 acres. what is the hydraulic loading in inJday'?o."'CC

WB ChDpter 13. WASTE TREATMENl' PONDS 231PRACTICE PROBLEMS 13.5: Population Loading and Population Equivalent1. A 4-acre wastewater pond serves a population of 1320 people. What is the populationloading on the pond?O.f'"'Cv =pl- =\>0"" •pL =2. A wastewater pond serves a population of 5460 people. Ifthe pond covers 18.5 acres,what is the population loading on the pond?o..r

232 WB Chapter 13 • WASTE TREATMENT PONDS4. A 250.000-gpd wastewater flow has a BOD content of 2160 mg/L. Using an averageof0.2 Ibs BOD/day/person. what is the population equivalent of this flow?'2... e,oI 000 :;, 1..,1."'" C;:S. ~L.l ("l.' v O I'VI:JI t-) ) '- ',000,000 oj .

WB Chapter 13· WASTE TREATMENT PONDS 233PRACTICE PROBLEMS 13.6: Detention Time1. A waste treatment pond has a total volume of 17 ac-ft. If the flow to the pond i$ 0.42ac-ft/day. what is the detention time of the pond (days)?DT ::,-=+ r. c. \.1o .w. L " ... \.! ) _A'J /ANS 40. S d" l

·234 WB Chapter 13· WASTETREATMENf PONDS4. A waste treatment pond has an average length of 680 it, an average width of 420 ft,and a water depth of 4 ft If the flow to the pond is 0.47 ac-ftlday what is the detentiontime for the pond?~~C-' ~ • 1..4-20 ~u "3" S (.40