Question

A wastewater treatment plant designed for a community of 60,000 people has a flow of 100 gal/person/day and a biochemical oxygen demand (BOD) loading of 0.2 lb/person/day. The treatment plant has a permit limit for BOD equal to 15 mg/L.

a. (6 pts) What is the concentration (in mg/L) of BOD coming into the plant (i.e., as raw, untreated sewage)?

b. (2 pts) When the treatment plant is treating its waste and meeting its permit limit, what is the removal efficiency (in percent) of the plant?

Answer #1

A wastewater treatment plant designed for a community of 60,000
people has a flow of 100gal/person/day and a biochemical oxygen
demand (BOD) loading of 0.2 lb/person/day. The treatment plant has
a permit limit for BOD equal to 15 mg/L.
a. (10 pts) What is the concentration (in mg/L) of BOD coming
into the plant (i.e., as raw, untreated sewage)?
b. (2 pts) When the treatment plant is treating its waste and
meeting its permit limit, what is the removal efficiency...

Problem #3: Biochemical Oxygen Demand (BOD) and Stream
Quality
A wastewater
treatment plant designed for a community of 45,000 people has a
flow of 100 gal/person/day and a BOD5 loading of 0.2
lb/person/day. The upstream characteristics of the receiving waters
are:
stream flow rate =
20 cfs and BOD5 = 2 mg/L
The water quality
standards require the in-stream BOD5 to be less than 7
mg/L in this stretch of the river.
The minimum BOD
removal efficiency that the treatment...

You have been retained to design a wastewater treatment plant using
a conventional activated sludge process for a town of 40,000
people. The industrial flow contribution to the sewer system is
300,000 gallons per day. Effluent discharge standards require
effluent BOD5 and total suspended solids concentration of <10
mg/l.
Assume the following design criteria are applicable:
Domestic sewage flow = 100 gal/cap/day (including I/I)
BOD loading = 0.18 lbs/cap/day
TSS loading = 0.20 lbs/cap/day
BOD removal in primary = 33%...

Wastewater treatment
The Ampang Jaya Municipal Council with a population of 350,000
and several industries discharged 11 MGD of raw sewage into an
activated sludge system treatment plant. The average concentration
of BOD5 is 240 mg/L and the suspended solids is 260
mg/L.
If the average domestic per capita sewage flow is 225 L/c.day,
what is the average flow of the industrial wastewater (in
MGD)?
marks)
If the average BOD5 load from the domestic sewage is
55gcapita-1day-1, determine the average...

The volumetric flow to the ACME wastewater treatment plant is 25
MGD. The influent soluble BOD5 is 200 mg/L and the effluent soluble
BOD5 is 8 mg/L. The plant is designed to operate with a mean cell
(biomass) residence time of 10 days. The yield coefficient is 0.6
mg biomass/mg substrate, and the biomass decay rate is 0.09/day.
The reactor is to operate at a biomass concentration of 2500 mg/L.
The thickened underflow biomass concentration from the secondary
clarifier is...

A 14 mgd wastewater treatment plant has a primary clarifier that
treats an influent with 800 mg/L of solids and a removal efficiency
of 55%. Sludge at the bottom of the tank is pumped at a rate of 0.1
mgd.
a. What is the effluent solids concentration from the clarifier
(in mg/L)?
b. What is the solids concentration in the sludge at the bottom
of the tank (in mg/Land %)?
c. The primary sludge is further processed in a digester...

A completely mixed activated-sludge process is being designed
for a wastewater flow of (2.64 mgd) using the kinetics equations.
The influent BOD of 120 mg/Lis essentially all soluble and the
design effluent soluble BOD is 7 mg/L, which is based on a total
effluent BOD of 20 mg/L. For sizing the aeration tank, the mean
cell residence time is selected to be10 days and the MLVSS 2000
mg/L. The kinetic constants from a bench-scale treatability study
are as follows: Y...

A 1.0 � 106 gallon reactor is used in a sewage-treatment plant.
The influent biochemical oxygen demand (BOD) concentration is 100
mg/L, the effluent BOD concentration is 25 mg/L, and the flow rate
through the reactor is 500 gal/min. (a) What is the first-order
rate constant for decay of BOD in the reactor? Assume that the
reactor can be modeled as a comply mixed flow reactor (CMFR).
Report your answer in units of per hour. (b) Assume that the
reactor...

A wastewater treatment plant disposes of its effluent in a
surface stream. Characteristics of the stream and effluent are
given in the table below.
What will be the dissolved oxygen concentration in the stream
after 2.0 days? (10 Points)
What will be the lowest dissolved oxygen concentration as a
result of the waste discharge? (10 Points)
Parameter
Wastewater
Stream
Flow, m3/s
0.2
5.0
Dissolved Oxygen, mg/L
1.0
8.0
Temperature, o C
15.0
20.2
BOD5 at 20oC, mg/L
100
2.0
k1...

You are tasked with conducting BOD studies for a waste treatment
facility and its discharge to a nearby river. You are told that the
facility removes 93% of the BOD in total with a discharge rate of
1.0 m3 /s. you sample the receiving water and find that it has a
0.5 mg/L deficit from saturation concentration (saturation is at
9.7 mg/L) and a BOD5 content of 10 mg/L. The river flows at a speed
of 0.25 m/s and has...

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