An activated sludge plant receive 5.0 MGD of wastewater with a BOD of 220 mg/L. The primary clarifier removes 35% of the BOD. The sludge is aerated for 6 hr. The food-to-microorganism ratio is 0.30. The recirculation ratio is 0.2. The surface loading rate of the secondary clarifier is 800 gal/day-ft2. The final effluent has a BOD of 15 mg/L. What are the (a) BOD removal efficiency of the activated sludge treatment processes (secondary BOD removal), (b) aeration tank volume, (c) MLSS, and (d) secondary clarifier surface area? If 0.5 pound of oxygen is required for each pound of BOD entering the aeration tank and the density of air is approximately 0.075 lb/ft3, and the air is 20.9% oxygen by volume, calculate air requirements per day.

What is the correct statement regarding individuals involved in Health Surveillance?
Select one:

1.   The Responsible Person does not necessarily have specific training in the recognition of potential ill-health
.
2.   The Responsible Person will make a diagnosis of a worker in the absence of an Occupational Health doctor or nurse

3.   If a worker displays any evidence of ill-health, they should be referred to the Occupational Health doctor, nurse, or other Healthcare professional.

4-Occupational Health doctors and nurses are examples of Responsible Persons X

5. 2 and 3 . x

6. None of the above. X

: How the presence of water in soil affects the property of soil and its load-carrying capacity? Also, mention how the seasonal variation of the water content of soil will affect the settlement characteristics of the foundation?

Case study: Impact of infrastructure system.

Topic chosen : japan bullet train ( shinkansen )

what is the Impact of infrastructure system on a society.

Recognize the need and engage in the civil engineering life-long learning process.

Select these three to use it in the report:

1-The natural environment.

2-Economic considerations.

3-Impact due to failure.

Case study: Airport sustainability planning and design.

Airport chosen : Tokyo haneda airport.

Conduct case study on airport sustainability planning.

Comprehend the importance of sustainability on airport planning and design and describe sustainable airport planning initiatives and solution.

Determine the daily primary sludge production during the following wastewater treatment with these operating characteristics:

Flow = 5000 gpm (gallons per minute)

Influent SS = 180 mg/L

Removal efficiency = 60%

Volatile solids = 70% of SS

Specific Gravity of volatile solids = 0.967

Fixed solids = 30% of SS

Specific Gravity of fixed solids = 2.4

Sludge solids content = 5.00%

What is a key difficulty to be overcome when selecting observed seismograms for the design of a structure? Briefly summarize two alternatives.

A ski lift carries a maximum capacity of 100 people/min to a height of 225 feet, calculate the electrical input power required of the motor to meet these conditions if the motor has an efficiency of 85%. Assume the average weight of each person is 160 lb.

A.) 50 kW

B.) 82 kW

C.) 96 kW

D.) 110 kW

1. Consider water flowing upwards through the 22.5^o reducing elbow (22.5^o angle to horizontal axis). If diameters of the elbow at entrance point and exit points are 0.02540 m and 0.01905 m respectively, elbow is 0.1 m high, velocities of water are 5 m/s and 9 m/s at entrance point and exit point respectively, and density of water is 1000 kg/m³_, moment flux correction factor = 1.02.
2. 1. Determine gage pressure at inlet
3. 2. Determine vertical component of force of the system, if weight of the system is 0.2 kg.

Describe what is capillary barrier and explain mechanism behind capillary barrier for solid waste disposal ?

Use 50,000 psi for the

yield stress of steel, and limit deflection to y max= span/360.

Factor of safety shall be evaluated based on Yield Stress.

Problem

1. Select the lightest beam to span 40 feet between supports. There is no load on the beam

A three storey structure having a square footprint of 225 m² is constructed on a clayey deposit. The structure is planned to be supported by square isolated footings having a width of 2m and spaced at 5m center to center. A typical borehole indicates that the soil consists of 2m fill layer at the top (g=17KN/m³) followed by a very stiff clay layer 2m thick (gsat=18.5KN/m³) underlain by a normally consolidated soft clay layer of 4.5m thickness (gsat=17KN/m³) followed by a rock layer extending down to the bottom of borehole. The foundations are laid on top of the stiff clay layer. Water table is located at the top of the stiff clay layer. Undisturbed samples were taken from the middle of each clay layer and consolidation tests done on undisturbed samples indicated the following:

 Stiff Clay: Cc=0.15; Cs = 0.02; P_c = 120 kPa; e₀=0.9

 Soft Normally Consolidated Clay: Cc=0.38; Cs = 0.06; e₀=1.0

a) Draw a sketch representing the various problem components.

b) The isolated foundations are subjected to a stress of 140 kPa. Calculate the consolidation settlement. Consider the very stiff clay as one layer and divide soft clay layer into two equal sub-layers. Calculate settlement under one typical foundation.

c) What would be the maximum additional stress applied on a central foundation from two neighboring foundations (situated at the left and right sides of the central foundation). Is it necessary to consider the additional stresses from neighboring foundations in the settlement calculations?

d) A concern is the differential settlement between isolated adjacent footings. It was decided to change the design to have the structure founded on a raft foundation subjected to a stress of 45 kPa. Compute the consolidation settlement and comment on the results.

A one-way solid concrete slab is to be used for a simple span
of 18 ft. In addition to its own weight, the slab carries a superimposed dead
load of 50 psf and a live load of 75 psf. Using the strength method with
f ′c = 4 ksi and fy = 60 ksi, design the slab for minimum overall thickness.

(account for weight of slab)

It is desired to use a 12-in.W-shape for a column to support a beam. Select a trial size for the column for the following data: column factored axial load from above is 485 kips, factored beam reaction is 100 kips, and unbraced column height is 18ft.

* Check the section found to see if it complies with
the AISC interaction equations for axial compression plus bending.* (Interaction Formula Check)