Activated Sludge & BNR Process Control WorkshopRoyCEU.com

Which aeration mode is intended to dilute high demand influent loadings?
1. Plug flow
2. Step feed
3. Complete mix
4. Contact stabilization
What is typically the limiting factor in sustaining growth of microorganisms in the
declining growth phase?
1. Oxygen
2. Time
3. Food
4. Volatile bugs
Which adjustment will normally improve denitrification in a conventional aeration tank?
1. Increase the air supply
2. Increase the D.O.
3. Decrease the D.O.
4. Shut off the RAS
Which group of bacteria is responsible for converting nitrite to nitrate?
1. Facultative
2. Nitrosomonas
3. Nitrobacter
4. Heterotrophic
Which activated sludge process re-aerates the RAS before being introduced into the influent wastewater flow?
1. Step feed
2. Complete mix
3. Contact stabilization
4. Plug flow
Which growth phase is predominant in extended aeration?
1. Declining growth
2. Endogenous respiration
3. Log growth
4. Filamentous
Which condition may indicate too much food is still available in the MLSS leaving the aeration tank?
1. Low OUR/RR in aeration inlet
2. High OUR/RR in aeration inlet
3. Low OUR/RR in aeration outlet
4. High OUR/RR in aeration outlet
Where is the highest demand for oxygen in a plug flow aeration tank?
1. At the effluent weir
2. In the middle of the tank
3. Equally throughout the tank
4. In the beginning of the tank
Which conditions typically generate a larger volume of new cellular growth?
1. High F/M with low D.O.
2. Low F/M with high D.O.
3. Low F/M with high D.O.
4. High F/M with high D.O.
Given the following Ortho P data for inlet and outlet of a BNR fermentation tank, does this appear to be a problem?
* Fermentation Inlet Ortho P is 7.0 mg/L
* Fermentation Outlet Ortho P is 4.0 mg/L
1. Yes: Ortho P is too low in the fermentation outlet
2. Yes: fermentation outlet Ortho P should be 2 to 4 times the concentration of the inlet
3. No, the fermentation tank is designed to remove phosphorus directly
4. Both "A & B"
Which best describes the nitrification cycle?
1. NO₃ is converted to NH₃
2. NH₃ is converted to NO₂ and then to NO₃
3. NH₃ is converted to NO₃ and then to NO₂
4. NO₂ is converted to NH₃ and then to NO₃
What is a typical SRT in a log growth phase?
1. High – above 15 days
2. Moderate – about 7 days
3. Low – below 3 days
4. It can’t be measured
Given the following data, calculate the lbs of alkalinity required for nitrification:
Data:

• Flow = 26.5 mgd
• Inf TKN = 42 mg/L
• Eff NH₃ = 0.75 mg/L
• 90% TKN converted to NH₃
• 7.14 lbs Alkalinity consumed for each lb of NH₃ Converted
1. 8,188 lbs
2. 66,276 lbs
3. 6,795 lbs
4. 58,465 lbs
Which parameter best describes the balance of food to microorganisms?
1. SRT
2. F/M
3. MCRT
4. GSA
Which adjustment will normally improve denitrification in a 5-stage Bardenpho process?
1. Decrease the Internal Recycle rate
2. Increase the D.O.
3. Increase the D.O.
4. Increase the Internal Recycle rate
What problems will be experienced with phosphorus removal if D.O. is present in the fermentation zone?
1. No problems … P removal will be high
2. P release will be high but P uptake will be low
3. P release will be hindered and P uptake will be reduced
4. The fermentation zone should have high D.O.
Which best describes sludge volume index?
1. Numerical indicator of bug population
2. Volume to weight ratio of mixed liquor
3. Volume to volume ratio of mixed liquor
4. Removal efficiency of BOD
Given the “Fate of Phosphorus” profile, why does TP reduce through the 1st anoxic zone?
1. Phosphorus is still being released
2. Remain the same speed
3. Shut-off the aerator
4. Increase the VFD speed
What adjustment will the VFD aerator make when the ammonia value is higher than the target value?
1. Decrease the VFD speed
2. Remain the same speed
3. Shut-off the aerator
4. Increase the VFD speed
What adjustment should be considered if ammonia leaving the aerobic zone is too high?
1. Decreasing the oxygen input, thereby increasing denitrification, will reduce the ammonia levels
2. Increasing the oxygen input will improve nitrification
3. Reduce MLSS levels below 1,000 ppm
4. Increase the internal recycle rate