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Wastewater Collection Systems: Questions and Answers for Wastewater Treatment, Exams of Water and Wastewater Engineering

A comprehensive set of questions and answers related to wastewater collection systems and treatment processes. It covers various aspects of wastewater treatment, including the basic components of trickling filters, aerobic and anaerobic conditions, detention time calculations, effluent polishing, and odor and ponding problems in trickling systems. The document also includes multiple-choice questions and answers on topics such as bod, alkalinity, anaerobic decomposition, entrained air, fecal coliform, vulnerability assessment, cod, scada systems, mpn, and mechanical equipment overheating.

Typology: Exams

2024/2025

Available from 12/16/2024

ChitCode
ChitCode 🇬🇧

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Wastewater Collections Level

2 2024-2025. Questions &

Correct Answers. Graded A

3 basic parts of trickling filters – ANS

  1. The media (and retaining structure)
  2. The under-drain system
  3. The distribution system Aerobic – ANS a condition in which "free" or dissolved oxygen is present int he aquatic environment. Anaerobic – ANS a condition in which "free" or dissolved oxygen is NOT present int he aquatic environment. Calculating Detention Time – ANS
  4. Flow in gallons per day
    1. Tank dimensions or volume Chemical Formula Ammonia – ANSNH 3 Chlorine Dioxide - ANSClO Detention Time – ANS Wastewater should remain in clarifier long enough to allow settling for solid particles. If the tank is too small for the quantity of flow and the settling rate of the

particles, too many particles will be carried out the effluent of the clarifier. Detention Time Hours for Settling Tanks - ANS2.0-3.0 Hours Effluent Polishing – ANS A physical treatment process to remove effluent suspended solids. Accomplished by filtration of secondary effluent to remove suspended solids caused by bulking solids or pin floc problems. Free Chlorine – ANS Cl Hydrogen Sulfide – ANS H2S Hypochlorite – ANS OCL- Media Depth Ranges for Trickling Filters – ANS 3-8 ft for rock media; 15- 30 ft for synthetic media Methane – ANS CH Nitrate – ANS NO3- Nitrite – ANS NO2-

Rotating Biological Contactors RBS – ANS a secondary biological treatment process for domestic and biodegradable industrial wastes. Staff Gage – ANS located that 0 is the same elevation as the weir crest Sulfur Dioxide – ANS SO Tricking Systems: Methods to Solve Odor Problems – ANS

  1. Maintain aerobic conditions in sewer collection system and in the primary treatment units
  2. Check ventilation in filter. Heavy biological growths or obstructions in the underdrain system will cut down ventilation. 3. Increase recirculation rate to provide more oxygen to the filter bed and increase sloughing
  3. Keep wastewater splash from the distributors in the filter and away from exposed structures, grass, and other surfaces. Tricking Systems: Methods to Solve Ponding Problems – ANS
  4. Spray filter surface with high pressure washer or steam
  5. Hand turn or stir the filter surface with rake, fork, or bar. Remove any accumulation of leaves or other debris.
  6. Dose the filter with chlorine at the 5 mg/l for several hours.
  1. Flood filter, keeping the media submerged for 24 hours will cause the growth to slough
  2. Shut off flow to the filter for several hours allowing growth to dry out Trickling Filter Description – ANS large diameter, shallow, cylindrical structures filled with stone or plastic media and has an overhead distributor. Trickling Filter Media – ANS rock, slag, coal, bricks, redwood blocks, molded plastic, or any other durable material. Trickling Filter Media Stacking – ANS provide empty spaces (voids) for air to ventilate the filter and keep conditions aerobic. Trickling Systems: Filter Flies – ANS
  3. Increase recirculation rate.
  4. Keep orifice openings clear, including end gates of distributor arms.
    1. Apply approved insecticides with caution to filter walls and other plant structures.
  5. Flood filter for 24 hrs at intervals frequent enough to prevent completion of insect life cycle. (as short as 7 days)
  6. Shrubbery, weeds, and tall grass provide sanctuary , good housekeeping and grounds maintenance will minimize fly problems.

Trickling Systems: Sloughing Problems – ANS periodic uncontrolled sloughing of biological slime growths from the filter; increasing recirculation pump rate to weekly basis will help to induce controlled sloughing rather than slime build up. Underdrain System of Trickling Filters – ANS sloping bottom. Center channel which collects filter effluent. Includes redwood stringers, prefabricated blocks of concrete, vitrified clay, or other suitable material. Zoogleal Film – ANS slime growth that contains the living organisms that break down the organic material. A BOD can be removed from the incubator at 5 days plus or minus... A. 1 hour B. B. 2 hours C. C. 3 hours D. D. 4 hours – ANS C. 3 hours Alkalinity is a measure of the ability of wastewater to.. A. Neutralize base B. Neutralize acid C. Dissolve organics D. Maintain constant temperature – ANS B. Neutralize acid

Anaerobic decomposition of wastewater produces.. A. Ammonium Chloride B. Hydrogen Sulphide C. Carbon Monoxide D. Copper Sulphate – ANS B. Hydrogen Sulphide Entrained air frequently contributes to... A. Reduced wet well capacity B. Less odor around the pump station C. Lower electrical costs D. Pump cavitation – ANS D. Pump Cavitation Fecal Coliform results are reported as MPN per... A. 10mL B. 50 mL C. 100 mL D. 1000 mL – ANS C. 100 mL Reviewing all aspects pf the wastewater treatment system to determine what would occur during various types of emergency situations is known as a(n)? A. Management Effectiveness Survey B. Environmental Audit

C. Comprehensive Performance Evaluation D. Vulnerability Assessment – ANS D. Vulnerability assessment Wastewater entering a treatment plant is typically.. A. Somewhat warmer than unheated tap water B. The same temperature as unheated tap water C. Somewhat cooler than unheated tap water D. Very much cooler than unheated tap water – ANS A. Somewhat warmer than unheated tap water What's one advantage of a COD test over a BOD test? A. Shorter test time B. More accurate C. Safer D. Less chemicals needed - ANSA. Shorter test time What's the purpose of a SCADA system? A. Clean grease lines B. Justify more cleaning crews C. Control equipment and collect data D. Set collection and data appointments - ANSC. Control equipment and collect data When performing an MPN, the sample dilution is considered positive when... A. The Durham tube is found upside down B. The sample turns colour from amber to brown C. No bubbles are found in the Durham tube D. Gas bubbles are found in the Durham tube - ANSD. Gas bubbles are found in the Durham tube Which of the following causes overheating of mechanical equipment? A. Water Hammer B. Under greasing c. Over- greasing D. Dried out packing - ANSC. Over-greasing