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This comprehensive document covers the fundamental principles and operational aspects of wastewater treatment plants. It provides detailed information on various treatment processes, including primary, secondary, and tertiary treatment, as well as the management of sludge and other byproducts. The document delves into the specific operational parameters, troubleshooting techniques, and best practices for maintaining efficient and effective wastewater treatment systems. It serves as a valuable resource for wastewater professionals, students, and anyone interested in understanding the complexities of wastewater treatment and management.
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An Imhoff cone is used to measure solids. A. suspended B. colloidal C. volatile D. settleable ✔✔D. settleable (Operation of Wastewater Treatment Plants, Volume 1 by Kenneth D. Kerri) A flume is widely used for measuring wastewater flow. ✔✔Parshall (Operation of Wastewater Treatment Plants, Volume 1 by Kenneth D. Kerri)
Velocity of flow in a grit channel must be reduced to a range of to fps in order for grit to properly settle. ✔✔.7 to 1.4 fps (Operation of Wastewater Treatment Plants, Volume 1, 3. by Kenneth D. Kerri) With respect to grit removal systems, grit is traditionally defined as particles larger than 0.21mm (0.008 in) (65 mesh) and with a specific gravity of greater than. ✔✔specific gravity of grit is 2.65 or greater (EPA Wastewater Technology Fact Sheet, Screening and Grit Removal) Mechanically cleaned bar screens feature bars set at to degrees from vertical. ✔✔Bars set at 0 to 30 degrees from vertical. (EPA Wastewater Technology Fact Sheet, Screening and Grit Removal)
What do we mean by Total Suspended Solids (TSS) in wastewater? ✔✔All the solids that can be filtered out including: settleable solids and non-settleable solids (colloids) (New Mexico Wastewater Systems Operator Certification Study Manual) The wastewater in a sewer line should move at a speed that will prevent the deposition and buildup of solids in the sewer; this is called a "scouring velocity". A minimum velocity of fps provides this scouring or self-cleaning velocity. ✔✔The wastewater in a sewer line should move at a speed that will prevent the deposition and buildup of solids in the sewer; this is called a "scouring velocity". A minimum velocity of 2 fps provides this scouring or self-cleaning velocity. (New Mexico Wastewater Systems Operator Certification Study Manual) Wastewater treatment ponds: Facultative ponds are feet deep ✔✔Facultative ponds are 4 - 8 feet deep (New Mexico Wastewater Systems Operator Certification Study Manual)
Wastewater treatment ponds: Anaerobic ponds are feet deep ✔✔Anaerobic ponds are > feet in depth (New Mexico Wastewater Systems Operator Certification Study Manual) Typical Primary Clarifier Efficiencies: Settleable Solids expected removal efficiency % to % ✔✔Typical Primary Clarifier Efficiencies: Settleable Solids expected removal efficiency 95% to 99% (New Mexico Wastewater Systems Operator Certification Study Manual) Typical Primary Clarifier Efficiencies: Suspended Solids expected removal efficiency % to % ✔✔Typical Primary Clarifier Efficiencies: Suspended Solids expected removal efficiency 40% to 60% (New Mexico Wastewater Systems Operator Certification Study Manual)
C. The Specific Oxygen Uptake Rate (SOUR) in the primary clarifier is greater than 3000 mg O2/L/hr D. The sludge contains from 4.0 to 8.0 percent dry solids in TS laboratory testing E. All of the above ✔✔A. sludge gasification causes large clumps of sludge to float on the water surface. Pump cavitation may be caused by: A. Loss of discharge pressure due to open hy-drants or line breaks B. Closed suction valve C. Obstruction in the suction line D. Low suction head due to drop in water level E. All of the above ✔✔E. All of the above
(New Mexico Wastewater Systems Operator Certification Study Manual) A minimum dissolved oxygen (D.O.) level of mg/L is recommended in the aeration tank for most basic types of activated sludge processes. ✔✔A minimum dissolved oxygen (D.O.) level of 1.0 mg/L is recommended in the aeration tank for most basic types of activated sludge processes. Maintaining > 1.0 mg/L of D.O. contributes to establishing a favorable environment for the organisms, which produces the desired type of organism and the desired level of activity. (New Mexico Wastewater Systems Operator Certification Study Manual) If the D.O. in the aeration tank is allowed to drop too low for long periods, undesirable organisms, such as may develop and overtake the process. ✔✔If the D.O. in the aeration tank is allowed to drop too low for long periods, undesirable organisms, such as filamentous type bacteria may develop and overtake the process. (New Mexico Wastewater Systems Operator Certification Study Manual) Typical operating parameters for conventional activated sludge systems:
What is the main difference between sludge from primary and secondary clarifiers? ✔✔The main difference between the sludge from primary and secondary clarifiers is that the primary sludge is usually denser than secondary sludge. (Operation of Wastewater Treatment Plants, Volume 1, question 5.0A by Kenneth D. Kerri) What are some causes of floating sludge (bulking) in a primary clarifier? ✔✔• Sludge decomposing in tank, lifted by gasification
What are some causes of black and odorous septic wastewater in primary clarifier effluent? ✔✔• Improper sludge removal
from 3 to 6 mg/L in the filter effluent from rock media and from 4 to 8 mg/L in the filter effluent from synthetic media. (Operation of Wastewater Treatment Plants, Volume 1, section 6.4B by Kenneth D. Kerri) The tiny, gnat-sized filter fly is known also as? ✔✔Psychoda (Operation of Wastewater Treatment Plants, Volume 1, section 6. by Kenneth D. Kerri) Trickling filter flies can be controlled by what methods? ✔✔1. Increasing the recirculation rate
(Operation of Wastewater Treatment Plants, Volume 1, section 6.4F by Kenneth D. Kerri) True or False: A trickling filter should be taken out of service during icy conditions? ✔✔A trickling filter should not be taken out of service during icing conditions because the quality of the effluent will be reduced and additional maintenance problems could develop (Operation of Wastewater Treatment Plants, Volume 1, section 6.4G by Kenneth D. Kerri) MPN is the of coliform-group organisms per unit volume of sample water. Expressed as a density of population of organisms per mL of sample water. ✔✔MPN is the Most Probable Number of coliform-group organisms per unit volume of sample water. Expressed as a density of population of organisms per 100 mL of sample water. (Operation of Wastewater Treatment Plants, Volume 1, section 7. by Kenneth D. Kerri)
Nitrification in nature is a two-step oxidation process of ammonium (NH4+) or ammonia (NH3) to nitrate (NO3−) catalyzed by two ubiquitous bacterial groups. The first reaction is oxidation of ammonium to nitrite by ammonia oxidizing bacteria represented by the (a.) genus. The second reaction is oxidation of nitrite (NO2−) to nitrate by nitrite-oxidizing bacteria, represented by the (b.) genus. ✔✔(a.) Nitrosomonas, (b.) Nitrobacter is an aerobic process in which bacteria change the ammonia and organic nitrogen in wastewater into oxidized nitrogen (usually nitrate). The second-stage BOD is sometimes referred to as the "nitrogenous BOD" (first-stage BOD is called the "carbonaceous BOD"). ✔✔Nitrification is an aerobic process in which bacteria change the ammonia and organic nitrogen in wastewater into oxidized nitrogen (usually nitrate). The second-stage BOD is sometimes referred to as the "nitrogenous BOD" (first-stage BOD is called the "carbonaceous BOD"). (Operation of Wastewater Treatment Plants, Volume 1, section 7. by Kenneth D. Kerri) is the anoxic biological reduction of nitrate nitrogen to nitrogen gas. ✔✔Denitrification is the anoxic biological reduction of nitrate nitrogen to nitrogen gas. In secondary clarifiers the
nitrogen bubbles produced as a result of denitrification can attach to the biological floc and float the floc to the surface. This condition is often the cause of rising sludge. (Operation of Wastewater Treatment Plants, Volume 1, section 7. by Kenneth D. Kerri) The stage is a stage of decomposition that occurs in the biological treatment processes when aerobic bacteria, using dissolved oxygen, change carbon compounds to carbon dioxide. ✔✔The carbonaceous stage is a stage of decomposition that occurs in the biological treatment processes when aerobic bacteria, using dissolved oxygen, change carbon compounds to carbon dioxide. (Operation of Wastewater Treatment Plants, Volume 1, section 7. by Kenneth D. Kerri) If the DO is too high in an aeration basin, may form and the secondary clarification process may not be able to remove the. ✔✔If the DO is too high in an aeration basin, "pinpoint" floc may form and the secondary clarification process may not be able to remove the "pin" floc.
True or False: A facultative treatment pond is seeded with specially selected algae to optimize the treatment process for the climate and conditions. ✔✔False. Algae simply appear in a pond on their own without seeding. They are found in soil, water, and air and multiply under favorable conditions. (Operation of Wastewater Treatment Plants, Volume 1, section 9.3B by Kenneth D. Kerri) What does a definite green color in a treatment pond indicate? ✔✔A definite green color in a pond indicates a flourishing algal population and is a good sign. (Operation of Wastewater Treatment Plants, Volume 1, section 9.5C by Kenneth D. Kerri) When should a wastewater treatment pond be started? ✔✔Ponds should be started during the warmer months because higher temperatures are associated with efficient treatment processes. (Operation of Wastewater Treatment Plants, Volume 1, section 9.5B by Kenneth D. Kerri)
What should be done if the pH and DO in a pond are dropping dangerously low? ✔✔Check the loading. The loading may need to be reduced or stopped. Recirculating the water from a healthy pond to the problem pond should help the situation. Recirculation from outlet to inlet areas is beneficial for seeding, DO, and mixing. (Operation of Wastewater Treatment Plants, Volume 1, section 9.6L by Kenneth D. Kerri) What is the maximum daily withdrawal rate of chlorine gas used for wastewater disinfection, from a one ton cylinder? ✔✔400 lbs. The maximum withdrawal rate of chlorine gas from a 100/150 pound cylinder is 40 pounds per day; for a ton container, this rate is 400 pounds per day. True or False: pH generally will be affected significantly by a clarifier. ✔✔False. pH generally will NOT be affected significantly by a clarifier. (Operation of Wastewater Treatment Plants, Volume 1, comprehensive review questions # by Kenneth D. Kerri)
