Biology of Wastewater Treatment and Sewer Systems Quiz
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Questions and Answers

Which type of wastewater is discharged from residences and commercial facilities?

  • Domestic (sanitary) wastewater (correct)
  • Industrial wastewater
  • Storm water
  • Infiltration/Inflow

    • What is the term for water that enters the sewer system through leaking joints, cracks, or porous walls?

  • Infiltration (correct)
  • Inflow
  • Storm water
  • Industrial wastewater

    • Which type of wastewater contains predominantly industrial wastes?

  • Infiltration/Inflow
  • Industrial wastewater (correct)
  • Domestic (sanitary) wastewater
  • Storm water

    • What is the term for storm runoff resulting from rainfall and snowmelt?

    <p>Storm water</p> Signup and view all the answers

    Which type of growth is used in the activated sludge process?

    <p>Suspended cultures</p> Signup and view all the answers

    What affects the aeration period and treatment efficiency in the activated sludge process?

    <p>F/M ratio</p> Signup and view all the answers

    What is the purpose of the biological treatment in wastewater?

    <p>Convert organics in wastewater into biomass</p> Signup and view all the answers

    Which factors affect biomass production and food utilization in wastewater treatment?

    <p>Temperature, pH, toxins, salt concentration</p> Signup and view all the answers

    What is the role of microorganisms in wastewater treatment?

    <p>Convert organics in wastewater into biomass</p> Signup and view all the answers

    What is important for the design of biological systems in wastewater treatment?

    <p>Understanding biological principles, kinetics of metabolism, and mass balance</p> Signup and view all the answers

    Which type of process is the activated sludge process?

    <p>Suspended-culture process</p> Signup and view all the answers

    What are the important parameters for the suspended-culture process in wastewater treatment?

    <p>MLSS, MCRT/SRT, and HRT</p> Signup and view all the answers

    What is the purpose of the F/M ratio in the activated sludge process?

    <p>Affects the aeration period and treatment efficiency</p> Signup and view all the answers

    What type of organisms are involved in wastewater treatment?

    <p>Microorganisms</p> Signup and view all the answers

    What is the role of air for microorganisms in wastewater treatment?

    <p>Maintain growth and adjust to environmental factors</p> Signup and view all the answers

    What are the two types of biological growth used in wastewater treatment?

    <p>Suspended cultures and attached growth</p> Signup and view all the answers

    Which method is used to separate non-biodegradable grit from organic suspended solids in wastewater?

    <p>Channel-type horizontal-flow grit chambers</p> Signup and view all the answers

    What is the primary purpose of fine screens in wastewater treatment?

    <p>Mechanically cleaning on a continuous basis</p> Signup and view all the answers

    What can backflow of influent wastewater cause in screening?

    <p>Septic shock loading with H2S production</p> Signup and view all the answers

    What is the purpose of comminution in wastewater treatment?

    <p>Shredding and returning screenings to the wastewater flow</p> Signup and view all the answers

    What is the primary function of grit chambers in wastewater treatment?

    <p>Protecting mechanical equipment from abrasion</p> Signup and view all the answers

    Which type of screens are used for filtering out larger and smaller particles in wastewater treatment?

    <p>Bar screens</p> Signup and view all the answers

    What is the role of primary treatment in wastewater treatment?

    <p>Sedimentation for gravitational settling</p> Signup and view all the answers

    What is the purpose of disposal methods for screenings in wastewater treatment?

    <p>Managing waste from the treatment process</p> Signup and view all the answers

    Which flow measurement devices are used in wastewater treatment?

    <p>Parshall flumes and Palmer-Bowlus flumes</p> Signup and view all the answers

    What is the purpose of secondary treatment in wastewater treatment?

    <p>Biological conversion of dissolved organics</p> Signup and view all the answers

    What is the primary factor affecting the efficiency of sedimentation in wastewater treatment?

    <p>Types of solids</p> Signup and view all the answers

    What is the role of bar screens in wastewater treatment?

    <p>Filtering out larger and smaller particles</p> Signup and view all the answers

    What is the primary aim of primary wastewater treatment?

    <p>Removal of a portion of suspended solids and organic matter by settling or sedimentation</p> Signup and view all the answers

    What is the main focus of tertiary wastewater treatment?

    <p>Removal of nutrients and toxic compounds</p> Signup and view all the answers

    What is the purpose of preliminary wastewater treatment?

    <p>Removal of large solids to prevent damage to the remainder of the unit operations</p> Signup and view all the answers

    What is the primary objective of secondary wastewater treatment?

    <p>Removal of biodegradable organics and suspended solids</p> Signup and view all the answers

    What is the purpose of solids treatment and disposal in wastewater treatment?

    <p>Collection, stabilization, and subsequent disposal of the solids removed by other processes</p> Signup and view all the answers

    What is the classification of wastewater treatment methods that includes physical unit operations?

    <p>Physical unit operations</p> Signup and view all the answers

    What is the first operation performed on incoming wastewater for the purpose of removing materials that might damage equipment or hinder further treatment?

    <p>Screening</p> Signup and view all the answers

    What are coarse screens used for in wastewater treatment?

    <p>Remove coarse solids from wastewater</p> Signup and view all the answers

    What is the optimum dissolved oxygen (DO) concentration for aerobic processes?

    <p>1.5 – 2.5 mg/L</p> Signup and view all the answers

    What can over-aeration (DO 5-6) lead to?

    <p>Undesirable microorganisms and filamentous bulking</p> Signup and view all the answers

    What are the remedies for filamentous bulking in wastewater treatment?

    <p>Adjusting F/M ratio, DO levels, dosing with H2O2</p> Signup and view all the answers

    What is the purpose of a primary clarifier in the context of trickling filters?

    <p>To avoid media clogging</p> Signup and view all the answers

    What is the role of wastewater ponds and lagoons in natural purification processes?

    <p>Providing aerobic and anaerobic zones</p> Signup and view all the answers

    What are the aeration techniques used in wastewater treatment?

    <p>Air diffusers (fine and coarse bubble) and mechanical aerators</p> Signup and view all the answers

    What do attached growth systems like trickling filters and biotowers facilitate in wastewater treatment?

    <p>Wastewater treatment through attached biomass</p> Signup and view all the answers

    What is the characteristic feature of biotowers in wastewater treatment?

    <p>Modular synthetic media for a vertical arrangement</p> Signup and view all the answers

    What is the primary purpose of wastewater ponds and lagoons?

    <p>Natural purification processes</p> Signup and view all the answers

    What are the causes of poor settling due to filamentous bulking in wastewater treatment?

    <p>Wrong DO levels, insufficient nutrients, fluctuating organic waste loading</p> Signup and view all the answers

    What is the impact of high aeration levels in wastewater treatment?

    <p>Beneficial effects</p> Signup and view all the answers

    What are the operational and wastewater characteristics causes of non-filamentous organisms in wastewater treatment?

    <p>Over-aeration, improper loading, toxic substances</p> Signup and view all the answers

    What is the optimum range of dissolved oxygen (DO) concentration for aerobic processes?

    <p>1.5 – 2.5 mg/L</p> Signup and view all the answers

    What can over-aeration (DO 5-6) lead to in wastewater treatment?

    <p>Undesirable microorganisms and filamentous bulking</p> Signup and view all the answers

    What is the primary cause of poor settling due to filamentous bulking in secondary clarifiers?

    <p>Wrong DO levels</p> Signup and view all the answers

    What are the causes of non-filamentous organisms in wastewater treatment?

    <p>Over-aeration and improper loading</p> Signup and view all the answers

    What are the remedies for filamentous bulking in wastewater treatment?

    <p>Adjusting F/M ratio and dosing with H2O2</p> Signup and view all the answers

    Which aeration technique involves air diffusers and mechanical aerators?

    <p>Completely mixed reactors</p> Signup and view all the answers

    How are wastewater ponds and lagoons aerated?

    <p>Through artificial aeration</p> Signup and view all the answers

    What is the primary role of attached growth systems like trickling filters and biotowers in wastewater treatment?

    <p>To enable attached biomass treatment</p> Signup and view all the answers

    What is the primary function of a primary clarifier in the context of trickling filters?

    <p>To prevent media clogging</p> Signup and view all the answers

    What distinguishes biotowers from trickling filters in wastewater treatment?

    <p>Use of synthetic media</p> Signup and view all the answers

    What is a distinct limitation of trickling filters and biotowers in wastewater treatment?

    <p>Odor problems</p> Signup and view all the answers

    What is the primary purpose of wastewater ponds and lagoons in natural purification processes?

    <p>To provide oxygen for aerobic and anaerobic zones</p> Signup and view all the answers

    Study Notes

    Biological Wastewater Treatment Overview

    • Biological treatment uses microorganisms to convert organics in wastewater into biomass.
    • Wastewater requires a variety of organisms for complete treatment.
    • Microorganisms involved in wastewater treatment are similar to those in natural systems but are carefully controlled in engineered reactors.
    • Factors affecting biomass production and food utilization include temperature, pH, toxins, salt concentration, oxidants, and nutrient deficiency.
    • Microorganisms need air to maintain growth and can adjust to a wide range of environmental factors.
    • Design of biological systems requires understanding of biological principles, kinetics of metabolism, and mass balance.
    • Two types of biological growth used in wastewater treatment are suspended cultures and attached growth.
    • Suspended cultures include activated sludge, ponds, and lagoons.
    • The activated sludge process is a suspended-culture process with various common variations.
    • Design and operational parameters of the activated sludge process include F/M ratio, MLSS, MCRT/SRT, and HRT.
    • The F/M ratio affects the aeration period and treatment efficiency in the activated sludge process.
    • MLSS, MCRT/SRT, and HRT are important parameters for the suspended-culture process.

    Wastewater Treatment and Sewer Systems

    • Types of sewer systems include sanitary sewer system, storm sewer system, and combined water system
    • Contaminants of concern in wastewater treatment include suspended solids, biodegradable organics, pathogens, nutrients, priority pollutants, refractory organics, heavy metals, and dissolved inorganics
    • Wastewater treatment objectives involve the removal of suspended and floatable material, treatment of biodegradable organics, elimination of pathogenic organisms, removal of toxic compounds, and removal of nutrients
    • Division of wastewater treatment systems includes preliminary wastewater treatment, primary wastewater treatment, secondary wastewater treatment, tertiary wastewater treatment, and solids treatment and disposal
    • Preliminary wastewater treatment involves the removal of large solids to prevent damage to the remainder of the unit operations through screening, comminution, grit removal, and flotation
    • Primary wastewater treatment aims to remove a portion of suspended solids and organic matter by settling or sedimentation, removing about 60% of the solids and about 30% of BOD
    • Secondary wastewater treatment is directed principally for the removal of biodegradable organics and suspended solids, including biological treatment by activated sludge, fixed-film reactors, lagoons, and pond systems
    • Tertiary wastewater treatment involves the polishing of secondary effluent, primarily focusing on the removal of nutrients, toxic compounds, increased amounts of organic material, suspended solids, and removal of ions and salts through ion exchange and reverse osmosis processes
    • Solids treatment and disposal includes the collection, stabilization, and subsequent disposal of the solids removed by other processes
    • Classification of wastewater treatment methods includes physical unit operations, chemical unit processes, and biological unit processes
    • Preliminary treatment methods include screening, which is the first operation performed on incoming wastewater for the purpose of removing materials that might damage equipment or hinder further treatment
    • Coarse screens are used to remove coarse solids from wastewater, consisting of vertical bars spaced 1 or more centimeters apart and inclined away from the incoming flow, with solids retained by the bars usually removed by manual raking in small plants while mechanical cleaner units are used in larger plants

    Wastewater Treatment Techniques and Challenges

    • Dissolved oxygen (DO) concentration is crucial for aerobic processes, with an optimum value of 1.5 – 2.5 mg/L.
    • High aeration levels (DO 4) are beneficial, but over-aeration (DO 5-6) can lead to undesirable microorganisms and filamentous bulking.
    • Filamentous bulking in secondary clarifiers hinders settling and can impact the performance of activated sludge systems.
    • Causes of poor settling due to filamentous bulking include wrong DO levels, insufficient nutrients, and fluctuating organic waste loading.
    • Operational and wastewater characteristics causes of non-filamentous organisms include over-aeration, improper loading, and toxic substances.
    • Remedies for filamentous bulking include adjusting F/M ratio, DO levels, dosing with H2O2, and pre-treating wastewater to remove toxins.
    • Aeration techniques include air diffusers (fine and coarse bubble) and mechanical aerators used in plug flow and completely mixed reactors, respectively.
    • Wastewater ponds and lagoons provide natural purification processes through aerobic and anaerobic zones, with oxygen for lagoons being provided by artificial aeration.
    • Attached growth systems like trickling filters, biotowers, and rotating biological contactors facilitate wastewater treatment through attached biomass.
    • Trickling filters use stationary medium and intermittent wastewater doses to achieve treatment efficiency, requiring a primary clarifier to avoid media clogging.
    • Biotowers use modular synthetic media to enable a vertical arrangement for wastewater treatment, addressing issues such as odor and vector problems.
    • Trickling filters and biotowers have distinct features and limitations, such as odor problems, vector issues, and the need for pre-treating wastewater.

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    Description

    Test your knowledge of biological wastewater treatment and sewer systems with this informative quiz. Explore concepts such as microorganism involvement, factors affecting biomass production, design principles, types of sewer systems, contaminants of concern, and the division of wastewater treatment systems. This quiz will enhance your understanding of the key principles and processes involved in biological wastewater treatment and sewer systems.

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