Wastewater Treatment and Sewer Systems Quiz

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Questions and Answers

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

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

What type of water enters the sewer system through leaking joints, cracks, or porous walls?

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

What is defined as the presence in water of impurities in such quantity and of such nature as to impair the use of the water for a stated purpose?

  • Industrial wastewater
  • Storm water
  • Inflow
  • Water pollution (correct)

What is runoff resulting from rainfall and snowmelt?

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

What is the optimal range of Dissolved Oxygen (DO) concentration in aerobic processes?

<p>1.5-2.5 mg/L (D)</p> Signup and view all the answers

What can over-aeration, indicated by DO levels of 5-6, lead to in wastewater treatment?

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

What is filamentous bulking in wastewater treatment?

<p>When the biomass in the secondary clarifier is difficult to settle (C)</p> Signup and view all the answers

What are some operational solutions for filamentous bulking in wastewater treatment?

<p>Adjusting F/M ratio, DO levels, dosing with H2O2, and pre-treating wastewater (A)</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 (C)</p> Signup and view all the answers

What are ponds and lagoons used for in wastewater treatment?

<p>Natural purification processes, with aerobic and anaerobic variations (A)</p> Signup and view all the answers

What do attached growth systems like trickling filters utilize for wastewater treatment?

<p>Various organisms (B)</p> Signup and view all the answers

What do trickling filters use as a medium for wastewater treatment?

<p>Packed solid medium (A)</p> Signup and view all the answers

What type of media do biotowers use for wastewater treatment?

<p>Modular synthetic media (D)</p> Signup and view all the answers

What is critical for the success of an activated sludge system in wastewater treatment?

<p>The performance of the final clarifier (B)</p> Signup and view all the answers

What plays a critical role in the treatment of wastewater?

<p>Aeration, nutrient levels, and wastewater characteristics (A)</p> Signup and view all the answers

Which type of biological growth/culture is used in wastewater treatment where microorganisms are suspended in the wastewater either as single cells or as clusters of cells called flocs?

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

What is the main factor affecting the rate of biomass production and food utilization in biological wastewater treatment?

<p>Temperature (B)</p> Signup and view all the answers

Which process is a suspended-culture process with sludge returns and may be completely mixed or a plug-flow process?

<p>Activated sludge process (C)</p> Signup and view all the answers

What does extended aeration result in, in terms of treatment efficiency and biomass production?

<p>High degree of treatment with little biomass produced (C)</p> Signup and view all the answers

What is the purpose of the activated sludge process in wastewater treatment?

<p>Biological treatment of wastewater (B)</p> Signup and view all the answers

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

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

Which factor is not considered to affect the rate of biomass production and food utilization in biological wastewater treatment?

<p>Pressure (D)</p> Signup and view all the answers

What is the main requirement for microorganisms to maintain growth in biological wastewater treatment?

<p>Air (C)</p> Signup and view all the answers

What is carefully controlled in engineered reactors in biological wastewater treatment?

<p>Microorganisms (B)</p> Signup and view all the answers

Which process involves a high degree of treatment with little biomass produced?

<p>Extended aeration (A)</p> Signup and view all the answers

What are the design and operational parameters in the activated sludge process?

<p>F/M ratio, MLSS, MCRT/SRT, and HRT (C)</p> Signup and view all the answers

Which type of process is the activated sludge process?

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

What are the contaminants of concern in wastewater treatment?

<p>Suspended solids, biodegradable organics, pathogens, nutrients, priority pollutants, refractory organics, heavy metals, and dissolved inorganics (D)</p> Signup and view all the answers

What is the primary objective of preliminary wastewater treatment?

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

What is the main focus of secondary wastewater treatment?

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

What is the purpose of tertiary wastewater treatment?

<p>Polishing of secondary effluent, primarily the removal of nutrients, toxic compounds, increased amounts of organic material, suspended solids, ions, and salts (A)</p> Signup and view all the answers

What does solids treatment and disposal involve in wastewater treatment?

<p>The collection, stabilization, and subsequent disposal of the solids removed by other processes (B)</p> Signup and view all the answers

What are the three classifications of wastewater treatment methods?

<p>Physical unit operations, chemical unit processes, and biological unit processes (B)</p> Signup and view all the answers

What is the primary purpose of chemical unit processes in wastewater treatment?

<p>Removal or conversion of contaminants brought about by the addition of chemicals or other chemical reactions (D)</p> Signup and view all the answers

What does biological treatment primarily aim to remove in wastewater?

<p>Biodegradable organic substances and nutrients (D)</p> Signup and view all the answers

What is the main focus of primary wastewater treatment?

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

What does secondary wastewater treatment primarily involve?

<p>Biological treatment by activated sludge, fixed-film reactors, lagoons, and pond systems (C)</p> Signup and view all the answers

What is the primary purpose of grit removal in wastewater treatment?

<p>To remove organic suspended solids from wastewater (B)</p> Signup and view all the answers

What can inefficient screening in wastewater treatment lead to?

<p>H2S production (B)</p> Signup and view all the answers

What is the purpose of flow measurement in wastewater treatment?

<p>To quantify the wastewater flow (B)</p> Signup and view all the answers

What does primary treatment in wastewater treatment involve?

<p>Separation of heavier suspended particles from water (A)</p> Signup and view all the answers

What is the main purpose of comminution in wastewater treatment?

<p>To shred intercepted coarse solids and return them to the wastewater flow (C)</p> Signup and view all the answers

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

<p>To filter out particles from wastewater (B)</p> Signup and view all the answers

What is the primary purpose of disposal of screenings in wastewater treatment?

<p>Grinding for organic wastes (A)</p> Signup and view all the answers

What is the main objective of secondary treatment in wastewater treatment?

<p>Biological conversion of dissolved and colloidal organics into biomass (D)</p> Signup and view all the answers

What is the primary purpose of sedimentation in primary treatment of wastewater?

<p>To separate heavier suspended particles from water (D)</p> Signup and view all the answers

What are the primary factors affecting sedimentation tank efficiency in wastewater treatment?

<p>Cleanliness (D)</p> Signup and view all the answers

What is the main purpose of aerated grit chambers in wastewater treatment?

<p>To minimize digester cleaning frequency (C)</p> Signup and view all the answers

What is the primary purpose of Parshall flumes and Palmer-Bowlus flumes in wastewater treatment?

<p>To quantify the wastewater flow (B)</p> Signup and view all the answers

Flashcards

Sanitary Sewer System

A system that carries domestic and industrial wastewater.

Storm Sewer System

A system designed to collect and transport rainwater runoff.

Combined Sewer System

A sewer system that carries both wastewater and stormwater.

Wastewater Contaminants of Concern

Include substances harmful to the environment or human health found in wastewater.

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Objectives of Wastewater Treatment

The removal of suspended and floatable materials, treatment of biodegradable organics, elimination of pathogenic organisms, removal of toxic compounds and nutrients.

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Preliminary Wastewater Treatment

The initial stage of wastewater treatment that removes large debris.

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Primary Wastewater Treatment

A stage removing suspended solids and organic matter through settling.

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Secondary Wastewater Treatment

Biological processes to remove biodegradable organics and suspended solids.

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Tertiary Wastewater Treatment

Further polishing of wastewater, removing nutrients and toxic compounds.

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Solids Treatment and Disposal

Processes for handling and disposing of solids removed during treatment.

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Physical Unit Operations

Treatment using physical forces like gravity and screening.

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Chemical Unit Processes

Using chemicals to remove or convert contaminants.

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Biological Unit Processes

Using microorganisms to remove organics and nutrients.

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Fine Screens

Used to filter out particles from wastewater and cleaned mechanically .

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Comminution

Shredding coarse solids and returning them to wastewater flow.

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Grit Removal

Separating non-biodegradable grit from organic matter.

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Grit Removal Facilities

Facilities for grit removal like channel, aerated, and vortex types.

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Purpose of Grit Chambers

Protect equipment, reduce deposits, and minimize digester cleaning.

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Flow Measurement

Parshall flumes and Palmer-Bowlus flumes are used.

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Primary Treatment Sedimentation

Separates heavier suspended particles from water, producing clarified effluent and concentrated sludge.

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Secondary Treatment

Biological conversion of dissolved and colloidal organics into biomass.

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Study Notes

Wastewater Treatment and Sewer Systems

  • There are three types of sewer systems: 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.
  • The treatment objectives in wastewater treatment are the removal of suspended and floatable material, treatment of biodegradable organics, elimination of pathogenic organisms, removal of toxic compounds, and removal of nutrients.
  • Wastewater treatment systems are divided into preliminary treatment, primary treatment, secondary treatment, tertiary 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.
  • Primary wastewater treatment involves the removal of 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, and includes biological treatment by activated sludge, fixed-film reactors, lagoons, and pond systems.
  • Tertiary wastewater treatment involves polishing of secondary effluent, primarily the removal of nutrients, toxic compounds, increased amounts of organic material, suspended solids, ions, and salts.
  • Solids treatment and disposal involves the collection, stabilization, and subsequent disposal of the solids removed by other processes.
  • Wastewater treatment methods are classified into physical unit operations, chemical unit processes, and biological unit processes.
  • The physical unit operations include screening, mixing, flocculation, sedimentation, flotation, filtration, and gas transfer.
  • The chemical unit processes involve treatment methods in which the removal or conversion of contaminants is brought about by the addition of chemicals or by other chemical reactions, such as precipitation, adsorption, and disinfection. Biological treatment is used primarily to remove the biodegradable organic substances and nutrients in wastewater.

Wastewater Treatment Processes Overview

  • Fine screens are used to filter out particles from wastewater and should be cleaned mechanically on a continuous basis.
  • Bar screens and manual cleaning methods are employed for fine screen maintenance.
  • Disposal of screenings involves various methods such as hauling to disposal areas, burial, incineration, and grinding for organic wastes.
  • Inefficient screening can lead to septic shock loading and H2S production, with fermentation starting in 2 hours.
  • Comminution involves shredding intercepted coarse solids and returning them to the wastewater flow.
  • Grit removal is essential to separate non-biodegradable grit from organic suspended solids in wastewater.
  • Grit removal facilities include channel-type horizontal-flow grit chambers, aerated grit chambers, and vortex-type grit chambers.
  • Grit chambers serve to protect mechanical equipment from abrasion, reduce pipeline deposits, and minimize digester cleaning frequency.
  • Flow measurement in wastewater treatment commonly utilizes Parshall flumes and Palmer-Bowlus flumes.
  • Primary treatment involves sedimentation to separate heavier suspended particles from water, producing clarified effluent and concentrated sludge.
  • Factors affecting sedimentation tank efficiency include types of solids, age of wastewater, rate of solids flow, cleanliness, and mechanical condition.
  • Secondary treatment typically involves the biological conversion of dissolved and colloidal organics into biomass, which can then be removed by sedimentation.

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