Biological Wastewater Treatment Process Quiz

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Questions and Answers

What defines the trickling filter process in biological wastewater treatment?

Wastewater is treated with chemicals

Air is forced into the wastewater

Microorganisms are introduced into the liquid phase

Wastewater is spread over a fixed bed of media (correct)

What is a key advantage of using a Membrane Bioreactor (MBR) compared to the conventional activated sludge process?

It operates without an aeration tank

It utilizes a polymeric membrane for bio-solids separation (correct)

It requires fewer microorganisms

It employs gravity settling for bio-solid separation

Which substances are NOT significantly removed by biological treatment processes in wastewater management?

BOD5

Heavy metals

Phosphorus (correct)

Soluble solids

What instrument is typically used to measure solids that readily settle in wastewater?

Imhoff cone Signup and view all the answers

What percentage of BOD5 and soluble solids do biological treatment processes typically remove?

85% Signup and view all the answers

What type of technology describes the process where microorganisms degrade soluble organic impurities?

Membrane Bioreactor Signup and view all the answers

Why is it important for the discharged wastewater temperature not to exceed 2-3°C of the ambient temperature?

To maintain the population balance of the aquatic ecosystem Signup and view all the answers

What type of processes are considered tertiary wastewater treatment?

Advanced treatment processes added to existing treatment Signup and view all the answers

What method is used to measure soluble solids in a wastewater sample?

Evaporation and weighing of dry mass Signup and view all the answers

Which of the following is not a characteristic of odor in wastewater treatment?

It is a direct pollutant. Signup and view all the answers

Which disinfection method is NOT typically part of advanced wastewater treatment?

Sedimentation Signup and view all the answers

What is the primary method of bio-solids separation in a conventional activated sludge process?

Gravity settling Signup and view all the answers

Which chemical is commonly used in the COD test for wastewater analysis?

Potassium dichromate (K2Cr2O7) Signup and view all the answers

What does BOD measure in wastewater?

The oxygen required for organic matter oxidation Signup and view all the answers

In the COD testing process, which substance is utilized as a catalyst?

Silver sulfate (Ag2SO4) Signup and view all the answers

What type of organic matter does COD primarily estimate in wastewater?

Total organic matter Signup and view all the answers

What is the primary purpose of flow equalization in wastewater treatment?

To improve treatment process efficiency Signup and view all the answers

Which of the following processes is NOT part of primary treatment in wastewater treatment?

Flocculation Signup and view all the answers

What does the coagulation process primarily involve when treating wastewater?

Destabilization of solid particles Signup and view all the answers

Which chemical is typically utilized to promote coagulation in wastewater treatment?

Aluminum sulfate Signup and view all the answers

What is a key factor to be considered during a jar test in coagulation?

Turbidity of the sample Signup and view all the answers

What is the role of flotation in wastewater treatment?

To separate fine particulates and grease Signup and view all the answers

Which statement about equalization basins is accurate?

They balance wastewater parameters over time. Signup and view all the answers

In the context of coagulation and flocculation, what must be done to enhance alkalinity prior to treatment?

Add sodium carbonate if needed Signup and view all the answers

What is a key reason for considering the footprint area in selecting wastewater treatment technology?

Land acquisition is becoming increasingly difficult and expensive. Signup and view all the answers

Why is operational cost an important criterion in selecting wastewater treatment technology?

It influences the total costs of running the project over time. Signup and view all the answers

What must be considered regarding the capability of wastewater treatment technology?

It must accommodate potential future increases in wastewater production. Signup and view all the answers

What is the primary purpose of diluting wastewater samples in the BOD test?

To provide essential minerals for microbial activities Signup and view all the answers

Which of the following is NOT a selection criterion for wastewater treatment technology?

Initial construction time Signup and view all the answers

Which type of bacteria is required to decompose organic materials in the presence of oxygen?

Aerobic bacteria Signup and view all the answers

What is measured in a BOD test after a five-day period?

Biochemical Oxygen Demand (BOD5) Signup and view all the answers

How does the increasing population in municipal areas affect the selection of wastewater treatment technology?

It necessitates technologies that can handle increased wastewater production. Signup and view all the answers

What process does Total Organic Carbon (TOC) measurement primarily involve?

Combustion of organic matter to CO2 and water Signup and view all the answers

What do anaerobic bacteria utilize for energy in their metabolic processes?

Sulfates and nitrates Signup and view all the answers

In primary treatment processes, what is the main goal of physicochemical processes in wastewater treatment?

To remove particulates and coarse materials from the wastewater stream Signup and view all the answers

Which of the following contaminants are sources of nitrogen and phosphorus in wastewater?

Artificial fertilizers and synthetic detergents Signup and view all the answers

What is a significant drawback of anaerobic bacteria compared to aerobic bacteria in wastewater treatment?

Their metabolic processes are significantly reduced Signup and view all the answers

What is a key advantage of Dissolved Air Flotation (DAF) in food wastewater treatment?

It reduces oil, grease, and suspended particulates Signup and view all the answers

What is the primary mechanism by which sedimentation removes solids from wastewater?

Gravity acting on solids with higher density Signup and view all the answers

Which of the following is a disadvantage of using Dissolved Air Flotation (DAF)?

It may incur high capital and operating costs Signup and view all the answers

What percentage of biochemical oxygen demand (BOD5) removal is typically achieved during primary sedimentation?

25 to 50% Signup and view all the answers

In the context of food wastewater treatment, what floating material is a common candidate for flotation processes?

Oil and grease Signup and view all the answers

Which substance is NOT effectively removed during primary sedimentation?

Soluble biochemical oxygen demand Signup and view all the answers

How does the Dissolved Air Flotation (DAF) system facilitate the removal of solids from wastewater?

By pressurizing air in closed tanks to form bubbles Signup and view all the answers

During primary treatment of wastewater, which item is least likely to be removed?

Dissolved nutrients such as phosphorus Signup and view all the answers

Study Notes

Wastewater Treatment Overview

Wastewater is a significant environmental concern in food processing and manufacturing.
The majority of wastewater volume originates from cleaning operations throughout processing and transportation.
Treatment cost depends on wastewater characteristics: daily discharge volume and strength.

Wastewater Treatment Process

Collection System/Pump Station: Raw sewage enters the treatment plant.
Headworks: Screens filter out large objects. Grit and debris are removed and taken to landfills.
Primary Treatment: Solids settle at the bottom of tanks; fats, oils and grease rise to the top.
Liquid Stream: This includes Headworks, Primary Clarifier, Bioreactor, Secondary Clarifier, Disk Filter, UV Disinfection, and Back to the River.
Solid Stream: This involves Gravity Thickener, Fermenter, Digester, Biosolids Settling, Biosolids Transport off-site, Biosolids Beneficial Land Application, and Composting.

Physicochemical Wastewater Treatment Processes

Wastewater characteristics significantly impact treatment costs.
Two key characteristics influencing cost are daily discharge volume and relative strength.
The decision-making process is both technical and economic.

Characteristics of Wastewaters in Agriculture and Food Processing

Wastewater composition varies widely between food processing facilities.
No two facilities have identical wastewater characteristics even with similar processing capabilities.

Characteristics of Wastewaters (Data)

Specific wastewater characteristics for various industry groups like meat, dairy, canned goods, grain, and others are presented in detailed tables.
Specific figures for the volumes and organic loading are provided for different industry groups

Wastewater Treatment Strategies

Treatment strategies vary depending on the industry type (e.g. vegetables, fruits, fishery, poultry, dairy).
The tables provide summary of sources of wastewater streams and relevant treatment strategies for different food and agricultural operations

Parameters for Physicochemical Treatment of Wastewater

pH: A measure of acidity, indicating growth conditions for microorganisms used in biological treatment.
pH values vary with wastewater sources, environmental conditions and storage duration, impacting chemical substance and biological matter decomposition.
Solids content: Suspended solids (not dissolvable) and dissolved solids differ in their impact on water bodies (settling or floating) and are measured using tools like the Imhoff cone.
Soluble Solids: Measured using evaporation and subsequent weighing method.
Temperature: Discharged wastewater temperature should not exceed the ambient temperature range of 2 -3 degrees Celcius to balance aquatic ecosystem population.
Odor: Prolonged exposure to wastewater odors may have adverse effects on wastewater treatment plant workers and surrounding residents.
The tables provide the characteristic data for different industry types.

Wastewater Parameters for Biological Treatment

BOD and COD: Indicators of the organic matter content in wastewater.
COD (Chemical Oxygen Demand): Estimating organic matter using chemical oxidation methods (Potassium permanganate or Potassium dichromate).
BOD (Biochemical Oxygen Demand): Measuring the oxygen consumed via aerobic process/metabolism of microorganisms. Used for determining the organic matter extent.
BOD Test: Methodology for wastewater analysis to determine BOD5. It involves diluting waste sample with a nutrient solution, keeping it at a constant temperature for 5 days, and measuring dissolved oxygen at the start and end of the duration.

Total Organic Carbon

TOC (Total Organic Carbon): A method based on combusting organic matters in a wastewater sample to obtain CO2 and Water, then the gases are measured using an Infrared analyzer.

Nitrogen and Phosphorus

Sources of nitrogen and phosphorus in food and agricultural wastewater include artificial fertilizers, synthetic detergents and metabolic compounds from protein materials.

Basic Microbiology in Wastewater Treatment

Aerobic Bacteria: Require oxygen to decompose organic materials, producing carbon dioxide, water and energy.
Anaerobic Bacteria: Thrive without oxygen; use compounds like sulfates and nitrates to create energy and a much longer metabolism duration.

Physicochemical Wastewater Treatment Processes (Primary Treatment)

Physical removal of suspended solids involves various processes like screening, grit removal, and sedimentation in tanks.
These processes are essential in pre-treating the wastewater for further treatment stages.

Physicochemical Wastewater Treatment Processes (Equalization Basins)

A method to balance process parameters flow rate, strength, pH, and temperature of wastewater streams.
It stabilizes wastewater conditions over a 24-hr period which is important to prepare water for biological and chemical processes.
Important to address the irregular variations in wastewater characteristics.

Physicochemical Wastewater Treatment Processes (Coagulation and Flocculation)

Coagulation: adding chemicals to wastewater to break down suspended matter.
Flocculation: the process of particles clumping together. Enmeshment of colloids is mainly due to the precipitation of insoluble Fe(OH)3 or Al(OH)3 when coagulants like FeCl3 or AlCl3 are used in wastewater.
These steps reduce the number of suspended particles in water that settle poorly for other treatment processes.

Physicochemical Wastewater Treatment Processes (Jar Test)

A laboratory determination of the most appropriate reagent dosage to coagulate wastewater using different chemicals.

Physicochemical Wastewater Treatment Processes (Flotation)

A process to remove oil and grease, fine particles, and other suspended light materials from waste water. Especially useful in food & processing waste waters and materials that do not settle well with other treatment methods.

Physicochemical Wastewater Treatment Processes (Dissolved Air Flotation)

Using air to carry suspended solids to the surface, and removing by skimmer.

Physicochemical Wastewater Treatment Processes (Sedimentation or Clarification)

Removal of suspended solids from wastewater via sedimentation by the action of gravity.
Removal of solids via sedimentation tanks is a crucial process for primary treatment to treat heavy metals and organic solids for further treatment.

Results of Primary Treatment

Removal of biochemical oxygen demand (BOD), total suspended solids, oil & grease, and some organic nitrogen & phosphorus, and heavy metals.

Biological Wastewater Treatment Processes

Secondary Treatment: Aims to remove dissolved and colloidal organic matter after primary treatment.
Aerobic Processes: Utilizing aerobic microorganisms using oxygen to degrade organic waste, including processes like aerobic lagoons, activated sludge treatment & conventional activated sludge process.
Anaerobic Processes: Using anaerobic organisms without oxygen. Useful for high-strength wastewater but needs high bacterial concentration and longer exposure time.
Membrane Bioreactor (MBR): Combining the biological treatment with membrane filtration, typically for high-strength wastewater.
Rotating Biological Contactor (RBC): A biological treatment process using rotating discs containing microorganisms to degrade organic pollutants in wastewater.
Trickling Filter: Wastes are distributed using a fixed media of rocks, gravel, plastic substrate and wastewater flows downwards to allow microorganisms to consume pollutants.
Aerobic Lagoons: Natural treatment method using microbial communities (bacteria and algae) for removing organic pollutants.

Tertiary Wastewater Treatment

Additional unit operations after primary and secondary treatment for specific removal requirements.
Processes such as disinfection (chlorination, ozone, UV) is common.

Selection of Wastewater Treatment Technology

Footprint (land area): A crucial factor in technology selection because land is usually expensive.
Operational Cost: Long-term running costs of the treatment technology, which must be considered alongside initial cost.
Capability of Further Extension: The technology needs to be adaptable to future expansion needs as population and wastewater generation trends may change.

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Description

Test your knowledge on biological wastewater treatment processes, including trickling filters, Membrane Bioreactors, and the removal efficiency of biological treatments. This quiz covers key concepts, instruments used, and characteristics of wastewater management techniques.