Wastewater Treatment Processes and Components, Exams of Advanced Education

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How much of the population is on individual sewage disposal systems? - Correct Answer-1/3 of population What is the time limit for wastewater traveling to the waste water facility? Why? - Correct Answer-2 days Fresh wastewater is easily treated and highly putrid Septic wastewater requires more treatment, cost, and energy How fast does wastewater move through sewer pipes? - Correct Answer-2 feet per second Any slower and water tends to decay faster and become septic How far are manholes placed apart? Why? - Correct Answer-300 - 500 feet away, to check and monitor sewage leaks How much water does an average American use per day? - Correct Answer-50 - 100 gallons per day What time is sewage at its heaviest flow through the wastewater treatment plant? - Correct Answer-3 - 9 PM What are the 5 types of wastewater sources? - Correct Answer-1) Domestic Waste

2. Industrial Waste
3. Ground Water
4. Storm Drain Runoff
5. Municipal Waste Domestic Water - Correct Answer-Sanitary waste out of a home, general businesses, and institution Sewage from toilets, water from showers/baths, sink/kitchen Industrial Waste - Correct Answer-Waste discharged from a manufacturing plant Cooling water, canning, meat processors, hospitals, restaurants, refineries, plating process, and others that require treatment before dumping into common sewer system

Ground Water - Correct Answer-Can infiltrate the sewer system by the cracks in the sewer pipe Storm Drain Runoff - Correct Answer-Waste that is generated from rainstorm sources and ground water runoffs Infiltration can come from leaky pipes or high water table sources via an open drain National Pollution Discharge Elimination System (NPDES) - Correct Answer-Federal law Prohibits draining of any type of wastewater onto public streets Municipal Waste - Correct Answer-Sewage or wastewater that is going to be treated in a municipal waste water plant (domestic and plant sources) Leachate - Correct Answer-Liquid waste coming out of the ground at refuse landfill; wastewater at a landfill Can be from rain water seeping into the landfill or intentional dumping of liquid waste Can also be applied when wastewater (leachate) enters a system (such as a sewer system from a crack in the sewer pipe) or an opening introducing foreign waste into the wastewater system What is the breakdown of fresh (raw) wastewater? - Correct Answer-99.8% is liquid (water) 0.2% is solids What is the breakdown of the solids in fresh (raw) wastewater? - Correct Answer-50% is considered putrescible (organically degradable) What happens when putrescible waste in wastewater is not treated? - Correct Answer- Produce foul odors If it enters a lake untreated, a nitrification process can develop, which causes algal that severely deplete the oxygen of the lake water Gray Water - Correct Answer-Fresh wastewater In clear flask, it looks light gray, slightly turbid, and has a musty but not offensive odor Dissolved oxygen level and biological activity should not be high Septic Water - Correct Answer-Highly putrid, often black colored wastewater

Rotten egg odor (hydrogen sulfide) Septic - without air, wastewater is undergoing anaerobic decomposition Putrescible Waste - Correct Answer-Waste that bacteria can spoil or degrade Sewage - Correct Answer-Water that contains putrescible or chemical matter Dead organic or plant chemical matter Industrial Wastewater - Correct Answer-Potable water that was used as a cooling fluid in industrial processes What is the pH range of wastewater? - Correct Answer-6.0 - 0. 6.5 - 8.5 average when wastewater enters treatment plant What is the units for wastewater concentrations? - Correct Answer-mg/L = ppm parts per billion = ppb Why are nitrogen and phosphorous levels in wastewater treatment plants important? - Correct Answer-Compounds help provide the necessary life giving nitrogen for the bacteria and plants to thrive and grow What can sulfates, grease, and oils in sufficient amounts possibly cause at a wastewater treatment plant? - Correct Answer-Explosion or fire Solids in Wastewater - Correct Answer-1) Organic - carbon, oxygen, hydrogen molecules

2. Inorganic - minerals, salts, sand, gravel, dirt, silt
3. Suspended Solids - visible suspension removed by sedimentation or filtration (settles within 1 hour from gravity, 75% organic/25% inorganic)
4. Colloidal - minute solid matter stays in suspension in the wastewater
5. Salts - Dissolved solids in wastewater What are the temperature types of bacteria? - Correct Answer-1) Hot Zone (Thermophillic Zone)
6. Medium Zone (Mesophillic Zone)
7. Cold Zone (Psychrophillic) Thermophillic Zone - Correct Answer-'Hot Zone'

Thermophillic bacteria thrive in warm to hot environments 113°F - 158°F Thermoduric - Correct Answer-Heat resistant bacteria Mesophillic Zone - Correct Answer-'Medium Zone' Mesophillic bacteria thrive in cool to warm environments 59°F - 112°F Psychrophillic Zone - Correct Answer-'Cold Zone' Psychrophillic bacteria thrive in cold to cool environments 35°F - 50°F Anoxia - Correct Answer-Water source is depleted of dissolved oxygen Below 4 mg/L, cannot support fish life Can be reversed with aeration or promotion of reasonable algae growth What two pathogenic organisms are known to survive up to 2 weeks in wastewater? - Correct Answer-Typhoid Dysentery What can survive the sludge digestion process? - Correct Answer-Hookworm eggs Surface Disposal - Correct Answer-Liquid drained onto land by surface disposal pipes Tile Fields Disposal - Correct Answer-A shallow in-ground collection of pipes or tiles that is segmented loosely in the ground to allow the treated water to percolate into the earth Fails in high ground water situations Subsurface Disposal - Correct Answer-Leach lines are laid 2 to 5 feet underground and release treated wastewater underground through percolated pipes Leach lines are 4 in thick pipes loosely connected to deliver treated wastewater Dilution Disposal - Correct Answer-If a large body of water is nearby (rivers, lakes, streams), may be used to dispose treated wastewater What is wastewater that is being treated called? - Correct Answer-Effluent

Absorption - Correct Answer-Something is taken INTO the material; 'ab' for ABsorb Adsorption - Correct Answer-Something that adheres to the material; 'ad' for ADhere How much does one gallon of water weigh? - Correct Answer-8.34 lbs What is the volume of one cubic feet of water? - Correct Answer-7.48 gallons What are the steps of the wastewater treatment process? - Correct Answer-1) Preliminary Treatment

2. Primary Treatment
3. Secondary Treatment
4. Tertiary Treatment Preliminary Treatment - Correct Answer-Bar Screening - removal of large debris/objects Grit Removal - removal of sand/gravel Pre-Aeration - freshens water by introducing oxygen, helps remove oil/floating scum Flow Meter - measures rate of flow Chlorine - used if wastewater is highly active or reactive Primary Treatment - Correct Answer-Sedimentation - also known as clarification tanks, removes solids that can settle and other floating debris Secondary Treatment - Correct Answer-Collect raw sludge and locate to another treatment site or area for sludge digestion Biological, chemical, and physical treatment to removal solids and dissolved solids of the wastewater Tertiary Treatment - Correct Answer-Final step, makes water physically attractive Filtration - use of filters to remove particles, colors, odors, turbidity Disinfection - treating wastewater to destroy pathogenic bacteria before leaving treatment plant Biological Treatment Process - Correct Answer-Aerobic Treatment Process Anaerobic Treatment Process Aerobic Treatment Process - Correct Answer-1) Activated sludge
5. Trickling filter

3. Oxidation ponds
4. Composting
5. Subsurface disposal field Anaerobic Treatment Process - Correct Answer-1) Sludge digestion
6. Methane production
7. Septic tanks
8. Composting Bar Screens (Preliminary Treatment) - Correct Answer-Metal grate with thick straining bars, spaced out 1 to 3 inches apart Clogged easily, must be cleaned and changed frequently Communitor - Correct Answer-Heavy duty garbage disposal that grinds up the paper and rags that get filtered out by bar screens Transported to landfills for disposal Grit Chambers (Preliminary Treatment) - Correct Answer-Chambers that slow down the velocity of the incoming wastewater, permitting the heavier solids to settle out quickly Removes quickly setting solids (sand, dirt, gravel, stone) 2 chambers with a special screening system, 1 minute retention time and automatic cleaning system Scum, Foam, and Oil Removal (Primary Treatment) - Correct Answer-Scum skimmers skim the top of the tanks where the wastewater effluent flows Skimmers have paddles which move along the top layer of the tank as the scum and other floating material collect Collected material is routed to another holding tank, likely treated Sedimentation Tanks/Clarification Tanks (Primary Treatment) - Correct Answer-Used to settle out smaller sized suspended particles from wastewater Velocity of flowing water dictates the settling characteristics of the solid particles Separates organic and inorganic solids Retention time is 1-2 hours Chemical flocculants/polymers can be added to increase flocculation of fine particulates and aid in the sedimentation process

Sludge - Correct Answer-Solids collected from sedimentation tanks Chemical Feed Units for Flocculation or Coagulation (Primary Treatment) - Correct Answer-Alum Electrolytic Polymers Bentonite Chemical flocculation is the physical process to clump up the harder to settle smaller solids, 'sludge' Aeration Tanks (Primary Treatment) - Correct Answer-Oxygenate wastewater to promote aerobic bacteria to grow, attract other bacteria, clump together, and settle out by gravity What are the three qualities that wastewater is judged by? - Correct Answer-1) Biological Oxygen Demand (BOD)

2. Total Solids
3. Volatile Solids What is the BOD before and after treatment? - Correct Answer-Before: 200 mg/L After: 120 mg/L What is the Total Solids before and after treatment? - Correct Answer-Before: 800 mg/L After: 600 mg/L What is the Volatile Solids before and after treatment? - Correct Answer-Before: 440 mg/L After: 300 mg/L Biochemical Oxygen Demand (BOD) - Correct Answer-Oxidation reduction potential of bacteria The BOD Test measures the dissolved oxygen level of wastewater that is used up by a group of bacteria or microorganisms within the process of aerobic oxidation The BOD Test - Correct Answer-Determines amount of dissolved oxygen needed by aerobic biological organisms in a body of water to break down organic material present in a given water sample at certain temperature over a specific time period Dissolved Oxygen (DO) - Correct Answer-Dissolved gaseous oxygen in water Water tends to hold more dissolved oxygen better at cold temperatures

What is the primary function of filtration during secondary treatment of wastewater? - Correct Answer-1) Provide more oxygen to the filtered medium

2. Provide more surface area for aerobic bacteria to live on and work on the waste matters Intermittent Sand Filter (Secondary Treatment) - Correct Answer-Sand bed inside a shallow trough of approximately 30 inches in depth Purpose is for the aerobic bacteria inside the filter to work and to oxidize the bio-matter Good for small treatment facilities What are the types of filters used during secondary treatment? - Correct Answer-1) Intermittent Sand Filter
3. Slow Sand Filter
4. Rapid Sand Filter
5. Trickling Filter or Bio-Filter Trickling Filter or Bio-Filter (Secondary Treatment) - Correct Answer-Used in many larger community systems Consists of a bed of rocks (or plastic); center of tank has a large rotary arm to pump wastewater through and distribute it through multiple spray heads Aerobic bacteria that live on the filter media consume and oxidize the wastes; constantly running Filters 10 to 30 million gallons/acre feet/per day Aeration Tanks (Secondary Treatment) - Correct Answer-Holding tanks where oxygen is added to wastewater to activate the aerobic bacteria Putrescible nutrients start to clump together (flocculation) and sink to the bottom of the tank (raw sludge) Usually maintained to up to 4 hours Why is reclaimed water only used for irrigation purposes and not for consumption? - Correct Answer-Although better physical quality than that of tap water, treatment process does not effectively eliminate viruses Stabilization Pond (Lagoonization) - Correct Answer-Pond of a large volume of water (3- 5 feet in depth) to promote aerobic activity and purify the water source Shallow depths promote temperature mixing and aeration of water

Nitrogen and phosphorous are present promoting algae growth with the available sunlight and oxygen 45-60 days before being used Sludge - Correct Answer-The solid portion of wastewater Accounts for 0.2% of total wastewater, but 50% ratio of putrescible matter Three Types:

1. Raw Sludge
2. Activated Sludge
3. Digested Sludge Raw Sludge - Correct Answer-Fresh sewage solids which putrefaction has not taken place Collected from sedimentation and aeration tanks Most biologically reactive and putrefaction starts immediately given proper environment Must be handled quickly/efficiently Activated Sludge - Correct Answer-Sludge that contains bacterial agents which can digest the sludge into inorganic materials "Mixed Liquor" Biologically reactive and can degrade rapidly Digested Sludge - Correct Answer-Product of total digestion (anaerobic) processes Most stable Organics have been oxidized by anaerobic microorganisms through anaerobic digestion Resembles used coffee grounds and can be added to soils as a conditioning source What are the types of raw sludge treatment processes? - Correct Answer-1) Digesters
4. Sludge in the Acidic State Digesters - Correct Answer-Conducted in huge tanks, oxygen is removed creating an anaerobic environment Heat is added so anaerobic bacteria can react to the sludge to its highest efficiency

Putrescible matter is broken down into oxygen, carbon dioxide, water, nitrates, phosphates Acid forming anaerobic bacteria is introduced, converts the organic compounds into acetic acid and other low concentration acids As more raw sludge is digested, the concentration of acid rises, eventually killing off the acid forming bacteria Sludge in the Acidic State - Correct Answer-Gas forming anaerobic bacteria introduced and begin to digest the low acids Byproducts of gases (methane, carbon dioxide, hydrogen sulfide gas); "healthy state" Turns sludge into humus Healthy State of Digester - Correct Answer-65% Methane 34% Carbon Dioxide <1% Hydrogen Sulfide Gas "Sick State" otherwise Humus - Correct Answer-Digested sludge that is considered an excellent soil conditioner Alternative Disposal Systems - Correct Answer-1) Pit Privy

2. Cesspools
3. Septic Tanks Pit Privy - Correct Answer-Simple hole dug in ground for waste disposal, most primitive method for waste disposal Used in emergencies Cesspools - Correct Answer-Also called leaching pools, pits into which concrete, brick or cement block walls have been placed; wastewater flows into the cesspool and drains or "percolates" into the soil through perforated walls Sewage is not treated Illegal to build but still legal to own Similar in design to a well but the waste water is designed to seep into the ground from the cesspool vault

Why do cesspools overflow? - Correct Answer-1) Too much liquid leaches out and saturate the surrounding ground

2. Solids form at the bottom of the cesspool and saturate the ground with sludge
3. Cesspool solids should be pumped out regularly (couple times a year) Seepage Pit - Correct Answer-Cesspool but with treated wastewater Pipe Colors - Correct Answer-Purple - reclaimed (recycled) water Yellow - steam, gas, or oil Green - sewer Blue - potable water Red - electrical White - leach line What does a purple pipe represent? - Correct Answer-Reclaimed (recycled) water What does a yellow pipe represent? - Correct Answer-Steam, gas, or oil What does a green pipe represent? - Correct Answer-Sewer What does a blue pipe represent? - Correct Answer-Potable water What does a red pipe represent? - Correct Answer-Electrical What does a white pipe represent? - Correct Answer-Leach lines Plain Sedimentation - Correct Answer-Settling or storage of water, such as would take place in a reservoir, lake, or basin, without the aid of chemicals Microstraining - Correct Answer-Filtering surface may consist of very finely woven fabrics of stainless steel, nylon, bronze, or other resistant material Designed to reduce the suspended solids, insects, and nuisance organisms (including plankton) Alum - Correct Answer-Aluminum Sulfate Coagulant to flocculate solids in water Floc - Correct Answer-Flocculent mass Formation of particles in water after a coagulant is added

What are some other coagulants used aside from alum? - Correct Answer-Copperas (ferrous sulfate) Ferric sulfate Ferric chloride Sodium aluminate Pulverized limestone Bentonite Clays What are some coagulant aids to improve coagulation and floc strength? - Correct Answer-Sodium silicate Polyelectrolytes Polymers What is used as a microflocculant? - Correct Answer-Ozone, reduces need for less alum What does iron in excess mean? - Correct Answer-0.3 to 0.5 mg/L Stains laundry and plumbing fixtures and cause water to appear rusty Not harmful What does manganese in excess mean? - Correct Answer-Stains laundry and plumbing fixtures, brown or black Not harmful Volatile Organic Chemicals (VOCs) - Correct Answer-Organic compounds that easily become vapors or gases Synthetic Organic Chemicals (SOCs) - Correct Answer-Organic (carbon based) chemicals that are less volatile than VOCs SOCs are used as pesticides, defoliants, fuel additives and as ingredients for other organic compunds They are all man made and do not naturally occur in the environment Granulated Activated Carbon (GAC) - Correct Answer-Proven option to remove certain chemicals, particularly organic chemicals, from water GAC filters also can be used to remove chemicals that give objectionable odors or tastes to water such as hydrogen sulfide (rotten eggs odor) or chlorine

Cross-Connection - Correct Answer-Physical connection between a potable water system and a nonpotable water supply Backpressure - Correct Answer-Pressure in the nonpotable water system exceeds that in the potable water system Backsiphonage - Correct Answer-Pressure in the potable water system becomes less than that in the nonpotable water system due to a vacuum or reduced pressure developing in the potable water system