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92 Cards in this Set
- Front
- Back
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What is combined chlorine?
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The sum of the chlorine species composed of free chlorines, and ammonia, including monochloramine, dichloramine, and trichloramine.
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Define 'Breakpoint Chlorination'
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Addition of chlorine to water or wastewater until the chlorine demand has been satisfied.
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Define 'Breakout Chlorine'
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A point at which chlorine leaves solution as a gas because the chlorine feed rate is too high. The solution is saturated and cannot dissolve anymore chlorine.
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What is combined available chlorine?
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The total chlorine present as a chloramine or other derivatives, that present in water and is still available for disinfection and oxidation of organic matter.
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What are Chloramines?
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Compounds formed by reaction of hydrochlorous acid (for aqueous chlorine) with ammonia.
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What are the microorganisms that remove ammonia nitrogen?
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Nitrobactors
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How many lbs of bio-solids are generated by an activated sludge plant per lb of BOD?
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.5-.75 lbs
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Heavy brown foam is typically caused by which bacteria?
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Nocardia
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How many lbs of chlorine per day per 1000 lbs MLSS under aeration are needed to control nocardia?
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2-4 lbs.
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Five to six filamentous filaments per activated sludge floc particle produce a strong floc particle. True or False?
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True
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Microscopic examination of activated sludge reveals a few free swimmers and amebias, not much else. This is a indication of what?
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A young sludge age.
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For the most part, the bacteria that inhibit the activated sludge process are?
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Facultative heterotrophic soil organisms that can live with or without elemental oxygen.
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In an activated sludge system, the process of nitrification is?
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Where ammonia is biologically converted into nitrate primarily through aerobic process.
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At 15 degrees C, MCRT should take how many days to assure effluent is nitrified?
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20 days
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A typical detention time for an extended aeration plant is how many hours?
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24 hrs
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What is the typical test performed to control the solids in the aeration tank?
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Mixed Liquor Suspended Solids
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What is flocculation?
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The gathering of fine particles after coagulation to form larger particles, by gentle mixture.
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How long is waste water aerated for in a preareation treatment process?
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10-45 min.
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What is bulking?
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Clouds of billowing sludge that occur in the secondary clarifier when the sludge does not settle properly. Usually caused by filamentous bacteria or bound water.
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In general the solids content in waste water is?
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.1%
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In general what is the percent of suspended solids in the amount of total solids?
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30%
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What is the general amount of dissolved solids in total solids?
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70%
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What chemical is added to neutralize residual chlorine?
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Sulphur dioxide ( SO2)
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Contact basins are designed to provide approximately how many minutes of contact time?
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20-30 min
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Ponds that treat raw waste water are called?
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Raw waste water lagoons or waste stabilization ponds
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Advanced methods of waste treatment include what?
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Coagulation-sedimentation; absorption; electrodyalisis; reverse osmosis; chemical oxidation; and polymers.
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Advanced methods are used to?
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Reduce nutrient content. (Nitrate and phosphate)
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Aerobic ponds are?
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3-4 ft deep and have DO thru out their entire depth.
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Anaerobic ponds are?
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Ponds with no DO throughout their depth.
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How are scum blankets controlled?
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Mixing of digester contents and burning or burying skimming a instead of pumping them to the digester.
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What is digester gas made up of?
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70% methane and 30% carbon dioxide.
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When is sludge considered properly digested?
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When 50% of organic matter has been destroyed.
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How long does it take for sludge to be properly digested?
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Approximately 30 days at 95 degrees F (35 degrees C).
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How long does it take waste to reach the end of the aeration tank?
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4-8 hrs.
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Effluent from the aeration tank is called what?
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Mixed liquor
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What is the efficiency of the trickling filter?
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Removing 70-85% BOD causing waste and suspended solids.
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2 hrs detention time in the primary clarifier will remove __ suspended solids?
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60%. Reducing BOD 30%.
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What is the flow in the primary tank?
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0.03 ft per sec
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What does preliminary treatment consist of?
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Screening, sand and grit removal.
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What are evaporation ponds used for?
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Dispose of effluents into the atmosphere.
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What is Alkalinity?
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The capacity of water or waste water to neutralize acids.
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What is a buffer?
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A solution or liquid whose chemical makeup neutralize acids or bases.
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What is head?
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The vertical distance , height or energy of water above a point.
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What is head loss?
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Indirect measure of loss of energy or pressure.
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Aerated grit channels have a detention time of?
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3-5 min. 3 min at peak flows.
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How often should channels with chain and flight collectors be inspected? Bearings and anchor bolts?
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Chains and flight collectors twice a year. Bearings and anchor bolts every time the channel is dewatered.
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What does a mechanical seal do?
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Prevents wastewater from reaching and damaging bearings.
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Stalk ciliates indicate a young sludge. True or False?
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False
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Filamentous organisms in an over abundance in the final clarifier may lead to what?
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Bulking of sludge
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What is MPN?
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Most Probable Number of coliform group organisms per unit of sample of water.
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What are coagulants?
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Chemicals that cause fine particles to clump together (floc) into larger particles, making it easier to skim or settle and remove.
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An Imhoff cone measures what?
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Volume of settable solids
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Septic conditions are caused by?
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Anaerobic bacteria
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What are colloids?
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Very small particles, finely divided solids that remain dispersed in liquid for a long time, due to their small size and electrical charge. They do not settle well.
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What is the most common reason for waste water to contain large amounts of sand, gravel and grit?
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Storm events
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Combined wastewater is defined as?
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Storm and sanitary lines combined.
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Which organisms would most likely be associated with poor treatment or old biomass?
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Amoebas
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Which organisms would likely be associated with very clear plant effluent, low BOD, and low suspended solids?
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Stalk ciliates
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Aerobic bacteria will live in an environment that contains only?
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Oxygen
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Anaerobic bacteria will only live in an environment that completely lacks?
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Free or dissolved oxygen
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BOD has a test time of?
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5 days
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What is the flow in the grit channel?
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1 ft per sec
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What ponds are used after primary treatment?
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Oxidation ponds
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What is photosynthesis?
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A process in which organisms , with the aid of chlorophyll, convert carbon dioxide and inorganic substances into oxygen and additional plant material, using sunlight for energy. All plants grow by this.
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What is the most common flow measuring device?
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Pashall flume
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What is the flow in sewer pipes, or collection lines?
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2 ft per sec
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What does NPDES stand for?
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National Pollutant Discharge Elimination System
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What are the two types of bacteria in a digester?
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Acid formers and gas formers.
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Why are digesters mixed?
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Bring food and organisms together, provide a uniform temp and prevent formation of scum blanket.
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What is detritus?
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Grit
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What is a limit switch?
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Device that regulates or controls the travel distance of a chain or cable.
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When bars are placed 3/8-2in apart they are called?
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Bar screens
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When bars are placed 3-4 in apart they are called?
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Racks
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What is the reason for preareation?
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To freshen the wastewater and separate oils and grease.
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What happens if the DO in the aeration tank is to low?
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Filamentous organisms will thrive and sludge floc will not settle in the secondary clarifier.
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What is the activated sludge process?
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Oxidation and removal of soluble or suspended solids or material that were not removed by previous treatment. Conversion of dissolved and suspended material to settable solids is the main objective.
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What two methods are used to supply air to the bacteria?
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Mechanical and diffused aeration
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What are the three most common types of package plants?
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Extended aeration, contact stabilization, and complete mix.
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What is a floc mass made up of?
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Bacteria, fungi, yeast, Protozoa, and worms.
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What happens when DO is too high in the aeration basin?
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Pin floc will develop and not be roved from the secondary clarifier.
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What is activated sludge?
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Sludge particles in raw or settled wastewater producing growth of organisms in the aeration basin in the presence of DO. And is teaming with bacteria, fungi and Protozoa.
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What is DPD?
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A method for measuring the chlorine residual in water. A titration comparing color with color standards. DPD= N,N-diethyl-P-phenylene-diamine.
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What is free chlorine?
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A chlorine in a gaseous or liquid form. Free chlorine combines with water to form hypochlorus and hydrochloric acids. Usually combines with ammonia or nitrogen or other organic compounds to form combined chlorine compounds.
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What is a reagent?
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A pure chemical substance that is used to make a new product or used in chemical tests to measure, detect, or examine other substances.
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What is an air gap?
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An open vertical space between drinking water supply and the point of use in waste water treatment plant. Prevents the contamination of drinking water by back syphoning.
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Why should sulphur dioxide be kept away from moisture?
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Because it produced sulfuric acid when exposed to moisture, (H2SO4)
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What is the most popular chemical method for dechlorinaton?
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Sulphur dioxide
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Why is sulphur dioxide a popular method for dechlorination?
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It uses the same chlorination equipment and makes extensive training of operators unnecessary.
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Is sulphur dioxide heavier or lighter than air?
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Heavier than air.
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Which emergency kit would you use for a 100-150 lb chlorine cylinder? A, B, or C?
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Kit A
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Which emergency kit would you use on a tanker car or tank trucks of chlorine? A, B, or C?
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Kit C
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Which emergency kit would you use on a 1 ton tank of chlorine? A,B, or C?
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Kit B
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