TX CLASS C WASTEWATER TREATMENT LICENSE QUESTIONS AND CORRECT ANSWERS VERIFIED LATEST 2023, Exams of Waste Management

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TX CLASS C WASTEWATER TREATMENT

LICENSE QUESTIONS AND CORRECT

ANSWERS VERIFIED LATEST 2023- 2024

GRADE A +

Preliminary Treatment - ANSWER>>>the 1st stage of sewage treatment where large debris, such as sticks, grit, and rags pas through a screen followed by a grit chamber, where the flow of water is slowed enough to allow for sedimentation. What stage of treatment is grit removal usually accomplished in? - ANSWER>>>preliminary treatment Rotating Biological Contactor - ANSWER>>>a type of biological secondary treatment process How are protozoa (cause of amoebic dysentery) destroyed? - ANSWER>>>disinfection Other than stream discharge, what are other ways to dispose of effluent wastewater? - ANSWER>>>aquifer recharge, evaporation in a pond, and application to farm land by irrigation Clean Water Act - ANSWER>>>gives the basic structure for regulating discharges of pollutants into the waters of the United States

Texas Water Code - ANSWER>>>gives the TCEQ jurisdiction over discharges of waste into or adjacent to water in the state Who reviews plans and specifications for new construction projects before construction begins? - ANSWER>>>TCEQ Water quality fees may be as high as ____________ per permit? - ANSWER>>>$115, Administrative penalties, up to __________ per day for each violation, may be assessed against any violator. - ANSWER>>>$25, Every city with more than ________ in population needs to establish a water pollution control program and hire qualified personnel to administer it. - ANSWER>>>10, State law requires that reports are to be submitted no later than the ________th day of the following month. - ANSWER>>> What are major surface waters classified as for the purposes of water quality management and designation of site-specific standards? - ANSWER>>>segments Inflow - ANSWER>>>direct discharges of storm water or surface water into a wastewater collection system (storm drains, roof gutters, yard drains, basement sump pumps and broken manholes and wastewater lines).

Cycles of decay include - ANSWER>>>carbon, nitrogen and sulfur A flow totalizer is required when the plant design flow is more than - ANSWER>>>0.5 MGD Non-hazardous wastes include - ANSWER>>>chlorides, alkalinity, color, phosphorous and iron Hazardous wastes include - ANSWER>>>cyanide, sulfides, organics and gasoline Synergistic Effect - ANSWER>>>reaction between waste streams How many cubic feet of screenings per million gallons of wastewater will coarse screens remove? - ANSWER>>>0.5 to 6. Preaeration benefits - ANSWER>>>freshen wastewater, scour gases and remove grease Main purpose of sedimentation tank - ANSWER>>>allow scum to rise and solids to settle under quiescent (low velocity) conditions How much settleable solids is removed in primary settling?

• ANSWER>>>90-95% How much suspended solids is removed in primary settling? - ANSWER>>>50-70%

How much BOD is removed in primary settling? - ANSWER>>>35% How much total organic matter is removed in primary settling? - ANSWER>>>20-30% What percentage of suspended solids will settle out within 2 hours? - ANSWER>>>70% Required minutes of detention time for peak flow? - ANSWER>>> Required minutes of detention time for design flow? - ANSWER>>> Benefits of removing grit - ANSWER>>>wear on pump impellers, line stoppages and taking up space Too high a velocity in a grit chamber can result in what? - ANSWER>>>excess grit in primary clarifier One of the benefits of pre-aeration is - ANSWER>>>gas and grease removal Why does grit need to be washed? - ANSWER>>>because organic matter clings to it What is a flow equalization used for? - ANSWER>>>to reduce excessive flows or organic loads

In an Imhoff tank, the lower compartment serves as the... - ANSWER>>>digester Wastewater is treated by what organisms? - ANSWER>>>bacteria, fungi, algae, plants, animals and protozoa How many basic cell structures are there? - ANSWER>>> What factors affect biological growth? - ANSWER>>>dissolved oxygen level, temperature, pH and available food What is the most important microorganism in wastewater treatment? - ANSWER>>>bacteria In what ways are bacteria classified? - ANSWER>>>shape, oxygen needs, temperature and metabolism In the removal process, what must bacteria do? - ANSWER>>>gather food, digest food, utilize food and give off by-products What limiting factors affect bacteria growth? - ANSWER>>>pH, temperature, moisture and food What must the operator control in order for microorganisms to do their job? - ANSWER>>>the environment

What by-products are excreted by microorganisms? - ANSWER>>>CO2, H2O and NH3 and polysaccharides Treatment pond classifications are... - ANSWER>>>wastewater stabilization ponds, aerated lagoons, facultative lagoons, anaerobic lagoons and hyacinth ponds What will a wastewater stabilization pond effectively reduce? - ANSWER>>>BOD and bacteria Anaerobic lagoon dissolved oxygen content... - ANSWER>>>none Facultative lagoon dissolved oxygen content... - ANSWER>>>DO on top and none at bottom Wastewater stabilization pond dissolved oxygen content...

• ANSWER>>>DO throughout (top, bottom and middle) Depth of wastewater stabilization pond - ANSWER>>>3- 5 ft deep Wastewater stabilization ponds are... - ANSWER>>>aerobic, dependent upon sunlight and shallower than facultative lagoons Benefit of multiple inlets and outlets in treatment ponds are... - ANSWER>>>prevention of short-circuiting and will assure an evenly distributed flow

Describe activated sludge... - ANSWER>>>is fluffy and difficult to settle with approximately 99% moisture content How many times should a clarifier concentrate mixed liquor solids? - ANSWER>>>at least two times Purpose of wasting solids from an activated sludge system is... - ANSWER>>>remove excess biological solids, inert solids and old/dead microorganisms Control parameters for activated sludge plants - ANSWER>>>oxygen levels, wasting rates, sludge quality, return rates and aerator solids levels The air requirements in an activated sludge process are governed by... - ANSWER>>>organic loading on the plant Sludge bulking is corrected by.... - ANSWER>>>restoring environmental balance to favor floc-forming bacteria over filamentous organisms Rising sludge and gas bubbles can be caused by... - ANSWER>>>denitrification in the final clarifier What test can give operators a visual check on sludge quality? - ANSWER>>>30-minute settling test A conventional activated sludge process has primary clarifiers that remove about ________ percent of the organic load.. - ANSWER>>>30-40%

What activated sludge process parameters can an operator change directly? - ANSWER>>>aeration rates, waste rates, and return sludge rates What happens when the return sludge rate is too low? - ANSWER>>>there will be insufficient organisms to treat the waste load entering the aeration basin and the sludge blanket in the secondary clarifier could become too high Physical causes of sludge bulking are... - ANSWER>>>excessive hydraulic loading, settled sludge that is not promptly removed from the clarifier, inadequate weir lengths and improper ratio of depth to surface area of the final clarifier SVI Formula (Sludge Volume Index) - ANSWER>>>30 min settle test/MLSS x 1000 Normal range for SVI (sludge volume index) - ANSWER>>>70- 150 What DO levels (in aeration) are optimal to maintain health of aerobic microorganisms? - ANSWER>>>2-4 mg/L How deep should the clarifier blanket be? - ANSWER>>>filling the bottom 1/

Define F/M ratio - ANSWER>>>food to microorganism ratio How is F/M ratio calculated? - ANSWER>>>by dividing the pounds of incoming BOD (food) by the pounds of MLVSS (microorganisms) in the aeration tank What conditions should an operator observe in a well controlled activated sludge process? - ANSWER>>>surface turbulence/uniform roll pattern; foam/small amount of light-colored, crisp foam; odors/mild, earthy; color/medium-brown What conditions should an operator observe in a well controlled clarifier? - ANSWER>>>very little surface scum; a sludge blanket covering 1/4 of the bottom; uniform weir flow (all the way around); almost no rising solids and overflow should be clear and free of floc What type solids cannot go onto a trickling filter? - ANSWER>>>large suspended solids Important factors to a well operating trickling filter... - ANSWER>>>continuous food supply, aerobic conditions and a moist zoogleal mass Basic elements of a trickling filter are... - ANSWER>>>floor and walls; distributor arms; underdrains and media

What must be durable and provide enough surface for bacterial growth with a trickling filter? - ANSWER>>>filter media The zoogleal mass on a filter is composed mainly of what?

• ANSWER>>>bacteria and algae The materials resulting from the stabilization of waste material as it passes through a trickling filter are... - ANSWER>>>water, nitrates and carbon dioxide What are zoogleal solids called that are washed off a trickling filter? - ANSWER>>>sloughings (which settle in the final clarifier) Units commonly used to measure the rate of hydraulic loading are... - ANSWER>>>lb/ft/day Units commonly used to measure the rate of organic loading include... - ANSWER>>>lb BOD/acre ft/day and lb BOD/1000 ft3/day Trickling filters may be classified as.... - ANSWER>>>high-rate; roughing; standard-rate The underdrain system of a standard rate trickling filter should be... - ANSWER>>>designed to flow half-full The recirculation ratio of a trickling filter has an effect on...
• ANSWER>>>organic matter removal; odors; filter flies

The biological growth on the disc of a rotating biological contactor should... - ANSWER>>>contain approximately 50,000 mg/L solids; be 0.05-0.1 inch thick after one or two weeks; and be gray to brown in color The RBC (rotating biological contactor) unit must be preceded by a... - ANSWER>>>primary clarifier or fine screen A condition(s) that adversely affect(s) the operation of a rotating biological contactor is... - ANSWER>>>toxic materials from industrial wastes; hydrogen sulfide; high or low pH A buildup of solids in the tank of the rotating biological contactor may be caused by... - ANSWER>>>poor primary clarification Advanced treatment processes strive to provide a ______________ removal level of specific compounds, suspended solids, and oxygen-demanding materials than cannot be achieved through secondary treatment alone. - ANSWER>>>higher Direct filtration of secondary effluent is often used to reduce _____ solids to low levels. - ANSWER>>>suspended The most important factor affecting filter performance is the _____ of the secondary effluent applied to the filter. - ANSWER>>>quality

Proper __________ is essential to filter performance. - ANSWER>>>cleaning What is the absorbent most commonly used for water treatment? - ANSWER>>>Activated carbon The use of granular activated carbon (GAC) for ______________ removal is common. - ANSWER>>>organic What can cause problems in granular activated carbon (GAC) treatment? - ANSWER>>>biological growth What has been tried as oxidizing agents in wastewater treatment? - ANSWER>>>chlorine dioxide (ClO2) Ozone (O3) Chlorine (Cl2) Many over look what kind of oxidizing agent as an oxidant because of its relative ineffectiveness in conventional waste treatment? - ANSWER>>>ozone Laboratory-scale studies have shown that the changes occurring in the settlement of the floc are greatly influenced by what? - ANSWER>>>biological activity What is a common coagulant used for chemical precipitation? - ANSWER>>>aluminum sulfate; sodium aluminate and ferric sulfate

What is a factor that influences the operation of sludge thickeners? - ANSWER>>>solids surface loading, temperature of the sludge entering the unit and biological activity of the sludge The proper pH for anaerobically digested sludge will... - ANSWER>>>be from 6.8 to 7. Primary volatile acids are converted by methane bacteria to... - ANSWER>>>methane and carbon dioxide The digester temperature should not change more than ______ degree C per day. - ANSWER>>> Anaerobic digester mixing methods include - ANSWER>>>gas mixing and mechanical mixing A cause of poor quality supernatant liquor could be... - ANSWER>>>digester overload Scum in a digester is mostly... - ANSWER>>>undigested grease Digester gas may be used to ________ digesters. - ANSWER>>>heat Digester gas should contain about _____________ methane - ANSWER>>>65-75%

Digester trouble signs include... - ANSWER>>>an increase in CO2 content and a decrease in volatile solids reduction Since the majority of _______ digesters are open tanks, digester liquid temperatures are dependent on weather conditions and can fluctuate extensively. - ANSWER>>>aerobic A minimum value of _________ of oxygen should be maintained in the aerobic digester at all times. - ANSWER>>>1.0 mg/L The following processes are used to dewater sewage sludge: - ANSWER>>>vacuum filters, filter presses and centrifuges Sludge drying time is affected most by... - ANSWER>>>degree of digestion The depth of sludge drawn to a drying bed should be... - ANSWER>>>about 9 inches The moisture content of sludge transported to a municipal landfill should be less than __________. - ANSWER>>>80% The most expensive method for the final disposal of sludge is... - ANSWER>>>incineration