Wastewater Grade 2 Exam 2024-2025. Questions & Correct Answers. Graded A+, Exams of Waste Management

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Wastewater Grade 2 Exam

2024-2025. Questions &

Correct Answers. Graded A+

during the day, what typically happens to a pond as a result of the algae? - ANSalgae uses carbon dioxide, which raises pH how can the efficiency of trickling filter be improved? - ANSadd recirculation how does an activated sludge system remove waste from wastewater? - ANSbiological treatment how often should grit be removed from the grit channel? - ANSdaily how often should the sludge at the bottom of a clarifier be pumped?

• ANSfrequently throughout the day if you are testing the pH of a wastewater sample, what is the maximum recommended holding time? - ANSi must be tested immediately In general, how will warmer temperature affect the settling rate of solids in a clarifier? - ANSIncrease the settling rate one to two percent of the digester gas in an anaerobic digester consists of: - ANShydrogen, nitrogen, hydrogen sulfide and other gases prior to entering a permit-required confined space, what should you verify? - ANSa standby person should be located outside the entrance to the confined space, while another person should be within sight or call of the standby person. the effectiveness of disinfection is determined by: - ANSthe coliform concentration in the effluent the purpose of disinfection is to: -

ANSdestruction or inactivation of pathogenic bacteria the temperature of the plant influent is: - ANSslightly warmer than tap water What are collids? - ANSvery small, finely divided solids that remain dispersed in a liquid for a long time what are commonly used to control chlorine feed rate for disinfection? - ANSflow and chlorine residual what are mostly removed in the grit channel? - ANSsand, eggshells, cinders, and heavier particulate matter what are screenings? - ANSpieces of wood, root, rags, and other large debris what are the main sources of domestic sewage in the collection system? - ANShouseholds and commercial establishments what are the two categories of coliform bacteria? - ANStotal and fecal what causes primary effluent to become black and odorous? - ANSimproper sludge removal from the clarifier what cold happen if the sludge line is isolated by closing the valves on each end for several days? - ANSgas production could increase the internal pressure and cause the line to fail what could cause a sudden drop in pH of the influent? - ANSacidic chemical in the influent what could cause short-circuiting in a clarifier? - ANSUneven weir settings what could cause the slime growth on a rotating biological contractor to appear black? - ANSit could indicate solids or organic overloading what could happen if the dissolved oxygen content in the aeration tank is too low? - ANSfilamentous organisms could thrive and percent the sludge floc come

settling properly in the secondary clarifier what could happen if the volatile acid/alkalinity ratio starts to increase, and corrective action is not taken immediately? - ANScarbon dioxide content in the digester gas will increase what could happen if you are exposed to very high concentration of hydrogen sulfide? - ANSit could quickly lead to death what creates hydrogen sulfide? - ANSdecomposing organic matter under anaerobic condition what does black sludge at the bottom of a secondary clarifier located downstream of a trickling filter signify? - ANSsludge has stayed in the secondary clarifier to long what does healthy activated sludge smell like? - ANSearthy what does the "F" in F/M ratio represent? - ANSthe food for the microorganisms flowing into the aeration tank, in lbs/day what does the "M" in F/M ratio represent? - ANSThe mixed liquor volatile suspended solids in the aeration tank what happens when there is more food in the influent to the aeration tank? - ANSmore oxygen is required in the aeration tank what impact does temperature have on the reaction rate of microorganisms in wastewater? - ANSreaction rate doubles with every 18 degree Fahrenheit increase in temperature until higher temperature inhibits biological activity what is a "dead spot" in an activated sludge process? - ANSan area in the aeration tank that has insufficient mixing what is a common type of grit collector? - ANSChain-driven scrapers called

"flights" what is a common way to determine the organic strength of wastes in the influent? - ANStest for the biochemical oxygen demand what is a major cause of repeated sludge bulking? - ANSHigh food-to-microorganism loading rates what is a vulnerability assessment? - ANScontingency planning to determine the vulnerability of the utility during various types of emergencies and identify corrective actions to reduce the risks what is accomplished by the activated sludge process? - ANSremove soluble or finely divided suspended materials what is an air gap? - ANSBackflow prevention what is an MCRT? - ANSan expression of the average time a microorganism will spend in an activated sludge process what is an MSDS? - ANSa document that contains important information about a chemical, such as safe exposure level, flammability rating, and first-aid procedures What is biomass? - ANSa mass of organic material consisting of living organisms that feed on the wastes in sewage what is chloramine? - ANScombined chlorine - a chemical that is formed when chlorine reacts with ammonia what is commonly used to control the odor of hydrogen sulfide? - ANSchlorine what is equivalent to organic solids? - ANSvolatile solids What is freeboard in a waste stabilization pond? - ANSthe vertical distance from normal water surface to the top of the levee what is one of the benefits of COD test over a BOD test? - ANSshorter test period what is sludge age? -

ANSA rough indicator of the length of time a pound of solids is maintained under aeration what is sludge bulking in an activated sludge process? - ANSwhen mixed liquor solids slowly and compact to a limited extent what is the carbon dioxide content of a properly functioning anaerobic digester? - ANS to 35% by volume what is the color of a pond that is operating properly? - ANSdeep green color what is the correct formula for solids in raw wastewater? - ANSnon-settleable solids + settleable solids = total suspended solids what is the difference between the setting rate of activated sludge and raw sludge? - ANSactivated sludge settles slower than raw sludge what is the difference between the sludge from a primary clarifier and secondary clarifier? - ANSprimary sludge is denser than secondary sludge what is the equivalent of 1 mg/L? - ANS1 ppm what is the expected BOD removal efficiency in a facultative pond? - ANSmostly between 70 to 80% what is the first steps of lockout/tagout procedure? - ANSnotify all affected employees that a lockout or tagged system is going to be used and the reason why what is the incubation period for the BOD test? - ANSFive days +/- 3 hours what is the methane content in a properly operating anaerobic digester? - ANS65 to 70% by volume what is the most common imbalance in an anaerobic digester? - ANSexcess acid formation what is the most common piece of laboratory equipment , which is used mainly to mix

chemicals and measure approximate volumes. - ANSbeaker what is the only reliable method of detecting hydrogen sulfide?

• ANSatmospheric monitoring what is the permissible exposed limit for chlorine gas vapor during a normal 8-hour workday and a 40-hour workweek? - ANS0.5 ppm what is the purpose of a parshall flume - ANSMeasure flow rate what is the purpose of the grit channel? - ANSRemove heavy inorganic wastes what is the purpose of the seal water at the stuffing box in a pump? - ANSlubricate the packing what is the recommended daily maintenance activity for a clarifier? - ANSinspect the chains, sprockets, and flights what is the smile growth on a trickling filter called? - ANSzoogleal film what is the typical BOD removal efficiency in a primary clarifier? - ANS20 to 50% what is the typical detention time for a primary clarifier? - ANS1.5 to 2 hours what is the typical removal efficiency for bacteria in a primary clarifier? - ANS25-75% what is the typical removal efficiency of settleable solids in a primary clarifier? - ANS95 to 99% what is true about surface loading and detention time? - ANSthey are directly related to flow what is true during the colder winter months? - ANSModify operations to increase solids under aeration to provide more microorganisms to treat the BOD what is true if the F/M ratio increases? - ANSMore DO is needed what is used to control filamentous organisms? - ANSchlorine what is used to determine the amount of

microorganisms in the aeration tank? - ANSmixed liquor volatile suspended solids (MLVSS) what might cause sludge to rise in a clarifier? - ANSgasification from aging sludge what might cause thick billows of white sudsy foam in the aeration tank? - ANSMLSS is too low what must you do before entering a room with harmful concentration of chlorine gas in the air? - ANSwear self-contained breathing apparatus (SCBA) what problem could most likely cause a centrifugal pump to discharge at a reduced rate? - ANSdamaged impeller what should be done if a largge amount of organic matter is found in the grit channel? - ANSincrease the velocity of wastewater what should be done if SVI is high and there is an excess of normal filamentous microorganisms in the activated sludge process. - ANSchlorine the return activated sludge what should be done if you observe a small, steady stream of water leaking from the pump packings? - ANSdo nothing. the leaking is required to cool and lubricated the dynamic surface. what should be done to find a small chlorine leak? - ANSTie a rag on a stick, dip the rag in a strong ammonia solution, and hold the rag near the suspected points what should be mostly found in healthy activated sludge? - ANSfree-swimming and stalked ciliates what should you do if there is a thick, dark foam on the surface of an aeration tank? - ANSincrease sludge wasting what should you do if you are mildly exposed to chlorine gas? -

ANSimmediately evacuate the contaminated area, remain clam, keep warm, breathe lightly, and avoid coughing what type of disinfection is gaining in popularity, and expected to become a practical alternative to chlorination? - ANSUltraviolet (UV) disinfection what type of process is the activated sludge system? - ANSaerobic What type of sludge would you expect in an aeration tank if the content is dark and has low DO? - ANSseptic sludge when is a confined space considered oxygen- deficient? - ANSin atmospheres where the oxygen content is less than 19.5% by volume. when would you expect reduced algae population and less oxygen released into a pond? - ANSfall and winter, when the weather is cool and sunlight is reduced where is the correct location for a vent inside a room storing chlorine gas? - ANSwithin 12 inches of the floor where is the proper sampling location for an effluent form a wastewater treatment plant? - ANSprior to discharge into receiving wataers which document is written record that accurately traces the custody of wastewater samples through all phases of monitoring program? - ANSchain of custody form which gas diminished your sense of smell? - ANShydrogen sulfide which is true about chlorine demand? - ANSchlorine demand = chlorine dose - chlorine residual which is true about chlorine gas? - ANSit is 2.5 times heavier than air which law regulates wastewater discharge to receiving waters? - ANSclean water

act which of the following best describes per-chlorination? - ANSaddition of chlorine to wastewater at the entrance to the plant, and used for odor control, BOD reduction, grease removal, and aid sedimentation which of the following could be the cause of ponding in a trickling filter? - ANSexcessive orgnic loading which of the following describes the appearance of healthy activated sludge? - ANSbrown with a moderate amount of crisp, white foam which of the following enters the headworks of a treatment plant? - ANSinfluent which of the following is a collection of individual samples obtained at regular intervals? - ANScomposite which of the following is an improper way to control an anaerobic digester? - ANScontrol the acid formation so that it is larger than the methane formation which of the following is not associated with a trickling filter? - ANSfilamentous bacteria which of the following is not associated with an aeration tank? - ANSRBC which of the following is not true about chlorine gas? - ANScommon chlorine gas concentration at treatment plants is 12.5% which of the following is not true about permitted confined space entry? - ANStesting for atmospheric hazards is not required as long as a blower is in use which of the following is one of the basic rules of laboratory work? - ANSnever pipet hazardous material with your mouth, even if the pipet has been sterilized Which of the following is true about a positive

displacement pump? - ANSIt must never be started with the discharge valve closed which of the following is true about algae in a pond? - ANSduring the daytime, the algae will release oxygen for the aerobic bacteria in the pond which of the following is true about the extended aeration process? - ANSit has low F/M ratio which of the following is typically treated by biological processes? - ANSdissolved and non-setteable organic material which process includes a blower? - ANSactivated sludge which toxic gas is commonly found in septic wastewater and smells like rotten eggs? - ANShydrogen sulfide which type of bacteria is used for a trickling filter? - ANSaerobic bacteria who must be included in a hearing conservation program to prevent hearing loss? - ANSemployees whose normal noise exposure equals or exceeds an 8-hour time-weighted average of 85 decibels Why is mixing important in an anaerobic digester? - ANSSpeeds up digestion rate