CWEA Environmental Compliance Inspector Grade 1 Questions with Correct Solutions

Floatable solids are easy to measure. True or False? False A well operated digester normally receives sludge at about __________% volatile solid and reduces it to about ________________% volatile solids. 70-75%, 25-30% According to OSHA, which of the following oxygen in air concentration is the lowest safe concentration for humans to breathe in order to avoid the hazard of oxygen deficiency? 19.5% oxygen The population equivalent factor for BOD is 0.17 lb/day/BOD/person Which microorganisms are found in a good settling mixed liquor? Rotifers, stalked ciliates, and free swimming ciliates Which heavy metal is the most stringent for land application? Mercury Grit chambers that are designed to remove grit at a velocity of 0.5 to 1.0 ft/sec The purpose of adding sodium thiosulfate to a microbiological (such as fecal coliform) sample bottle is to Remove any chlorine residual present Which of the following types of wastewater would settling occur most rapidly? Cold wastewater Old wastewater Septic wastewater Strong wastewater Strong wastewater The disadvantage of using a constant percentage return activated sludge flow control is Clarifier is subjected to maximum solids loading when it contains maximum amount of sludge Under which conditions should sludge wasting normally be increased? A dark brown scummy foam appears on the aeration tank surface The outlet of a forced ventilation system for a chlorinator room should be located Near the floor If packing is not maintained properly There will be a loss of suction from air being allowed to enter the pipe. Turbidity in wastewater is caused by Finely divided suspended material One of the primary reasons why air should be excluded from the digester is that... The entrance of air mixed with gas produced in the digester could create an explosive mixture True or False: Barminutors and comminutors are installed for different purposes False What are the end products of the aerobic biochemical reaction? H2O and CO2 What does pump maintenance include? a. Checking operating temperatures of bearings b. checking packings glands c. lubricating the impeller d. all of the above all of the above Pump packing should be Tightened down to a drip The fusible plug that is in all chlorine containers? a. May be used as a tap for the chlorine source b. Should be removed after the cylinders are empty c. Should never be removed or tampered with d. Should be removed prior to withdrawing chlorine from the container Should never be removed or tampered with A piston or diaphragm pump would be used for pumping... Primary sludge Collection system variables that could upset an activated sludge process include... Activities of collection system maintenance crew What type of pump is not seriously damaged if the discharge valve is closed for a short time, while the pump is running? Centrifugal pump Which of the following chemicals would be the most effective in achieving a pH adjustment of 8.4 so nitrification can take place in an RBC? Soda ash Acids should never be added to chlorine solution because they... Cause chlorine gas to be released Which of the following is a method for treating flow to the primary settling tank that would increase grease removal, efficiency of that unit? Preaerate Name three waterborne diseases Typhoid fever, dysentery, cholera When organic waste our discharged to receiving water, oxygen is depleted by... Bacteria Sludge wasting from secondary clarifiers are normally required in order to control... Aerator mixed liquor solids An application for renewal of an NPDES permit must be submitted __________ days before the previous permit expires 180 From a public health standpoint, which of the following is the safest sludge for soil conditioning purposes Heat dried sludge The major purpose of an inlet baffle in a settling tank is to Reduce velocity and disperse flow What is the primary purpose of forced draft ventilation in lift stations? Remove dangerous gases High-rate, anaerobic digestion refers to the fact that the organic waste material is applied to an anaerobic reactor at high ___________ loading rates Volumetric As a digester approaches "sour" conditions: a. Alkalinity of solids decreases. b. Concentration of volatile acids increases. c. Amount of methane production decreases. d. All of the above. All of the above The concentration of volatile, solid in the feed sludge to a digester is an indirect measure of what? "Food" available for bacteria in the digester What is the typical detention time in a mesophilic digester? 28 days The presence of white pillowing foam on an aeration tank indicates... The aeration tank is underloaded organically What purpose do the chemicals that are added to the distilled water for the BOD test serve? They adjust the pH within the desirable range and provide essential elements for the growth of the biological life actually exerting the oxygen demand An operator runs a Winkler by the azide modification of the Winkler method. He runs out of standard sodium thiosulfate. Which reagent can be used instead? Phenylarsenine oxide