Wastewater Treatment Class I

Wastewater Treatment Class I a) alert the operator on duty Always alert the operator on duty before shutting down any equipment so as to prevent the possibility of harming personnel or affecting process performance as a result of the shutdown. Ans- The first step the maintenance staff should take in properly locking and tagging out a piece of equipment is to... a) alert the operator on duty b) turn the equipment off at the motor control center (MCC) c) pull the switch on the electrical panel to "OFF" d) fill out the tags b) secured together If two or more floor coverings are required, secure them together to prevent trips and falls from the coverings separating. Ans- When working in an area with two or more floor coverings, be sure that they are always... a) overlapping one another b) secured together c) separated from one another d) at the entrances and exits only c) keep it close to your body and use leg strength When lifting any object manually, use your legs and keep the object close to to your body in order to minimize the risk of back injury. Ans- When manually lifting any object, be sure to... a) hold it at arm's length b) keep your back bent and hold it low c) keep it close to your body and use leg strength d) keep your knees locked and bend at the waist a) 19.5% The quality of air in a confined space is of utmost importance. Ambient air contains approximately 21% oxygen and atmospheres with oxygen concentrations below 19.5% are considered unsuitable for occupancy. Levels below 19.5% can lead to injury, loss of consciousness or death. Ans- Oxygen deficiency becomes a concern when the oxygen level in a confined space is less than... a) 19.5% b) 22.5% c) 25.5% d) 28.5% d) MSDS Material Safety Data Sheets provide information on chemical hazards, and health, safety and environmental concerns of chemicals. Ans- Which of the following provides safety information for potentially hazardous or toxic materials? a) CERCLA b) OSHA c) CFR d) MSDS b) 2-5 mg/L While many facilities operate in a range of 1-4 mg/L, the optimum range of DO for a conventional activated sludge facility is 2-5 mg/L Ans- Conventional activated sludge systems typically operate with a DO range of... a) 0-1 mg/L b) 2-5 mg/L c) 4-7 mg/L d) 7-9 mg/L a) screenings Large debris, large floating solid material, and fibrous material are categorized as screenings. It is necessary to remove this material before the wastewater reaches any pumps or equipment in order to prevent damage. Ans- Large debris (sticks, rocks, etc), large floating solids, and fibrous materials (rags, strings, cloths, etc.) are categorized as... a) screenings b) scum c) grit d) floc b) centrifugal Centrifugal pumps are primarily used for transporting influent and effluent wastewater. Positivedisplacement pumps, such as a progressing cavity pump, are used to transport sludge. Ans- Pumps are often required to bring wastewater into a treatment plant. What types of pumps are typically used to lift influent wastewater? a) air-lift b) centrifugal c) positive displacement d) progressing cavity a) detention time The detention time represents the time required for a unit volume (tank volume) of wastewater to pass through a tank at a given flow rate. Ans- The time it takes for a unit volume of wastewater to pass entirely through a primary clarifier is called... a) detention time b) hydraulic loading rate c) overflow time d) weir loading rate d) ultraviolet radiation Ultraviolet radiation is the second most common form of disinfection used in the U.S. today. Its popularity has grown because of its effectiveness and the fewer safety concerns compared with chlorine disinfection. Ans- After chlorine, what is the most common effluent wastewater disinfection technique or agent used in the U.S. today? a) bromine chloride b) chlorine dioxide c) ozone d) ultraviolet radiation c) light brown and frothy Healthy mixed liquor should have a uniform light brown color, should be slightly frothy, and should have a mild musty smell. Close examination of a mixed liquor sample should reveal floc formations, which are clusters of microorganisms and other suspended solids that are loosely bound together. Ans- Healthy mixed liquor in an activated sludge process should have what appearance? a) black with gray foam b) dark brown, covered with a greasy tan foam c) light brown and frothy d) gray with no foam of any kind a) parshall flume Devices used for flow measurement are typically divided into two categories, open-channel and closedpipe. Devices typically used are flumes, weirs, mechanical meters, magnetic meters, and ultrasonic meters. A counterweighted float-level indicator and downward looking acoustic sensors are used to measure the level in a well, tank, or chamber. A nephelometer is used to measure turbidity in liquids. Ans- Which of the following is a typical piece of flow measuring equipment? a) parshall flume b) nephelometer c) downward looking acoustic sensor d) counterweighted float-level indicator a) an area where conditions are very calm and no mixing is taking place The best visual indication of a dead spot in a biological reactor is the existence of an area where conditions are very calm and no mixing is taking place. These areas may also collect a lot of foam since there is no turbulence to disperse the foam. Dark colored sludge in a particular area may also be a sign of a dead spot. However, a dark area may be attributed to a septic recycle stream or an industrial dye rather than a dead spot. Measurement of the DO level in that area will determine its status. Ans- A "dead" spot in an activated sludge biological reactor is typically identified visually as... a) an area where conditions are very calm and no mixing is taking place b) an area where the sludge seems lighter than the rest of the reactor contents c) an area with only a small amount of foam on the surface d) an area with no foam on the surface c) mild, musty Healthy mixed liquor should have a uniform light brown color, should be slightly frothy, and should have a mild musty smell. Ans- Healthy activated sludge has what type of smell? a) rotten egg b) sharp, acidic c) mild, musty d) antiseptic b) mg/L The typical range for MLSS in a conventional activated sludge plant is mg/L. Some alternate activated sludge process modes, such as high-rate or contact stabilization, could have MLSS concentrations as high as 10 000 mg/L. Ans- The mixed liquor suspended solids (MLSS) concentration range for a conventional activated sludge process is...