Wastewater Treatment Operations and Regulations Exam Questions with Verified Answers (Graded A+)

Wastewater Treatment Operations and Regulations Exam Questions with Verified Answers (Graded A+) Drop in DO levels - Answers A significant decrease in dissolved oxygen levels affecting fish life. High coliform counts - Answers Elevated levels of coliform bacteria indicating potential contamination. Increase in dissolved mineral concentrations - Answers A rise in the concentration of dissolved minerals in water. Organisms in wastewater causing diseases in the fish - Answers Pathogenic organisms present in wastewater that can harm fish health. Probable cause of septic conditions in primary sedimentation tank - Answers Excessive grease in the influent wastewater. Best solution to correct septic conditions - Answers Increase the sludge withdrawal rate. Characteristics to measure immediately after sampling - Answers Temperature, pH and DO. Significant errors in sampling and analysis - Answers Improper sampling techniques. Surface loading of the clarifier - Answers Calculated as 238 gal/day/sq. ft. Probable cause of insufficient feed rate from chlorinator - Answers The chlorination system has vacuum leaks at the joints, gaskets or tubing. Cause of increasing coliform counts - Answers A gradual build-up of solids in the chlorine contact chamber. Cause of inadequate chlorine residual - Answers Automatic control device is malfunctioning. Probable cause of failing coliform count in effluent - Answers Too much chlorine demand in the mixing zone. Growth favoring conditions in wastewater - Answers Low DO levels, nutrient deficiencies, and low pH favor the growth of bacteria. DO levels in aeration tank for activated sludge - Answers Must be kept between 2.0-5.0 ppm. Detention time in aeration basin for extended aeration - Answers 24 hours. Probable cause of sludge floating in secondary clarifier - Answers A decrease in the sludge pH. Solution for sludge floating in secondary clarifier - Answers Increase the sludge retention time and decrease the return activated sludge rate. Conditions indicating mechanical bulking - Answers Low DO levels, low pH of mixed liquor, and high SVI. Action to take after toxic load enters plant - Answers Stop all wasting, add nutrients, lower the return activated sludge rate and decrease the organic load. Contact stabilization mode in activated sludge process - Answers Bugs digest the food and are returned hungry to the original aeration tank. Successful trickling filter operation - Answers Maintaining a good growth of organisms on the filter media. Effect of winter temperature on trickling filter efficiency - Answers A decrease in the amount of BOD removed from the wastewater. Probable cause of low pH in aerobic digester - Answers Nitrification is occurring and wastewater alkalinity is low. Key indicator of anaerobic sludge digestion process - Answers Volatile acid to alkalinity relationship. Effect of ponding on biological growth system - Answers It will cause lower BOD removal efficiencies for the unit. Secondary treatment effluent limitation for disinfection - Answers Shall achieve an effluent containing no more than 5 ppm of BOD and 5 ppm of TSS or 90% removal of each. Chlorine maintenance requirement for disinfection - Answers Maintenance of adequate chlorine residual is required for basic level of disinfection. Total chlorine residual after 15 minute contact time at average daily flow - Answers 1.5 ppm Total chlorine residual after 15 minute contact time at peak hourly flow - Answers 1.0 ppm FDEP chapter dealing with domestic wastewater residuals - Answers 62-602 Cycle of life, death and decay involving organic nitrogenous matter - Answers Nitrogen cycle System of pipes that carry wastewater from homes, businesses and industries - Answers Sanitary sewer Infiltration into the collection system causes significant increases in flow rates - Answers From breaks or open joints Suspended solids in water in sewerage, when placed in a large quiescent tank - Answers Settleable solids Secondary (or final) clarifiers are needed to - Answers Remove solids from trickling filter and activated sludge processes Material that settles out of wastewater during the primary settling phase - Answers Sludge Activated sludge - Answers A biological treatment process Purpose of sludge digestion - Answers To decompose enough of the organic matter to avoid creating a nuisance To remove nitrogen and phosphorous effectively - Answers Tertiary treatment processes Probable cause of obnoxious odor, flies and other insects at the headworks of the treatment plant - Answers An accumulation of rags and debris at the preliminary treatment process An Imhoff cone is used to - Answers Determine settleable solids Significance of running a fecal coliform test - Answers To indicate pathogenic organisms Hydraulic loading in gpd/sf for a rotating biological contactor treating a flow of 3.5 MGD - Answers 2.8 Organic loading in pounds of soluble BOD per day per 1,000 sq. ft. of media surface - Answers 21.7 Bacteria that require free oxygen for their life process - Answers Aerobic bacteria Main purpose of pretreatment of wastewater - Answers Separate coarse material from the wastewater Purpose of sedimentation of wastewater - Answers To allow the flow velocity to be reduced so that the settleable solids will settle out Secondary treatment is a process to - Answers Convert dissolved or suspended materials into a more stable form which will separate from the water Pretreatment equipment consists of - Answers Screen, comminutor and grit chamber Properly operated shredding process helps protect downstream equipment from - Answers Clogging Short-circuiting in a sedimentation tank can occur when - Answers Wastewater is passing through the tank too quickly Samples for making laboratory tests on wastewater should be - Answers Representative of the wastewater to be tested BOD incubation is for - Answers 5 days at 20 degrees C pH scale ranges from 0 to 14 with - Answers 7 being a neutral solution