wastewater practice exam

Wastewater Practice Exam 2023 Odors occur when treatment becomes Ans- Anaerobic What should an operator do before entering a manhole Ans- Test for all hazardous gases and oxygen levels and ventilate the manhole before entering What treatment devices is commonly used to separate and remove large solids from raw wastewater Ans- a mechanically raked bar screen What diseases are caused by pathogenic organisms that may be present in raw wastewater? AnsHepatitis, typhoid, paratyphoid, dysentery, and cholera What is typically used to dewater sludge? Ans- Belt press, Drying beds, solid bowl centrifuge, and gravity thickener Calculated the volume in gallons of a rectangular aeration tank that is 60 feet long, 30 feet wide and 20 feet deep Ans- 269,280 What is typically used whenever wastewater cannot flow to the treatment plant by gravity Ans- Lift station A centrifugal pump must be ? or it will not pump Ans- Primed One common type of weir design for measuring flow is Ans- V-Knotch The operator would need to increase or decrease if the ? loading on the plant is high Ansincrease/Organic A simple method for indication when to waste sludge is Ans- Total sedimentation test Landfill applied sludge must have a solids content of at least ? Ans- 20% Effluent dosage of chlorine in the contact chamber must produce a total combined residual of ? Ans1.0mg/L after 20 minutes TCEQ allows the reuse of wastewater, some of these uses include Ans- irrigation, aquifer recharge, cooling towers and fire protection Organic solids include Ans- organic materials from plant, animals or humans Dangerous gases are produced during bacterial decomposition of organics in wastewater. The main gases are Ans- Hydrogen sulfide, carbon dioxide and methane The majority of Dissolved Oxygen in raw sewage come from Ans- Potable drinking water Approximately How many pounds does each person contribute of BOD to the system daily Ans- 0.17 If the operator of a system received a call that a lift station is production of a strong smell of "Rotten eggs" this would be an indication that Ans- Hydrogen sulfide gas is present Sources of wastewater include Ans- Domestic, Storm water, commercial, food processing, agricultural and industrial A sewer manhole provides access into the system for cleaning or services. A manhole is typically located ? Ans- At changes in alignment, diameter, grade, direction and intersection Identify the 3 basic types of lift stations Ans- Dry, Wet and pneumatic How many feet must new manholes have an inside diameter of? Entry access must be at least how many inches? Ans- 4 feet and 30 inches What type of pump most commonly used in a lift station is Ans- Submersible In order to maintain 2 feet per second and velocity in a 6 inch main line, the fall per 100 feet of pipe will be Ans- 0.50 percent or 6 inches What is the primary cause of stoppage in a collection system Ans- grease and roots What type of gas is very toxic and deadens the sense