California Water Treatment Operator Exam, Water Treatment Processes: all 49 questions
All questions from the Water Treatment Processes section for California Water Treatment Operator Exam, each with the correct answer.
- 2001What is the main purpose of coagulation in water treatment?
- 2002Which chemical is most commonly used as a primary coagulant in drinking water plants?
- 2003Rapid (flash) mixing is used in a coagulation process to
- 2004Flocculation basins use slow, gentle mixing because
- 2005Which condition generally makes alum coagulation LESS effective?
- 2006When alum is added to water, it consumes alkalinity. If the raw water alkalinity is too low, the operator may need to add
- 2007What is the purpose of a sedimentation basin?
- 2008Tube settlers or plate settlers improve sedimentation mainly by
- 2009Floc that is small and cloudy (pin floc) and does not settle well may indicate
- 2010A jar test is performed to
- 2011A sedimentation basin is 40 ft long, 20 ft wide and 12 ft deep and receives a flow of 0.5 MGD. What is its detention time?
- 2012What is the primary purpose of filtration in a water treatment plant?
- 2013Turbidity in water is a measure of
- 2015The rate at which water is applied to a filter, expressed in gpm per square foot of surface area, is the
- 2016As a filter run progresses, head loss across the filter normally
- 2017Which event is the main trigger for backwashing a filter?
- 2018What is the effect of backwashing a filter too long at a high rate?
- 2019What is surface wash used for in a filter backwash?
- 2020A filter has an area of 200 sq ft and a backwash rate of 15 gpm/sq ft. What is the backwash pumping rate?
- 2021A filter with an area of 400 sq ft produces 2.88 MGD. What is the filtration rate in gpm/sq ft?
- 2022Which of the following is a purpose of disinfection?
- 2023Which gas is commonly fed as a primary disinfectant in water treatment, and is stored as a liquid under pressure in cylinders?
- 2024What is the approximate available chlorine content of commercial sodium hypochlorite (liquid bleach) used at water plants?
- 2025Which form of chlorine is most effective as a disinfectant?
- 2026Chlorine demand is defined as
- 2027A plant adds 3.2 mg/L of chlorine and has a free chlorine residual of 0.8 mg/L. What is the chlorine demand?
- 2028The point where adding more chlorine produces a rise in free chlorine residual in proportion to the dose is called
- 2029What is the main reason chloramines are used as a secondary disinfectant in some distribution systems?
- 2031The CT value used in disinfection is calculated as
- 2032A clearwell provides a T10 contact time of 40 minutes with a free chlorine residual of 1.2 mg/L. What is the CT?
- 2033If the required CT is 60 mg/L-min and the actual CT is 90 mg/L-min, the inactivation ratio is
- 2034Which of the following disinfection byproducts is regulated as total trihalomethanes (TTHM)?
- 2035Which action is most effective for reducing the formation of disinfection byproducts in a treatment plant?
- 2036Which treatment technique is commonly used to control corrosion of lead and copper in a distribution system?
- 2037Water that is corrosive generally has
- 2038Which of the following is a sign of a corrosion problem in the distribution system?
- 2039Which of the following is a common taste and odor control method at a treatment plant?
- 2040A musty or earthy odor in a surface water source in the summer is often caused by
- 2041Which two metals are most commonly removed from groundwater because they cause staining and taste problems?
- 2043Iron and manganese are often removed by
- 2044Fluoride is added to water systems to
- 2046Best Available Technology (BAT) as used in drinking water regulation refers to
- 2047Which technology is a recognized BAT for removing arsenic from drinking water?
- 2048Which process is a common treatment to remove nitrate from groundwater?
- 2049Granular activated carbon filters remove organic chemicals mainly by
- 2050Which chemical is generally added to water after filtration to raise the pH and reduce corrosion?
- 2051Which sequence correctly lists the steps in conventional surface water treatment?
- 2052Direct filtration differs from conventional filtration because it
- 2053Which disinfectant provides a lasting residual in the distribution system?