Wastewater Laboratory Analyst Exam Questions with Correct Solutions (Graded A+) Already Passed

Wastewater Laboratory Analyst Exam Questions with Correct Solutions (Graded A+) Already Passed Sources of Wastewater - Answers Homes and businesses (domestic) and industries Why treat wastewater? - Answers Protect the downstream user and protect the environment Types of Waterborne Diseases - Answers Cholera, Typhoid, Hepatitis, Amoebic Dysentery, Gastroenteritis Cholera - Answers An acute intestinal infection. Short incubation period, less than one day to five days. Causes a copious, painless, watery diarrhea that can quickly lead to severe dehydration and death if treatment is not promptly given. Caused by Vibrio cholerae Typhoid Fever - Answers Sudden onset of sustained fever, severe headache, nausea, and severe loss of appetite. Caused by Salmonella typhi Hepatitis - Answers Inflammation of the liver. Most common cause is infection with one of 5 viruses (A, B, C, D, and E). Symptoms are yellowing of the skin and eyes (jaundice); dark urine, extreme fatigue; nausea; vomiting and abdominal pain. It can take several months to a year to feel fit again. Giardiasis and E.coli - Answers Symptoms include diarrhea, gas or flatulence, stomach cramps, upset stomach or nausea. Cryptosporidiosis - Answers The most common symptom of cryptosporidiosis is watery diarrhea. Can lead to dehydration and death in immunocompromised persons. Wastewater - Answers The spent water of a community from homes, businesses, and industries. Industrial Controls - Answers Sewer Use Ordinance and Industrial Pretreatment Permitting Program Sewer Use Ordinance - Answers Local ordinance that addresses what is prohibited from being discharged and sets limits for particular pollutants Physical Characteristics of Wastewater - Answers Temperature normally warmer than tap water (10 - 20 degrees C/ 50 - 70 degrees F), Color is grey, Odor is musty, Turbidity - suspended and colloidal solids Chemical Characteristics of Wastewater - Answers Alkalinity, Chemical Oxygen Demand, Conductivity, Dissolved Oxygen, Oxidation-reduction potential (ORP), pH Alkalinity - Answers Measure of the ability of the wastewater to neutralize an acid, expressed as mg/L CaCO3, high in areas with hard water (groundwater), low in areas with soft water, secondary treatment affects alkalinity Chemical Oxygen Demand - Answers the amount of specified oxidant that reacts with the sample under controlled conditions, expressed as mg/L, normal range 200-600 mg/L Conductivity (Specific Conductance) - Answers The ability of an aqueous solution to carry an electric current, related to dissolved solids concentration, measure in micrometers per cm at 25 degrees C, can range from 50 - 1500 micrometers per cm, increases with inorganic content Dissolved Oxygen - Answers molecular oxygen present in wastewater, temperature dependent (higher temp = lower DO), low DO favors filaments and anaerobes, zero DO is anaerobic, normally 2 Oxidation-reduction potential (ORP) - Answers the intensity or ease of electron loss (oxidation) or electron gain (reduction), also called redox potential, measured in millivolts, normal domestic influent = -200mV, ranges from 50 - 400 mV pH - Answers a measure of the intensity of the hydrogen ion concentration in a solution, pH scale of 0 - 14, measured in Standard Units (SU), normal value for raw WW is 6.5 - 7.0 Biological Characteristics - Answers Biochemical oxygen demand, pathogenic microorganisms Biochemical Oxygen Demand (BOD) - Answers a measure of the organic strength of wastewater, uses up the oxygen in discharged directly into a receiving water, 200 mg/L Pathogenic Microorganisms - Answers bacteria and viruses Collection System - Answers a network of pipes, equipment, and appurtenances that collect, pump, and transport wastewater Collection System Purpose - Answers safely transport wastewater from a community to a wastewater treatment facility Types of Collection Systems - Answers Sanitary sewer, storm sewer, combined sewer Combined Sewer Systems - Answers built in the 1800s, caused too many problems, illegal to build now, CSO: Combined Sewer Overflow Conveyance System Components - Answers sewer mains, interceptors, trunk lines, lift stations, force mains, manholes Manholes - Answers Opening to a sewer line for the purpose of permitting operators or equipment to enter or leave a sewer (inspection, maintenance, removal of solids) Wastewater is Collected and Conveyed - Answers Water flows by gravity from homes and business to a sewer main, sewer main flows downhill, sewer main empties into a lift station Lift Stations - Answers designed to pump wastewater from the bottom of a hill up to the top of the next hill; the pipe that the water travels through, under pressure, is called a force main; water from the force main is discharged into a sewer main at a higher elevation Conveyance System Challenges - Answers Grease clogs, roots entering pipes through cracks and joints, infiltration and inflow Infiltration - Answers the seepage of groundwater into the sewer system system through cracked joints or pipes Inflow - Answers direct discharge into the sewer system through illegal connections or surface water entering through faulty joints or displaced manhole covers New Sewer Mains - Answers Must be tested before added to the system (proper slope, no obstructions, no dips), check for unintentioanl openings (missing manhole covers and cross-connections) Broken Sewer Mains - Answers can lead to major spills, cause poor public relations, may cause fish kills, are unsightly Types of Watewater Contaminants - Answers large items (sticks, rags), inorganic materials (sand, clay, eggshells), organic chemicals (pesticides, herbicides), microorganisms Treatment Plant Processes - Answers Screening, grit removal, biological treatment, clarification, filtration, disinfection, dechlorination, solids handling (digestion, thickening, dewatering) Screening - Answers Removes large items from the wastestream (rags, sticks, etc) Grit Removal - Answers Removes inorganic contaminants from the wastestream (slow flow to 1 ft/sec, inorganic solids settle out, removed by a conveyor with buckets) Biological Treatment - Answers Microorganisms biodegrade the organic matter, break it down into non-harmful components Clarification - Answers Slows the flow of water down, sludge settles to the bottom and is returned to the basin or sent to the digester, clear water is sent to filtration or disinfection Filtration - Answers Disk filters with cloth media for example, purpose is to remove colloidal and fine particulate matter Disinfection - Answers Purpose is to kill or inactivate pathogenic microorganisms, chlorination, UV disinfection Dechlorination - Answers Chlorine can be harmful to aquatic life, sulfur dioxide is added to remove the residual chlorine just prior to the water being discharged into the receiving stream