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Wastewater Treatment
Exam Prep for Wastewater
| Question | Answer |
|---|---|
| What is the most common reason for a wastewater to contain intermittent large amounts of sand, gravel, and grit? | storm events |
| Combined wastewater is defined as: | sanitary wastewater and stormwater runoff |
| In general, the solids content in wastewater is about: | 0.1% |
| In general, what is the percentage of suspended solids in the amount of total solids is about: | 30% |
| Generally, the percentage of dissolved solids in the amount of total solids is about: | 70% |
| Which type of organisms would most probably be associated with poor treatment or young biomass: | Amoebas |
| Which type of organisms would most probably be associated with very clear plant effluent, low biochemical oxygen demand (BOD), and low amounts of suspended solids? | Stalked ciliates |
| Aerobic bacteria will reproduce and live in an environment that contains only: | Oxygen |
| Anaerobic bacteria will produce and live only in an environment that completely lacks: | Free or dissolved oxygen (DO) |
| The biochemical oxygen demand (BOD) test usually has a specific time of: | 5 days |
| An Imhoff cone measures | Volume of settleable solids |
| Septic conditions are caused by: | Anaerobic bacteria |
| Scum is usually removed in the ___ treatment stage. | Primary |
| When domestic wastewater enters natural waters, what species deplete most of the oxygen? | Aerobic bacteria |
| Once the oxygen is depleted in a naturaly body of water, which organisms take over? | Anaerobic bacteria |
| The major gas produced by anaerobic decomposition is: | Methane |
| Another name for primary treatment is: | Sedimentation |
| Digester gas is ___ when mixed with air in the proper proportions. | Extremely explosive |
| A pond that is used to treat raw wastewater is called: | A waste stabilization pond |
| A pond that has an aerobic top layer and an anaerobic bottom layer is called: | A faculative pond |
| What is the angle of the bars on a manually cleaned bar screen? | 30 degrees |
| What is the angle of the bars on a mechanically cleaned bar screen? | 45 to 60 degrees |
| What is the ideal wastewater velocity in feet per second through screen channel? | 1.5ft/sec |
| What is the ideal wastewater velocity in ft/s for grit removal in a grit chamber? | 1 ft/sec |
| What is the water content of screened material? | 80% |
| What is the wastewater velocity range in ft/sec for grit removal in a grit chamber? | 0,7 to 1.4 ft/sec |
| Which on of the following chemicals gives water its greatest capacity to neutralize acids? | Hydroxide |
| The bar rack is used: | When the bar screen is out of service |
| What is the average detention time of wastewater in a primary clarifier? | 2hr |
| Which one of the following gases is irritating to the eyes? | Chlorine |
| Activated sludge clarifiers accept material to be settled from: | An aeration tank |
| According to Clean Water Act, secondary treatment is defined as a wastewater plant producing an effluent that has no more than ___ total suspended solids and no more that ___ BOD5. | 30mg/L, 30mg/L |
| The color of the biofilm on a rotating biological contactor would appear ___ under normal operating conditions. | Gray |
| A primary effluent and returned activated sludge mixture is called: | Waste activated sludge |
| The mixture of organisms and solids in water that is removed from the settling tank is called: | Mixed liquor |
| Under normal operating conditions, what color is the activated sludge? | Dark chocolate brown |
| What tests could an operator use to make process changes immediately if a problem develops? | Chemical Oxygen Demand (COD) test |
| The main workers in the activated sludge process are: | Bacteria |
| A yellow gas flame from a digester's waste gas burner may indicate a poor quality gas with a: | High CO2 content |
| Ponds used in series after primary wastewater treatment are sometimes called: | Oxidation ponds |
| The most common type of pond is: | Foculative pond |
| Which one of the following nuisance organisms is controlled simply by the water surface being disturbed by wind or currents? | Mosquitoes |
| When is the dissolved oxygen in a waste pond the lowest? | Sunrise |
| What would be most likely solution, if the influent to a wastewater treatment plant had an H2S odor? | Add treatment chemicals |
| What is the main reason why wastewater treatment plants remove phosphorus from their effluent before discharging to a lake or river? | To reduce the growth of algae |
| What is the color of liquid chlorine? | Amber |
| How many times heavier than air is chlorine gas? | 2.5 times |
| Free available chlorine consists of: | Dissolved chlorine gas, hypochlorous acid, and hypochlorite ion |
| The fusible plug on a chlorine cylinder will start to melt at approximately: | 160F |
| This solids treatment method usually has 20 days of retention time: | Aerobic Digestion |
| The solids treatment method processes solids in a sealed unit: | Anaerobic Digestion |
| This solids treatment method produces methane gas that can be used in other plant processes: | Anaerobic Digestion |
| This solids treatment method cures the final product and then it may be applied to farmlands: | Composting |
| This solids treatment method uses evaporation but also requires a great deal of labor: | Sand drying beds |
| This solids treatment method uses a partially submerged rotating drum: | Vacuum filter |
| These solid treatment methods use a coagulant polymer and pressure: | Belt filter and plate |
| Tests such as pH, temp, and dissolved oxygen should always be performed within ___ after collection. | 15min |
| When calibrating a pH meter, the buffers used should bracket the expected pH and: | Be at least 2 pH units apart |
| A test method for determining dissolved oxygen is the: | Azide modification of the Winkler titration method |
| How long can a dissolved oxygen sample wait for analysis using the modified Winkler method, if it is preserved with sulfuric acid? | 8hrs |
| BOD5 samples can be preserved by: | Storing them in fridge above freezing and up to 4C |
| The maximum holding time for preserved BOD5 samples is: | 2 days |
| Which one of the following tests is least likely to effectively help an operator control a waste plant process? | BOD5 |
| the maximum holding time for a preserved total suspended solids sample is: | 7 days |
| The state regulatory body must be notified of all unusual or extraordinary discharges by telephone within: | 24hrs |
| The state regulatory body must be notified of for any noncompliance that could adversely affect that states waters or that could endanger public health within: | 24hrs |
| Electomotive force (emf) is also known as: | Voltage |
| Electron flow is measured in: | Amps |
| What type of fuses would most likely be used to protect a meter? | Dual element fuses |
| What class of fire involves electrical equipment? | Class C |
| When a permit is required to enter a confined space, who may sign the permit? | Entry supervisor |
| Which one of the following is a measure of a materials opposition to the flow of electric current? | Ohms |
| What class of fire involves oil and grease? | Class B |
| Why is it essential to ventilate a valve vault before entry? | Remove dangerous gases |
| The primary purpose of check valves is to prevent: | Water from flowing in two directions |
| Which one of the following infectious diseases is not transmitted by wastewater? | The acquired immune deficiency syndrome virus (AIDS) |
| Which one of the following gases is least likely to collect in a belowground vault? | Carbon Monoxide |
| When working in a manhole, your vehicle, whenever possible; should be placed: | Between the manhole and oncoming traffic |
| OSHA requires that adequate protection, such as shoring, be placed in any trench that is: | 5ft greater in depth |
| How far back from the opening of a trench should soil excavated from that trench be placed? | 2ft at least |
| In a trench, ladders are required every: | 25ft |
| How many ladders are required to be in a 5ft deep trench when six people are working down in the trench? | Six ladders |
| Which is not an essential ingredient for all ordinary fires? a. ignition source b. fuel c. heat d. oxygen | a. ignition source |
| If some clothes are on fire, what class of fire is it? | Class A |
| If some magnesium is on fire, what class of fire is it? | Class D |
| What is the minimum number of people that should be on site working at a confined space site, where one of them in entering a manhole? | 3 |
| What type of fire extinguishers should be in pump stations | A-B-C chemical type |
| What piece of laboratory glassware is primarily used to mix chemicals and measure approximate volumes? | Beaker |
| The electric potential between two points is measured in: | Volts |
| What is the most common use today for a positive displacement pump? | Chemical feed pump |
| Which laboratory glassware will give the most accurate measurements of liquids? | Burettes |
| Which laboratory glassware is used for measuring volumes? | Graduated Cylinders |
| People working in and around wastewater must be immunized for: | Tetanus |
| Which one of the following laboratory tests has a zero holding time? | Chlorine Residual |
| Water is used as a standard becuase it has unique properties and is readily available in its pure state. Which standard is used? | Kilogram |
| What acids are formed when water reacts with nonmetal oxides? | Acid Anhydrides |
| Which one of the following is not a hydrate? | Sodium Nitrate |
Created by:
Ironhawk893