click below
click below
Normal Size Small Size show me how
Waste/Water
Wastewater management
Question | Answer |
---|---|
What two aspects of waste water must be managed? | quantity and quality |
What does MLD stand for? | Mega Litres per Day |
What four factors is waste water flow dependent on? | number of users time of day season temperature |
T or F. Wastewater is 99.9 percent water. | T |
What are two examples of organics that may be found in wastewater? | carbs and lignin |
The characterization of wastewater depends on which things? | standard of living population per capita consumption. time of day temperature climate |
What is the ideal ratio of BOD5 to COD for bacteria to work? | greater than 0.5 |
Selecting treatment processes depends on which things? | Characteristics, effluent quality, and cost/land availability |
What are the major processes in waste water treatment? | Primary (phys/chem) Secondary (bio) Teritiary(extras) |
What are three major parts of primary treatment? | solid removal by bar screen grit removal by chamber, and primary clarification |
Describe primary clarification. | Solids settle down into sludge which is slowly scraped off from the bottom. |
How much BOD and TSS is removed by primary treatment? | 1/3 BOD removed and 2/3 TSS removed |
Describe Newton's law. | terminal velocity equates to the forces of gravity compared to the drag force |
Describe Stoke's law. | terminal velocity is different for different flow regimes. |
What fuel gas can come from anaerobic biological treatment? | methane |
How might you identify a clarifier in an aerial photograph? | they are circular |
Is secondary treatment usually anaerobic, or aerobic? | aerobic |
Describe the activated sludge method of treatment. | Soluble organics are degraded by microbes. Microbes and any solids become part of the sludge, and a part of this is recycled as activated sludge. |
What are the mechanisms of activated sludge? | Organics are oxidized for energy. They are synthesized into the protoplasm. They become part of the microbe's biomass. |
What is another word for activated sludge? | Suspended growth. |
What are some limitations of activated sludge? | nitrogen cannot be removed, and bulking may occur |
Describe a biofilm. | A biofilm is a sheet of microbes which grow on a surface. Sewage is sprayed on top, and the organics are aerobically decomposed on top, and anaerobically decomposed below. |
Describe a rotating biological contactor. | Not unlike a slushee machine, biofilm is around the edge of the tube. it is rotated in water so that half the time there is aerobic decomposition, and the other half there is anaerobic decomposition. |
Advantages and disadvantages of activated sludge. | Adv. - larger volumes and greater variation in nutrients can be handled. Disadv.- large footprint and bulking |
Advantages and disadvantages of biofilm. | Adv.- smaller footprint Disadv.- cannot handle oil/grease and is more sensitive. |
What is a bioreactor? | Activated sludge and biofilm working in the same system |
At the end of secondary treatment, does N go up or down? | Up |
What are the four major things that happen in tertiary treatment? | N removal P removal Filtration Organic removal |
How is N removed in tertiary treatment? | Ammonia is removed by nitrification followed by denitrification. In other words, converted to nitrates then to N gas |
What conditions are necessary for denitrification? | C source and anoxic |
What are the stages of P removal? | Alum is flash mixed to coagulate the P out. Then there is an anaerobic stage, an aerobic stage, and a clarifier. |
Explain the biological component of P removal. | Facultative anaerobes produce fatty acids. These are consumed by P accumulating microbes, and P is released. In the aerobic stage, these microbes gorge on the P. In the clarifier, the microbes are removed as sludge. |
How does activated carbon remove additional organics? | Organics adsorb onto carbon binding sites. |
What are three methods of disinfection? | UV, ozone, and hydrogen peroxide. |
How is sludge dealt with? | It is first thickened, then digested into compost |
What are sources of waste water? | Potable water, storm water, and industry. |
What are sinks of waste water? | Environmental discharge and re use |
What makes up storm water in an undeveloped environment? | 10 percent surface, 50 percent ground, 40 percent evapotranspiration. |
What makes up storm water in an urban environment? | 43 percent surface, 32 percent ground, 25 percent evapotranspiration. |
What are some impacts of untreated water? | aesthetic, human health, environment health |
At the federal level, what regulations are there for water quality? | CEPA and fisheries act |
At the AB level, what regulations are there for water quality? | EPEA and facility-specific |
At Edmonton' s level, what regulation exists for water quality? | Sewer use bylaw |
Summarize the EPEA | People have a duty to report, remediate, and that adverse effects found will lead to investigations. |
How are requirements established? | Performance evaluations and discharge limits |
What is a target? | A concentration used to aim for |
What is a trigger? | A concentration that needs action when reached |
What is a limit? | Regulatory level |
How do you derive discharge limits? | Based on if it is a point or non-point source |
What are the four zones on the DO sag curve? | degradation, decomposition, recovery, and clean water |
Why is BOD linked to low oxygen? | High BOD means that organics are easily converted by microbes, and this uses up oxygen |
What does TIE stand for? | Toxicity identification evaluation |
What does TRE stand for? | Toxicity reduction evaluation |
What are the largest wastewater producers, from most to least? | 1. Pulp/Paper 2. Meat processing 3. Bitumen |
What do you have to consider when selecting a management system? | The characterization of the wastewater, and the objective of treatment. |
What are five primary treatment processes in industrial wastewater management? | 1. Equalization 2. Neutralization 3. Stripping 4. Flotation 5. Sedimentation |
Summarize equalization. | Parameters are stabilized |
Summarize neutralization. | pH is neutralized |
Summarize flotation. | Dissolved air flotation is used to remove suspended solids and oil/grease. |
Summarize stripping. | Tray towers remove selected constituents via PMT |
What is PMT? | Pollutant media transfer |
What is a common coagulant? | Alum |
What is the purpose of coagulation? | To increase sludge mass |
What substance is often used for adsorptive purposes? | Granulated activated carbon |
Differentiate between conventional and crossflow filtration. | Conventional is vacuum filtration. Crossflow is when the wastewater flows across the filter |
What are the four types of coal. | Anthracite, bituminous, sub bituminous, and lignate |
When did coal mining start in AB and why? | 1800s; steam engines and heating |
When did oil and gas industry start in AB? | Early 1900s |
Where was the first Pulp mill in AB? | Hinton |
Where are the three oil sands deposits in AB? | Peace river, Athabasca, and cold lake |
Three sinks of wastewater in petroleum refining. | Wastewater, steam loss, product water |
What are the streams of wastewater in petroleum refining? | Tank sediment/water Desalination Sour water Caustic soda |
How and why are tank sediments removed? | They are removed by settling to prevent tank erosion. |
What two chemicals are in sour water? | H2S and ammonia |
What are some characteristics of petroleum wastewater? | High COD and BOD Phenols, Ammonia FOG BTEX Metals |
Differentiate between the High and Low TDS trains. | High has two Oil and gas removal stages. Low only has one |
What does API stand for? | American Petroleum Institute |
How are oil and water separated? | API seperators or dissolved air flotation |
Three methods of wood pulping: | Mechanically, semi-chemically, chemically |
What is the sequence of processing in a pulp mill? | Handling Pulping Digesting Bleaching Dry/bail stock prep |
What is Black liquor | Black liquor is a product of digestion which is burned to make steam for power |
Characteristics of pulp wastewater | Dioxins/furans Chlorinated stuff BOD/COD TSS |
Types of sludges | Chemical(primary), biosolid(secondary), combined |
Methods of sludge handling | Digestion, thickening, dewatering, drying |
How does sludge digestion work? | Lime is added til pH 12 Aerobic digestion Anaerobic digestion |
How does anaerobic digestion of sludge work? | Hydrolysis, fermentation, and methanogenesis |
What are three effective ways of dewatering? | Centrifugation, rotary drum, and belt filter press |
How does a sludge drying bed work? | Essentially air drying |
From what substance is oil and gas formed from? | Kerogen |
How is kerogen formed? | anaerobic decay of of biological matter |
Example of conventional oil and gas | Oil derrick |
Example of unconventional oil and gas | Fracking or oil sands |
What is fracking | High pressure put into shale to release oil and gas |
Crude oil v bitumen | bitumen is from oil sands and is heavier |
Two methods of oil sands extraction | surface mining and SAGD |
Methods of bitumen recovery | gravity settling and bitumen-water separation |
Three stages of gravity settling | separation, aeration, and froth treatment |
Stages in froth treatment | Mix, separate, recover |
Why is diluent needed to transport bitumen? | Bitumen freezes at 30 degrees |
Does industry treatment use tertiary wastewater treatment to reduce P and N? | No, but municipal does |
Three steps in municipal wastewater treatment | Screening, grit chambers, and primary clarifiers |
How is nitrogen removed in a municipal wastewater facility? | N is removed by nitrification then denitrification. |