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ENCN347 > Week 6: Treatment Technologies > Flashcards

Week 6: Treatment Technologies Flashcards

(109 cards)

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1
Q

List all the SW treatment processes.
(Most important shown in bold)

A
  • Sedimentation
  • Flotation
  • Filtration
  • Adsorption and ion exchange
  • Flocculation or Precipitation
  • Microbial degradation and conversion
  • Bioaccumulation/uptake
  • Inactivation
  • UV degradation
  • Volatilisation
  • Chemical degradation/transformation
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2
Q

What pollutants might we remove by sedimentation?

A
  • Suspended solids
  • Metals
  • Pathogens
  • Anything bound to solids
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3
Q

What factors influence sedimentation?

A
  • Velocity
  • Energy
  • Turbulence
  • Particle Size
  • Density
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4
Q

What might we remove by flotation?

A
  • Hydrocarbons
  • Plastics and microplastics
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5
Q

What factors influence flotation (reverse process of sedimentation)?

A
  • Buoyancy (particle size and density)
  • Velocity
  • Energy
  • Turbulence
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6
Q

What might we remove by filtration?

A
  • Sediment/solids
  • Some pathogens
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7
Q

What factors influence filtration?

A
  • Size of filter pores/diameter of polllutants
  • Depth of filter
  • Angle of filter
  • Fluid velocity
  • Shape of particles
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8
Q

What might we remove by adsorption (binding to surface) + ion exchange?

A
  • Metals
  • Dissolved organics
  • Phosphate
  • Nitrogen species
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9
Q

What factors influence adsorption + ion exchange?

A
  • Adsorbent material
  • Chemical functional groups
  • pH
  • Contact time
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10
Q

What might we remove by flocculation & precipitation?

A
  • Metals
  • Colloidal particles (clays, organics)
  • Phosphate
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11
Q

What factors influence flocculation and precipitation?

A
  • pH
  • Salinity
  • Mixing
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12
Q

What might we move by microbial degradation?

A
  • Organics
  • Nitrogen
  • Phosphate
  • Metals
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13
Q

What factors influence microbial defgradation?

A
  • pH
  • Temperature
  • Concentration
  • Light
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14
Q

What might we remove by bioaccumulation/uptake?

A
  • Nitrogen
  • Phosphate
  • Metals
  • Organics
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15
Q

What factors influence bioaccumulation/uptake?

A
  • Temperature
  • Light
  • Growth stage
  • pH
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16
Q

What might we remove by inactivation?

A
  • Pathogens
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17
Q

What factors influence inactivation?

A
  • Time
  • Light (UV)
  • Temperature (colder is more effective)
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18
Q

What might we remove by UV degradation?

A
  • Certain organic compounds
  • Microplastics
  • Pathogens
  • Hydrocarbons may transform
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19
Q

What factors influence UV degradation?

A
  • Sunlight
  • Temperature
  • pH
  • Mixing/depth
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20
Q

What might we remove by volatilisation?

A
  • Volatile organic carbon
  • Ammonia
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21
Q

What factors influence volatilisation?

A
  • Temperature
  • Concentration
  • pH
  • Mixing depth
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22
Q

What might we remove with chemical degradation?

A
  • Organic compounds
  • Nitrogen species
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23
Q

What factors influence chemical degradation?

A
  • Temperature
  • Concetration
  • pH
  • Other chemicals
  • Time (it is a slow process)
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24
Q

What are some pretreatment systems?

A
  • Macro (or gross) pollutant traps
  • Propietary sediment devices
  • Swales
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25
What are some soakage systems?
- Swales (soakage) - Infiltration chambers - Rain garden/biofilter/soakage basin - Permeable pavement
26
What are some detention-type systems?
- Detention basins (wet ponds or dry basins) - Retention basins (dry basins) - Household rain tanks
27
What are some constructed wetland systems?
- Surface flow wetlands - Subsurface flow wetlands
28
What are some building integrated systems?
- Green roofs - Living walls
29
What are some proprietary filters?
Package designs usually combining sedimentation and filtration - Jellyfish - Storminater - ...
30
What are some considerations for selecting a treatment device?
- Cost - Amenity - Cultural and social alignment - Target pollutant removal - Robustness - Size/land area/excavation - Maintenance - Flow - Topography - WT, bedrock, other constraints
31
Describe Te Taiao (Mana Whenua alignment).
The environment that surroudns us, comprising whenua, wai, ahurangi (climate across time) and koiora (all living communities - people, plants, animals).
32
Describe Kaitiakitanga (Mana Whenua alignment).
Guardianship and protection of the natural environment by mana whenua based on the Maori world view.
33
Describe Mauri tu (Mana Whenua alignment).
Protection and awareness of the life force within all matter. The connection between spiritual, physical and temporal realms.
34
What are the 3 levels of a treatment system?
Primary Secondary Tertiary
35
Outline the processes, pollutants and examples of primary treatment.
Processes: - Hydraulic, physical processes resulting in screening and rapid sedimentation Pollutants: - Litter, coarse sediments Examples: - Catch pit inserts, filter strips, litter traps, sediment ponds
36
Outline the processes, pollutants and examples of secondary treatment.
Processes: - Filtration resulting in fine particle and sediment removal. Pollutants: - Fine sediment and attached pollutants. Examples: - Swales, infiltration trenches, pervious pavement, bioretention devices.
37
Outline the processes, pollutants and examples of tertiary treatment.
Processes: - Biological, chemical, thermal processes. - Provide removal through enhanced sedimentation, biological uptake, adsorption to sediments, UV inactivation. Pollutants: - Nutrients, dissolved heavy metals, temperature, pathogens. Examples: - Bioretention devices, wetlands
38
Descibe macro pollutant traps.
Debris collection upstream of other treatment devices to collect: - plastic waste - rocks - sticks/branches - leaves/organic debris. Physical treatment processes: - straining - sedimentation - flotation
39
Gross Pollutant Traps (GPT), sumps and propriety sedimentation devices have good removal capability for ...
- Sediment - Oil and grease
40
What are swales?
Broad channels to slow water runoff and direct it towards further treatment devices. Typically vegetated to improve filtration of sediment and other pollutants, and slow water movement.
41
How do swales align with Mana Whenua?
- They are suitable for native grasses - Vegetated swales with minimal maintenance (avoids machine mowing) - Natural filtering of sediment is in line with principles of Taiao and kaitiakitanga
42
What are the advantages of swales?
- Simple construction and well-understood maintenance - Can help to separate road traffic and pedestrians - With suitable subsoil, can provide area for infiltration - Use of rocks as check-dams can provide additional (minor) storage
43
What are the disadvantages of swales?
- Can pose danger to traffic pulling off road - Occupies a signficant corridor of land - Not suitable on steep slopes exceeding 8% or on geotechnically unstable ground - Not suitable for extreme event management or volume control
44
What are the different types of swales?
Grass swale: - Most simple - Provides good sediment removal - Vegetation can be more complex Bio-swale: - Some crossover with biofiltration device. - Sandy or engineered media area for various chemical and biological processes including denitrification Wet swale: - Like an elongated wetland - Constant standing water in the bottom
45
Swales have good removal capability of:
- Sediment - Temperature Also, moderate removal of oil & grease, heavy metals. and pathogens.
46
What treatment mechanisms do swales use?
- Filtration - Sedimentation - Adsorption
47
When is it desirable to select a swale?
- Main goal is natural conveyance - Collection along large area (e.g. road length) - Low maintenance and cost - Small degree of detention
48
When is it not desirable to select a swale?
- Steep slope - Low structural-load bearing soil - Thermal load to water - High ground water table - high sediment load with no pretreatment
49
What are bioretention/rain gardens?
Planted depressions/lowered gardens with deep engineered media base for storing and filtering water prior to infiltration to groundwater or passage downstream. (Rain gardens, tree pits, stormwater planters, bioretention swales)
50
What are some advantages of bioretention/rain gardens?
- Provides retention, detention and treatment - High level of treatment comparative to other natural techniques - Provide enhanced aesthetic, ecological and amenity benefits - Easily incorporated into traditional landscaping
51
What are some disadvantages of bioretention/rain gardens?
- Specific construction and maintenance required - Plant establishment and replacement during startup - Not suitable for extreme event management or volume control
52
How do bioretention/rain gardens align with Mana Whenua?
- Provides treatment through soil and can eliminate mixing of waters through retention - Suitable for native plants. Could be harvestable - Typical locations are suitable for educational signage of cultural context and area history - Hand weeding aligns with principles of Taiao and kaitiakitanga
53
What are the different types of bioretention devices?
- Raingardens - Tree pits - Planter box - Bioretention swale
54
Bioretention treatment devices have excellect removal capability of:
- Sediment - Oil & grease - Pathogens - Temperature Good removal of organics, nitrogen, heavy metals.
55
What treatment mechanisms do bioretention devices use?
Uses filtration, sedimentation, adsorption, degradation through soil, volatization, denitrification, vegetation uptake, detention storage.
56
When is it desirable to use bioretention devices?
- Infiltration is desired - Treatment is necessary - Amenity / greenspace contribution - Localised small systems for upstream management
57
When is it undesirable to use bioretention devices?
- High groundwater table - Low permeability soils - Maintenance costs
58
What is a dry retention pond (soakage basin)?
Basins that are designed to fill with water during a storm event, percolating it slowly into the gorund below. During dry periods, they can serve as spaces for other activities.
59
How can dry retention ponds align with Mana Whenua?
- Incorporate upstream treatment to ensure no mixing of clean and unclean water in the subsurface - Cultural monitoring during excavation
60
Dry retention ponds have excellent removal capability of:
Sediment, oil & grease, pathogens, storm volume, temperature. Good removal of organics, heavy metals. Moderate removal of nitrogen and phosphorus.
61
What treatment mechanisms do dry retention ponds use?
Uses filtration, sedimentation, adsorption, removal with sediment,
62
When is it desirable to use dry retention basins?
- Large-scale retention is required - Prefer public owned than private owned infiltration facilities - Downstream end of process - Amenity is important - Upstream treatment elements exist
63
When is it not desirable to use dry retention basins?
- Land area is critical - Shallow groundwater - Impermeable or too permeable soils - Sloped land
64
What are pervious pavement?
Solid surfaces designed for pedestrians or traffic that also allows the infiltration and detention or percolation of water beneath the surface through a porous structure. (Porous asphalt, permeable pavers, porous pavers, stabilised aggregate)
65
What different characteristics do different types of pervious pavement have?
- Hydraulic conductivity - Strength - Maintenance - Clogging - Appearance - Cost
66
Pervious pavement has good treatment capability of:
Temperature. Moderate removal of sediment. Effectively no treatment.
67
When is it desirable to use pervious pavement?
- Infiltration is desired - No room for swales - Low maintenance - Avoid pooling and sheet flow on impervious surfaces
68
Why might it not be desirable to use pervious pavement?
- High sediment load - Installation cost - Heavy traffic area. High surface shear forces - Sloped areas
69
What are dry detention ponds?
Basins that are designed to fill with water during a storm event, releasing it slowly to the downstream stormwater system. During dry periods they can serve as spaces for other activities.
70
How do dry detention ponds align with Mana Whenua?
- Planted with natives. Can be used for harvesting. - Incorporate educational signage
71
What are some advantages of dry detention ponds?
- Attenuate downstream flows to minimise flooding and erosion - Provide green space for amenity/activity between storm events - Aesthetically pleasing greenspace in urban and suburban areas - Easier maintenance than wet pond detention systems
72
What are some disadvantages of dry detention ponds?
- Temporary standing water can be a safety hazard - Creates a dammed water hazard - No retention or significant improvement in water quality
73
Dry detention ponds have excellent removal capability of:
Storm volume (via detention)
74
Why might it be desirable to use dry detention basins?
- Large-scale detention is required (volume control is the goal) - Prefer public owned than privated owned facilities - Mid- to down-stream process - Upstream treatment elements exist
75
Why might it not be desirable to use dry detention basins?
- Land is restricted - Sensitive cold-water fish community downstream - Poor structural-quality soil - Sloped land - Treatment is necessary objective
76
What is a wet detention pond?
Basins that permanently hold water and can provide additional live storage detention as flows increase, but releasing water more slowly from the outlet.
77
How do wet detention ponds align with Mana Whenua?
- NOT SUPPORTED? [Mixing of stormwater (dirty) with existing (clean) waterbody. - Native plants, amenity, biodiversity
78
What are some advantages of wet detention ponds?
- Attenuate downstream flows to minimise flooding and erosion - Aesthetically pleasing landscape in urban and suburban areas - Natural haven for avian and aquatic species - Enhanced green corridor for existing riparian environments
79
What are some disadvantages of wet detention ponds?
- Standing water can be safety hazard (drowning) - Can attract mosquitos and other pests/vectors - No retention or significant improvement in water quality - Can cause increase in water temperatures
80
Wet detention ponds have excellent removal capability of:
Storm volume. Good removal of sediment. Moderate removal of oil & grease, organics, nitrogen, phosphorus, heavy metals.
81
Why might it be desirable to use wet detention basins?
- Large-scale detention required (volume control is primary goal) - Prefer public owned than private owned facilities - Mid- to down-stream process - Amenity and biodiversity aspects are important - Upstream treatment elements exist
82
Why might it be undesirable to use wet detention basins?
- Land is restricted - Sensitive cold-water fish community downstream - Poor structural-quality soil - Sloped land - Mana whenua alignment
83
What are some advantages of rainwater tanks?
- Allow water reuse (garden irrigation etc.) - Actively engage the public in stormwater management - Allow first flush capture to not leave the site - Do not require major earthworks - Can provide large portion of residential detention - Work well with downstream devices - Suitable for steep sloped areas - Good sediment removal
84
What are some disadvantages of rainwater tanks?
- Distributed maintenance responsibilities to public, with regular inspection and cleaning - Cost per tank owner - Poor aesthetics - First flush may get discharged with no treatment
85
How do rainwater tanks align with Mana Whenua?
Reuse or recharge is in-line with kaitiakitanga, Mauri Tu and Taiao
86
What are (constructed surface) wetlands?
Densely planted ponded areas utilizing submerged and riparian plants that mimic chemical and biological processes occurring in natural wetland systems.
87
How can wetlands align with Mana Whenua?
- Involvement in early design - Plant species selection, including harvestable species - Educational and cultural signage - Align closely with principles of kaitiakitanga, Taiao and Mauri Tu
88
What are some advantages of wetlands?
- Reduce downstream flood potential and erosion - Water quality improvement (treatment) - Aesthetics - increased amenity value for communities, including educational opportunities - Increased biodiversity
89
What are some disadvantages of wetlands:?
- Does not provide significant detention relative to size - Plant selection can be limited and plant maintenance is intensive - Can attract pests if not well maintained - Can potentially increase water temperature if insufficient shading from vegetation
90
Wetlands have excellent removal capability of:
Sediment, oil & grease, organics, heavy metals. Good removal of nitrogen, phosporus, storm volume. Moderate removal of pathogens, temperature.
91
Wetlands use the following treatment mechanisms:
- Filtration - Sedimentation - Adsorption - Removal with sediment - Biodegradation - Denitrification - Degradation through soil - Vegetation uptake - Detention storage
92
Why might constructed wetlands be desirable?
- Treatment required - Flow attenuation desired - Downstream end of process - Amenity aspect important - Shallow groundwater
93
Why might constructed wetlands not be desirable?
- Land area is critical - Maintenance budget low - Receiving environment has sensitive cold-water fish - Sloped land
94
What are some building-integrated systems?
- Green/Living roofs - Green/Living wall
95
What are green/living roofs?
Planted rooftops designed to filter and slow the runoff or precipitation on the urban structure, while providing other building amenities and utility.
96
How can green/living roofs align with Mana Whenua?
- Align with principles of Taiao (protection of environment) - Provide opportunity for native species introduction into urban environment - Depending on building type, can provide educational opportunities
97
What are some advantages of green roofs?
- Reduced visual impact of buildings (urban greening) - Pervious device - Improved building thermal efficiency - Improved noise abatement - Urban dust and particulates air filtering - Reduced urban heat island effect
98
What are some disadvantages of green roofs?
- High construction costs and increased structural requirements of building to support it - Intensive system startup - High maintenance costs - Not suitable for extreme event flow management - Potential for increase insect/pest presence around building
99
Green roofs have excellent removal of ____ and moderate removal of _______.
Temperature Sediment, oil & grease, organics, nitrogen, phosphorus, heavy metals, pathogens, storm volume (Filtration, adsorption, microbial, uptake)
100
Why might it be desirable to use green roofs?
- Onsite retention is desired - Reduce onsite impervious area - Urban greening - Building envelope benefits - Shallow groundwater preventing other infiltration based techniques - Sloped land
101
Why might it not be desirable to use green roofs?
- Low budget system required - Structural reinforcement of building required or roof too sloped - Maintenance requirements - Climatic conditions (snow, frost, seasonality)
102
What are green/living walls?
Planted walls designed to filter and slow the runoff of precipitation on the urban structure, while providing other building amenities and utility.
103
How can green/living walls align with Mana Whenua?
- Align with principles of Taiao (protection of environment) - Provide opportunity for native species introduction into urban environment - Depending on building type, can provide educational opportunities
104
What are some advantages of green walls?
- Reduced visual impact of buildings (urban greening) - Improved building thermal efficiency - Improved noise abatement - Urban dust and particulates air filtering - Reduced urban heat island effect - Not limited to buildings
105
What are some disadvantages of green walls?
- High construction costs and increased structural requirements of building to support it - Intensive system startup - High maintenance costs, especially taller installations - Not suitable for extreme event flow management - Potential for increase insect/pest presence around building
106
Green walls have excellent removal capability of:
Organics. Good removal of sediment, nitrogen, heavy metals, pathogens. Moderate removal of phosphorus, storm volume, temperature.
107
Why might it be desirable to have green walls?
- Onsite retention is desired - Urban greening - Building envelope benefits (thermal, acoustic) - Shallow groundwater preventing other infiltration based techniques - Polluted roofs requiring good level of treatment - Sloped land
108
Why might it not be desirable to have green walls?
- Low budget system required - Structural reinforcement of building - Maintenance requirements - Humidity and pests
109
How do you select a treatment system?
- Impervious surfaces? - Pollutants? - Nearby surface water body to be protected? Water quality sensitivity? - Soil permeability and groundwater table? Infiltration feasible? - Space constraints? - Budget and maintenance requirements? - Stakeholder engagement? - Safety?

ENCN347 (10 decks)

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