Final Study Terms Flashcards
how does water pollution happen?
- water pollution occurs when discharges of energy or materials degrade water
How is water pollution measured
Water pollution is measured by the concentration of pollutants in the water body and their effects on other water uses
What are some water pollutants of concern?
- Oxygen-demanding wastes
- nutrients
- thermal pollution
- toxic material
- acidification
- pathogens
What is one of of the most important measures of the quality of water?
DISSOLVED OXYGEN (D.O.) present
What is eutrophication?
A process whereby water bodies receive excess nutrients that stimulate excessive plant growth
This enhanced plant growth, often called an algal bloom, reduces dissolved oxygen in t he water when dead plant material decomposes and can cause other organisms to die
What are some causes of thermal pollution?
- Power plants creating electricity from fossil fuel and water used as cooling agent
- Deforestation of shoreline
- soil erosion
What are some toxic materials that can affect the health of aquatic organisms?
heavy metals (heavy metals only bad when they show up in large amounts due to industrialization)
pesticides (herbicides, insecticides, fungicides, nematicides, rodenticides)
volatile organic compounds (vinyl chloride, tetrachloroethylene PCE)
What are some effects of acidification?
Acid deposition (acid rain and acid particles)
Minerals (mercury, aluminum, lead become more soluble and therefore more harmful in low pH environments)
What are pathogens and how do they affect water quality?
Pathogens are disease-causing bacteria, viruses and protozoa, usually from human sewage
- Bacteria (cholera, dysentery, typhoid)
- Viruses (hepatitis)
- Protozoa (dysentery, giardiasis)
- Helminth (parasitic worms)
what are the steps of wastewater treatment?
***depends of effluent discharge requirements (ocean, inland stream, environmentally sensitive lakes, streams, estuaries, groundwater)
- Preliminary treatment
- Primary treatment
- Secondary treatment
- Advanced (tertiary) wastewater treatment
Classification of preliminary treatment (for wastewater)
pumping, screening, grit removal
Classification of primary treatment (for wastewater)
sedimentation (a portion of suspended solids and organic matter removed approx. 30% BOD and 60% TSS
Classification of secondary treatment (for wastewater)
Further treatment of effluent from primary treatment for residual organic matter and suspended solids removal approx. 90% BOD and TSS
Typically biological reactors (i.e. activated sludge process, trickling filter)
Classification of advanced (tertiary) wastewater treatment (for wastewater)
Effluent from secondary treatment may be further treated to reduce specific chemical constituents in wastewater (phosphorous, nitrogen) if discharged to environmentally sensitive estuaries
what are the mechanisms that affect DO in rivers?
oxygen demanding wastes removes DO
photosynthesis adds DO during the day
plants remove DO at night
respiration of organisms living in water and sediments removed DO
tributaries add their own DO inputs and DO demands
rising water temps reduces oxygen solubility in water
winter ice blocks atmospheric recharge
Describe the lake water quality for the season of winter
lake is thermally stratified with cold (approx 0 deg) water near the surface and warmer (2-4 deg) denser waters near the bottom
Describe the lake water quality for the season of spring
As the surface waters warm toward 4 deg in spring, they become denser and sink, bringing colder waters to the surface to warm
the process of mixing by convection, aided by wind energy, circulates the water column, leading to an isothermal condition termed spring turnover
Describe the lake water quality for the season of summer
As lake waters continue to warm above 4 deg, the lake thermally stratifies. Surface waters are significantly warmer and less dense than the lower waters during summer stratification
Describe the lake water quality for the season of fall
The input of solar energy decreases and heat is lost from the lake more rapidly than it is gained.
As surface waters cool, they become denser, sink, and promote circulation through convection, aided by wind, this phenomenon called fall turnover again leads to isothermal conditions
What are the different types of air pollution?
- industrial smog
- sulfurous smog
- photochemical smog
- criteria pollutants
- inside home/workplace pollution
What are the criteria pollutants
- CO
- NOx
- SOx
- VOC
- O3
- particulate matter PMx
What happens during unstable conditions of atmospheric stability?
- vertical movement of an air parcel in atmosphere is encouraged upward or downward
- Most commonly develop on sunny days with low wind speeds
- land surface quickly absorbs heat and transfers some heat to the surface air layer, air warms becomes less dense than surrounding air so it rises vertically
What happens during stable conditions of atmospheric stability?
- vertical movement of an air parcel is discouraged
- under very stable conditions, cooler layer of air near land surface is capped by an upper warmer air layer, this called inversion and prevents vertical motion of an air parcel
what happens during neutral stability conditions of atmospheric stability?
- occurs when the environmental lapse rate is same as dry adiabatic lapse rate, vertical movement of air is neither encouraged nor supported under these conditions
- typically occurs on a windy day when cloud cover prevents strong heating or cooling of the land
what is definition of temperature inversion?
occurs when a warmer layer of air resides above a cooler surface layer
- areas prone occur where large populations of humans reside (coastal zones, valleys, locations near mtns)
What are some environmental impacts of incineration?
- Emissions (chlorinated compounds, heavy metals)
- Collected ash - contains toxic materials (may have to be treated as hazardous waste, particulate matter size important)
favorable attributes to WTE incineration
- volume reduction
- immediate disposal
- less land requirement
- destruction of hazardous materials
- energy recovery
unfavorable attributes to WTE incinceration
- potential release of toxic substances
- potential hazardous ash recovery
- public perception
What some design criteria used for landfill design?
- solid waste quantity projections and site life requirements
- liner requirements
- leachate disposal requirements
- landfill support facilities
- landfill cover material requirements
- surface water management system requirements
- gas control requirements
- determine disposition of waste material already onsite
- local dimensional and construction methods requirements
- availability of local material, power and water, other utilities
- landfill closure requirements
Descriptors on leachate (how it forms, etc.)
- solid waste typically contains some moisture
- the water flowing through the waste is called leachate
- leachate contains dissolved contaminants from buried solid waste (TDS - total dissolved solids)
- Capture or restriction of leachate is controlled by liners, monitoring wells, piping, pumps and capping of landfill
What happens when waste starts to Decompose in landfills
decomposition is slow but it does happen
During the degradation, four processes happen:
- organic matter is stabilized
- leachate production
- landfill gas generation
- settlement
What are the different phases of landfill decomposition
- aerobic
- acid
- methanogenesis (unsteady)
- methanogenesis (steady)
Vancouver landfill gas collections facts
- goals in collecting and combusting landfill has include: odor reduction, landfill gas emission reductions, energy recovery
- methane has greenhouse gas potential of 21 times CO2
- collecting and burning PFG significantly reduces greenhouse gas emissions due to the conversion of methane to CO2
What are some of the materials used for closure of a landfill?
- solid to contour the areas to achieve design elevations
- a geomembrane liner as an impermeable barrier
- aggregate to convey landfill gas and stormwater to collection systems below and above the liner
- topsoil to support the growth of grass and future vegetation
definition of unsaturated zone
air, water and soil. water is held in tension and is considered unavailable
definition of water table
upper bound of the saturated zone
definition of saturated zone
water and soil. water flows as groundwater
definition of capillary fringe
up to 100% saturated but water is held in tension
definition of aquifer
saturated layer that is permeable enough to allow water to flow fairly easily through it. water can be pumped out at an economical rate
definition of aquitard
saturated layer that is not permeable enough to allow water to flow easily through it. water cannot be pumped out at an economical rate
definition of artesian
confined aquifer with water that flows upward out of a well (no pumping)
definition of perched
groundwater above a low permeability layer, usually above an aquifer
definition of groundwater
the water contained in interconnected pores below the water table in an aquifer
definition of groundwater flow
the movement of water through openings in sediment and rock; occurs in the zone of saturation
different types of containment transportation
- advection: due to groundwater
- dispersion: due to irregular flow paths
- diffusion: due to concentration gradient
What is advection (groundwater)
- movement due to groundwater flow
- contaminant (plume) moves with groundwater
- similar to a rubber ducky flowing on a river - it moves at the same speed as the river
What is dispersion (groundwater)
- due to irregular flow paths
- micro, macro and mega scale dispersions
- smaller pores = higher velocity
- higher velocities = higher dispersion
what is diffusion (groundwater)
- due to a concentration gradient
- contaminant plume moves from high concentration to low concentration
- important is low velocity souls (clays and bedrocks)
how are dispersion and diffusion similar?
they cause the contaminant (plume) to move beyond what would have been expected with just advection alone
what is sorption? (groundwater)
- refers to the property of a solute (dissolved) to either attach to the surface of a solid (adsorption) and/or then penetrate the solid (absorption)
- retardation causes the mean (average) contaminant velocity to be slower than the groundwater velocity
definition of NAPLs
do not readily dissolve in water
definition of LNAPLs
lighter than water
definition of DNAPLs
denser than water
definition of a non-aqueous phase liquids
- blobs, blebs, globules, ganglion, form as NAPL migrates through the subsurface
- immobile - not connected, do NOT flow
- long term source of groundwater contamination
- difficult to remove or remediate
what are some groundwater remediation technologies?
- fluid pumping technologies (groundwater pump and treat, SVE, air sparging)
- mass destruction technologies (bioventing, oxidation, MNA)
- enhanced fluid pumping technologies (heat, steam, high vacuum, surfactants)
- enhanced bioremediation technologies (reactive zone, election donors)
what happens during pump and treat?
- uses advective treatment methods to remediate contaminated aquifer (P&T) and vadose (SVE) zones
- advective methods rely on a fluid to move through the geology, have the contaminant transfer to the fluid, and then the fluid is brought above ground for treatment
- water and air have typically been those fluids
remediation technologies: pumping
- NOT CONSIDERED A REMEDIATION TECHNOLOGY ANYMORE
- used as a hydraulic containment technology
how are groundwater plumes controlled?
- hydrodynamic/hydraulic control
- extracted groundwater must be treated prior to release
what is a disadvantage of groundwater P&T
- rebound (tailing)) occurs due to:
- adsorption/desorption
- back diffusion
- NAPL ganglion
- Heterogeneities
what does SVE (soil vapour extraction) air flushing do for remediation?
- unsaturated zone - soil remediation
what does AS (air sparging) air flushing to for remediation?
saturated zone - plume remediation
what do PRBs (permeable reactive barriers do for remediation?
- passive interception and in situ treatment of dissolved contaminants in ground water
what are the two different types of PRBs?
- passive ( no moving parts, no pumping, no on-going additives)
- semi-passive (some maintenance activities, additives, etc.)
what is ISCO and how is it used as a remediation technology
- Oxidation chemically converts hazardous contaminants to non-hazardous or less toxic compounds that are more stable, less mobile, and/or intert
- oxidizing agents most commonly used are:
(ozone, hydrogen peroxide, permanganate)
when is ISCO used?
- used to remediate groundwater and soil
- applicable to a variety of soil types and grain sizes (silts and clays)
- applicable to treat (VOCs (PCE, TCE, DCE, BTE)
- rapid destruction/degradation of contaminants
- produces no significant wastes
what is MNA (remediation technology)
- monitored natural attenuation
“naturally-occurring processes in soil and groundwater environments that act WITHOUT HUMAN INTERVENTION to reduce the mass, toxicity, mobility, volume or concentration of contaminants in those media”
when is MNA used?
- used as remedial alternative must be fully protective of human health and the environment
- typically used in conjunction with active remediation of source zones (removal, treatment or containment)
- use of MNA must be supported through scientific line-of-evidence approach
- monitoring must continue until remedial objectives are achieved
what is a reactive zone?
- created through injection of air, oxygen, O2 releasing compounds (ORC), etc
- designed to treat or immobilize contaminants through biodegradation
what is thermal remediation technology?
- soil or groundwater
- heat can destroy or volatilize contaminants
- in-situ technology - uncertainties related to uniform heating/treatment due of subsurface variabilities
what are the different types of thermal remediation technologies?
- electrical resistivity heating
- conduction heating
- steam injection
what is phytoremediation?
- uses plants to address contaminant issues
- objectives can be for (containment and control, removal and destruction)
what is phytoremediation applicable for?
- metals
- pesticides
- explosives
- oils
- solvents
- can also prevent wind, rain, and groundwater from carrying contaminants off-site
