Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Waste Management > Liquid Waste Test > Flashcards

Liquid Waste Test Flashcards

1
Q

Modern treatment

A

TSS

BOD5

Coliform CFU

Primary Treatment

Secondary Treatment

Tertiary treatment

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

TSS

A

Total suspended solids Measure of the total organicBacteria/inorganic particles

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

TSS equation

A

TSS = ((A – B) X 1000)/C Expressed in terms of mg/l where A = weight of filter paper and residue B = weight of clean filter paper C = volume of sample filtered ml

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Cons of TSS

A

Oxygen load sedimentation of receiving environment

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

BOD

A

Amount of DO “demanded” by aerobic organisms to break down the amount of organic material in a given water sample at a given temperature over time. *mg/L of oxygen.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

BOD5

A

*Test typically carried out at 20°C for 5 days in the dark* in a sealed container, *Requires active microflora and aerobic conditions

* Dark to eliminate photosynthesis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

BOD5 equation

A

BOD5 = (DOo – DO5) X 300 ml\ (Volume of sample ml)

where DO – dissolved oxygen = (mg/L)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

CFU

A

=colony forming units: coliforms are indicators of sewage pollution and proportional disease potential.

*Beaches close when the geometric mean of the sampling results exceeds 200 CFU/100 mL of water.

*screened raw sewage: Clover and Macaulay Points: (range of 3 to 13 × 106 CFU/100 mL)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Degrees of Treatment

A
  • Preliminary
  • Primary
  • Secondary
  • Tertiary
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Peliminary Treatment

A

Screens (6-25 mm) out coarse solids (rocks, rags, plastics, etc.) and grit (sand/gravel), landfill.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Primary treatment

A

Primary treatment screens wastewater, and performs some rudimentary Clarification/Settling treatment to remove crude solids and skim off grease, oil and fat.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Secondary Treatment

A

Secondary (or biological) treatment removes DO-demanding organic substances by using bacteria to convert degradable organic matter into bacterial cells (Reduces TSS/BOD). The wastewater is then clarified by separating treated liquid from grown bacterial cells by settling.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Tertiary Treatment

A
  • also referred to as effluent polishing.
  • Tertiary processes include filtration, lagooning, nutrient removal, and disinfection: eg. Chlorination and de-chlorination, UV.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Modern Liquid Waste Disposal

A
  • Septic Tanks
  • Discharge to a water body
  • Treatment Plants
    • Publicly Owned Treatment Works (POTW)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Septic Field Systems

A
  • In areas where large scale municipal sewers are not available, landowners use on-site wastewater disposal and treatment.
  • On-site wastewater treatment allows for the collection of waste, removal of material through settling and dispersion of effluent through soil
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Septic Tank Regulations Health Act

A
  • Subject to subsections (3) and (4) (b), a person must not construct

(a) a holding tank less than 15 metres from a well, or
(b) a sewerage system less than 30 metres from a well.

combined domestic sewage flow of:
< 22.7 m3/d (22, 700 l/d)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Types of Septic Systems

A
  • Type 1
    • treatment by septic tank/field only ”anaerobic”; 50-60% solids reduction; soil filtration.
  • Type 2
    • effluent consistently TSS < 45 mg/L and BOD5 < 45 mg/L, Aerobic- O2 injection; lower solids = smaller drainage field
  • Type 3
    • TSS < 10 mg/L, BOD5 < 10 mg/L
      median < 400 CFU/100 mL
      O2 injection; disinfection: chlorination/de-chlorination, ozone, or UV light. Smallest fields
    • Good for soil depth < 15cm (0.5 ft.); slow percolation rates
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Regulations EMA

A
  • this regulation applies to all discharges to ground and water if flows are: ≥ 22.7 m3/d (22,700 l/d)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

CSO

A
  • Combined sewage outfalls
  • have highly variable discharges; some infrequently, while others activate every time it rains.
    ex, late summer storms, when it has not rained for a while, have the most pollutants. ….oil, grease, fecal coliform from pet and wildlife waste, and pesticides enter the sewer system.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Direct ocean discharge

A
  • Preliminary treatment using 6mm screens
  • Eg.
    • Clover Point:
      - 1.16 km offshore,
      - 200 m multiport diffusers
      - 65 metres deep. Maximum Daily Flow:
      118,600 m3/day = 118,600,000 l/day
    • Macaulay Point:
      - 1.72 km offshore,
      - approx. 150 m multiport diffusers
      - 60 m deep.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Preliminary wastewater treatments

A
  • Screens
    • remove chunks of wood, rags, plastics that could clog pipes and equipment.
  • Comminutors
    • cutter blades after screens to chop and shred solids and rags that pass screens.
  • Grit Chambers
    • reduce input flow velocity allowing heavier mechanically abrasive/nonbiodegradable particles (sand, stones, coffee grounds, eggshells) to settle prior to entering pump systems and primary treatment stages.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Primary Treatment wastewater

A
  • gravity SETTLING tanks: “primary clarifiers”
  • Detention times typically 1-3 hours
  • Mechanical sludge collectors remove settled solids to sludge hoppers
  • Surface skimmers to remove floating grease and other floating materials.
    (Preliminary screening and gravity settling comprise primary treatment)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

Secondary Treatment wastewater

A
  • Biological treatment: uses microbes such as bacteria and protozoa to reduce suspended solids and BOD (typically by 85%) by using the organic pollutants as food
  • Aerobic process; requires O2
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

2 common types of biological (secondary) treatment systems:

A
  • Activated Sludge process eg. SPWWTP
  • Trickling Filter
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

Activated Sludge Process

A
  • Microbial sludge from treatment process are introduced into an aeration tank forming an active suspension of biological solids called activated sludge.
  • Activated sludge and wastewater = mixed liquor.
  • Aeration: O2 for organics decomposition
    • vigorous mixing for microbial/sewage contact.
    • typically requires about 6 hrs of aeration.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

Microbial Growth Curve - Activated Sludge

A
  • Instead, growth follows a typical pattern that has a lag phase, exponential phase, maximum stationary phase and death phase.
  • F/M Food to Microorganism ratio important
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

Trickling Filter

A
  • Typically a bed of crushed rock covered with an active slime film of microbial populations which aerobically decompose organics in the wastewater.
  • primary treated wastewater is sprayed onto the filter surface.

-Rocks are 75mm (3 in) so do not filter, but provide a large surface area for microbial contact and
biodegradation.

-Filter effluent is conveyed to the
secondary clarifier.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

Tertiary Wastewater Treatment

A

Remember.. Seconary treatment:

  • removes 85-95% of TSS and BOD, leaving around 30 mg/l of each in 2o effluent. But not nutrients, pathogens, inorganics, toxic substances..

**Tertiary treatment is generally only used in sensitive environments due to its costliness. ..often doubling the cost of secondary treatment.

**mostly applied in wastewater discharges to rivers, lakes or sensitive marine environments.

29
Q

Removal of nutrients in tertiary treatment: Nitrogen

A
  • Biological nitrification-denitrification
    • 2 step process (“advanced secondary treatment”)

*Nitrification - Secondary effluent (low in organics) sent to alternate (low O2) tank where chemoautotrophic nitrifying bacteria convert NH3 -> NO3 (less toxic , but still N) .. Aerobic

*Denitrification - Methanol (for carbon source), and O2 added to effluent: denitrifying bacteria convert NO3 -> N2 (to atmosphere) … Anaroebic

30
Q

Removal of nutrients in tertiary treatment: Phosphorus

A
  • Inputs from urine and feces and… synthetic detergents
    • typically chemical precipitation and coagulation
    • using Al2SO4 (alum) (also FeCl3, Ca)

Al ions react with PO43- to form insoluble precipitate (AlPO4) which settles out.

  • Coagulants can be added at primary or secondary clarifiers or aerated sludge stage.
31
Q

Tertiary treatment: Lagoons

A
  • Cost effective if you have the land and the time
    –retention times from 2-3 days to weeks depending
    on flow requirements. Increased TSS/BOD reduction
  • Prolonged solids settling and biological degradation: native plants, bacteria, algae, and small zooplankton filter nutrients and small particles (pathogens) from the water.
  • Tertiary level lagoons typically aerobic; depth 0.5 to 1.5 m to facilitate photosynthetic algae ( N and P uptake/removal)
32
Q

Tertiary Treatment: Effluent polishing

A

Filtration:

Sand filtration
Microscreen filtration
Membrane filtration
Activated Carbon

33
Q

Tertiary treatment: Filtration

A
  • Particulate matters are retained in the filter material through straining, adhesion and adsorption.
  • Constant buildup of particulates decreases flow and increases pressure in system.
  • Backflushing is required to periodically clean filters.
34
Q

Tertiary: Sand filtration

A
  • Sand filtration: can be gravity fed, but typically involve pressurized rapid flow filters, with auto backflushing cycles.
  • Smaller sand grains provide more surface area and higher removal efficiency, but require more pump
    pressure and more frequent backwashing.
  • Most use grain in the range 0.6 to 1.2 mm.
35
Q

Tertiary: Microscreens

A
  • Microscreens: woven steel wire mesh as small as 20μm
  • Typically screens configured as a rotating drum, with effluent entering into the drum and exiting through the microscreen perimeter.
36
Q

Tertiary: Membrane filtration

A
  • Membrane filtration: is a generic term for a number of different, very characteristic separation processes.
  • Specific pore sizes for target contaminants:
    Microfiltration ≥ 100 μm
    Ultrafiltration ≥ 10 nm
    Nanofiltration ≥ 1 nm
    Reversed osmosis < 1 nm
37
Q

Tertiary: Activated carbon filter vessels

A
  • based on activated carbon adsorption: high degree of microporosity, just one gram of activated carbon has a surface area in excess of 500 m2,
38
Q

Tertiary: Pathogen disinfection

A
  • Chlorination/Dechlorination
  • UV Disinfection
  • Ozone
39
Q

Chlorination/Dechlorination

A
  • Oxidizes cell wall and enzyme constituents
    • relatively low cost, proven effectiveness in achieving the required pathogen kills.
    • Residual chlorine is toxic to biota so effluent must be dechlorinated prior to discharge
    • Regulation requires the residual chlorine is to be limited to 0.01 mg/L (10 μg/L)
40
Q

UV Disinfection

A
  • (254 nm)
  • destroys the nucleic acids in pathogenic organisms, disrupting DNA, disabling vital cellular functions: mutagenic to bacteria, viruses and other micro-organisms.
  • UV disinfection is most effective in high clarity purified water (i.e. reverse osmosis ) as microorganisms buried within suspended particles may be shielded from the UV light and pass through the unit unaffected.
  • Highly filtered water also facilitates transmittance of UV throughout the effluent water column.
41
Q

Ozone O3

A
  • very strong oxidant and virucide.
    Direct oxidation/destruction of cell walls and nucleic acid.
  • Requires an ozone generator: O3 gas stream is pumped into effluent contact chamber……”bubble stream”.
  • Ozone is more effective than chlorine in destroying viruses and bacteria.
  • no harmful residuals that need to be removed after ozonation ; ozone decomposes rapidly. May increase DO due rxns with water
  • Expensive infrastructure and power requirements
42
Q

Biosolids

A

Sludge

The residuals of suspended solids that form at the bottom of the wastewater treatment clarification tanks.

  • Under proper circumstances, sludge can be put to beneficial (fertilizer)use…therefore affectionately termed Biosolids

*May contain any various levels of metals, toxins, residual pharmaceuticals etc. derived from residential and industrial sewage origins.

*2 classes

  • Class A & Class B

*The sludge is transformed into biosolids using a number of treatments such as thickening, dewatering, drying, and lime/alkaline stabilization.

*Biosolids are initially 3 to 7% solids, but may reach 30% after dewatering and 40% after drying for 6 weeks….now “liftable”.

43
Q

EMA: Biosolids

A
  • Organic Matter Recycling Regulation (OMRR)

*allow the sludge to be beneficially recycled in accordance with the requirements of this regulation

44
Q

Class A & Class B Biosolids

A
  • Class A: Highest quality biosolids achievable under OMRR; lower fecal coliforms and lower trace elements than
  • Class B: More liberal application permitted…but not in CRD
45
Q

Wastewater treatment program CRD

A
  • wishes to establish a Commission for the purpose of administering the Core Area Wastewater Treatment Program.
  • The Commission is a separate, project-specific body established by bylaw that oversees the execution of the Seaterra Program. It ensures the program will be delivered on time, within budget and meet the desired environmental and social outcomes. The Commission oversees the procurement process for all components of the Program.
    The Commission operates autonomously of the Committee and Regional Board. However, the Commission is required to seek CRD Board and funder approval on pre-determined items as detailed in the CRD bylaw.
46
Q

Metals: Liquid waste

A

Many metals are required in TRACE amounts in living orgasms for enzyme activity, in higher concentrations they are toxic.

Heavy metals do not just disappear during treatment, they are either in the resulting water, in the sludge or in residuals after filtering!

47
Q

Toxic effect of metals

A

Many metals **Bioaccumulate ** in the soft tissues of animals. Once absorbed, compete with other ions and bind to proteins, leading to impaired enzymatic activity resulting in damage to many organs throughout the body.

Mercury (Hg): Causes damage to nervous system, kidneys,
and vision. Concern for fetal development
**Lead (Pb): ** Causes damage to kidneys, nervous system,
learning ability, ability to synthesize protein,
and nerve and red blood cells.
Cadmium (Cd): Causes damage to kidneys.
**Arsenic (As): ** Causes damage to skin, eyes, and liver.
May also cause cancer

48
Q

Heavy Metal Inputs

A
  • Commercial inputs
  • Domestic inputs
  • Storm Runoff
  • ….and natural sources (soil erosion)
49
Q

Few problems associated with heavy metal influent

A
  1. Contributes to effluent aquatic/marine toxicity
  2. Bioconcentration effects limit the ultimate disposal
    options for stabilized sludge (biosolids)
  3. High concentrations of heavy metals in wastewater
    can cause toxic shock to activated sludge ….lowers
    efficiency…possible restart of system ($)
50
Q

Removal of Heavy Metals: Methods

A
  • Adsorption
    - Activated sludge
    - Activated Carbon
  • Phytoremdiation
  • Chemical precipitation
  • Ion Exchange resins
51
Q

Activated Sludge: Adsorption

A
  • Entrapment of precipitated metals in the sludge floc matrix
  • Extracellular adsorption of soluble metals
  • Assimilation and accumulation of metals within the cell.

To be removed, adsorbed metals have to be transferred into the liquid phase…… then the liquid phase treated.

52
Q

Treated liquid phase after adsorption: (AOR technology)

A

Heller process

  • Acid combination (HNO3, H2SO4, *) solubilizes heavy metals from sludge,
  • complexing agents precipitate metals from liquid phase,
  • oxidizing conditions destroys bacterial pathogens and many toxic chemicals(herbicides/pesticides)
  • Dewatering and pH balancing of biosolids further dilutes remaining metals

……..smelter process is one option available to recover the extracted heavy metals

53
Q

Treated liquid phase after adsorption: Phytoremediation

A
  • Various plant species are Hyperaccumulators that bioaccumulate metals from soils/biosolids
    -mustard plants, alpine pennycress, hemp, ferns,
    pigweed…
    • Pros: inexpensive, natural process-low
      environmental footprint, phyto-mining
    • Cons: Long term commitment (slow growing)
      Limited to depth of roots; Food chain concerns..
  • ex.. Chinese ladder brake, Indian mustard, Cannabis sativa
54
Q

Treated liquid phase after adsorption: Activated Carbon

A
  • Adsorption using activated carbon is the most efficient classical method
  • Powdered Activated Carbon Treatment (PAC)
  • Granular Activated Carbon Treatment (GAC)
  • removal rate from water can be more than 99% for various metal ions.
  • Low-cost or bioadsorbents (e.g. zeolite, peat, eggshells, shell fish (chiton)… Incinerated municipal garbage flyash, etc
55
Q

PAC

A

Powdered Activated Carbon Treatment

  • Powdered AC added directly to 1o, 2o or activated sludge tanks, becoming a component of the resulting sludge.

*relatively high cost and separation of biosorbents from sludge still a problem (no recycling or regeneration) = “secondary waste”

56
Q

GAC

A

Granulated Activated Carbon Treatment

  • Granulated form commonly in filter beds/canisters
    Granular form relatively easy to collect regenerate and recycle
  • Three commonly used types of GAC processes:
  1. Fixed Bed
  2. Multiple Fixed Bed…Series Reactors
  3. Pulsed (Moving Bed) System
57
Q

Fixed Bed:

A
  • Stationary Bed: BATCH system
  • Stationary Bed: SERIES system
  • Moving Bed: system
58
Q

Stationary Bed: BATCH system

A
  • must be shut down for renewal/backwashing
  • used in situations with very low influent concentrations and relatively low flows.
  • Typically gravity fed
59
Q

Stationary Bed: SERIES system

A
  • redundant series system; one filter shut down for renewal/backwashing while others remain on line.
  • produces a higher level of treatment due to passes through multiple filter beds.
  • also used in situations with very low influent concentrations and relatively low flows….influent under pressure (pumped)
60
Q

Moving Bed: system

A
  • System can operate continuously without shutdown for media renewal.
  • Wastewater pumped in through bottom-Fresh AC media constantly fed in from top- spent media removed from bottom and discarded or regenerated
  • used in high water flow rates and/or high influent solute concentrations applications.-…pumped.
61
Q

Thermal regeneration of Activated Carbon

A
  • Thermal regeneration generally involves the following steps:
    • Drying at 100-150 Co to remove H2O
    • Volatilization of lighter organics at 150-315 Co
    • Pyrolysis of heavier organics up to 800 Co
    • Regeneration of AC up to 1040 Co

Non volatiles (metals) accumulate and must be disposed of or chemically extracted (by caustic (eg. NaOH) or acid (eg.H2SO4) stripping… more $

62
Q

Limitations on filtering activated carbon treatment

A
  • Systems can not tolerate suspended solids in the influent stream (due to clogging).
    - Limited to wastes with low organic concentrations (< 5%).
  • High operating costs due to carbon costs /system requirements. (AC costs @ $ 800-2000/tonne)
  • Disposal of contaminated carbon can be problematic if it is not regenerated.
63
Q

Chemical Precipitation

A
  • Most common: Precipitation by hydroxide formation method…….
    • Eg. Using NaOH, or Ca(OH)2, optimum pH 8 – 11
    The precipitation typically follows the reaction:
    Mn+ + nOH- M n+(OH-)n
  • Alum (Al2(SO4)3) added to act as flocculant to enhance settling………up to 99% removal possible

*Sludges still a problem …… If metal settling stages not segregated from other process flow sludges.

64
Q

Ion Exchange Resins

A
  • Ion exchange resins are water-insoluble polymers which can absorb positively charged ions from solution and release equivalent amounts of other (less toxic) positive ions into the solution. Removal of > 99% of metals with selective resins
  • The positively charged ions in cationic resins such as H+ are exchanged with positively charged metal ions, in the wastewater.
  • Regenerated with strong acid solutions (used resin typically transported offsite for treatment).

(Sludge metals must be acid solubilized prior to Resin treatment).

65
Q

Biosolids Management: After thickening and dewatering

A
  • Lime Stabilization
  • Digestion
    - Aerobic  \< 5MGD
 - Anaerobic  \> 5MGD biogas
66
Q

Lime Stabilization

A
  • *OMRR: Schedule 1**
  • *Class A Biosolids:** > pH 12 for 72hrs (>52 Co for at least 12hrs), then air dried at >pH12 to 50% solids.

Addition of lime (CaO): increases pH up to 12.4

  • (cell membranes/pathogens destroyed)
  • vector barrier to infesting flies and insects
  • CaO has low solubility = persistent, inhibits pathogen regrowth
  • CaO/H2O reaction (exothermic)= to 70 Co……pasteurization
  • high pH reduces solubility and mobility of metals
  • Ca ions react with sulphur species (eg H2S) to destroy odors
67
Q

Aerobic Digestion

A
  • Essentially a continuation of the activated sludge process. Wastewater pumped from 2o clarifier to aerobic digesters
  • Pros:
  • Reduction of degradable solids of 40-50%
  • Lower capital costs/maintenance
  • Shorter retention times (6-8 days) vs anaerobic (15-20 days)
  • Cons:
    Final sludge harder to dewater
    Indicator organisms often present in final sludge; odors
    Open tanks have To fluctuations which may reduce efficiency
68
Q

Anaerobic Digesters

A
  • Organic matter + H2O CH4 + CO2 + H2O
  • Pros:
  • Reduction of solids (25-45%) for disposal or processing
  • Efficient pathogen reduction
  • CH4 production…clean fuel for plant power generation
  • Mesophilic/Thermophilic heat production
  • reduced odors
  • Cons:
  • High capital costs
  • Organic loads in residual liquid may require treatment.
  • Longer retention times; 15-20 days
69
Q
A

Waste Management (3 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions