Transcript C-1 Overview of WW and Systems Insp 2012

Overview of Wastewater and System
Types
Source
Distribution
Box
Septic
tank with
effluent screen
Drainfield (soil treatment area)
Soil
NC Certified Subsurface Systems Inspector School
Characterizing wastewater
• What’s in it?
• How much is there?
• What are the consequences of inadequate
treatment?
Composition of Domestic Wastewater
Toilet
Toilet
Laundry
Laundary
Bathing
Bathing
Kitchen
Kitchen
Garb.
Grinder
Garb.
Grind.
Misc.
Misc
Organic material
• Waste from plant or animal sources
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Can be dissolved, a solid or
a liquid
Broken down and consumed
by microbes (aerobes and
anaerobes)
As it decays, dissolved
oxygen is depleted
Measured as BOD5
Inorganic material

Stable compounds

Not easily broken down by microorganisms
 Minerals,

metals, dissolved salts
Sand, silt, cadmium, copper, lead, zinc, sodium
 Residential
flows have low metal content
 Stormwater, inflow and infiltration

Cracked pipes, leaky manhole covers
Solids
• Total solids
– Any suspended or dissolved material
• Organic or inorganic
• Settleable solids
– Heavier suspended particles that settle out during preliminary
treatment
Solids (cont.)
• Total suspended solids (TSS)
– Solids that don’t pass through filter paper
– Mixture of organic and inorganic particles
• Total dissolved solids (TDS)
– Solids that pass through a filter
– Minerals, salts, metals, ions
TSS impacts on treatment
 High levels lead to clogging
 Reduce efficiency of treatment system
 Block or plug distribution pipes
 Seal off and plug voids in soil and filters
Fats, Oils, and Grease
(FOG)
• Animal or vegetable-based FOG
– Residential kitchens
– Degradable by microorganisms
• Petroleum-based FOG
– Industry/automotive repair
– Bath oils, moisturizing cream, tanning oils
– Not readily broken down by microorganisms
Environmental impacts of FOGs
• Adds to thickness of septic
tank scum layer
• Clog pipes, treatment
systems, drainfields
• Collect and harden on
surface, trap trash, plants
and other materials
• Cause foul odors and attract
insect pests
FOG
Pathogenic organisms
Clostridium in
septic tank
Staphylococcu
s
Rhinovirus –
common cold
Influenza virus
Pseudomonas
in drainfield
E. coli
0157H7
Pathogenic organisms

Disease-causing organisms
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Bacterial, viruses, Helminths (worms), protozoa
Comfortable in human digestive system
Conditioned to living in low oxygen
conditions
Difficulty surviving in air-filled environments
Health impacts
• Pathogens can cause disease in humans
– Typhoid
– Cholera
– Dysentery
– Hepatitis
– Salmonellosis
– Poliomyeilitis
Bacteria
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Extremely common in sewage
Microscopic, single celled organisms
Found naturally
Host cell not needed for reproduction
Some are pathogenic – indicator organisms
– Fecal Coliforms
Fecal coliform
• Indicator microorganism
– Cultured in standard tests to
indicate contamination
• Measured as colonies/100 mL
Infectious dose and persistence
Infectious doses and pathogen persistence under optimal conditions
Pathogen
Infectious dose
Persistence
Viruses
1-10 particles
Months to years
Bacteria
Shigella
10 - 100 spores
Cholera
1,000 - 10,000,000
Campylobacter
100-1,000,000
Cryptosporidium
1 oocyst (10 in healthy
volunteers)
Giardia
10-100 oocysts
Roundworms
1- 10 eggs (embryonated)
Protozoa
Days to weeks
Months to 2
years
Weeks to 7 years
Helminths
Tapeworms
1-800
Nutrients
• Essential for growth of living organisms
 Major

nutrients
N, P, K
 Secondary

nutrients
Mg, Ca, S
 Micronutrients

Cu, Zn, Mn, Mo, B
Health impacts
• Nitrate (NO3-)
– Blue baby syndrome – methemoglobinemia
– Bloodstream is starved of oxygen
– May also be problematic to older adults
– Linked to miscarriages, birth defects, cancer
Environmental impacts of excess nutrients
• Eutrophication: nutrient enrichment of surface
waters
– Can occur naturally
– Accelerated by inefficient or incomplete
wastewater treatment
– Algal blooms, depletion of dissolved oxygen
– Fish kills and harm to other wildlife
– Surface scum, increased odor, insects
– Increases cost and difficulty of drinking water
purification
• Freshwater-phosphorous; Marine – nitrogen
Metals
• Inorganic chemical compounds
– NOT often found in residential wastewater
– Present in vitamins in very low amounts
– Stable and resistant to decomposition
– Some essential for animal & plant nutrition
– At higher levels some can be highly toxic
Persistent organic chemicals
• Stable organic compounds
– Slow to decompose; can persist in soil and
groundwater for years
– Many are synthetic
– Not usually found in residential wastewater unless
homeowner flushes something they shouldn’t
• Solvents & household cleansers
• Paint
• Medical products
Source
• The user
• The amount of flow
• Everything that goes down the drain
Wastewater Loading
• Quality
– Organic Load
• Quantity
– Hydraulic load
WASTEWATER QUANTITY
• Daily Flow
– Design
– Actual
• Flow Estimates
– People served
– Square Footage
• Peak Flows
– Daily - Runoff Period
– Weekly
– Seasonal
Wastewater Treatment Processes
• Physical
• Chemical
• Biological
– Aerobic
– Anaerobic
Point vs. non-point sources
• Point source
– Can identify the source
• Non-point source
– Source is less clear
Introduction
to
Onsite Wastewater Systems
Parts of a subsurface system
•
•
•
•
•
•
•
Source
Collection systems
Primary treatment or Pretreatment
Advanced treatment
Disinfection
Distribution
Dispersal
Source
• Flow
• Constituents
Flow
• Design daily flow
– Based upon projected flow from facility
• Bedrooms, seats, people
• Actual average daily flow
– Varies considerably
– Average daily flow >70% of design is a red flag
Collection Systems
• A collection system
– gathers wastewater from sources
– conveys it to treatment system
– components may include:
• sewer lines, force mains, manholes, pumps, holding tanks
• Types of collection systems
– Gravity
– Pressure
– Combined
Primary treatment components
• Typically, a septic tank
Advanced treatment components
• Some type of aerobic treatment
ATU’s
Media Filters
Disinfection components
• May be required to reduce pathogen levels
UV
Light
Chlorine
Distribution components
D-box
Pressure Manifold
Dispersal components
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Trenches
Beds
Low-pressure pipe (LPP)
Drip dispersal
Basic Types of Onsite Wastewater
Systems used in North Carolina
Basic Gravity System Components
Source
Distribution
Box
Septic
tank with
effluent screen
Drainfield
or
Soil Treatment Area
Soil
X-section of conventional trench
Innovative Trench
components: Gravelless
Systems
Shallow placement drainfield
Suitable Fill
Drainlines and Gravel
Aerobic Soil
Water Table
Areal Fill (“Mound”) drainfield
Suitable Fill
Trenches
Aerobic Soil
Water Table
Installation of mound
Pressure-dosed gravity
Source
Dosing
Tank
Septic Tank
with effluent
screen
Drainfield
Soil
Manifold in
Vault
Long manifold on flat site
Basic LPP System Components
Source
Dosing
Tank
Septic Tank with
Effluent screen
LPP Laterals
Aerobic Soil
Sleeved pipe
Low Pressure Pipe (LPP)
Basic Drip Irrigation System Components (Direct
ST Effluent)
Source
Dosing
Tank
Septic Tank with
Effluent screen
Headworks
assembly
Drip Laterals and supply
and return manifolds
Aerobic Soil
Basic Drip Irrigation System Components (Adv.
Treated effluent)
Source
Septic Tank with
Effluent screen
Media filter and
possible
recirculation
Dosing
Tank
Headworks
assembly
Drip Laterals and supply
and return manifolds
Aerobic Soil
Advanced Treatment
Sand, Peat, Textile, ATU
Single pass pressure dosed sand filter
with pump basin – cross section
ATUs
`
Questions?