Transcript IDEM Operator Certification Information Part I

Wastewater Operator
Certification Information
Terms
CWA – Clean Water Act passed in 1972
 NPDES – National Pollutant Discharge
Elimination System – permit good for 5 years
(must reapply 180 day prior to expiration date)
 PE – Population Equivalency – how plants are
designed – design for 20 years future growth
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PE, capita = (Flow, MGD)(BOD, mg/L)(8.34lb/gal)
0.17 lbs/BOD/capita/day
* An operator should be present during construction to become
familiar with the plant, including the equipment, machinery and
the operation of it. Provides you with the opportunity to relate
your plant to the drawings.
Overview
Collection Systems
 Rain Water I & I
 Wastewater Flow
 Preliminary Treatment
 Secondary Treatment
 Solids Handling
 Tertiary Treatment
 Laboratory
 Safety
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Rain Water Inflow and Infiltration
(I&I)
Enters collection system through cracks and
holes in pipes, open cleanouts, cross
connections, manholes, #1 cause – leaking
pipe joints
 Can cause hydraulic overload at WPCF,
decreased capacity due to sand and grit
accumulation, lift station pump failures and
overflows, increased operating costs
 Accounts for 30% of wastewater flow
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Liftstations
Must maintain a velocity of 2ft per second
to stop solids from settling and H2S from
forming, when unable to reach that velocity
build a lift station – lift flow to a higher
elevation where it can again flow by gravity
 Has forced ventilation to prevent toxic gas
fume build-up
 Most common is air-lift pump
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Wastewater Contents
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Domestic waste is 99.9% water
Contains pathogenic (disease causing) bacteria,
viruses, cysts that can cause Typhoid, Cholera,
Dysentery, Polio and Hepatitis
Floatable – floats to surface (scum & grease)
Settleable – settles to bottom
Suspended – won’t float or settle (same weight as
water)
Dissolved – such as food dye
Colloidal – finely dissolved that remains in
suspension causing turbidity (cloudiness) due to
its size and electrical charge
Raw Wastewater Solids Composition
Wastewater is
99.9% water
Dissolved solids makes up
the highest percent of solids
Dissolved and
Suspended
Solids make up
Total Solids
Preliminary Treatment
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To remove material that can damage or plug up
equipment – grit, rags, plastics, sticks, etc.
Flow Equalization / Surge Basins
Bars Screens / Bar Racks
Moving or Rotating Screens
Shredding / Grinding
Grit Chambers / Channels
Odor Control
Pumps (not considered treatment, but located in
head works of plant)
Pumps
Impeller vane
damage
Cavitation
 The formation of partial vacuums in a liquid
by a swiftly moving solid body (as a
propeller) or by high-intensity sound waves
 The pitting and wearing away of solid
surfaces (as of metal or concrete) as a result
of the collapse of these vacuums in
surrounding liquid
Sedimentation and Floatation
Sedimentation and Floatation happens in
both Primary and Secondary (or final)
clarifiers
 Purpose – to remove settleable and
floatable solids from raw ww
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– Organic solids have high oxygen demand
(BOD)
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Primary Clarifiers follows grit removal
– Velocity 1.0 to 2.0 feet per minute
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Secondary Clarifier follows any biological
treatment
Primary VS Secondary Sludge
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Primary is denser (heavier)
Primary is darker in color
(dark chocolate)
Effluent (liquid on top) is
gray in color
Secondary is lighter is color
(milk chocolate)
Secondary is mainly
microorganisms (lighter)
Effluent is clear
Rotating Biological Contactor
(RBC)
Mechanical or air operated drive units rotate the
media through wastewater
 Biomass is attached to the moving media (attached
growth)
 40% of the media is immersed in ww
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Covered
RBCs
Sequencing Batch Reactors (SBR)
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Treatment is carried out in a single tank
through sequencing stages
Handles periodic flows or batch dumps with
ease
Especially well suited for industries
– Automatic control through Programmable Logic
Control (PLC)
– Stable due to high sludge age and long retention
time
– Less costly to build – no need for sludge handling –
can be sent directly to drying beds or composting
process
BOD/N/P
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The ratio of biochemical oxygen demand to nitrogen to
phosphorus should be 100/5/1. If the organic loading
rate increases the appropriate N & P need to be added
at a point where the incoming wastewater is highly
mixed to provide nutrients needed by the microbes.
The pounds of N & P required per day will be about
10% of the organic solids (dry weight) produced every
day. The P required will be one-fifth of the N
requirement. The amount of P & N added daily are
equal to the difference between the quantity required
and the quantity in the waste. Aqueous ammonia or
anhydrous ammonia may be added to provide the
nitrogen. Phosphate fertilizers or phosphoric acid from
a waste acid facility may be used to provide P.
Conventional Activated
Sludge
Detention time – 4 to 8 hours (6 hrs)
 Sludge Age – 3.5 to 7 days
 MLSS – 1,000 to 3,000 mg/L
 DO – 2 to 4 mg/L or ppm
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– High (>5.0) shear floc, waste energy
– Low (<0.5) lead to bulking, poor effluent
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Mixing
– Distributes oxygen evenly
– Brings food in contact with microorganisms
– Prevents septic conditions on bottom of tank
Nitrification Cycle
Heterotrophic Bacteria – Carbonaceous Stage
Get energy from the oxidation of organic materials
 Common bacteria in wastewater
 This bacteria is responsible for denitrification
 Form floc – fast growing
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Autotrophic Bacteria – Nitrogenous Stage
Get energy from inorganic materials or from the
sunlight (some are algae)
 Are the nitrifiers
 Sulfide oxidizing organisms
 Do not form floc – slow growing
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Sludge Floc
Floc under electron
microscope
Good floc
Notice the large
Floc looks like a lace
thing running
doily, almost no clear
through this – that
water between the floc
is a filament. The
particles, not way for
small rice shaped
this to settle. Acts more
objects are the floc
like a parachute.
forming bacteria
(heterotrophic).
Young – weak lacy
You
can clearly
make
Floc
is almost
see through,
out
each floc
particle
very
fragile
looking.
Sharp
andinsee
pretty clear
edges
comparison
to the
liquid
outside
of the floc.
Good Floc.
Filaments
are
There
is
very
little
starting to reach outside
filament
outside
of the
the floc
particles.
floc and the floc is
“roundish” in shape.
Old – dark and falling
apart
Ponds
Primary Pond or
Lagoon
Secondary
or Two Stage
Pond
This is
how it
works
Tertiary or
Three Stage
Pond
Feed the Primary
Heat and Mix
theisNo
Sludge
transferred
Heating or Mixing – allow
Digester with Primary
Primary
orDigester
– solids
(pumped)
fromto
the
settle and liquids
Secondary (WAS)
called
Sludge
primary
because
Primary
Digester
(supernatant)
to the to float to the
it is the first digester
–top
Secondary
Digester
– some gas production
creates gas
Chemical Stabilization
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Lime
– Addition of lime adds to the overall quantity
of solids that must be disposed
– High costs
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Chlorine
– pH will drop <3.5 (acidic)
– Lime may be added before dewatering
Sludge Incineration
Use dewatered sludge
 Converts dewatered sludge by combustion
to carbon dioxide and water vapor
 Reduce volume up to 90%
 Most common is MHF (multiple hearth
furnace)
 Temperature 1,300 – 1,700°F
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Only use the chlorine
wrench when opening or
closing cylinders – open
100%, close then reopen
¼ turn only
Trunions – used to
Fusible plug – center is
turn ton cylinders so
lead – will melt at 158
the valves are
to 165ºF to release
straight vertically
gas instead of liquid or
when opening
explosion
Train cargo cars (Class C)
Ton (2,000 lb) cyliners (Class B)
Biological Treatment
Luxury Uptake of Phosphorous –
modification of activated sludge
 Definitions
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– Aerobic (oxic): free DO is present
– Anoxic: oxygen is deficient or present as
combined oxygen in Nitrate (NO3) and
Sulfate (SO4)
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Anaerobic: No oxygen
Safety
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Top three injuries in wastewater in order:
– Back
– Leg
– Hand
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Lockout/Tagout
– Everyone who is working on
that piece of equipment must
sign/date/add lock
Lab Miscellaneous
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Meniscus (commonly found in pipettes) – read at
the bottom of the curve or the top of the curve
You can preserve a metals sample for 6 months
 BOD solution water make-up – phosphate buffer,
magnesium sulfate, calcium chloride, ferric chloride
 A bottle containing only dilution water is called a
blank
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Pretreatment
Total toxic organics (TTO) refers to the sum of
the masses or concentrations of certain toxic
organic pollutants found in the regulated
discharge at a concentration greater than 0.01
mg/L
 Inspection – minimum of once per year or as
needed
 Sampling – Significant Industrial User (SIU) at
least annually and self monitored semi-annually
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