Wastewater Misc

OSHA

Occupational Safty and Health Administration

lockout

blocking hazardous energy using locks

group lockout device

Gang lock \- often have space for six locks.

Proteins are also called

Amino acids

Volatile

easily evaporates or turns into a gas can be burned off at high temperatures

pH Sollection sample

Container: Polyethylene, fluoropolymer, or glass containers Analyze within 15 minutes of collection Grab or composite samples For composites, cool to < (Less than) 6c during collection

pH buffer store at?

room temp

when taking pH use these while taking a test to mix solution

stir plate & stir bar

report pH

to the nearest 0.1 pH unit can not average results unless you "log" button

What are 3 criteria that define a space as confined space?

1. Large enough to enter and work

2. Limited or restricted entry/exit

3. Not designed for continuous occupancy

1 Cubic foot is? to Gal

7.48 Gal

1 Gallon is? to lb of water

8.34 lb of water

analytical balance

a high-precision scale used to measure very small masses.

desiccator

a sealed container used to keep moisture away from samples.

BOD5 sample is done by

incubated for 5 days at 20c

CBOD5 removal from primary clarifier is typically?

25-30%

Aliquot meaning?

Little amount of a larger sample

Adsorption

Sticking to the surface

Absorption

Soaking it in

Chemicalis typically used for wet scrubber odor control at the headworks of a plant

Sodium hydroxide

Velocity number for proper grit removal in a grit channel?

1.0 ft/sec (target)

Acceptable range: 0.8 – 1.2 ft/sec

⚠️ What happens if it’s off?

- Too slow (1.2 ft/sec)→ Grit stays in flow and goes downstream (wears out pumps)

Particulate

- Tiny solid particles suspended in water

- You might see cloudiness (turbidity)

- Can often be settled or filtered out Examples:

- Dirt, sand, organic solids \- Biomass (activated sludge)

-Anything measured as TSS (Total Suspended Solids)

Soluble

- Completely dissolved in water

- You can’t see it—it’s at the molecular level

- Passes through filters (like TSS filters) Examples:

- Sugar in water \- Ammonia (NH₃) \- Nitrate (NO₃⁻)

- Dissolved oxygen

Gould sludge age (GSA)

A way to estimate how long the microorganisms (biomass) stay in your activated sludge system.

👉 In simple terms:“How old is the sludge (bugs) in your plant?”

Plug Flow

Breakdown

- Flow pattern:

Moves in one direction (inlet → outlet) like a “plug” \

- Mixing:

Very little back-mixing

- Tank shape:

Long and narrow

What happens inside

- Front: High BOD (food), high activity

- Middle: BOD decreasing

- End: Low BOD, possible nitrification Key advantages

- Efficient BOD removal

- Natural “staging” (different zones in one tank)

- Good process control

Complete Mix

What it is - Wastewater is instantly and uniformly mixed throughout the tank

- Same conditions everywhere in the basin Key characteristics

- Mixing: Complete (no zones) - Conditions: Uniform (same BOD, DO, MLSS everywhere)

- Flow pattern: Influent is diluted immediately

What happens inside

- Food (BOD) is evenly distributed

- Microorganisms all experience same environment

- No “front” or “end” like plug flow

Advantages

- Handles shock loads wel

l - Stable and predictable

- Easier to control

Step Feed

What it is- A modification of plug flow where influent is added at multiple points along the aeration tank instead of just the front Key characteristics \- Flow pattern: Still plug flow, but staged influent \- Food (BOD): Spread out along the tank \- Loading: More evenly distributed What happens inside \- Prevents overloading at the front \- Maintains food for bacteria throughout the tank \- Reduces oxygen demand spikes at the inlet Advantages \- Better process control \- Handles shock loads better than standard plug flow \- Improves oxygen use efficiency \- Can help prevent bulking

Contact Stabilzation

What it isA two-stage activated sludge process: 1\. Contact tank (short time, rapid adsorption of BOD) 2\. Stabilization tank (longer time, organisms digest the food) How it works Step 1: Contact tank \- Raw wastewater + return sludge (RAS) mix \- Bugs quickly adsorb (grab) food \- Short detention time Step 2: Clarifier \- Solids settle out Step 3: Stabilization tank \- Settled sludge (RAS) goes here \- Bugs digest the absorbed food (stabilize) \- Then returned to contact tank Key characteristics \- Separates adsorption and biological digestion \- Short aeration time in contact tank \- Longer aeration in stabilization tank

Supernatant

Liquid that is removed from a digester, between an upper layer of scum and a lower blanket of sludge

In general solids content in wastewater is about what %

0.1%

Angle of manual bar screen?

30 degrees

Mechanical bar screen angle

45 - 60 degrees

Ideal wastewater velocity through a screen channel?

1.0 - 2.0 ft/s

How much oxygen depletion (mg/L) is needed for a valid BOD test?

2.0mg/L The goal is to have at least one sample depleteby more than 2.0 mg/L oxygen and still have at least 1.0 mg/L oxygen remaining.This is known as the 2:1 rule.

Bacteria activity doubles every __degeree

18F (or 10C).

Primary clarifier: Surface Overflow Rate (SOR)

600 – 1,200 gpd/ft² (typical) Controls how fast water rises Lower = better settling ⭐ Surface Overflow Rate (SOR) (also called overflow rate or hydraulic loading rate) tells you how fast water is flowing across the surface area of a clarifier.

Primary clarifier: Detention Time

1.5 – 2.5 hours Time wastewater stays in tank Enough for solids to settle, not go septic

Primary clarifier: Weir Loading Rate (WLR)

10,000 – 20,000 gpd/ft Flow per length of weir Prevents short-circuiting and uneven overflow

Primary clarifier: Sludge Removal Rate

Continuously or every few hours Prevents septicity and rising sludge

Primary clarifier: BOD Removal %

25 - 40%

Primary clarifier: TSS removal %

50 - 70%

Glucose glutamic acid (GGA)

Glucose – a simple sugar that bacteria easily consumeGlutamic acid – an amino acid that bacteria also break down This mixture gives a known, repeatable food source for bacteria. Labs run it to make sure their BOD test is working correctly. (GGA) sample should usually give a BOD₅ result around 198 ± 30.5 mg/L (Standard Methods benchmark).

methane (element)

CH₄

Top blanket of sludge in a DAF is called?

Float, Because it floats on the surface

Step 1: standard temperature in the drying oven for the TSS test? Step 2: standard temp of muffle furnace for volatile solids test?

Step 1: 103 to 105ºC Step 2: 550ºC

acceptable D.O. in an aerobic digester?

0.5 to 1.5 mg/l

Is methane gas lighter or heaver than air?

lighter, it will rise

Polymers have 3 types of charges, these are?

positive charge - cationicnegative charge - anionic neutral charge - non-ionic. Typical wastewater sludge has a negative charge and requires a positively charged cationic polymer.

this process uses high speed spinning (G force) which is responsible for separating water from the sludge slurry. As water is removed and drained away, this results in increased solids concentration.

centrifuge

for each pound of nitrate used during denitrification, __lbs of oxygen is supplied BACK to the MLSS

2.8 lbs

Nitrification consumes alkalinity: __ mg/L Denitrification restores alkalinity:__ mg/L

Nitrification consumes alkalinity: 7.14 mg/L Denitrification restores alkalinity: 3.57 mg/L

acceptable (Standard Methods) temperature of a refrigerator storing samples is?

4°C

general term for scattering of small particles of matter dispersed in a liquid, gas or solid \- smaller than suspended solids \- bigger than dissolved solids

Colloidal

ph of: Sodium Hydroxide (caustic) Aluminum Sulfate (alum)

Sodium Hydroxide (caustic) - 12 to 14Used for: \- Raises pH (makes water more alkaline) \- Adds alkalinity to the system \- Helps maintain proper conditions for biological treatment Aluminum Sulfate (alum) - 4 to 6 Used for: \- Coagulation & flocculation Removes: \- - Suspended solids (TSS) \- - PhosphorusTurbidity

Psychoda (sigh-KOH-duh)

Small, fuzzy flies commonly called drain flies, filter flies, or sewer flies

Sanitary sewer pipelines are typically designed and constructed to maintain a minimum velocity of

2 feet per second

typical loading rate of TSS per person in domestic wastewater per day

.2 lbs/ person/ day

Total Kjeldahl Nitrogen (TKN)

Ammonia-Nitrogen (NH3) and Organic-Nitrogen (Org-N)

Endogenous respiration

when microorganisms run out of “food” (BOD) and start using their own stored material—or even their own cell mass—for energy.

Muffle Furnace test: Total solids - Fixed Solids = ?

Volatile Solids

chemical formula for ozone?

O₃

(SVI) Sludge volume index numbers, old or young sludge

Measures how well activated sludge settles in the secondary clarifier SVI of 80 or less, you will have very old sludge SVI of 80-150 - good settling SVI of > 150 - bulking sludge SVI of 250 or higher, you will have very young sludge (filament problem)

anaerobic digester should be adjusted by?

1 degree F per day

a filament that loves to live in wastewater that has sulfur compounds present, volatile fatty acids, high organic loading rates, low dissolved oxygen and low in nutrients.

Thiothrix

Which noise level in the workplace does OSHA require implementation of a hearing protection program?

85 decibels, 8 hours, time weighted average

A BOD bottle can be removed from the incubator at 5 days plus or minus ?

3 Hours

How long can a BOD sample be preserved before running the test?

48 hours at 4°C

What is MCRT Common MCRT times Conventional: Extended: Nitrification systems:

Tells you how long microorganisms stay in the system on average before being wasted Measured in days Low MCRT = younger sludge \- faster growing organisms \- more wasting \- can lose nitrification if too lowHigh MCRT = older sludge \- slower growing bugs survive \- better nitrification \- can lead to endogenous respiration if extremely high Conventional: 3-10 days Extended: 20-30 days Nitrification systems: 8-15 days

Sludge volume index (SVI)

Measures: \- How well activated sludge settles Units: \- mL/g Typical ranges: 50–100....Very good settling 100–150....Normal/acceptable >150....Bulking sludge likely >200....Poor settling

test

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