Wastewater Miscellaneous Concepts

A comprehensive set of vocabulary flashcards covering wastewater treatment processes, laboratory standards, safety protocols, and chemical properties based on lecture notes.

OSHA

Occupational Safety and Health Administration

Lockout

The process of blocking hazardous energy using locks.

Group lockout device

A gang lock that often has space for six locks.

Proteins

Also referred to as Amino acids.

Volatile

A substance that easily evaporates or turns into a gas and can be burned off at high temperatures.

pH Sample Collection Requirements

Use polyethylene, fluoropolymer, or glass containers; analyze within $15$ minutes; cool composite samples to < $6^\text{o}C$.

pH buffer storage

Should be stored at room temperature.

Mixing tools for pH testing

A stir plate and stir bar used to mix the solution during the test.

pH reporting requirements

Report to the nearest $0.1$ unit; results cannot be averaged unless using the "log" button.

Confined Space Criteria

1. Large enough to enter and work; 2. Limited or restricted entry/exit; 3. Not designed for continuous occupancy.

Cubic foot to Gallons conversion

$1$ cubic foot is equal to $7.48$ Gallons.

Gallon of water to pounds conversion

$1$ Gallon is equal to $8.34$ 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 incubation

Incubated for $5$ days at $20^\text{o}C$.

CBOD5 removal in primary clarifier

Typically ranges from $25-30\%$.

Aliquot

A little amount of a larger sample.

Adsorption

The process of sticking to the surface.

Absorption

The process of soaking it in.

Wet scrubber odor control chemical

Sodium hydroxide, typically used at the headworks of a plant.

Grit channel velocity

Target is $1.0\,ft/sec$; acceptable range is $0.8-1.2\,ft/sec$. If too slow ($> 1.2\,ft/sec$ in terms of negative performance), grit stays in flow and wears out pumps.

Particulate

Tiny solid particles suspended in water (measured as TSS) that cause turbidity and can be settled or filtered out.

Soluble

Substances completely dissolved in water at the molecular level, such as sugar, Ammonia ($NH_3$), Nitrate ($NO_3^-$), or dissolved oxygen.

Gould sludge age (GSA)

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

Plug Flow

A flow pattern moving in one direction with little back-mixing in a long, narrow tank, featuring high BOD at the front and low BOD at the end.

Complete Mix

A process where wastewater is instantly and uniformly mixed throughout the tank, maintaining uniform BOD, DO, and MLSS everywhere.

Step Feed

A modification of plug flow where influent is added at multiple points along the aeration tank to spread BOD and oxygen demand.

Contact Stabilization

A two-stage activated sludge process using a short-term contact tank for adsorption and a longer-term stabilization tank for digestion.

Supernatant

Liquid removed from a digester between the upper scum layer and the lower sludge blanket.

Typical wastewater solids content

Approximately $0.1\%$.

Manual bar screen angle

$30$ degrees.

Mechanical bar screen angle

$45 - 60$ degrees.

Ideal screen channel velocity

$1.0 - 2.0\,ft/s$.

The 2:1 rule (BOD test)

A valid test requires at least $2.0\,mg/L$ oxygen depletion and at least $1.0\,mg/L$ remaining.

Bacteria activity doubling rate

Activity doubles every $18^\text{o}F$ (or $10^\text{o}C$).

Primary clarifier: Surface Overflow Rate (SOR)

Typical range of $600-1,200\,gpd/ft^2$; controls how fast water rises.

Primary clarifier: Detention Time

$1.5-2.5$ hours; ensures solids settle without becoming septic.

Primary clarifier: Weir Loading Rate (WLR)

$10,000-20,000\,gpd/ft$; flow per length of weir to prevent short-circuiting.

Primary clarifier removal efficiency

Removes $25-40\%$ of BOD and $50-70\%$ of TSS.

Glucose glutamic acid (GGA)

A repeatable food source used to check BOD test accuracy; benchmark result is $198 \pm 30.5\,mg/L$.

Methane formula

$CH_4$.

Float

The top blanket of sludge in a Dissolved Air Flotation (DAF) unit.

TSS Drying Oven Temperature

$103$ to $105^\text{o}C$.

Muffle Furnace Temperature

$550^\text{o}C$ for the volatile solids test.

Aerobic digester D.O. level

Acceptable range is $0.5$ to $1.5\,mg/L$.

Methane density

Lighter than air; it will rise.

Polymer charges

Cationic (positive), anionic (negative), and non-ionic (neutral); wastewater sludge usually requires cationic polymers.

Centrifuge

A process using high speed spinning (G force) to separate water from sludge slurry.

Denitrification oxygen credit

$2.8\,lbs$ of oxygen is supplied back to the MLSS for each pound of nitrate used.

Alkalinity and Nitrogen cycle

Nitrification consumes $7.14\,mg/L$ alkalinity; Denitrification restores $3.57\,mg/L$ alkalinity.

Refrigerator storage temperature

$4^\text{o}C$ per Standard Methods.

Colloidal

Particles smaller than suspended solids but bigger than dissolved solids that scatter light.

Aluminum Sulfate (alum) pH and usage

pH of $4$ to $6$; used for coagulation and flocculation to remove TSS, phosphorus, and turbidity.

Sodium Hydroxide (caustic) pH and usage

pH of $12$ to $14$; used to raise pH and add alkalinity.

Psychoda

Small fuzzy flies known as drain, filter, or sewer flies.

Sanitary sewer design velocity

Minimum of $2\,ft/sec$.

Domestic wastewater TSS loading rate

$0.2\,lbs/\text{person}/day$.

Total Kjeldahl Nitrogen (TKN)

The sum of Ammonia-Nitrogen ($NH_3$) and Organic-Nitrogen (Org-N).

Endogenous respiration

When microorganisms utilize their own stored material or cell mass for energy due to lack of food (BOD).

Volatile Solids calculation

Total solids minus Fixed Solids.

Ozone chemical formula

$O_3$.

Sludge Volume Index (SVI) age indicators

$\leq 80$ indicates very old sludge; $> 150$ indicates bulking; $\geq 250$ indicates very young sludge.

Anaerobic digester temperature adjustment

Should be adjusted by $1^\text{o}F$ per day.

Thiothrix

A filament that thrives in wastewater with sulfur compounds, high organic loading, low D.O., and low nutrients.

OSHA Hearing Protection threshold

$85\,decibels$ at an $8$ hour time weighted average.

BOD bottle incubation window

$5$ days plus or minus $3$ Hours.

BOD sample preservation time

Maximum $48$ hours at $4^\text{o}C$.

Mean Cell Residence Time (MCRT)

Average time microorganisms stay in the system; typical ranges are Conventional ($3-10$ days), Extended ($20-30$ days), and Nitrification ($8-15$ days).