PART 1: WATER AND WASTEWATER TREATMENT

Water Treatment Plant

Generally takes water from the ground, surface, or rainwater sources, makes it drinkable and distributes it to storage tanks or directly to people

Wastewater Treatment Plant

Collects sewage from households and other wastewater from various sites, cleans it and releases it back into the environment at a safe level for humans, fish, and plants to be around

Wastewater Treatment Plant

take sewage water from residential, commercial and/or industrial sources

Water Treatment Plant

generally smaller operations

Wastewater Treatment Plant

much larger and more elaborate

Wastewater Treatment Plant

removes wide range of pollutants

Water Treatment Plant

better raw water quality, generally clean and just needs a bit of treatment and disinfection

Water Treatment Plant

small amounts of pollutants (ex. turbidity) are removed

Wastewater Treatment Plant

product water is disinfected and released back into a nearby waterway or recycled

Water Treatment Plant

product water is fit for human consumption

Wastewater Treatment Plant

generates residual solids that are rich in nutrients (can be applied to farmlands as a fertilizer)

Chemical Properties

Gases, metals, nutrients, pesticides, and other organic compounds

Biological Properties

Bacteria, viruses, protozoans, phytoplankton, zooplankton, insect, plant, and fish

Physical Properties

color, smell, temperature, taste, and turbidity (TSS)

Priority Pollutants

Treated on an individual-substance basis for regulatory control

TRUE

TRUE or FALSE
All priority pollutants are toxic.

organic

Most priority pollutants are _________, but biodegradable despite toxicity

Organics

Proteins, carbohydrates, fats and oils, petrochemicals, solvents, pharmaceutical, small and large molecules, solids and liquids

Dissolved Oxygen

This is a poorly soluble gas in water

As solubility of oxygen increases

• Temperature - increases

• Pressure - decreases

What is the relationship of the solubility of oxygen with Temperature and Pressure?

Lowering temperature

• increases DO saturation levels

• decreases biological metabolism rate

What does lowering the temperature do to DO saturation levels and biological metabolism rate?

BOD is maximum

DO is minimum when?

5 mg/L

EPA has set minimum stream DO levels at _______ in summer

Summer

When is the rate of biological metabolism at a maximum?

• WW must have maximum DO levels

• Minimum oxygen-demanding components when discharged

How to maintain DO level at >5 mg/L?

Biochemical Oxygen Demand (BOD)

an important measure of the waste organic strength

Biochemical Oxygen Demand (BOD)

measures the amount of oxygen that microorganisms require to break down organic matter present in a water sample

Biochemical Oxygen Demand (BOD)

a primary parameter in determining the strength and effects of a pollutant

BOD5 Test

Determines the oxygen demand* of a waste exposed to biological organisms (controlled seed) for an incubation period of 5 days

BOD5 Test

Measures decrease in DO concentrations in 5 days, which is then related to the sample strength

1-2 mg/L

What should be the BOD5 level for:

Safe drinking water

3-5 mg/L

What should be the BOD5 level for:

Moderately clean water

> 5 mg/L

What should be the BOD5 level for:

Near pollution source

Winkler’s method

What method is used to determine the dissolved oxygen content of one of the samples?

BOD5

measures the 5-day carbonaceous oxygen demand by aerobic bacteria, representing the readily biodegradable organic matter in wastewater

BOD20

indicates the total BOD, including slower-acting substances like grease and cellulose, after ~20 days

BODu (ultimate BOD)

signifies the total oxygen required for the complete breakdown of all organic matter

BOD20

BODu can be estimated by _______

COD (chemical oxygen demand)

a measure of the oxygen consumed by chemical oxidation of all organic compounds (biodegradable and non-biodegradable) and serves as a faster alternative to BOD tests for monitoring pollution.

less than 3 hours

How long do COD tests take?

TOC (total organic carbon)

more rapid (few minutes) measure of the organic content of wastes and may be correlated with BOD and COD for specific wastes

Inorganics

The direct result of inorganic compounds in the carriage water in industrial wastes

Softwater

Which have lower inorganics, softwater/hardwater?

sodium

Many food processing wastewaters are high in _________

Domestic wastewaters

__________________ have a balance in organics and inorganics

Process wastewaters

_________________ are deficient in specific inorganic compounds

6 and 9

Wastewaters should have pH values between __________ for minimum impact on the environment

WW tend to be corrosive (result of excess H ions)

What happens if pH is lower than 6?

precipitation of metal ions as carbonates or hydroxides

What happens if pH is greater than 9?

Alkalinity

__________ keeps pH values at the right level

Neutral organics (e.g. carbohydrates, aldehydes, ketones, alcohols)

These are biodegraded through organic acids, which must be neutralized by the available alkalinity

Bicarbonate alkalinity

This is the primary buffer in WW

sodium carbonate is better to be added than lime

If alkalinity is inadequate, __________________ is better to be added than _____

Lime

tends to be hard to control accurately, resulting in high pH levels and precipitation of Ca that forms part of the alkalinity

BELOW 37°C

Temperature is NOT a critical issue _______________ if WW is to receive biological treatment

65°C

Thermophilic biological WW treatment systems can be operated up to ______ with acclimated microbes

Low-temperature operations

____________________ (i.e., northern climates) result in slow reaction rates for both biological and chemical WW treatment systems

viscosity

Increased _____________ at low temperatures makes solid separation more difficult

10 to 30°C

Operating temperatures are generally kept between ______________

Total solids 

Residue remaining from WW dried at 103–105°C

Settlable solids

Solids that settle in an Imhoff cone in one hour

Imhoff cone

Settlable solids settle in an __________ in one hour

Dissolved solids

The portion that passes through a 2 µm filter

Suspended solids

solids captured on the filter

volatile and ash (fixed)

Combustion at 500°C further separates the solids into_______________

Inorganic solids

_____________ are mostly lost during combustion

Volatile fraction

____________________ approximates the organics present

Nitrogen and Phosphorous

Cause increase in aquatic biological productivity

Nitrogen and Phosphorous

Result in low DO and eutrophication

nitrosomonas

nitrifying bacteria

NBOD (nitrogenous BOD)

BOD exerted by organic and ammonium N in the water environment

CBOD (carbonaceous BOD)

organic BOD

TOD (Total Oxygen Demand)

must be satisfied in treatment of wastewaters with organics and ammonium

𝑇𝑂𝐷 ≅ 1.5(𝐵𝑂𝐷5) + 4 . 5 𝑇𝐾N

What is the formula for TOD?

PHOSPHOROUS

is not oxidized or reduced biologically

Ortho-P may be formed from organic and poly-P

PHOSPHOROUS is not oxidized or reduced biologically, but ______ may be formed from organic and ______

Ortho-p

may be removed by chemical precipitation or biologically with sludges

N and P

Many industrial wastes are very low in ________, which must be added if biologically-based treatment is used

Whole Effluent Toxicity (WET)

a term used to describe the toxic effects imposed on a species or population of aquatic organisms caused by exposure to an effluent

EPA

WET determines analytically by exposing sensitive indigenous organisms to effluents using WET test protocols by __________

17

EPA has established ________ analytical methods for testing acute and chronic toxicity of point sources

WET test

______ report on the general acute and chronic toxicity of all constituents in a complex effluent

toxicity of specific chemicals

What does a WET test not report on?

Oil and Grease

Tend to float on the water surface, blocking oxygen transfer, interfering with recreation, and producing an aesthetically poor appearance in the water

solvent-extraction

Measurement of Oil and Grease is by a _____________ procedure

• Pretreatment

• Primary Treatment

• Secondary Treatment

• Physical-Chemical Treatment

Stages of Wastewater Treatment

single- or multiple-unit processes

Pretreatment may include _______________________

Equalization

One of the most important pretreatment devices/processes

Equalization

Best suited for batch discharge of concentrated wastes

Flow equalization

tends to level out the hydraulic loads in treatment units

Mechanical mixing

____________________ may be adequate if the wastes are purely chemical in their reactivity

aeration mixing

Biodegradable wastes normally require _____________ so that the microbes are kept aerobic and nuisance odors are prevented

Diffused aeration systems

__________________ offer better mixing under variable load conditions than mechanical surface aeration

Operation on regular cycles

_________________________ determines the size of the equalization basin

None

What is the advantage in making the equalization basin any larger than necessary to level out wastewater variations?

2-day

Industrial operations on a 5-day, 40-hour week will normally make a _____ equalization basin as large as needed for continuous operation of the WW treatment system under uniform conditions

Acidic or basic ww

__________________ must be neutralized prior to discharge

Equalization basins

_________________ can be used as neutralization basins

Sodium Hydroxide (NaOH)

This is the easiest base material to handle in a liquid form and can be used at various concentrations for in-line neutralization with minimum equipment

Lime, Ca(OH)2

This remains the most widely used base for acid neutralization