INDUSTRIAL WASTEWATER MANAGEMENT Part B

Most widely used physical chemical process

Adsorption

Adsorption is Primarily for the removal of

soluble organics

Most common adsorbent

Activated carbon

What isotherm is commonly followed in adsorption

Freundlich Isotherm (y = kc^1/n)

Assuming equilibrium is reached, the isotherm provides the

dose of carbon required for treatment

(capacity of carbon is sef by the untreated waste pollutant concentration)

Countercurrent contacting

(capacity of carbon is set by the required effluent concentration)

Concurrent contacting

Which contacting process is preferred?

Countercurrent

is for well mixed slurry type contactors, requiring sedimentation, coagulation, flocculation and filtration; usually discarded after use

Powdered carbon

is more expensive but easier to regenerate

Granular carbon

This is utilized in countercurrent contactors

Granular carbon

Used as tertiary treatment after primary and biological

Adsorption

Adsorption processes must provide

Backwash

Some solids escape pretreatment

Adsorption

This happens to the carbon in adsorption even with extensive pre-treatment

Biological growth

Present practice applies __________________ for removal of all types of organics

carbon adsorption

Used fo treat industrial water supplies,

Ion exchange

Usually operated with the waste being run downflow through a series of columns containing appropriate resins

Ion exchange

Usual resin used in ion exchange

Zeolite

Capacity of the resin is a function of the

type and concentration of regenerant

For the removal of volatile substances from water

Air stripping

What is the key equation used in Air stripping?

Henry’s law

These types of contact towers are more efficient for air stripping

Counterflow or crossflow

Success in removing halogenated organics from water and wastes; removal of these toxic organics from the gas streams are now also required

Air stripping

Cost of stripping from gas often exceeds cost of stripping from _______

water

(used only when the concentration of the target compound is very low, requiring small quantity of oxidant)

Chemical oxidation

This process has very low efficiency since many side reactions consume the oxidant

Chemical oxidation

is satisfactory as a prefreatment to biological or carbon adsorption freatment, making recalcitrant organics easier to biodegrade and adsorb

Partial oxidation

with simultaneous exposure to UV light produce a self renewing chain reaction that can significantly reduce ozone dosage needed for oxidation

Ozone oxidation

Commonly used oxidants

• Ozone permanganate chlorine

• Chlorine dioxide

• Ferrate

Uses hydroxyl radicals (powerful, nonselective oxidant) to oxidize recalcitrant organic compounds fo the mineral end products of C0O2, H20, HCI, etc.

ADVANCED OXIDATION PROCESS (AOP)

are produced on site using a combination of traditional oxidation processes

Hydroxyl radicals

Fenton’s reagent

ferrous iron and H2O2

Efficient and cost effective

AOP

Most economical for treating industrial and hazardous waste streams that have low levels of recalcitrant contamination (<50 ppm)

AOP

Highest relative oxidation power

Titanium dioxide

Use selectively permeable (low permeability) membrane, in an apparatus with high surface area, to separate pollutants from water

Membrane processes

Most membranes are formulated from ________________________________, making the membrane able to discriminate by molecular size or weight

complex organics that polymerize during membrane preparation

It discriminates by hydrogen bonding characteristics

Reverse osmosis

combines biological degradation of waste products with membrane filtration

Membrane Bioreactors

MLSS

Mixed Liquor Suspended solids

MBRs are typically operated as activated sludge systems with high biomass concentrations (____________________) and long solids retention time (_______________)

MBRs are typically operated as activated sludge systems with high biomass concentrations (10,000 to 15,000 mg/L MLSS) and long solids retention time (30 to 60 days)

MBRs are feasible options for

• anaerobic treatment of municipal wastewaters

• anaerobic treatment of industrial wastewaters

2 Configurations of MBRs

• Side-stream

• Submerged

___________________ is wastewater that is produced on site that does not contain sewage and has been adequately freated for use in some parts of the industrial operation

Industrial reuse water