CME Project CME Project

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CME Project CME Project

Team Five

Equipo Cinco

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What is a membrane, you ask?

Most membranes are thin polymer films. Since the transport Most membranes are thin polymer films. Since the transport

rate through the membrane increases with decreasing rate through the membrane increases with decreasing

membrane thickness, techniques have been developed to membrane thickness, techniques have been developed to make ultra thin, separating films without sacrificing

make ultra thin, separating films without sacrificing membrane strength. For example, cellulose acetate membrane strength. For example, cellulose acetate

membranes can be made in an asymmetric form, where a membranes can be made in an asymmetric form, where a thin dense layer (0.01-0.1 micrometer) is supported by a thin dense layer (0.01-0.1 micrometer) is supported by a thick porous substrate (50-100 µm) which provides

thick porous substrate (50-100 µm) which provides strength but little resistance to transport.

strength but little resistance to transport.

Another technique is to make thin-film-composite Another technique is to make thin-film-composite

membranes where a thin, separating layer of one membranes where a thin, separating layer of one

material is cast on a porous support of another polymer.

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Membrane Separations Membrane Separations

Definition:

Processes for separating mixtures by using thin barriers (membranes)

between two miscible fluids.

A suitable driving force across the membrane, for example, concentration or pressure differential, leads to the preferential transport of one or more feed

components.

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More membrane separation More membrane separation

In dialysis, low-molecular-weight solutes and ions pass In dialysis, low-molecular-weight solutes and ions pass

through while colloidal particles and solutes with through while colloidal particles and solutes with

molecular weights greater than 1000 are rejected under molecular weights greater than 1000 are rejected under

the conditions of a concentration difference across the the conditions of a concentration difference across the

membrane.

In electrodialysis, ions pass through the membrane in In electrodialysis, ions pass through the membrane in

preference to all other species, due to a voltage preference to all other species, due to a voltage

difference.

In reverse osmosis, virtually all dissolved and suspended In reverse osmosis, virtually all dissolved and suspended

materials are rejected and the permeate is a liquid, materials are rejected and the permeate is a liquid,

typically water. Pressure differences up to 800 lb/in.2 (6 typically water. Pressure differences up to 800 lb/in.2 (6

megapascals) are used.

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What is waste?

Hazardous wastes may arise as by-products of industrial

processes. They may also be generated by households when commercial products are

discarded. These include drain openers, oven cleaners, wood and metal cleaners and polishes, pharmaceuticals, oil and fuel

A waste is considered hazardous if it exhibits one or more of the following characteristics: ignitability, corrosivity, reactivity, and toxicity.

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Industry ranking by hazardous waste generation*

Rank Industry Percent of total waste generated

1 Chemical and allied products 47.9

2 Primary metals 18.0

3 Petroleum and coal products 11.8

4 Fabricated metal products 9.6

5 Rubber and plastic products 5.5 6 Miscellaneous

manufacturing 2.1

7 Nonelectrical machinery 1.8

8 Transportation equipment 1.1

9 Motor freight transportation 0.8 10 Electric and electronic

machinery 0.7

11 Wood preserving 0.7

12 Drum reconditioning 0.1

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Waste what?... Wastewater!??

Water-carried wastes, in either solution or suspension, that Water-carried wastes, in either solution or suspension, that flow away from a community. Also known as wastewater flow away from a community. Also known as wastewater flows, sewage is the used water supply of the

flows, sewage is the used water supply of the

community. It is more than 99.9% pure water and is community. It is more than 99.9% pure water and is characterized by:

characterized by:

• volume or rate of flow, volume or rate of flow,

• physical condition physical condition

• chemical constituents chemical constituents

• bacteriological organisms that it contains. bacteriological organisms that it contains.

Depending on their origin, wastewaters can be classed as Depending on their origin, wastewaters can be classed as

sanitary, commercial, industrial, or surface runoff.

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Industrial Wastewater Treatment Industrial Wastewater Treatment

Wastewater streams that are toxic should be treated at the source, and there are a number of source treatment technologies available. For example,

Membrane processes, particularly reverse osmosis, are high-pressure operations in which water passes through a semipermeable membrane, leaving the

contaminants in a concentrate. In addition, wet air oxidation that oxidizes

organic materials at high temperature and pressure (2000 lb/in or 14 kilopascals and 550°F or 288°C) is restricted to very high concentrations of these

substances. Macroreticular (macroporous) resins are specific for the removal of particular organic materials, and the resin is regenerated and used again.

(McGraw-Hill AccessScience)

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Application of source treatment technologies

Technology Removal of bioinhibitor or

biotoxicant

Improvement of biodegradation

rate

Removal of contaminants for

discharge

Recovery, recycle substitution or

elimination Metals

precipitation X X

Chemical

oxidation X X

Wet-air

oxidation X

Macro reticular resin

X X

Adsorption

Carbon

adsorption X X X X

Membrane

process X X

Table of Wastewater Treatment processes

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Thanks Thanks

McGraw-Hill Access Science Lexus Nexus