Method of Dewatering Slurries using Leaf Filters (Filter Presses)

Patents & Technolo ies

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Light controls nanopore size

both particles of black carbon and

A US multi-institutional research

to a decline in the rate of climate

group has successfully used a

change.

CO 2 gas emissions, this could lead

simple ultraviolet beam of light to

Tyres, nuts • Hg removal

make precise adjustments to the size of nanopores in fine filters. Key to the pore size changes are photoacid molecules, which is

Scientists at the University of

this case are thin-film silica, that

Illinois, USA, and the Illinois State

uniformly

Geological Survey have found a

periodic

way to make effective activated

nanostructure. A light shone on

carbon adsorbents for the removal

self-assemble incorporate

and into

a

these molecules breaks them

of mercury (Hg) emissions from

apart to form an acid that causes

power plants, using old tyres and

silica to solidify locally. The

pistachio shells.

amount of solidification, which

Hg is a toxic pollutant that can

necessarily shrinks pore sizes to

enter rivers, lakes and the human

create a denser material, is

food chain, and coal-fired power

proportional to the amount of

plants are one of the largest anthropogenic sources of these

light shone on the membrane. According to researchers, the

and Sandia's Laboratory-Directed

methane,

precision is so great that it could

Research and Development progr-

(CFC) and black carbon particle

achieve the long-sought goal of membrane science, i.e.

amme. Sandia and the University

(soot).

membrane-based separation of

patent application on the process.

of New Mexico have filed a joint

oxygen from nitrogen. Using this technology the diameter of the pores of the membrane could be changed by 0.2 Angstroms (0.02

CO2 , no longer the bad guy

In a collaborative

research programme, funded by the Electric Power Research

The research looked at trends

Institute (EPRI) and the Illinois

in various greenhouse gases and

Office of Solid Waste Research,

noted that the growth rate of CO 2

adsorbents made from a variety of

in

feedstocks including high-sulphur

the

atmosphere

doubled

between 1950 and 1970, but

coal, waste tyres and pistachio

levelled off from the late 1970s to

shells, were evaluated for their

nanometres) for the optimisation

For

researchers

the late 1990s. The estimates of

effectiveness at removing two

agreed that climate change was

global climate forcings or factors

forms ofHg emissions - elemental

triggered by greenhouse gases,

that promote warming indicated

zeolite, thereby enhancing the

with carbon dioxide (C0 2) from

that

capability

of membranes molecules

by

to size.

years

emissions.

of oxygen-nitrogen separation. The process creates a tuneable

separate

many

chorofluorocarbons

it

was

the

processes

the burning of fossil being the

producing non-C0 2 greenhouse

main culprit.

gases

New research,

Zeolites are crystalline structures

however, indicates that fossil fuel

with tiny but unalterable pore sizes widely used by industry to

burning may not as important a factor as previously thought.

separate materials. As filters

NASA funded research at the

they are precise, but their pore sizes are unchangeable. The work

that

have

been

more

significant in climate change. Fortunatley, the growth rate of

Hg and mercuric chloride, from several different simulated combustion gas streams. The researchers found that although mercury removal was affected by the flue gas compositions, the tyre and

non-C0 2 greenhouse gases has

pistachio carbons had nearly five times larger capacity for the

Space

declined in the past decade, and if sources were reduced in the

adsorption of mercuric chloride

Studies, New York, USA, suggests

future, further changes in climate

than their coal-derived counterpart. Further, there no is shortage of raw materials - each year, more

Goddard

Institute

of

is funded by the US Department

that climate change in recent

due to these gases in the next 50

of Energy's Office of Basic Energy Sciences, the Defense Advanced

decades has been mainly caused by

years could be negligible. It

air pollution containing non-C0 2

concluded that if these reductions

than

Research

greenhouse

were coupled with a reduction in

disposed of in the USA alone.

Projects

Agency

gases

such

as

200

million

tyres

are

Patent Summaries Submerged Membrane Bioreactor for Treatment of Nitrogen Containing Water, Zenon Environmental Inc, Canada. WO 00/37369. Date of Publication: 29 June 2000.

Zeolite Membrane and a Process for ·the Production thereof, Corning Inc, USA. WO 00138910. Date of Publication: 6 July 2000.

Control Equipment for a Centrifugal Separator and a Method of Controlling a Separating Operation, Alfa Laval AB, Sweden. WO 00/37177. Date of Publication: 29 June 2000.

Method of Dewatering Slurries using Leaf Filters (Filter Presses), Stockhausen GmbH & Co KG, Germany. WO 00/40515. Date of Publication: 13 July 2000.

Underdrain Block for Filter Media System, Tetra Process Technology, USA. WO 00/37158. Date of Publication: 29 June 2000.

Method and Apparatus for Microfiltration, US Filter Corp, USA. WO 00/40513. Date of Publication: 13 July 2000.

18

November 2000

Filtration+Separation