Tuesday, April 28, 2009

Advanced Anerobic Digestion


At a time of heightened concerns about waste, climate change and the need for cleaner energy, it is worth pointing out that not all the news is bad. Technologies are redressing the balance -- and one of these is Advanced Anaerobic Digestion (AAD).

AAD will not turn muck into brass, or gold, but it does offer the potential to transform the sewage treatment process from a simple clean-up to one that recovers significant quantities of energy.

In the Northumbrian Water region, in the north-east of England, there are more than 400 (437 to be exact) sewage treatment works that all produce varying amounts of sludge. This material has to be removed from every works but, inevitably, it is difficult to handle and, to say the least, rather smelly.

To make this sludge stable to further degradation and (nearly) odour free, Northumbrian Water Ltd (NWL) has long employed anaerobic digestion techniques for about 10% of its total sludge.

These technologies harness natural oxygen-free decomposition by which organic materials break down to produce biogas – roughly made up of 65% methane and 35% carbon dioxide – along with a much reduced residue of stabilized organic material. The latter can be safely deployed as fertilizer. In fact, by returning it to the soil in this way, nutrient and organic matter cycles that occur naturally are completed.

In the last five years, however, technology has advanced significantly and a technique has been perfected that can do much more.

Advanced Anaerobic Digestion significantly enhances the benefits of anaerobic digestion by separating and optimizing the key process stages used in more conventional digestion systems.

A More Sophisticated Process

There are two main pre-digestion processes used in AAD in the UK — thermal hydrolysis (the Cambi process) or enzymic hydrolysis (the Monsal process). Currently there are examples of each in operation and under construction.

Regardless of which process is used, the key to the AAD process is a phase that significantly enhances the breakdown of organic materials by, for example, breaking down cell walls. With thermal hydrolysis this is achieved by an initial high temperature of 165°C combined with high pressure (6 Bar) for less than one hour, or with enzyme hydrolysis this is achieved by phasing an increased temperature from 42°C to 55°C over several days.

The result is a far greater conversion of organic matter into biogas when the material is transferred into the anaerobic digestion phase. Following this digestion phase, there is a 50% reduction in sludge volumes, combined with the additional biogas/CHP- derived energy being produced, and ultimately a better quality bio-solids fertilizer.

One of the major benefits of this, of course, is that energy from biomass, including sewage sludge, are classed as renewable and therefore contribute to meeting Britain’s international commitments to address climate change.

Using AAD reduces the mass of material that is required to be transported off site and offers the benefit of nutrient recovery from materials that are presently wasted.

Indeed, some particularly difficult materials, such as food wastes under the Animal By-products Order (ABPO), need the conditions of AAD to render them safe.

One other benefit that is not to be sniffed at, AAD results in reduced odour.

The digested sludge cake remaining after the process will be a Class A biosolid – a safe and low odour product containing no detectable levels of pathogens, such as E. coli, and may be used as a valuable agricultural fertilizer.


10 comments:

mayamba said...

Hello;
I am particularly concerned with the 50% volume of sludge reduction after digestion. This goes along way in reducing the volumes of biowaste after extracting such useful product.

Thanks.

Anonymous said...

Dear Author www.newandrenewableenergy.com !
I regret, that I can not participate in discussion now. It is not enough information. But with pleasure I will watch this theme.

Anonymous said...

I want to quote your post in my blog. It can?
And you et an account on Twitter?

Anonymous said...

burberry outlet online, ray ban sunglasses, air max, tory burch outlet, true religion, polo ralph lauren outlet, oakley sunglasses, oakley sunglasses, true religion jeans, ray ban, burberry outlet online, coach purses, longchamp outlet, coach factory, michael kors outlet, gucci outlet, louboutin, coach outlet store, coach outlet, tiffany and co, polo ralph lauren, chanel handbags, oakley sunglasses, oakley sunglasses, kate spade outlet, toms shoes, nike free, michael kors outlet, prada handbags, nike shoes, nike air max, louis vuitton outlet online, louis vuitton handbags, jordan shoes, coach factory outlet, ray ban sunglasses, oakley sunglasses, louboutin

Anonymous said...

ray ban, new balance shoes, ugg boots, louis vuitton, ugg boots, bottega, montre homme, lancel, nfl jerseys, nike air max, asics gel, celine handbags, ralph lauren, mulberry, rolex watches, tn pas cher, louboutin, soccer shoes, jimmy choo, nike free, juicy couture outlet, ugg boots, nike air max, air max, gucci, converse shoes, ferragamo shoes, chi flat iron, yoga pants, nike free, hollister, oakley, valentino, ray ban, supra shoes, karen millen, beats by dre, vans, jerseys, longchamp, louis vuitton, insanity, reebok outlet, ralph lauren, ghd, mcm handbags, timberland, birkin bag, abercrombie and fitch, oakley,

Zheng junxai5 said...

2015-07-24 zhengjx
longchamp pliage pas cher
gucci
longchamp pliage
coach outlet store online
cheap ray ban sunglasses
nike pas cher
tn pas cher
tory burch handbags
tory burch outlet
christian louboutin shoes
michael kors
chanel handbags
coach factory
burberry handbags
michael kors handbags
pandora bracelets
pandora charms
kate spade
tory burch shoes
beats by dre
true religion sale
true religion
prada outlet store
tory burch outlet online
gucci bags
air jordan uk
jordans for sale
ralph lauren uk sale
fitflops shoes
air force pas cher
pandora charms sale clearance
mcm bags
cheap oakley sunglasses
jordan shoes uk
mont blanc
chanel online shop
michael kors outlet
ray ban sunglasses uk
football jerseys
ralph lauren polo shirts

mmjiaxin said...

cheap jordan shoes
north face outlet store
ralph lauren outlet
ray ban outlet
winter coats
ugg boots
lacoste pas cher
coach outlet
ralph lauren,polo ralph lauren,ralph lauren outlet,ralph lauren italia,ralph lauren sito ufficiale
the north face outlet
snapbacks wholesale
nfl jerseys
coach outlet online
ray-ban sunglasses
pandora outlet
uggs outlet
louis vuitton outlet online
ed hardy clothing
tods outlet
snow boots
mm1202

Gege Dai said...

ugg boots
mizuno running shoes
rolex watches
gucci outlet
coach outlet
mulberry outlet
nike free run
hermes belt
ugg sale
toms outlet
ugg outlet
oakley sunglasses wholesale
michael kors outlet
michael kors handbags clearance
asics
ray ban sunglasses
ugg outlet
chrome hearts
fitflops clearance
ed hardy tshirts
air max 90
cheap nhl jerseys
chrome hearts outlet
oakley sunglasses wholesale
polo shirts
coach outlet
mulberry handbags
michael kors uk
mlb jerseys
ugg boots
michael kors outlet online
north face jacket
ralph lauren uk
michael kors outlet online
kobe bryant shoes
ralph lauren uk
ugg outlet online
0808jianxiang

兮兮 said...

20161021 junda
coach outlet
lebron james shoes
ralph lauren uk
nike trainers
michael kors wholesale
toms shoes
polo ralph lauren
uggs on sale
nike outlet
timberland boots

marko said...

Purchasing a house is not a light matter, clearly the money related establishment should make sure that you will have the capacity to pay for the home loan and that you are a dependable customer. Purchasing a house is not just opening a record with an apparel store or purchasing an auto.payday loans corona

New and Renewable Energy

New and Renewable Energy
Your source for the New and Renewable Energy News and Technologies