Thursday 9 August 2007

ANAEROBIC DIGESTION







Photos : Plenty of digestion going on at the Clonmany agricultural show.




What is Anaerobic Digestion and can it be used on the farm?
Anaerobic Digestion plants are springing up around the country. They are a way of converting animal waste into biogas energy (typically composed of 65% methane and 35% carbon dioxide). Some plants supply the farm with enough to power the house and sheds as well as selling the excess to the national grid.

The process of Anaerobic Digestion (AD) involves the breakdown of organic waste by bacteria in an oxygen-free environment. Anaerobic Digestion can take place in a specially designed AD plant (or naturally at landfill sites).

AD Plants
Farm, municipal or industrial-based AD plants convert waste material into biogas. Waste/feedstock is pumped into a closed vessel (digester), which has been inoculated with suitable bacteria. Anaerobic (0% oxygen) conditions are then maintained in the vessel and the temperature is held at a constant value (typically 370C).




The biogas produced can be upgraded to fossil ('natural') gas quality, but is normally used on site to generate heat and power.




The AD process residue can be separated into a liquid and fibrous part. The liquid can be returned to the land as a fertiliser and the solid fibre used as a soil conditioner.

What Types of manure are suitable?




In general, all manures can be digested.

Digestion of dairy and cattle manure has been successfully implemented
.
Digestion of only poultry or swine manure may present more challenges — other materials may be added to optimise the blend.

Sand or other inorganic materials will settle out in the digester and must be considered in the design. Many digesters will require shutdown and removal of built up materials after 10 years of usage.

AD systems work best with fresh manure — manure stored under barn may not be as suitable.

AD systems are not effective with highly diluted manure. Processes such as bypassing milk house wash water should be considered.

Some experts suggest that it is not reasonable to convert solid manure into a liquid in order anaerobically digest it.






Environmental.



SPEED RAMPS



Are speed ramps the most effective method of slowing traffic on the roads? Inishowen doesn’t have that many at the moment but there has been an epidemic of these ramps and other forms of traffic calming around Europe. Over the last few years there has been a big increase in people opposing them. Traffic calming does slow traffic down but does this fact alone reduce accidents? There is a group in the U.K. from a group of volunteers who call themselves the Association of British Drivers (ABD). This group has successfully recruited over 2000 members in their campaign to abolish speed cameras and ramps and other forms of traffic calming from the roads. They have some interesting points to make and the group is growing daily. ABD are experiencing a lot of opposition from pro-ramp groups who have implemented traffic calming measures for years without objection.



COMPLEX ISSUE
Mark McArthur-Christie, the ABD road safety and transport spokesperson had this to say. “Driving is a hugely complex issue, but the importance of driving safely is being reduced to just one issue: sticking to the numbers on a tin sign. There used to be the three E’s in road safety; Education, Engineering and Enforcement. That’s been reduced to just one, and we all know which”.

It was suggested to Mark that reducing speed limits must have a positive effect some of the time. He replies “The problem is that reducing speed limits is usually the first thing that’s done, when it should be the last. It also doesn’t stop accidents happening -what’s the best speed to knock a child down? I’d say it would be best if the collision didn’t happen at all, and we need to look at the causes, not just the symptoms”. The problem is now that people have been conditioned to think that accidents are caused by going too fast, and nothing else”


Here are some issues that the organisation mentions in their defence against any form of speed ramp.


ENVIRONMENTAL IMPACT
Accelerating after negotiating a ramp generates more pollution than if the hump wasn’t there.

Research carried out in Austria on a mile long stretch of road with six humps and a 40mph speed limit showed cars emitted 10 times more nitrogen oxide, 3 times more poisonous carbon monoxide and 25% more carbon dioxide than a vehicle that maintains a constant speed. The fuel consumption also rose by 25%. The report concluded, “A regular traffic flow would always therefore be more environmentally friendly”.


A police officer in a Subaru Impreza claims that he can “skim” speed bumps at 70mph!

Depending on the vehicle and the hump design, going over a hump at higher speed may cause less discomfort than a lower speed. Off road vehicles for example have been designed to get over bumps easily.

The noise of the vehicles is greatly increased as they slow down and speed up. Residents can be disturbed by the noise. The thumps of the vehicles in some heavy traffic areas has damaged the foundations of houses and in some cases the value of the properties actually fall as the houses become less desirable to live in.

Damage to vehicles increases dramatically where speed bumps have been put in place. Exhausts, bumpers, wheels and chassis can all get damaged. There is extra wear and tear on the clutch, gears, brakes and engines of the cars as well.

Drivers watching out for the ramps are less likely to see children on the road.

Speed ramps would cause motorists to take an alternative route to miss the obstacles, therefore making other small roads dangerous.

The bump as you hit a ramp has been known to cause serious injury to passengers of cars and buses. Two fire services drivers have incurred spinal damages of such an extent they can no longer work.

At night and in poor visibility, humps cause headlights to rise. This can dazzle other drivers and irritate residents as the beam bounces on their bedroom wall. Drivers might misinterpret the flash as a signal to pull out of a side road, which could cause a collision.

Humps discriminate against the severely disabled, elderly and frail, and those with serious back and neck problems. Jolts from the ramps could cause serious pain and discomfort to the extent that it could prevent people from leaving their homes by vehicular means


EMERGENCY SERVICES
One of the most serious issues is the slowing down of emergency services. An ambulance might even need to take an alternative route with someone who is seriously injured and in need of hospital treatment, which could cost the patient their life. An analysis carried out for the City of Boulder in Colorado, shows that 85 people there are likely to die due to delays in emergency vehicles, for every one life that is saved by speed ramps. I know that Inishowen isn’t a city and there probably won’t be hundreds of ramps to travel over every day. But if the emergency services had to pass over twenty ramps on the way to a fire, (and it is estimated that every ramp causes a delay of ten seconds), the vehicle would be delayed by over three minutes! A fire could sweep through a house in that time! The London Ambulance Service say that traffic calming claims the lives of 500 people a year in London alone!

TEST RUN
There are only a few people that drive too quickly and have a reckless disregard for other people’s safety. These are who the speed ramps are designed for. The vast majority of law-abiding drivers are suffering the irritation of having to negotiate their way over these humps. The offending drivers could still manage to break the speed limit in the gaps between the ramps. I did a test run on a road near me that has ramps and I managed to get the car to the speed limit in the gap. This didn’t break any laws but my method of driving was far less safe than if I had a clear road to drive down. The offenders might still offend but be far more erratic and have less concentration to see any other hazards.


ROAD RAGE
The term Road Rage is said to have come about when traffic calming was first introduced. The traffic might look slower but the driver’s heartbeats are racing. Imagine doing the school run or trying to get to work when you are ten minutes late. The ramps will be a major cause for distraction and irritation, making the driver less aware of any dangers.


DIFFICULT CHOICE
It’s a difficult choice to make when the issue of speed ramps and lives are mentioned. They do slow cars down and the majority of people welcome them. Residents on the estate where I live would love to see a few ramps put in place to make the estate safer. There are a few people on the other hand who can’t see why all the residents should have to put up with the inconvenience of driving over them just because of one or two inconsiderate people that drive too fast. One of the residents commented “The individual offenders could be made aware of their dangerous driving and be educated in good driving practices, or have their car away from them!” The debate continues…

INVERTED POTHOLES
Speed ramps are seen as a nuisance to many people and some even think that they are just inverted potholes. If this were the case the problem would be solved easily. Simply stop putting money into road maintenance! The council will save a fortune from their budget and we would all be reduced to driving over rough roads at 10 miles an hour!


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