What is landfill gas?

What is landfill gas? 

Gases are formed in a landfill when buried
wastes decompose (breakdown by 
bacteria) or volatize (change from a liquid 
or solid to a vapor). These bacterial and 
chemical processes create gases that are 
unlikely to pose any serious health 
hazards, but they may cause odors that 
some people find unpleasant.   

What do I smell? 

The most common type of landfill is the 
municipal solid waste facility, which 
accepts household and non-hazardous 
commercial and industrial waste. It 
typically contains 60% organic material,
such as food and paper. Because organic 
material tends to produce a great deal of
gas, municipal solid waste landfills have
the potential to produce odors. 
Sulfides and ammonia are the most 
common sources of odor in landfill gas. 
Sulfides produce a strong, rotten-egg 
smell that humans can detect even at very 
low concentrations. Ammonia produces a 
pungent odor that many people are 
familiar with because it is often used in 
household cleaning products. Both are 
normally present in the air, regardless of 
the presence of a landfill. 
                              
                

Is landfill gas hazardous to 
my health?
  
Landfill gas may cause temporary 
discomfort, but it is not likely to cause 
permanent health effects. At extremely 
high concentrations, humans may 
experience eye irritation, headaches, 
nausea, and soreness of the nose and 
throat. People with respiratory ailments 
such as asthma are especially sensitive to 
these effects. However, these temporary 
conditions are reversed as soon as the 
gases are reduced or eliminated.  
There is another group of chemicals, 
called non-methane organic compounds 
(NMOCs), which may be present in the air 
near a landfill, though they are not likely to 
reach harmful levels. NMOCs may occur 
naturally, or be formed by chemical 
processes. There is concern that longterm exposure to high levels of NMOCs 
could lead to health problems, but health
studies have been largely inconclusive. 
Currently, there is not enough information 
about the impacts that lifestyle choices, 
such as tobacco use, may have on 
compounding the health effects from 
exposure to landfill gases. 
Many people find the odors emitted from a 
landfill to be unpleasant. Although these
odors are undesirable, no medical 
attention is usually required. Landfill odors 
may cause temporary symptoms such as
nausea and headache, but their effect on
the comfort of individuals is difficult to 
evaluate, because different individuals 
may react differently to the same type and 
intensity of odor. 


What other hazards are 
associated with landfill gas?
  
The migration of landfill gas creates health 
and safety concerns when the gas enters 
buildings and other confined areas. Under 
these circumstances, landfill gas may 
contribute to the following hazards: 
 EXPLOSION HAZARD
Gases may form an explosive mixture 
when combined with air in specific 
proportions. Methane (odorless), is the
only gas likely to be produced in high 
enough concentrations to pose any 
real explosion hazard. However, 
methane is only explosive when
diluted to concentrations between 5% 
and 15%. There also must be an 
ignition source for an explosion to 
occur. 

 ASPHYXIATION HAZARD 

Asphyxiation occurs if there is not 
enough oxygen in the air to breathe. If 
landfill gases collect in a confined 
space, they have the potential to 
create an oxygen-deficient 
environment. Carbon dioxide is the 
gas most likely to create an
asphyxiation hazard. Symptoms of 
asphyxiation include headache, 
increased breathing and heart rate, 
and dizziness. These symptoms are 
reversed when exposure is eliminated.

How Do Coal-Fired Plants Work?

1. Heat is created
Before the coal is burned, it is pulverized to the fineness of talcum powder. It is then mixed with hot air and blown into the firebox of the boiler. Burning in suspension, the coal/air mixture provides the most complete combustion and maximum heat possible.

2. Water turns to steam
Highly purified water, pumped through pipes inside the boiler, is turned into steam by the heat. The steam reaches temperatures of up to 1,000 degrees Fahrenheit and pressures up to 3,500 pounds per square inch, and is piped to the turbine.

3. Steam turns the turbine
The enormous pressure of the steam pushing against a series of giant turbine blades turns the turbine shaft. The turbine shaft is connected to the shaft of the generator, where magnets spin within wire coils to produce electricity.

4. Steam turns back into water
After doing its work in the turbine, the steam is drawn into a condenser, a large chamber in the basement of the power plant. In this important step, millions of gallons of cool water from a nearby source (such as a river or lake) are pumped through a network of tubes running through the condenser. The cool water in the tubes converts the steam back into water that can be used over and over again in the plant.

The cooling water is returned to its source without any contamination, and the steam water is returned to the boiler to repeat the cycle.

All about Pumps

One day  when one of our water pumps failed in the cooling ponds one day, my boss gave me a requisition order and the keys to a company truck. He told me to go into the city and purchase another pump at the industrial supply house.

He said, “Get a water pump that pumps 30 psi [pounds per square inch] at 400 gpm [gallons per minute].” He wrote it on the requisition.

At the industrial supply house, the sales rep escorted me to the pump showroom. He said, “This is the water pump you need. It generates 70 feet of head at 400 gpm. Do you need a coupling and motor too?”

I said, “Wait a minute! I don’t need 70 feet of head. I want 30 psi at 400 gpm. What is 70 feet of head?” I thought the sales rep was trying to do a “bait-and-switch” on me. The requisition chit clearly stated 30 psi. I wondered why the sales rep used different terms. Indignantly, I walked away and went to a competing industrial supply house — where I repeated the same verbal exchange with their sales rep.

I know I’m not alone. This misunderstanding about head and pressure occurs daily all over the country … and, indeed, all over the world.

Pump users want pressure. Pump manufacturers supply feet (or meters) of head. In the final analysis, they are the same, just expressed from two different points of view. As someone who specifies and/or installs pumps, you need to know how these terms relate to each other.

Origins of head, pressure
Ancient Rome and Greece were supplied with running water in giant aqueducts, which carried fresh water from mountain lakes and streams down into the city. Underground clay pipes would carry the water by gravity to the different neighborhoods. The water would collect in fountains for the housewives to carry away daily in clay jars. A centurion normally guarded the fountain to prevent water theft or contamination.

That was 2,600 years ago — when water flowed by gravity, the flow was dispensed in jugs and barrels, and there were no pressure gauges or instrumentation. Still, it was generally understood that force (rated in units of energy) was required to elevate a quantity (volume or weight) of water against gravity. A certain amount of energy (force) was required to raise a jug of water from the fountain up into an oxcart or onto the housewife’s head.

In Greece 2,200 years ago, Archimedes developed the first practical constant-flow pump. The “Archimedes screw” would elevate water from a river up into an irrigation canal for agriculture. The screw was used as a bilge pump on the king’s barge. It would also lift well water up to the surface for the wives to carry home and use to pour their husbands’ bath. (The topic of women’s liberation requires another article.)

Beginning with the Archimedes screw and the Egyptian noria (another pumping device), pump force was rated in units of energy against gravity. For this reason, pumps are rated in “head” to express what we call pressure.

In 1643 the French inventor and mathematician Blaise Pascal, realized that air (the atmosphere) also has weight and that its force is applied in all directions, not just down with gravity. So, he clarified the concept of “pressure” as it is used in the physical sciences: He defined pressure as a force applied to an area, such as a pound of force applied to a square inch of area: thus, pounds per square inch.

A useful formula
Today, modern pump companies continue to rate a liquid’s force as a unit of energy against gravity. If we apply this same force in another direction — such as against the interior sidewall of a pressurized tank — we would use the term “pressure.”

In simple terms, the mathematical constant 2.31 converts a unit of energy against gravity into a unit of force against any other area. This constant converts a foot of head of water into pressure: Head in feet of water divided by 2.31 equals pressure in psi, and pressure in psi times 2.31 equals head in feet.

If the liquid is not water (examples: paint, chocolate syrup or gasoline), the liquid’s specific gravity must be factored into the formula.

The constant 2.31 comes from the following: A square foot of area contains 144 square inches; a cubic foot of ambient-temperature water weighs 62.38 (62.4) pounds per cubic foot at 70 F at sea level.

If I poured 1 pound of water into a tall, narrow vessel that occupies 1 square inch of floor space, I would fill that vessel to 2.31 feet of elevation. Now let’s apply this information with some examples.

Imagine you were on a clear mountain lake taking a ride in a glass-bottomed boat. If the viewing windows were 6 feet below the water’s surface, how much pressure would be acting on the glass panes? Answer: The pressure acting against the windows would be 2.6 pounds per square inch, or 6 feet ÷ 2.31 = 2.6 psi.

The pump rep was right
Here’s another example: Most communities will have an elevated tank of ambient water that supplies water pressure to the communities and neighborhoods below the tank. If the water in the tank is 150 feet above a kitchen faucet in one of the homes, what is the water pressure at the faucet (assuming no other influences on pressure)? Answer: 150 ÷ 2.31 = 65.8 psi.

A standard pressure gauge would record 66 psi. There would be 66 psi of water pressure available at the kitchen faucet, until someone opens the faucet and water flows. As the faucet is opened and water begins moving through the pipes, there would be a slight pressure drop due to friction between the water and the pipe’s internal walls.

Now let’s work in the other direction. If I want to buy a pump that develops 30 psi to pump water, what is my pump rating? What pump should I buy?

30 psi x 2.31 = 70 feet

If you need a pump to develop 30 psi of water pressure, then buy a pump that develops 70 feet of head.

So, it turns out that back in 1965, the pump sales rep was trying to show me the correct pump for my application.

Differential pressure
Allow me to refine a couple of points:

Pumps develop differential head, or differential pressure. This means the pump takes suction pressure, adds more pressure (the design pressure), and generates discharge pressure. So, the discharge pressure is equal to the suction pressure plus the pump’s design pressure. The discharge pressure of the pump should be approximately equivalent to the total dynamic head (TDH) required by the system (tanks, pipes, elbows, valves, flanges and fittings).

To monitor and control your pump, your pump should have a suction pressure gauge and a discharge pressure gauge installed on the pump. You are concerned with the differential.

Let’s say your pump is designed to develop 40 psi. Let’s say there are 3 psi of pressure in the liquid as it arrives into the pump. The suction pressure gauge will read 3 psi. The pump is designed to add 40 psi of pressure. The discharge gauge would read 43 psi. The differential is 40 psi.

If the pressure entering the pump is 25 psi, the discharge gauge will read 65 psi. The differential is 40 psi.

Sick pumps to behaving ones
I work as a engineert. Frequently I’m called to analyze a problem with a sick pump. I usually arrive to find the sick pump has no gauges installed. Or, maybe the sick pump has only a discharge gauge. The pump operator, installer or owner doesn’t know what the pump is doing. This is normally the source of the problem.

Operating a pump without gauges is like driving a car without a dashboard control panel. I mean, you need a timer and a temperature gauge just to cook a pan of biscuits in the oven.

After we control and monitor the differential pressure across the pump, the pump calms down and behaves. The discharge gauge is useless without the suction gauge. Remember, it is the differential pressure, or differential head.

Finally, if your system requires 50 feet of head at 600 gpm, then you will want to purchase a pump with best efficiency coordinates of 50 feet at 600 gpm on the pump performance curve. When reading these curves while choosing a pump, there is a certain optimum zone on the pump-curve graph that you want to stay in. That zone is where the pump operates most efficiently. Pump efficiency is the best combination of head and flow at the least energy consumption. Buy and use efficient pumps.

Handwriting analysis

Handwriting analysis is a surprisingly accurate way to gain insight into someone's personality and current emotional state. While it takes years of study and analyzation of hundreds, if not thousands, of writing samples to become a professional graphologist, you can become an amateur handwriting analyst by looking out for a few basic components of handwriting. Looking at the size, shape and baseline of someone's handwriting offers a quick analysis of their private and public persona.

Instructions

1. • 1
     Collect a writing sample. If you are analyzing yourself, write a few spontaneous sentences, sign the paper and date it. If you are analyzing someone else, have that person write a sample, sign and date it.
   • 2
     Examine the size of the handwriting sample. Large writing indicates a desire to be noticed and to stand out. Medium-sized writing reveals a desire to fit in, and small handwriting indicates a person who would rather blend in.
   • 3
     Compare the size of the sample signature to the handwriting sample. The signature indicates how a person wants to be perceived. The same principles as in Step 2 apply, but this analysis applies to the subject's public persona.
   • 4
     Notice the slant of the writing sample. Handwriting that strongly leans to the right indicates someone who is impulsive and enthusiastic. A slight right slant is consistent with a person who is sociable and outgoing. Vertical writing is characteristic of someone who is independent and practical. Left-slanted writing indicates a person who is reserved and possibly shy. Varying slants indicate an emotionally unpredictable person.
   • 5
     Compare the slant of the signature to the slant of the handwriting sample. The slant of the signature indicates how to person wants to be publicly perceived.
   • 6
     Analyze the baseline, or line against which letters are naturally written, of the writing sample. The baseline can change with a person's mood so this part of the analysis offers a glimpse into the current mood. A straight baseline is indicative of a stable, determined person. An up-sloping baseline shows a hopeful, optimistic person, while a down-sloping baseline could be a sign of pessimism or a tired, overwhelmed person. A varied baseline may indicate an emotionally indecisive mood.
   • 7
     Scrutinize the baseline of the signature in comparison to the baseline of the sample for a glimpse into how the person wants his mood to be viewed by the public.