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Some Thoughts About Management Of Organic Waste 3


Some thoughts about the Management of Organic Waste – Liquid and Solid.



 Bio gas is the product of anaerobic (in absence of air), digestion of organic material at various temperature ranges, depending on the outside temperatures, de type of material and the methanogens, which are decomposing this material.  There are numerous methanogens for different materials, temperatures, acidities etc. It at times will be necessary to start a culture if optimal results need to be obtained. This is especially the case in complex processes like slaughterhouse residues.

 Biogas consists of an average of 55 – 65% Methane (CH4) and 30 – 40% Carbon Dioxide (CO2). Further may contain Nitrous Dioxide (NO2), Hydrogen Sulfide (H2S), Sulfur Dioxide (SO2),   and traces of others. Safety Note: H2S should be dealt with, as it is aside from highly toxic also very flammable and corrosive. It may damage biodigesters and cause leaks, with dangerous results.

The compound of the captured gas depends a lot on the input material. If more woody material is used, obviously this will raise the CO2 content, while high protein material, influences H2S formation and so more. There are cures for many of these challenges.

It serves to determine the chemical composite of this input material. Not only to predict the composition of the output, but also to avoid feeding high levels of toxins as this might kill the “workers”, the bacteria or methanogens. This will immediately affect the gas production.

The gas can normally be used for generating electricity, heating and cooking, with the use in equipment with special nozzles. It is used for this reason in rural areas and thereby replaces wood and charcoal equipment, which is an enormous gain in eliminating emission of smoke,  CO2 and other contaminants, affecting the health of individuals.

Biogas Upgrade

 Although in many cases the output gas can be used as is, it may be necessary to upgrade the gas if used in engines. It is essential to remove most of the CO2 gas and also get rid of any Sulphur oxide  and remnants of H2S, as this affects moving parts and oxidation/erosion of most metals.

It forms with the catalyst, nitrous oxide, the acid H2SO4. Sulfur Dioxide is also a minor Greenhouse Gas. It is recognized by the strong pungent, choking odor. Already in the biodigester process a chemical compound, Ferro Chloride (FeCl3), can be used to precipitate the Sulphur or Sulfide into elemental, insoluble sulphur, avoiding most of it to enter in the output gas. The rest will be removed in the following step. So there are ways of getting rid of solids and other unwanted gases too.

There are various technologies in use, to upgrade biogas to renewable natural gas, with methane contents of 90 to even 98%. The most common are:

  •  Water scrubbing, most used practice
  • Chemical scrubbing, using amine solutions
  • Pressure Swing Adsorption (PSA)
  • Temperature Swing Adsorption (TSA)
  • Membrane technology, There are two membrane separation techniques: high pressure gas separation and gas-liquid adsorption
  • Finally a better alternative is to use biological purification, less cost of investment and operation.


 With overwhelming evidence that the globe is heating up and  all negative effects of that, it should be a must for everyone to participate in those measurements to mitigate the emissions of the gases causing this effect. With the right mindset, the task can be done. The longer we wait for action the greater this task will be.

Let us see to it that organic matter in our community is properly handled. There is now sufficient information available to do just that. Removing the gases in this material, should reduce the concentration in the atmosphere and as an important side result, provide a cleaner energy source.

Ordinary organic matter can be fed to the proper biodigester to produce methane gas and a cleaner organic fertilizer for traditional purposes. This material may consist of herbaceous plant material and animal waste at a 15 to 1 ratio.

The residues of slaughterhouses will have to be handled through biodigesters to avoid affecting public health in the most extended way possible. Sweden has some 15 year experience in this matter and applied for many patents. There are lots of challenges, but there are also solutions.

The Biogas produced, consists of an average of 60% Methane gas, 30 Carbon Dioxide and some other trace gases. Although this biogas can be used for heating and electrical energy generation, it is advantageous also to remove these trace gases from the biodigestion stage into the upgrading stage, to end up with renewable natural gas, with a methane content up to 98% and a much improved caloric value. As a fuel, this causes 50% less CO2 emission compared to fossil fuels and can be used in moving and stationary industrial energy applications, as is, or compressed in cylinders.

Imagine a rural world, where people can just flip a valve and start preparing their meals instead of having to start a polluting wood or charcoal fire. Imagine a city or other community where the garbage is no garbage, but properly separated and the organic matter used to produce renewable natural gas, offsetting much of the cost of waste management. Eliminating landfills with garbage comes brightly in the picture.

I stay open for whatever discussion about this matter. Use the contact form for questions and for comments you will find a form  to ventilate your opinion, at the bottom of the article.


Some Thoughts About Management Of Organic Waste 2


Some thoughts about the Management of Organic Waste – Liquid and Solid.

This document was last modified on: November 18, 2016

Organic Waste


Did you know that mankind is generating more than 3.5 billion tons of organic waste per year, from home as well as our other activities?
Why we should be thinking of ways to better manage our organic waste, is due to the fact that anthropogenic (manmade) emissions of methane, comes from the way we are managing this waste, liquid as well as solid. These emissions surpassed that of natural sources and are rising at an alarming rate in the last 150 to 200 years.

It is for sake of completeness that I need to mention that a substantial amount of atmospheric methane is destructed (sinks), due to stratospheric free radicals like OH, which are reducing methane to CHand water vapor.

Let’s assume that we cannot realistically manage natural emissions from wetlands, forests and others, but there is enough reason to tackle those emissions due to the way we do our daily business.

Areas of these emissions are mainly:

  • Maintenance of Industrial Installations, to stop or reduce leaks.
  • Agricultural Practices and Animal Husbandry in general.
  • Handling of Waste in cities and other communities.

As in Agriculture, rice paddies are a major source of Methane emission if the water in these paddies is not regularly refreshed. Circulating water by irrigating of the paddies, introducing more oxygen, is essential. New Zealand with a considerable agricultural/animal husbandry industry, which is for 50% responsible is contemplating destocking of cattle. This fits into the philosophy to eat less meat .

In general we should adapt a paradigm shift in the way we manage Our Waste and Organic Waste in particular, NOT AS JUST WASTE, BUT AS A RESOURCE. This means we have to Reuse, Reduce and Recycle all waste to infinity. That is the only way to sustainably keep our planet free of waste and hence control pollution in a general sense.

Importance of Managing Organic Waste

It is of the ultimate importance to improve the management of Organic Waste Liquid as well as Solid, as unmanaged storage of this material contaminates soils, waters and air. Think of all the bad odors in rivers and in certain neighbourhoods. In rural areas near live stock farms.

In the first place all residues from residencial, comercial and industrial areas should be separated in three different categories: Organics, Anorganics and Sanitary. In the Waste Management Companies further separation will take place. The Organic part should then be decomposed, either by aerobic or anaerobic systems.

Aerobic Decomposition

The organic material needs to be shredded to particles smaller than one cm. This proces takes place at open air and needs to be mixed with soil and fertilizers, especially carbon and nitrogen, to obtain a useful mix as organic fertilizer.

Many micro and macro organisms are instrumental in the decomposing process. Further de material need to be aerated and watered frequently to avoid overheathing  This proces takes place in Psychrophilic (12-22°) and Mesophilic (25-40°) temperature ranges, with specific bacteria.

But during the process certain Greenhouse Gases are escaping into the atmosphere, such as CO2, CO, N2O, H2S and some minors

Anaerobic Decomposition

The organic material needs to be shredded or ground to particles smaller than one cm. This process takes place in Biodigesters with methanogens under conditions without air. These are closed systems and have the advantage that the Greenhouse Gases captured, s.a. CH4, CO2, N2O, H2S etc., are not escaping in the atmosphere, making it the decomposing system of choice.


Short History of Biodigesters

There is evidence, that gas produced in biodigesters was used for heating purposes in Middle Eastern countries in the 10th -16th Century and in the 17th Century European investigators confirmed that there was a flammable gas in decaying organic  material. And in the next century it was confirmed that a correlation exist between the amount of organic waste and the amount of gas produced.

In the 19th Century it one investigator confirmed that methane was the main gas produced during anaerobic digestion of animal manure. A few decades later the first anaerobic digestion plant was built in Bombay (now Mombay) in India, while at the end of the 19th Century, in England gas was  captured from a sewer facility to use in street lighting. Further microbiological studies identified anaerobic bacterias were instumental in producing methane gas and what were the conditions for this production.

Many low technology digesters were built in China and India to treat waste in rural areas, while in Europe studies were followed up to buid more sophisticated anaerobic digesters. Sweden, Germany and Austria were taking the lead. Many types of material from other industrial waste were treated or pretreated  in biodigester to lower cost and capture gases.

The need for biodigestion

We should drastically increase the use of these anaerobic biodigesters because of, at least, the following benefits:

  • Capturing and utilizing a potent greenhouse gas.
  • Reducing harmful organic waste.
  • Reducing odor.
  • Destruction of pathogens from the waste.
  • Reduce contamination of soils and water bodies through leaching.
  • Carbon neutral technology.
  • Producing an organic fertilizer without harmful effects.
  • Avoiding leakage of toxins and pathogens from animal products .
  • Avoid tree felling for charcoal production.
  • Clean fuel for generating electrical energy with at least 50% less CO2 emission.

 A biodigester is constructed of metal and concrete or durable and flexible plastics en is meant to contain slurry of water and shredded, mostly herbaceous organic matter, but also material from slaughter houses, droppings from mainly cattle and other ruminants.  Material from slaughter houses may increase the production of CH4, significantly, although has many challenges. There are processes to cope with these challenges.

Under anaerobic (without air) condition, various species of bacteria, prevailing under this condition decompose the organic material. During this process gases are formed, cq. released, and captured in a dome like upper structure. The decomposed material or digestate sinks to the bottom and can be reclaimed from time to time, with special slurry pumps.

There are a multitude of different models of biodigesters and in sizes from small for uses in one family homes to medium or small businesses to large and larger used in businesses of substantial size. You also may find lagoon type  digesters, which are frequently used in larger farms and animal husbandry enterprises. These lagoons are covered with durable flexible polypropylene plastics, which are fairly easy repaired, if punctured.

In the state of Jalisco, Mexico, I visited some porciculture farms, annex animal food processors. They use lagoon type biodigesters fed with excrements of the pigs and covered with tough polypropylene. You can walk on top of it although a bit wobbly. From the gas produced, a generator is run, which provides electricity to the food plant.

Although some biodigesters are meant to be used for one badge at a time, the majority are designed for continuous operations. At one end, the shredded material is fed though an intake, constructed in such a way, that the material enters in the slurry in the container, avoiding the gas to escape. At the other end, a tube enters up to the bottom of the container, to make reclaiming of the decomposed digest possible.

The EPA in the USA estimates a potential for biodigesters in rural areas of 8000. (this will be verified, as it seems very few in my opinion)

In Europe, Germany has almost 7000 anaerobic digesters installed. Austria more than 500, while the rest of Europe accounts on the average just over 100. In developing countries, small-scale anaerobic digesters are used to meet the heating and cooking needs of individual rural communities. China has an estimated 8 million anaerobic digesters while Nepal has 50,000.While in the rest of Asia and Africa over the 500,000 are installed.

In Latin America and the Caribbean a Network for Bio Digester Technology (REDBIOLAC) was set up, coordinating the construction of biodigesters in the region. Already some eleven countries are participating in this NETWORK.

In various countries septic tanks are used, to process the sanitary waste of family homes and businesses. The process is similar as that of biodigesters but the gases are released freely into the air via a standpipe. This should be a good opportunity to convert them to biodigesters with all the advantages of these systems.

Sweden has done extensive studies with biodigestion and in the 18 years experience, filed patents for the various sub-processes. The have demonstration plant in Linköping, Sweden and one in the State of Michigan, USA. They also provide the technologies to overcome many of the challenges.

The Processes of Biodigestion are:

  1. Hydrolysis.
    The organic matter complex, carbon hydrates, fats and proteins are broken down into glucose mokecules, fatty acids and amino acids.
  2. Acidogenesis
    Bacteria decompose glucose molecules, fatty acids and aminoacids into volatile fatty acids and alcohols.
  3. Acetogenesis
    The volatile fatty acids and alcohols are converted into hydrogen, carbon dioxide (CO2) and ammonia (NH3).
  4. Metanogenesis
    Bacteria also called Methanogens are converting the hydrogen and resulting acetic acid into methane (CH4) and carbon dioxide (CO2).



Some Thoughts About Management of Organic Waste 1


Some thoughts about the Management of Organic Waste – Liquid and Solid.


This article will express the worry about increased levels of Greenhouse Gas (GHG) emissions and the effect on Global Warming.  The main GHG’s are Water Vapor, Carbon Dioxide, Methane, Hydrofluorides, Hydro Sulfide, Nitro Dioxide and some minor gases. The emissions of Methane, with the chemical formula CH4, is especially worrysome and therefore some thoughts were put in writing to promote technics to capture this gas and make further use of it.


The Globe consists of various eco systems mostly referred to as Biomes or Spheres. So we can distinguish the

  • Lithosphere or inner part of the earth, consisting of rocks
  • Pedosphere or soils or land mass
  • Hydrosphere or oceans, seas, rivers and all other bodies of water, ice or snow, the constant frozen part is also referred to as Cryosphere.
  • Atmosphere or air above the soils and oceans up to 4000m, where natural breathing is still possible.
  • Biosphere or habitats of all living organisms on earth, in the oceans and in the air.

The Globe keeps showing a steady increasing trend in temperatures, despite some small pauses on the way. The emissions of gases in the atmosphere, as prime source of this rise in temperature, are every time much higher and show no sign of relieve. The gases causing the greenhouse effect, shortly called GHG’s are, apart from the most common Water Vapor:

  • Carbon Dioxide (CO2)
  • Methane (CH4)
  • Nitrous Oxide or NOx (N2O)
  • Hydro Fluorocarbons
  • Per Fluorocarbons
  • Sulphur Hexafluoride and Hidrogen Sulfide(H2S)

The first three occur naturally in nature and are keeping our climate at a reasonable temperature level. These gases are also precursors of building blocks for life.

Global_CO2EmissionCO2 is normally absorbed by plants and exhaled by animals, including humans, but in the use of fossil fuels of all kind, and excessive deforestation and agricultural practices, humans are causing every time higher emissions of this gas. CO2 now causes some 60 – 70% of global warming. The concentration level in the atmosphere reached 400 parts per million (ppm) in 2013.

Global_CH4_emissionCH4, is also a building block of life and is found naturally in marsh lands and other areas with trapped organic material, such as under the melting ice caps, but excessively produced by:

  • Fossil fuel production, distribution, storage and use (33%).
  • Landfills, biomass mishandling and sewage (30%)
  • Agriculture (incl. rice paddies) and animal husbandry (36%)

Although the emission level is much less than CO2, the global warming potential (GWP) of this gas is 23 times higher and therefor an important contributor of capturing more heat, up to 30%. The concentration level in the atmosphere is about 1,800 parts per billion (ppb)

Warnings are coming out, to watch the Shale Gas production process, as it seems that substantial leaks of methane occur. I have no figures as most of the information is from private sources. There is a new methane detector on the market from a Californian firm, which can be installed in a car. I sure would suggest, giving it a try in those projects This new equipment, developed by the Silicon Valley firm Picarro, seems to be very sensitive and picks up levels of 1 ppb. Mounted in a car, the complete distribution network can be surveyed at smaller intervals.

N2O also occurs naturally, but is also produced by human activity in agriculture, animal husbandry and the industry. The GWP of this gas is 250 to 310 compared to CO2, 1.

Sulphur Hexafluoride, although non toxic is a 100% manmade gas and comes in small quantities in the atmosphere, but it has a GWP of 23,000 times that of CO2.
Hydrogen Sulfide (H2S) on the otherhand is highly toxic, flammable and explosive, with a GWP of 72. This gas is frequently found in fossil fuels and all efforts are made to remove it, as it is very corrosive to various metals.

The other gases are byproducts of industrial processes.
The National Oceanic and Atmospheric Administration (NOAA), confirms that Methane (CH4) leakages from industrial installations are much stronger than formerly thought (9%) and that lowering this leakages need to be addressed simultaneously with Carbon (CO2) leakages.

Concentration in the atmosphere, of principle gases in 1000 years

Climate Change

Rajenda Pachauri, the chairman of the Intergovernmental Panel on Climate Change (IPCC), said in his organization’s latest report provided: “unequivocal” evidence that since 1950 the atmosphere and oceans had warmed, and that scientists were now “95 per cent certain”, that humans were the “dominant cause”. In 2007 it was 90% and in 2001 66%. So if you want to know where Climate Change is coming from, look in the mirror.

This is not to give one a sense of guilt, but a hint to contribute more to mitigate the causes of Climate Change, reduce emissions of Greenhouse Gases, wherever you have a handle of it. Mind you that the effects of some gases, e.g. CO2 are globally, while others have more regional effects. Ultimately the warming of the planet and its disastrous results will in general be felt all over the world.

Global Temperature GraphThe higher temperatures caused by the rise of GHG emissions, are the cause of more severe weather patterns, larger and more severe storms, more frequent inundations and long drought periods and melting of ice and snow in areas of permanent ice caps (Cryosphere) .

The monster storms we have seen in the last years are, in my opinion, causing short term pauses in temperature rise, due to the huge masses of air moved over the large areas they cover.  The IPCC also mentions in this respect that in those periods solar activity was reduced and volcanic action blocked sunlight.

We can already notice the results from higher temperatures and melting Cryosphere, as the ocean levels are rising, resulting in more inundations of lower coastal areas. Also, higher temperatures increase the volumes of water bodies. There is a new NASA report out, based on observations(May2014), that the glaciers from the Western part of Antarctica’s  Cryosphere, are melting beyond point of return, which will raise the predicted Ocean levels to four feet or 1.20m at the end of this century. Many coastal areas will be permanently inundated. Mind you these are observations and not computer simulations.

Higher temperatures have also effect on living creatures in the oceans (Hydrosphere), moving conditions for the marine live and depleting their natural food, with negative consequences for coral reefs, salmon and other fish used frequently by humans and other predators.

It is clear that with all live on earth being tremendously intertwined, the climate change has far reaching negative impact on all live. Still there are some people, who for whatever reason, do not believe that the change is for the worst. Reasons I have heard are pointing in the direction of narrow-mindedness, let’s face it. Sure, some people like more prolonged warm seasons, but not at the risk of the increased suffering by the rest of the world population, human and other living beings alike. See also the documentary “Years of Living Dangerously” 




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