How Almond Waste Can Help Reduce Carbon Emissions

How Almond Waste Can Help Reduce Carbon Emissions

GetFacts not Hype
GetFacts not Hype
Scribol Staff
Environment, October 07, 2010

Almonds growing with blossoms in backgroundPhoto: Donarreiskoffer

Almond waste can be the almond shells, i.e. the hard part covering the kernel or nut, or the hulls a.k.a. the peel – the greenish-grey, fuzzy outside. As we will see, metal ion removal, phenol removal, pollutant removal, horticulture, agriculture, farming and more can be done with the use of almond waste and almond co-products.

The Use of Almond Waste on Metal Ions

Many metal ions are removed or greatly reduced by using parts of the almond. Zinc, Lead, Cu 2 (a type of copper), Cd 2 (a type of cadmium), Ni 2 (a type of nickel) and the cobalt ion (specifically cobalt II aluminate) have all been tested using parts of the almond and with great success. The author read a study (see sources) about its use on lead and cadmium, in which the results revealed almond parts responded better on lead than they did on cadmium, but then found another source where it was successful on cadmium.

Success with almond waste really does depend not only on the metal ion, but the time in contact with the ion, the temperature and the pH-value. Another determining factor is the ratio of metal ion concentration to the concentration of waste. Almond parts were also successful on Cr VI or Chromium 6, which is hexavalent chromium. You may remember this being used by PG&E in their holding ponds, which leached into the ground and contaminated the water in Hinckley, CA. PG&E lost that class action lawsuit for over $330 million, and the case spawned the Erin Brockovich movie, played by Julia Roberts.

Almond shell - covering of the kernel or nutPhoto: Horst Frank

The methods used are equally important, for there are sulfuric acid (h2so4), phosphorous acid, alkali-modified, carbon dioxide (Co2) and steam activated methods. Carbon dioxide methods should be shelved and replaced with other methods whenever possible. In one study, steam activated granular activated carbons or GACs were made from almond shells, which made a direct impact on copper.

In another study, a phosphorous acid activation technique was used for the almond shell GACs on copper, utilizing six methods of activation or activation/oxidation. Those methods were: activation only; standard; continuous; air; modified air; and quench, and then those values were compared to Norit RO 3515. In five of the six methods, almond shell GACs outperformed the Norit RO 3515, so nature won again.

The best performance of the almond shell tests on copper uptake were those shells exposed to the air activation treatment, where 400% more copper was removed than the use of Norit RO 3515. Wow!

Almond LeavesPhoto: Osvaldo Gago

Almond leaves were also tested on five metal ions and they too were very successful. The metals used were: Al 3 (a type of aluminum); Ag (silver) and Mn 2 (a type of manganese) as well as repeating two from above list, i.e. chromium and zinc for the test on the almond leaves.

The adsorption rates were rapid and within 180 minutes, 85% of the metal ions had been removed. The scientists also felt that the almond tree leaf waste had a strong potential for industrial waste application for the use in wastewater treatment plants. Moreover, they added that it was low in cost and easily available. You can’t beat that combination, particularly when it works!

Many metals in concentrated form are not just toxic to humans, but they all leach back into the ground or are dumped into our water sources, which affects every life form and increases the carbon footprint.

The way almond waste works in an aqueous solution is by chelation. Chelants are chemicals that form soluble complex molecules with ions and then inactivate them. Why does this occur? The short answers is that the almonds’ co-products, as carbon adsorbents, have a hydrophilic surface and are antioxidant polyphenols, which make them great at removing metals, but also act as great pollutant removers as we will see in the next section. The picture below is an example of a chemical structure of an EDTA chelate.

Chemical structure of EDTA chelate - chelation examplePhoto: Yikrazuul

Almond Waste Use on Phenols and Pollutants

Phenol is also removed by almond waste in aqueous solutions via adsorption. What is phenol? Technically, it is known as carbolic acid, an organic compound that is a white crystalline solid. However, colloquially, the word phenol refers to any compound that contains a six-member aromatic ring bonded directly to a hydroxyl, of which phenol is the simplest member. Although phenols occur naturally in the plant kingdom and can be used for medicinal properties, they can also be dangerous.

Phenols are used in the making of fungicides, herbicides, disinfectants, as additives for industrial purposes such as wood and plastics processing, and condensation with formaldehyde produces phenolic resins. Although these things make our lives easier, it’s not safe when they are dumped into our rivers, lakes and streams.

Petrochemical industries and oil refining industries are huge polluters of surface water and ground water through phenols. Some phenols are very soluble in water, but many industrial waste phenolic compounds are difficult – if not impossible – to be removed by conventional biological treatments. Plus, phenols are resistant to biodegration.

However, batch process and isotherm studies were carried out using almond waste, which proved to be successful in removing the phenols in both water and wastewater and were low-cost at the same time. Almond waste finished in a three-way tie for the number two spot with two other common natural wastes. Finishing second is not bad, considering the many uses of almond waste, and in the next paragraph you will see it can still hold its own with other pollutants.

Six compounds known as environmental pollutants were studied using almond shells against Calgon Filtrasorb 400, which is known as a popular carbon adsorbent of pollutants in water. Those pollutants were: Toluene, 1,4-Dioxane, Benzene, Acetonitrile, Acetone and Methanol. Although the shells had a higher surface area, the uptake of the pollutants was lower.

However, with that being said, the same six separate methods of phosphorous acid activation or activation/oxidation (from paragraph 5) were used, and some of those methods on some of those pollutants were comparatively close to the Filtrasorb, but with all six methods and six compounds collectively the Filtrasorb rated higher. (I do not see this as a loss, because the almond shells still rated very high and their use is a less expensive method and more natural, considering Filtrasorb is produced from bituminous coal (black coal) and steam activated. Coal- haven’t we heard enough?)

Ornamental Fig tree aka BenjaminPhoto: Kenpei

The Use of Almond Waste in Horticulture and Agriculture

Almond waste has its place in horticulture too.Although fresh shells can prohibit plant growth, dried shells can be a different story depending on what nut trees (some are actually dry fruits) are used. Walnut hulls contain juglone, which acts as a respiratory inhibitor in many plants, but almond shells can be used as culture substrates for ornamental plants.

One such test was performed on a ficus benjamina or Weeping Fig, otherwise known as Benjamin’s Fig. In some areas, this is an ornamental or decorative plant (more like a shrub), but in its native India or Australia, it produces a small fig as well and in tropical latitudes, it makes for a large, stately tree.

The almond shells were tested on the above plant in a soilless culture, which can exist in two forms, either hydroponic or substrate, of which the latter was studied. Substrate is different than the natural, regular dirt under your feet, but is a solid material composed of residual, mineral or organic material whether in pure form or a mixture (such as peat). Additionally, it allows the anchorage of the root system and is able to intervene in the complex process of the plant’s mineral nutrition. The test results revealed that almond shells mixed in with peat were a good substrate component to culture with ornamental plants.

Tomato - can use almond shells with peatPhoto: David Besa

Crops and soil also benefit from almond waste. Almond shells were a good substitute for peat as a substrate in tomato culture. Almond shells can also be a good source of humic material, which could improve the physical and chemical structure of the soil. Why is this? A large amount of inorganic material mixed with a small amount of organic material decreases soil fertility, but a large amount of waste (like almond shells) is an important contributor. The way this is reached is by oxidation of almond shells with nitric acid in the production of humic-based fertilizers.

Although almond waste used for soil fertilization management can be great, not all organic material should be used because of food safety reasons, human pathogens and microbial risks. Improper handling and use of animal wastes such as manure, urine, litter and biosolids can put the business of almond growers at risk, so imagine what other foods could be and have been affected.

In fact, the Almond Board of California does not support the use of manure as fertilizer, but if it is used, it must be applied properly and never be used when it’s non-composted. Almond shells are a natural organic way and yet, it’s just using the waste of the almond that would ultimately go to waste since it has little commercial uses at this time. So in essence, use your waste to reduce waste. What a concept!

It’s ironic that walnut hulls contain juglone, which is a respiratory inhibitor in many plants, yet does not fare as well as inhibiting weed growth as the almond shells do. Testing of walnut hulls as a weed smothering effect in the form of mulch was somewhat responsive on weed control; however the almond shell was more effective and wins again.

Dairy Cows eating hay - Holstein cows - bovinePhoto: Ellmist

Almond Waste Use in Dairy Farming

Almond co-products are also used for feeding livestock. Almond press meal is the residue of almond meats pressed for oil, with most of the oil removed, thereby leaving the remainder to be used in livestock feed, which contains 20% protein and 10% fat.

Additionally, the almond hull (organic or not) is also used in livestock feed at dairy farms and is a source of fiber. The picture above of dairy cows eating in a typical controlled feed setting (with hay) are not on the diet listed above but should be because it is more nutritional and safe than the genetically engineered seed that was developed and marketed by the Monsanto Company.

Another product of Monsanto, which is not allowed in many countries, but is still used by the United States is the recombinant bovine growth hormone or rBGH. This is an artificial or synthetic hormone injected into dairy cows to increase milk production. That’s not necessary, for it has been noted that cows milk well when almond hulls are part of a balanced feed ration. Keep in mind, Monsanto has been in and out of court over the decades for numerous products they make, and they were one of the manufacturers of Agent Orange during the Vietnam War. Need we say more?

Dairy farm with milking parlorPhoto: Gunnar Richter

Almond shell has been used as animal bedding in dairy farms, but obviously not used enough as cows are still getting sick from other bedding products that may be more well known, but less effective overall. Wood chips, wood shavings, saw dust and paper are just some of the products used in bovine bedding, but studies have shown that those products can affect the mammary glands. Why is this? The cows’ teat ends are in close or prolonged contact with the bedding where pathogens not only multiply in the materials mentioned above, but actually support the growth of pathogens, which leads to mastitis.

Mastitis can occur in many animals (and humans) and for different reasons, but bovine mastitis is an inflammation of the breast tissue usually accompanied by a systemic infection, which not only effects milk production, but can affect the mortality rate of the cow.

Mastitis not only occurs because of contagious transmission or contact with a milking machine, but also can occur from the bedding itself. This is called environmental mastitis.

Fresh bedding made of sawdust in particular, can be a source of contamination even before it’s used and has higher numbers of Klebsiella Pneumoniae than other types of bedding. This bacteria is found in sawdust bedding because it is sometimes made from green hardwoods, and when softwoods are used, it is often mixed with bark and soil, which is also a contributing factor.

Wood shavings are no better as livestock litter or farm bedding because not all wood is kiln dried (such as wood for construction materials) or because they are case-hardened or chemically treated. Furthermore, wood shavings can stick to the teats, providing almost constant contact. Veterinary medicine books have been published on the subject with respect to the bedding and diseases of cows as well as goats, sheep, pigs and horses.

In closing: Synthetic this, genetically engineered that, and yet natural and safe products are at our disposal, but that’s exactly what happened – they were disposed or swept aside for the so-called latest and greatest that man has invented, and all for the sake of greed. It is true that some of these positive techniques (of almond waste) are employed by farmers, but the testing mentioned above, which make up two thirds of this article, has gone unimplemented.

When the BP oil spill happened – where were those almonds shells? Almond co-products have many uses, and more uses for them are being explored every day. We are not talking about offsetting carbon with almond waste as much as we are talking about reducing or removing it. Since almond waste and almond co-products seem to win most battles, why would we not consider using them more?

Resources/References Cited:

 

  • Environmental Technology Vol 21, Issue 12, pgs 1337-1342, Dec 2000 – (almond husk tested on 3 metal ions, i.e. Ch, Cd, Cu)
  • Adsorption Science and Technology (Journal) Vol 21, Number 9, pgs 799-808, Nov 2003, publ by Multi-Science Publishing – (almond husk tested on metal ion, i.e. zinc)
  • Water, Air and Soil Pollution, Vol 199, Numbers 1-4, pgs 343-351, 2009 – (almond shells tested on metal ion, i.e. lead)
  • Journal of Hazardous Materials, Vol 97, Issues 1-3, pgs 49-57, Feb 28 2003 – (almond husk tested on metal ion, i.e. nickel)
  • Journal of Hazardous Materials Vol 166, Issues 2-3, pgs 925-930, July 30 2009 – (almond green hull tested on metal ion, i.e. cobalt)
  • Bulletin of the Chemical Society of Ethiopia Vol 21, Number 3, pgs 349-362, 2007 – (almond leaves tested on 5 metal ions)
  • USDA-ARS Southern Regional Research Center New Orleans, LA and Eastern Regional Research Center Wyndmoor, PA; Rec’d Nov 1998, accepted Feb 16, 1999, publ by Elsevier Science Ltd – (almond shells on 6 pollutants)
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