Olive waste disposal

Orchard waste includes unpicked fruit and pruning brush. Historically brush was used for energy on small landholdings but with availability of alternate energy sources and higher labor costs, only larger wood is still used for burning. Smaller wood and foliage can be chopped and incorporated into the soil or burned. Ashes can be spread on the fields to release potassium and trace elements. Increased production of olives has not been shown to justify expenses involved with such procedures in recent studies¹. Using brush for fuel or animal feed seems more promising.

Once the olives have been ground into a paste and mixed in the malaxation tanks, the paste is separated into three components; vegetable water, oil and the husk. The husk (pomace) contains the skins, pulp and pit fragments. This separation is most commonly achieved via a horizontal decanter centrifuge or an olive oil press.

Olive Press waste:

Presses produce a dry pomace and olive water. Because no water is typically added, waste production is minimal. Washing mats may consume water and produce waste water but this is not usually a disposal problem.

Olive Decanter Waste:

Olive Husk or Pomace is often sent to reprocessors who use steam and solvents to remove more oil (pomace oil). Sometimes the pits are removed from the pomace first. The left-over fibrous material is primary lignin and cellulose and has a high BTU content. It can be composted or burned. In California, the ripe olive industry burns pits to produce heat for processing needs. In Italy, some of the frantoios are heated by burning olive pits in what resembles a pellet stove. The pits can also be burned to produce heat to help with the malaxation process in cold climates.

Olive vegetable water is a big problem in many parts of the world. Many countries have restrictions against dumping agricultural waste products into city sewers or streams and rivers. Most areas allow a certain amount to be sprayed back into the orchard if it doesn't impact the water supply. The vegetable water contains valuable trace elements and potassium, phosphorus, etc. as well as organic compounds. Some of the ingredients in wastewater are valuable antioxidants such as polyphenols - The vegetable water is now being used in health foods such as CreAgri's Olivenol Polyphenol extract. Onsite water treatment plants can pre-treat the water to make it acceptable for municipal sewage systems. These plants can be costly but typically are not high energy consumers.

Stones or pits - Accumulates in plants where pitted or stuffed table olives are produced. Can be used for heating, building materials or for activated charcoal.

Crude Olive Cake - The residue which remains after the first pressing of the olives through traditional and continuous machines. There is still a small amount of oil in this cake. If not going on for further processing, this cake is often used for heating, for animal feed supplement or returned to the olive grove as a mulch.

Exhausted Olive Cake - The residue that is left after the above crude olive cake has any remaining oil extracted from it by using solvents such as hexane. This cake is also often used for heating, for animal feed supplement or returned to the olive grove as a mulch.

Partly Destoned Olive Cake - Produced if some of the crushed olive seeds are removed from the paste after processing. This cake is also often used for heating, for animal feed supplement or returned to the olive grove as a mulch.

Olive Pulp - The residual paste which is produced if the whole olive seeds are removed from the paste prior to processing. This residual paste has a very high water content and is difficult to store or dispose of.

Vegetable Water - The brown watery liquid which has been separated from the oil by centrifugation or sedimentation after pressing. The invention of two phase oil extraction has reduced the pollution problems of this waste product by up to 90%.

Source: An Introduction to Olive Oil Processing.

Composting is a low-cost and environmentally friendly method for turning two phase centrifuge effluent (TPOP) into organic fertiliser with a high content of organic matter. Olive trees are often planted in soil deficient in organic matter so creating a suitable amendment with waste is desirable. Tests have shown that adding bulking agents to the centrifuge pomace is important for the composting process. TPOP has poor porosity, an unbalanced nutrient content and has difficult to biodegrade compounds. J. Cegarra et al from the University of Espinardo found in a comparison of cotton residue, grape stalks, olive leaves and fresh cow bedding (straw), that the straw produced the best results and olive leaves the worst.

Processing Table olives can produce large quantities of waste water contaminated with lye or salt. The quantity of and type of contaminant depends on the method of processing.

Selcuk Gida has entered the food sector with a number of large investments, and it is also planning to apply to the Energy Ministry to get permission to produce energy from oil cake. Company officials said that this kind of energy production would be a first in Turkey. Selcuk Gida Executive Board Chairman Eli Alharal said that a new company had been set up under the name of Sel Energy A.S. for the oil venture. Sel Energy A.S. will produce energy from oil cake material, which is an environmentally-safe waste product made from olive oil. Selcuk Gida has been listed on the Istanbul Stock Exchange (IMKB) since July 1999. "The energy power station will be Turkey's first Biomass product and it will cost about $20 million," Alharal said. "The station will be established in Aydin's Germencik district and should be completed within 14 months. Some 40 percent of the energy will be used for Selcuk Gida A.S., 60 percent of the energy will sell to Turkey Electric Distributing Company [TEDAS]." Selcuk Gida exports reach $20 million. Alharal also said that Selcuk Gida was introducing its products through direct marketing in Europe, the United States and Israel. Some 95 percent of its dried fruit exports are sold under the Eagle brand. "Selcuk Gida has a large customer portfolio," he said. "Among our customers are the companies Carrefour, Continent, Coop Suisse Aldi and Lidl, and our exports increase every year. Selcuk Gida's exports in 1985 totaled $700,000. This number should increase to $20 million this year. We also have been working with Migros, Tansas, Kipa and Gima in the domestic market."

As reported in the Guardian Weekly, Endesa, a Spanish Electricity conglomerate intends to generate power by burning olive waste. Endesa is the leading electricity distributor with 43% of the country's total. Spain's 200 million olive trees make it the leading olive oil producer but also the leading producer of pomace, the pits and pulp left over from the olive press.

Throughout history creative minds have tried to find something to do with the olive residue. In Jordan and the Middle East "jift" is burned and used for animal feed. In Italy many small frantoios use the pomace to heat the buildings and the water used in the olive oil making process. Recent accounts from Australia tell of gadgets which make fire logs and building bricks from the pits. The waste can be composted and returned to the fields or used as mulch to keep down weeds. In countries where the pomace builds up into mountains during harvest season, disposal can be a big problem and has been considered toxic waste.

Endesa will build two olive waste fired power stations in Jaen and Ciudad Real. They will produce 32 megawatts, or enough to supply 100,000 people.

Since olive processors have overwhelmingly switched to 2 phase decanters in Spain, more pomace is being burned. Recent concern with polycyclic aromatic hydrocarbons (PAHs) has made the public leery of approving new plants which burn pomace. The PAHs are not high in olives but develop during the drying, extraction and burning of pomace. This has tipped the tide toward composting from energy production

Olive pressing wastes are used to make charcoal in Jordan. The commercial charcoal, for grills, braziers, water-pipes, etc., is the best selling charcoal in Jordan, prefered over other types of charcoal. There are at least 2 companies making charcoal in Jordan. I was unable to view the process at either company, it seems they are worried about people stealing their manufacturing process. I've tried the charcoal and it burns wonderfully. The charcoal is circular in cross section, about 3 cm in diameter. The length of the chunks varies. Maybe it is charred in a closed pipe of some kind.

A simple fermentation technique has the potential to help solve three major challenges of concern to rural Moroccans: how to safely dispose of 180,000 tonnes of olive 'dregs', which are cakes formed from crushed olive sediment; how to ensure that animal feed is affordable after the government reduces imports; and how to create opportunities for educated, jobless youth to start their own micro-businesses MORE

Reproduction of articles: Copyright 04/06/08 The Olive Oil Source. All rights reserved for all countries. Content from this site may be reproduced with attribution and hyperlink to The Olive Oil Source.

1. P. Amirante and F. Pipitone - Re-use of the by-products of olive growing and olive oil production, Olivae no. 93, October 2002

USDA News: 7/17/07 - Two Times a Charm: Recycling Acquaculture Water on Olive Trees

To help farmers and ranchers conserve water, especially precious in the arid Southwest, SARE-funded researchers at the University of Arizona combined shrimp and olive production to test whether they could produce two commodities using less water and commercial fertilizer.

�Arizona farmers are under a lot of economic and environmental pressure to be more efficient with the water they use to produce crops,� said project leader Kevin Fitzsimmons, a researcher at the University of Arizona. �We wanted to show how to pair crops with aquaculture, running water through fish or shrimp first, then putting it on their field crops.�

Not only can farmers reap a double benefit by using aquaculture pond or tank water to irrigate crops, but they also gain extra nutrients from fish waste. Fitzsimmons and his research team set out to find out how much benefit that effluent can provide as crop fertilizer. On a Gila Bend, AZ, shrimp farm, the team designed a plot of 120 olive trees, spaced along 10 rows. From the shrimp pond, they irrigated olive saplings and compared canopy height and trunk circumference to a set of trees watered from a well.

Effluent-treated trees grew larger than well-watered trees, supplying saplings with 1.6 to 5.6 kilograms of nitrogen per row from the shrimp waste. In the second year, they met the full nitrogen recommendation for olive trees. �A major point is that we're using the nitrogen and phosphorus in the waste from the shrimp to replace the N and P fertilizers that farmers would otherwise have to buy,� Fitzsimmons said. �We supplied close to 100 percent of nutrients needed for the trees at that size.�

Gary Wood, the shrimp farm's owner, continues to irrigate olive trees as well as durum wheat fields from his shrimp pond, which is fed by well water. Wood, who also received a farmer/rancher grant from SARE to develop direct markets for his Desert Sweet Shrimp, calls the system �a classic example of environmental synergy.�

Fitzsimmons also tested shrimp pond sludge�shrimp waste that settles to the bottom�on tomato plots at the university's Environmental Research Lab. The tomatoes amended with sludge in Fitzsimmons' project produced significantly more fruit than the tomatoes in the control plot with unamended soil: 141 grams of fruit per plant compared to 39 grams in the control plants. Through field days, Fitzsimmons' team publicized their results and, since then, close to a dozen Arizona crop farmers are trying to integrate fish and shrimp farming into their systems. Click for full article:

Composting Olive Pomace