Why Are Cities Planting Fast Growing Trees?

Most attention on recycling tends to go to materials produced by man – plastics, paper and electronics are probably the big three issues. That’s not the end of the story though. Trees and other plants make up a large percentage of what we throw away. According to EPA figures yard trimmings account for 13.5 percent of municipal solid waste – 110 pounds of grass clippings, old pot plants and dead Christmas trees for every American per year. Then figure in lopped branches from forestry, unharvested parts of crops and the huge amount of plant matter disposed of by the food industry and we’re talking about millions of tons of plant matter to be disposed of every year. If left to decompose it will release huge amounts of carbon into the atmosphere, so sending it to landfill counts as a very bad idea. What gets done to it instead?

Fast Growing Tree Trunk

Large public works projects such as roads and commercialized areas require the clearing of land. This is usually in the form of vacant forests of varying sizes. All of the trees and plants that are cleared get filtered to their respective industries; large trees get sourced for timber while the remaining shrubs and smaller plant material is filtered down the recycling line. Environmental advocates have pushed hard for reforestation bills that ensure whatever trees are cut down are replaced so that there is almost no negative environmental impact. Many municipalities have enacted laws such as these and are considered 1 for 1: however many acres of forest are cut down, they replace that same amount of land with new saplings to regrow the forest. Because the goal is to reforest cheaply and quickly, municipalities choose from a list of fast growing trees for their area so that the saplings mature quickly to continue pulling harmful greenhouse gasses such as CO2 from the air. Although these bills are not nationwide, they are quickly taking hold as more and more cities adopt these laws. So what happens with the actual trees and plants that are cut down and discarded?

Tree Farm

Probably the most valuable resource in plant waste is wood. What goes for recycling isn’t usually good enough quality to be used for timber or furniture, otherwise it would be used in those industries, but it’s still wood and it can be processed into several useful products. The basic way of processing it is by chipping. Foliage is stripped away and the wood is mechanically reduced to small chips of varying sizes. Where it goes from there depends on the type and quality of the wood. Softwood can be fully pulped and turned into paper, although most of the demand for that is met by recycling existing paper or wood from managed forests. Chips can also be formed into wood-based construction materials like particle board, which is cheaper than solid timber and performs better in many applications. It also reduces the need to cut forests for raw materials. Lower grades of particle board can be made from much of the wood sent to recycling.

Wood chips, waste and pulp

Another option that’s becoming more popular is biomass power. This is a fuel source, usually used for electricity generation, which exploits organic waste. Wood and a wide variety of other materials, including spent sugarcane, can be chipped and burned as a fuel in suitable boilers. This then generates steam, which turns a turbine to create electrical power. With carbon sequestration equipment fitted this is a low-pollution and sustainable method of generation that doesn’t use up scarce fossil fuels.

As well as wood there are huge quantities of soft plant matter to consider. The most efficient way to use this is through composting. By managing the decomposition of plant material a rich natural fertilizer can be produced. This has been done for thousands of years by simply piling waste in a heap and keeping it damp, but industrial processes have now been developed. Stricter control of the process improves the quality of the compost and also minimizes the emission of greenhouse gases like methane. The largest stainless steel building on the continent is a composting plant in Alberta, Canada; it’s the size of 14 NHL rinks and every year it turns 250,000 tons of waste into 80,000 tons of compost.

Tree and plant waste is produced in huge quantities and can be bulky, but because it’s all natural material it can be recycled using low-tech and usually economical methods. However it is carbon rich, which is potentially a serious environmental hazard. Properly managed, though, it’s a valuable resource and one that’s being exploited with increasing efficiency.

Recycling Gold, Silver & Other Precious Metals

For centuries, man has had an undying relationship with precious metals. These metals like gold and silver are prized not only for their beauty but also value. This is the only logical explanation for the high number of gold and other precious metals that can be found sitting in central bank vaults and jewelry boxes. According to U.S Geological Survey, there is roughly 171,300 tons of gold that have been mined in history. This is rising at a high rate of 3000 tons every year.


While nothing is wrong with gold, its mining is very bad for our environment. For every ring of gold, there are roughly 20 tons of toxic wastes being generated. And the toxic substances used in the process of mining the gold like mercury and cyanide pollutes both the air we breathe and the water we drink. In fact, gold mining is the number one source of mercury pollution. It is even ahead of coal-fired power stations.

Therefore, we cannot possible continue enjoying these precious metals when they wreak havoc on our planet. Options include using mining methods that are more eco-friendly. This might mean stopping dumping the toxic wastes into oceans and rivers or stop using things like mercury and cyanide. However, the best solution is recycling of the gold that we have already.

Silver recycling

Silver is normally found in electronic and electric scrap, photographic wastes, coinage and jewelry. Given that silver is used for several different things, recycling it is very important. The demand for silver increases as the population grows. Many ways exist to enable reusing and recycling of silver. They include the following.

Scrap Silver


The simplest way to recycle silver and turn it into silver bars.  Your local coin & bullion shop can assist you with this.  To view the types of silver bars that can be made with your unused silver, check out the photos & resources at www.goldeneaglecoin.com.

Selling or donating

If you have a silver jewelry, consider selling it to any jewelry store or even donating it to an organization. This way, the silver will be reused. Alternatively, the jewelry store could melt and recast it to form new jewelry.

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Recycling Industrial Waste Products

Industrial wastes if left unattended to can cause a lot of damage. Recycling industrial waste products makes a great impact in the world. It helps preserve the natural environment for ourselves and our future generations. It is apparent that the more years go by, the more the need for better management of waste products. This is because as the wealth increases, people buy more products and create waste. When the population increases, it means there are more people to create more waste.

Lifestyle changes such as fast food and new packaging and technological products are developed, meaning more products are more biodegradable. There are regulations that are in place to demand that industrial companies are recycling their wastes rather than disposing them off and damaging the environment.


The practice of recycling is no recent phenomenon. There are claims of the practice dating back to Plato in 400 BC. At this time household wastes such as broken pottery and tools were recycled because resources were limited. They were thus reused when new material was unavailable.

Before the industrial period, scrap bronze and other metals were collected and melted for reuse. Dust and ash from coal and wood were recycled as a base for brick making. In these times, recycling offered and economic advantage.

Industrialization catapulted the need for affordable materials. This is why scrap metals were sought after more than virgin ore. The railroads from the 19th Century to the automobile industry of the 20th Century, there was a need for the utilization of scrap metal. Peddlers made a living collecting pots, pans, machinery and sources of metal from dumps, city street and even door to door. This especially became more rampant during World War I.

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Go Green & Recycle Glass


Most of the inorganic waste in our homes can be recycled which is good news for the environment and all of us in return. The worrying trends of global warming, depleted ozone levels and air pollution are making the scenes of the After Earth movie appear more and more realistic. Recycling glass is pretty easy as it can be recycled an infinite number of times without it losing its quality, purity or strength. It is one of the most widely recycled materials with some countries like Belgium, Finland and Switzerland recycling over 90% of their glass and the UK recycling more than 50% of their container glass. In the US 5% of the garbage is made up of glass.



Recycling is not a new concept but rather one that has been around since the BC era. Archeological evidence uncovered over time shows that in the imperial Byzantine times, glass was recycled in the Sagalassos, the ancient city that is present day Turkey. Recycling of other materials like bronze coins and metals and using them to create other items like statues or weapons was a common practice in those periods. Even before the industrial revolution which made recycling a trend, recycling was still being practiced because it made economical sense to recycle some materials instead of using virgin material. Recyclable materials like aluminum and glass were used until they became too worn to be of any further use. In Britain, bricks were made using dust and ash as their base materials and scrap bronze as well as other metals in Europe were melted down and recycled in a perpetual cycle.

After the establishment of the environmental movement which was established in the 1960s, recycling became popular resulting in the establishment of drop-off recycling centers. A major milestone in the journey of recycling was covered when a universal symbol for recycling was introduced. The symbol was a Mobius strip which was designed in the later half of the 1960s by Gary Anderson. This was after a recycled-container company which was based in Chicago sponsored an art contest that was aimed at raising environmental awareness. The triangle has been used as a representation of the hierarchy of recycling that encourages people to reduce, reuse and recycle. The interest in recycling was also increased because of the rising energy costs that were being witnessed in the 1970s.

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Recycling Warships

Our everyday experience of recycling is mostly domestic waste, small items that need to be sorted and sent off according to the material they’re made from. Then of course there’s industrial waste, which often involves much larger volumes and more hazardous substances. Both of these recycling streams are usually handled through ongoing collection contracts. Sometimes really big jobs come up though, one-off recycling of major items. One example of this is ships. The US Navy has just sold a decommissioned aircraft carrier, the former USS Ranger, to International Shipbreaking Limited.
Ranger is a Forrestal-class strike carrier, 1,046 feet long and with a deadweight of 56,300 tons. Her construction began in 1954 and she entered service with the US Navy in 1957. A long and distinguished career followed, but by the early 1990s she was showing her age and she was decommissioned in 1993. Since then she has been docked in Bremerton, Washington as part of the mothball fleet, but now she’s bound for the breakers. A five-month tow round Cape Horn will bring her to ISL’s yard in Florida where she will be broken up over the next few years.
ISL paid the Navy a nominal sum for Ranger, just one cent. That’s because disposing of the ship is actually a profitable business and ISL expect to make a great deal of money from the job. The carrier has been demilitarized, with most of her systems stripped out apart from obsolete ones with no value beyond their material content, but she still has a lot of inherent worth. There are several hundred tons of electronic scrap and cabling but the bulk of her weight is steel. It’s particularly high grade steel and will come in at the upper end of the ferrous scrap market, with pricing probably close to $400 a ton. Some of her metal could sell for a lot more than that because steel from older warships has some unique and valuable properties.
Since 1945 hundreds of nuclear weapons have been detonated, mostly in testing. This has increased the level of radioisotopes in the atmosphere and on the earth’s surface, and one result is that modern manufactured objects usually have a harmless, but detectable, level of radioactivity. Usually this doesn’t matter but it causes problems for some advanced medical scanners, which need to be thoroughly shielded from radiation. The problem is that any newly manufactured shield will itself be slightly radioactive and this can interfere with the scanner’s readings. One solution is to build shields with steel salvaged from old warships. While Ranger was built after nuclear testing began her steel was cast before most of the tests, while atmospheric radioactivity was still much lower than today, so much of her plating is potentially useful. The best steel for shielding is battleship armor, which can be immensely thick – up to 18 inches – but today few battleships survive and all of them are run as museums. Older carriers like Ranger do include armor though, and while it’s rarely more than two or three inches thick it can be layered to create effective scanner shields. Steel armor from the 1950s can sell for thousands of dollars per ton, far more than its scrap value.
Most of the steel from a ship like Ranger will be sold as standard scrap, and in a few years she’ll be cars, refrigerator cabinets and razor blades. Smart scrapping can maximize her value though, so there are real benefits to technologically advanced shipbreakers like ISL compared to a badly paid crew with sledgehammers on a Bengali beach. Even old warships are a valuable resource and the more efficiently they’re recycled the better.

Recycling Fast Food Packaging

Cigarette butts might be the most common item of litter that’s discarded, but fast food packaging can’t be far behind. The nature of fast food – the fact it’s designed to be eaten on the go – means that wrappers, drink containers and disposable utensils need to be provided and are discarded after a single use. In terms of waste it’s extremely inefficient, and some of the materials used have also turned out to be problematic. Styrofoam boxes have been replaced with paper wraps by some of the large chains but they’re still widely used by smaller outlets; as well as using valuable petrochemicals to produce they don’t biodegrade and aren’t easy to recycle.

There are options for recycling Styrofoam; for example it can be chemically processed into a binder for high performance adhesives. Unfortunately this process isn’t widely used at the moment because it doesn’t offer any real cost advantages over alternative materials, so demand is low. Most other recycling programs are focused on industrial packing materials, such as foam peanuts, and don’t adapt readily to food packaging.

The priority for dealing with fast food waste has to be reducing the volume and persuading vendors to switch to more sustainable materials, and progress has been made with that. McDonalds, a pioneer of Styrofoam packaging, began switching to paper wraps and cardboard cartons as early as 1989. Many US cities have enforced local bans on the use of packaging that can’t be easily recycled, and similar insulated boxes made of biodegradable materials are now available (although they cost slightly more than the Styrofoam equivalents). However the current volume of waste has to be dealt with and it’s naturally desirable to recycle as much of it as possible.

While paper waste is generally less environmentally harmful than synthetic materials it can be a problem in the context of fast food packaging. Grease and other food residue tends to soak into the paper and many recycling programs won’t accept it; the result is it goes to landfill or for incineration. This is still better than landfilling Styrofoam but not ideal.

German chemical company BASF has now come up with a solution that would enable food packaging to be composted effectively, rather than disposing of it in landfill. It also uses up to 90 percent recycled materials in its manufacture. A problem with using recycled paper or cardboard for food applications has been that it’s usually contaminated with inks, which are potentially toxic. BASF have now developed a biodegradable polymer which can be used to coat recycled cardboard; this forms a food-safe barrier between the contents and packaging, preventing any contamination, but unlike earlier coatings can be composted along with the cardboard and food residue.

The new polymer is called Ecovio PS 1606 and it’s already qualified for both European and US standards. If it’s adopted on a large scale it could greatly reduce the amount of food packaging that ends up being buried or burned, and while it won’t solve the whole problem of fast food waste it would definitely be a major step in the right direction.

WtE – Waste To Energy

Waste to Energy is a major growth sector, and it has a lot of potential. While it’s obviously preferable to recycle waste wherever possible a percentage inevitably gets incinerated, and waste to energy (WtE) schemes do this in a more efficient way. By collecting heat from the incineration process power can be generated or combustible fuels such as ethanol produced. However WtE produces its own waste in the form of ash. Usually this goes to landfill, because it doesn’t have any further uses, but it can contain valuable materials in amounts that can be economically recovered. Because WtE often uses mixed waste a variety of materials can be involved, mostly metals.

The USA has a number of WtE projects but is lagging behind in reprocessing the ash. At the moment most of it is simply sent to landfill with no further processing once it’s been burned, but this is missing an opportunity to recover metals. In Europe, especially Scandinavia, there’s more of a focus on resource extraction and WtE technology is more advanced. Now the same processes are starting to be used in some US plants, with adaptations to suit local practices.

One feature of US WtE is that all the ash from the process is disposed of together. In Europe the lighter fly ash – the percentage recovered from the smokestacks – and the heavier bottom ash are separated. This makes reprocessing easier because the bottom ash tends to have higher levels of recoverable metals, so dealing with the ash from a US plant needs more efficient extraction. Now Danish company Meldgaard has come up with workable solutions and is using them at three separate locations.

Meldgaard has 20 years of experience in WtE recovery but up to now it’s all been in Europe. However improved technology means they can now handle mixed ash, especially when it comes to recovering non-ferrous metals. Ferrous metal recovery is relatively simple, because ferrous slag can be collected by magnets, but metals such as copper often need chemical recovery.

The first two US operations set up by Meldgaard collect ash from various plants and stockpile it for processing; the actual processes they use vary, because each WtE plant produces ash with distinct characteristics and material content, so it’s important to keep track of which plant a batch of waste came from. Their newest plant is different. It’s integrated with the WtE scheme, so ash is delivered straight from the incinerator to the recycling system. It’s then processed immediately, and the residue sent for landfill as usual. Because the ash has come directly from the burners it’s still moist; current US recyclers can’t deal with ash unless it’s dry, but the new process allows record recovery levels. Currently this operation can handle up to 500 tons per day, with recovered metals being shared between Meldgaard and the WtE operator.

As WtE becomes a more common solution for reducing landfill volume there will be increased potential for recycling the ash. It’s vital that new plants are set up to separate the ash streams, making recycling more efficient, and that recovery technology is regularly updated to maximize extraction. As well as reducing volume even more this could make WtE much more cost-effective.

Water Recycling In California

We talked about water recycling quite recently, but it’s in the news again as California continues down the dangerous road towards severe water shortages. A succession of dry years means the state’s traditional water reserves are running low, and unless there’s a long stretch of wet weather (and plenty of winter snow) water rationing is almost inevitable across huge areas. Government figures now show that all of California is in drought conditions, while 80 percent is experiencing a severe drought and over half “exceptional”. Analysis of tree ring data suggests it’s the driest period n at least 1,200 years.

As well as being bad news for the state’s residents the situation is also potentially disastrous for the vital agriculture industry.  Because of the dry climate California farmers rely heavily on irrigation for most crops and a drought leads to restrictions on what they can grow; if it continues long enough many could be forced out of business altogether, and there may even be irreparable damage to the land itself. Meanwhile cities need water for homes and businesses as well as essential public services, like the fire department. That makes it essential to use water as efficiently as possible and recycling has to play a major role there.

Water recycling is something that needs to be done at all levels, from the state through utility companies down to individuals. California is one of the world’s leading recyclers, with over 250 waste water processing plants currently operating – and that number’s set to grow. Currently up to 580,000 acre-feet of waste water is recycled every year, three times the amount processed in 1970, and by 2030 it’s likely to have quadrupled again. The main use of waste water is for irrigation; it’s much easier to treat it to this standard than to make it fit for drinking, while using it reduces the demand on natural water resources like reservoirs and aquifers.

Of course consumer demand puts pressure on resources to, but new recycling technology means it’s now much easier to make potable water from waste. Orange County’s Groundwater Replenishment System uses microfilters, reverse osmosis and UV disinfection to purify conventionally treated drainage water, which is then pumped into pools to refill the Santa Ana aquifers. This program treats 70 million gallons a day – enough to supply half a million people.

Recycled water can also be used in industry. Many industries use huge amounts of water; often it’s contaminated and needs treatment before it can be discharged, and other times it needs to be pure water. There are many other uses though, such as coolant. Cooling water doesn’t need to be potable and isn’t heavily contaminated in the process, so waste water that’s had a standard treatment can be easily used. Again this reduces demand on fresh sources.

While recycling will stretch water supplies as far as possible it can’t fully compensate for a lack of rainfall, so as long as droughts are a possibility it’s also vital that we look for ways to reduce consumption. One controversial issue is the cultivation of rice in California. Rice needs huge amounts of irrigation and many people say it’s not a suitable crop for a dry area; local food advocates disagree. This is just one of many issues that needs to be solved if we’re going to preserve our water supplies for the future.

More About Glass Recycling

Glass has been recycled longer than almost any other material except iron, and now it’s processed on a large scale in most industrialized countries. Even though the raw materials to produce new glass are cheap the process needs a lot of energy and much of this can be saved by recycling. Depending on its quality waste glass can be handled in various ways. In many countries breweries and other businesses that use glass run their own operations, cleaning and sterilizing returned bottles for reuse. Damaged bottles are sent off for further reprocessing along with glass obtained from bottle banks and household waste collections; separated by color, it can be melted down and formed into new objects with much lower energy consumption than producing new glass.

Despite the relative ease of recycling glass, however, the percentage reprocessed is still far below what it could be. In many areas it’s actually fallen over the past decades. As glass is replaced by plastics in many applications some recycling facilities have closed down through lack of demand, and the result is that glass that would have been processed goes to landfill. This is most common in smaller towns or sparsely populated areas.

One example of the decline in glass recycling is Anchorage, Alaska. The plant there closed in 2009, despite the fact the city produces 15,000 tons of glass waste every year, and transport issues make it difficult and expensive to ship this to alternative facilities. For the last five years the only collection program in the city has been a small-scale one run by Target stores, and this hasn’t been able to handle more than a fraction of the volume. Now Central Recycling Services, which acquired the plant in 2011, plans to reopen it. Part of the deal is that they dispose of around 800 tons of glass left behind by the previous operator, and to do this they plan to develop a new use for lower grade glass waste.

While the most familiar method of reusing glass is to make new containers from it there are also other potential applications. Glass is an abrasive material, and when it’s powdered the result is an abrasive that can be used for sandblasting. This was tried in Anchorage in 2007 but proved to be uneconomical. CRS have a new idea though; they plan to convert the scrap glass into a gravel-like substance that can be used as a concrete aggregate. Glass is ideal for this as it’s very strong in compression. CRS’s priority is to clear up the facility so they can restart conventional processing but huge amounts of low-quality glass waste, mostly broken and unsorted mixed-color scrap, is discarded every year; if they can develop an economical process for converting glass into gravel it could be quickly rolled out on a larger scale.

Anchorage city council is fully behind CRS’s efforts to make this a viable proposition and has pledged up to $85,000 to help them find a processing technique. The potential gains, both financial and environmental, make that a very shrewd investment.

Recycling Scrap Prices

A major goal of recycling is to cut the environmental impact of manufacturing and resource exploitation to the minimum, preserving valuable minerals for future generations and reducing energy use that contributes to climate change. It’s easy to get focused on these worthy aims and forget that there are also economic aspects; while many argue that environmental improvements are worth pursuing at any price it can be difficult to make that viewpoint stick with voters, especially when the global economy is still as fragile as it currently is. Families who’re struggling to pay energy bills right now might not be sympathetic to price hikes intended to avoid damage in the future, and hard-pressed businesses will be reluctant to add extra costs when it’s all they can do to stay afloat.

One area of recycling where economic factors are having an impact right now is the market for scrap ferrous metals. The most valuable ferrous scrap is steel, especially high grade stainless, but the key resource that affects prices is iron ore – and right now that’s heading down. Reduced demand from heavy industry, mostly in China, has depressed prices to below $71 per ton, a five year low. This has a serious impact on the cost effectiveness of recycling ferrous scrap. While much of the cost of processing ore into usable iron or steel is in the energy required low ore prices help offset this, especially when more exotic alloys are involved. To preserve the quality of stainless steel careful sorting is needed in the recycling process, and that takes more investment in technology.

The obvious result of low iron prices is a fall in the market value of scrap iron and steel, and this is exactly what we’re seeing now. In fact there’s been a delay, with scrap holding up well for several months while ore dropped, but the connection has now firmly re-established itself and scrap dealers are reporting sharp falls on all grades. Standard shredded steel scrap is now selling for around $320 per ton, with analysts expecting it to keep falling at least to the end of this year. Stainless 304 grade has shed more than $100 and is now selling around the $1,300 point, with the 316 grade down up to $150 at a shade over $2,000. The main driver here is reduced demand and an abundant supply of chromium.

From a recycling point of view the main concern here is that the scrap industry will be less willing to invest in expensive processing equipment when demand for the recovered metal is weak and prices correspondingly low. The raw material – ferrous scrap – is cheaper and likely to fall even more, but the facilities needed to produce high quality steel from it is an inflexible cost. The best long-term solution to this problem is the development of more efficient processes that cut energy costs and make recycling a more economically robust proposition. The benefits of recycling might always make environmental sense, but to promote it we need to make sure it makes financial sense too.

Recycling Textiles

Two or three generations ago people kept clothes for years, often repairing them or handing them down within the family. The result was that textiles were used quite efficiently, and maximum use was extracted from them. Over the last few decades that’s changed, and both the availability of cheaper garments and the accelerating pace of fashion trends have turned clothes into short-lived commodities that are often disposed of after a couple of years, or even sometimes a matter of months.

The increased disposability of textiles matters, for two reasons. Firstly, many textiles are now made from synthetic fibers, which are often made from scarce petrochemicals. Secondly, even natural fabrics need energy to manufacture and transport, and land used for textile production isn’t available for food. That makes it vital to recycle textiles wherever possible and this is a growing sector of the waste management industry. Textiles can be recycled at several levels, either for their original purpose or for new ones.

The simplest method of textile reuse is to simply get more use out of old clothes. Many discarded garments are still completely usable and can either be sold secondhand or distributed through social programs or foreign aid projects. Recycling containers for clothing are becoming common in several countries. Usually this method is restricted to clothing that doesn’t need any repair.

Where clothing or other textiles have been heavily worn or damaged it’s normally impossible to reuse them. At that point more traditional recycling methods come into play to recover raw materials. Sorting centers usually grade textiles by quality, fabric and degree of damage or soiling. Heavily soiled textiles often go to landfill because cleaning facilities are not available, but cleaner items can be processed. One common application is to turn  suitable fabrics into rags. These have multiple uses in industry, as either cleaning materials or packing. Cotton waste is especially useful and is often picked into loose fibers.

Large quantities of waste textiles are used to produce flocking –short, fine fibers often used for car interiors, door insulation or furniture padding. Depending on the intended use the processing can be basic shredding, or more sophisticated techniques designed to produce flocking of a uniform size and color. Graded fabrics can also be reduced to fibers, cleaned and straightened, then spun into new yarn suitable for knitting or weaving.

A high priority for recycling is artificial fabrics, especially those originally derived from oil. Because oil is a strictly limited resource it’s unacceptable to dispose of these unnecessarily, and polyester is a good candidate for recycling. Waste polyester textiles can be shredded, turned into pellets then chemically converted and repolymerized into polyester chips. These chips are a raw material that can be heated, recolored and spun into new polyester fabric.

Currently even countries with advanced recycling programs perform relatively badly when it comes to textiles – even the Nordic countries only achieve a 17 percent reuse rate. Increasing this would both save resources and cut CO2 emissions significantly. The main priorities are to encourage the public to repurpose textiles where possible or, if they dispose of them, to clean and sort them before doing to. This will make future recycling far easier.

Recycling IP Addresses

When we talk about recycling we usually mean physical goods and the materials they contain. In the modern connected world these aren’t the only valuable resources though, and there are others that might lack physical existence but are still finite and need to be conserved. One of the most important is IP addresses.

Most modern computers, tablets and smartphones use the TCP/IP protocol to communicate and share data with each other, and this set of standards is built around the concept of IP addresses. A traditional IPv4 address consists of four numbers, separated by periods; each number can be anywhere between 0 and 255. In fact the whole IP address is a single 32-bit number that can be broken down into subnets or operated as a single large network. Each device on the network needs to have a unique IP address; for it to work properly duplicates cannot exist. The problem is that using a 32-bit number means there are a total of about 4.3 billion addresses available – and the pool of available ones is running out.

When the IPv4 standard was written in 1981 it was hard to believe there would ever be so many connected devices, but the unbelievable has become reality and in fact the 4.3 billion limit has already been exceeded. To keep the internet working some hard work has been necessary. The main effort has been towards developing and deploying IPv6, which uses 128-bit addresses and so offers 3.4×1038 unique identifiers – enough for every person on earth to have millions of devices. However many systems still depend on the older technology, so it’s vital to get the most possible use out of the existing pool.

One common technique is Network Address Translation, or NAT. This allows multiple devices to connect to the internet through a single external IP address. There are limitations to NAT, because it doesn’t always allow end to end connectivity between individual devices, but it can significantly increase the number of consumer devices that can be operated. Most broadband routers function as NAT systems – there is one IP address that connects to the internet, but a large number of devices can be connected downstream using private IP addresses (usually 192.168.xxx.xxx).

Larger-scale efforts are also being made to free up addresses. Many large blocks were previously allocated to organizations that aren’t using all of them, and the body that allocates address space, IANA, has the option of reclaiming and reissuing all or part of these blocks. There are technical issues with this, because some hardware isn’t set up to use certain address ranges, but it could potentially add up to a billion more addresses.

The IPv4 address space can’t last in the long term – whatever measures are taken the growing number of connected devices, especially the always-on ones envisaged for the “internet of things”, will exhaust the supply. The future lies with IPv6. In the meantime, however, clever use of NAT and reclaimed address blocks should keep things going until the newer protocol becomes more widespread.

Recycling Cataytic Converters

Since the 1970s catalytic converters have helped to dramatically improve air quality, particularly in urban areas. As well as turning highly toxic carbon monoxide into inert carbon dioxide they eliminate emissions of unburnt fuel from the exhaust, breaking it down into water and more carbon dioxide. While carbon dioxide emissions have their own issues the immediate problem is much less than spewing out carcinogenic hydrocarbons. Newer models also deal with nitrogen oxides, converting them to oxygen and harmless nitrogen gas. The effect on pollution levels has been dramatic.

Of course any technology also presents some challenges, and catalytic converters are no exception. In this case the main one is the value of the materials they contain. As well as their basic structure, which is usually a metal casing holding an internal structure of heat-resistant ceramic or kanthal, there’s the catalyst itself. This is where most of the potentially reclaimable value of the device lies.

When exhaust gases enter the converter they’re channeled through a matrix of fine channels, lined with the metal catalyst. The catalyst, together with heat supplied by the exhaust system itself, promotes the chemical reactions that turn pollutants into less harmful atmospheric gases. A variety of metals are suitable for use in converters but most of them have some disadvantages, such as longevity or the possibility that under some running conditions new toxins could be created. The three most effective and reliable ones, however, are platinum, palladium and rhodium. These are all precious metals with a value of hundreds, or even thousands, of dollars an ounce. It’s obviously not cost effective to discard them when a vehicle is scrapped. Both to recover value and preserve limited resources, the catalyst needs to be recovered for reuse.

The recycling process begins when either a car is scrapped or an old converter is handed in to a specialist for exchange. There are a number of businesses which specialize in recycling them but a similar process is used throughout the industry. First the casing is cut open and processed as normal scrap. The internal components, which carry the catalyst in foil form, may consist of beads or a lattice. However the foil isn’t pure catalyst; it also incorporates the “wash coat”, which ensures that exhaust gases are evenly spread over the catalyst. Often this is bonded to a ceramic substrate.

To begin the separation process the wash coat and substrate are pulverized, usually with a hammer mill; the result is a fine powder. The wash coat, which is mostly aluminum, is removed by dissolving in caustic soda. Non-metals like ceramic can usually then be floated out, or the metal content removed by dissolving in a strong acid (which the ceramic resists). The precious metal content is then removed from the solution. This can be done by precipitating it out chemically, but a more effective method is electrolysis – a current is passed through the solution between two electrodes, and the catalyst will be deposited as a pure metal around one of them.

A new technology is currently being developed in Japan, based on the plasma arc furnaces that are widely used for processing electronics scrap. This system employs rapid, extreme heating followed by quenching in cold water. The process separates the catalyst from the substrate and wash coat, greatly reducing the use of toxic chemicals.

Catalytic converters are now an established part of any modern vehicle, but they depend on scarce and expensive resources. With the materials in a single unit now worth more than $1,000, recycling them is both cost-effective and environmentally sound.

Recycling MDF

Medium density fiberboard, or MDF, is one of the most widely used materials for furniture manufacture and is also popular in the construction industry. It’s relatively cheap, easy to manufacture into diverse shapes and its strength is much more predictable than solid timber. The problem is that MDF is a product of an age when efficient use of raw materials wasn’t a high priority, for producers or consumers, and that shows up when it comes to recycling. It’s not an easy material to reprocess; although the bulk of it is made up of wood particles it also contains significant amounts of adhesives, usually urea-based, and is often faced with various types of plastic. As a result of this most of it has traditionally been disposed of in landfills. It’s a bulky material, however, and while it usually deteriorates quite quickly it can take many years for the resin-impregnated wood to actually biodegrade. Carcinogens are also released in the process.

A lot of effort has gone into finding ways to recycle MDF, and several challenges have been identified. The main one is the adhesive which holds the product together; for many potential uses, including remanufacturing into new MDF, this must be removed. The easiest way to do this is by shredding the material and soaking it, to form a slurry, then heating it. It works, but uses large quantities of water and energy. UK company MDF Recovery Limited hope to make the process more efficient with a new ohmic heater they’ve developed specifically for MDF recycling; shredded MDF is soaked then an electric current is passed through it, resulting in rapid heating and breakdown with much less use of water. The recovered material is high enough grade to be manufactured into new MDF.

An alternative technology is the Micro Release process; this uses microwaves to break down MDF, and again it recovers wood fiber that can be remanufactured into fresh MDF. Both of these technologies are too new to judge how many times the material can be recycled before the fibers break down too much, but even a single reuse will add up to a significant cut in both landfill usage and wood consumption.

There are other options apart from reusing the wood particles for MDF. One of the simplest is just to shred the material then burn it, using the heat produced to generate energy for the recycling plant. Burning without energy recovery reduces the amount going to landfill but is wasteful, especially considering the potential uses for recovered particles. Another method now coming into use is to break down the MDF using the standard technique then compost it for agricultural use; this works best with MDF dust and is a good option for waste produced during the manufacture of MDF products. It does require a very high level of efficiency at removing the adhesive, to avoid the possibility of carcinogenic substances entering the food chain.

In 2004 over a million cubic meters of MDF was produced, and almost all of this is going to be disposed of at some point. Right now the majority goes to landfill, but with annual production continuing to increase this isn’t viable as a long-term solution. It’s vital that the new processing technologies are developed further and put into widespread commercial use; then perhaps MDF can be made as environmentally friendly as it is affordable and versatile.