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68-622: The Bourtange Swamp had the shape of a V. The western leg covered the valley of the Hunze and ranged towards the city of Groningen . The western part was bordered by the Hondsrug . The eastern leg was located in the valley of the Ems . Between these two legs lays Westerwolde . At its greatest extent the swamp was about 3000 km. The swamp arose around 5000 BC. The area was already inhabited before this happened, as shown by archeological finds such as

136-837: A Ramsar site . In Germany peat harvesting continued in the 21st century. Several bog bodies were found in the bog, including the Weerdinge Men (found near Weerdinge in Drenthe ), Aschbroeken Man , also from Drenthe, Roter Franz (Neu Versen in Emsland ) and the Kibbelgaarn body (Kibbelgaarn in Groningen ) 52°53′45″N 7°15′35″E  /  52.89583°N 7.25972°E  / 52.89583; 7.25972 Hunze The Hunze (also Oostermoerse Vaart , Oostermoersche Vaart , Drentsche Diep and Schuyten diep )

204-408: A food trend in 2016, being used as an additive to impart a "slightly smoky" taste and a dark coloring to products including hotdogs, ice cream, pizza bases, and bagels. People taking medication, including birth control pills and antidepressants , are advised to avoid novelty foods or drinks that use activated charcoal coloring since it can render the medication ineffective. Activated charcoal

272-421: A 50-mesh sieve (0.297 mm). Powdered activated carbon (PAC) material is finer material. PAC is made up of crushed or ground carbon particles, 95–100% of which will pass through a designated mesh sieve . The ASTM classifies particles passing through an 80-mesh sieve (0.177 mm) and smaller as PAC. It is not common to use PAC in a dedicated vessel, due to the high head loss that would occur. Instead, PAC

340-499: A pesticide, animal feed additive, processing aid, nonagricultural ingredient and disinfectant. In organic winemaking, activated carbon is allowed for use as a processing agent to adsorb brown color pigments from white grape concentrates. It is sometimes used as biochar . Activated carbon filters (AC filters) can be used to filter vodka and whiskey of organic impurities which can affect color, taste, and odor. Passing an organically impure vodka through an activated carbon filter at

408-560: A plasma sample to be analyzed for abnormalities otherwise affected by the DOACs. Carbon adsorption has numerous applications in removing pollutants from air or water streams both in the field and in industrial processes such as: During early implementation of the 1974 Safe Drinking Water Act in the US, EPA officials developed a rule that proposed requiring drinking water treatment systems to use granular activated carbon. Because of its high cost,

476-470: A substrate for the application of various chemicals to improve the adsorptive capacity for some inorganic (and problematic organic) compounds such as hydrogen sulfide (H 2 S), ammonia (NH 3 ), formaldehyde (HCOH), mercury (Hg) and radioactive iodine-131 ( I). This property is known as chemisorption . Many carbons preferentially adsorb small molecules. Iodine number is the most fundamental parameter used to characterize activated carbon performance. It

544-414: A surface). Activation is analogous to making popcorn from dried corn kernels: popcorn is light, fluffy, and its kernels have a high surface-area-to-volume ratio . Activated is sometimes replaced by active . Because it is so porous on a microscopic scale, one gram of activated carbon has a surface area of over 3,000 square metres (32,000 square feet), as determined by gas adsorption. For charcoal,

612-419: Is a form of carbon commonly used to filter contaminants from water and air, among many other uses. It is processed ( activated ) to have small, low-volume pores that greatly increase the surface area available for adsorption or chemical reactions that can be thought of as a microscopic "sponge" structure ( adsorption , not to be confused with absorption , is a process where atoms or molecules adhere to

680-439: Is a measure of activity level (higher number indicates higher degree of activation ) often reported in mg/g (typical range 500–1200 mg/g). It is a measure of the micropore content of the activated carbon (0 to 20  Å , or up to 2  nm ) by adsorption of iodine from solution. It is equivalent to surface area of carbon between 900 and 1100 m /g. It is the standard measure for liquid-phase applications. Iodine number

748-525: Is a process by which a porous carbon can be coated with a biocompatible polymer to give a smooth and permeable coat without blocking the pores. The resulting carbon is useful for hemoperfusion . Hemoperfusion is a treatment technique in which large volumes of the patient's blood are passed over an adsorbent substance in order to remove toxic substances from the blood. There is a technology of processing technical rayon fiber into activated carbon cloth for carbon filtering . Adsorption capacity of activated cloth

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816-649: Is a river located in the border area of Drenthe and Groningen , east of the Hondsrug , in the Netherlands . The Hunze used to run through to the Wadden Sea , first at Pieterburen and later at Zoutkamp , via the Lauwerszee . The name means "marsh or mud (stream)". The name of the area, Hunsingo , refers to this river, which originally flowed into the Wadden Sea. The Hunze valley probably formed in

884-629: Is considered to be in the high-mercury subcategory and is banned from landfilling (Land-Ban Rule). This material is now accumulating in warehouses and in deep abandoned mines at an estimated rate of 100 tons per year. The problem of disposal of mercury-laden activated carbon is not unique to the United States. In the Netherlands, this mercury is largely recovered and the activated carbon is disposed of by complete burning, forming carbon dioxide (CO 2 ). Activated, food-grade charcoal became

952-456: Is defined as the milligrams of iodine adsorbed by one gram of carbon when the iodine concentration in the residual filtrate is at a concentration of 0.02 normal (i.e. 0.02N). Basically, iodine number is a measure of the iodine adsorbed in the pores and, as such, is an indication of the pore volume available in the activated carbon of interest. Typically, water-treatment carbons have iodine numbers ranging from 600 to 1100. Frequently, this parameter

1020-416: Is designated by sizes such as 8×20, 20×40, or 8×30 for liquid phase applications and 4×6, 4×8 or 4×10 for vapor phase applications. A 20×40 carbon is made of particles that will pass through a U.S. Standard Mesh Size No. 20 sieve (0.84 mm) (generally specified as 85% passing) but be retained on a U.S. Standard Mesh Size No. 40 sieve (0.42 mm) (generally specified as 95% retained). AWWA (1992) B604 uses

1088-699: Is generally added directly to other process units, such as raw water intakes, rapid mix basins, clarifiers, and gravity filters. Granular activated carbon (GAC) has a relatively larger particle size compared to powdered activated carbon and consequently, presents a smaller external surface. Diffusion of the adsorbate is thus an important factor. These carbons are suitable for adsorption of gases and vapors, because gaseous substances diffuse rapidly. Granulated carbons are used for air filtration and water treatment , as well as for general deodorization and separation of components in flow systems and in rapid mix basins. GAC can be obtained in either granular or extruded form. GAC

1156-614: Is greater than that of activated charcoal ( BET theory ) surface area: 500–1500 m /g, pore volume: 0.3–0.8 cm /g) . Thanks to the different forms of activated material, it can be used in a wide range of applications ( supercapacitors , odor absorbers, CBRN-defense industry etc.). A gram of activated carbon can have a surface area in excess of 500 m (5,400 sq ft), with 3,000 m (32,000 sq ft) being readily achievable. Carbon aerogels , while more expensive, have even higher surface areas, and are used in special applications. Under an electron microscope ,

1224-441: Is made for general purposes based on their size, preparation methods, and industrial applications. Normally, activated carbons (R 1) are made in particulate form as powders or fine granules less than 1.0 mm in size with an average diameter between 0.15 and 0.25 mm. Thus they present a large surface to volume ratio with a small diffusion distance. Activated carbon (R 1) is defined as the activated carbon particles retained on

1292-697: Is made from petroleum pitch and supplied in diameters from approximately 0.35 to 0.80 mm. Similar to EAC, it is also noted for its low pressure drop, high mechanical strength and low dust content, but with a smaller grain size. Its spherical shape makes it preferred for fluidized bed applications such as water filtration. Porous carbons containing several types of inorganic impregnate such as iodine and silver . Cations such as aluminium, manganese, zinc, iron, lithium, and calcium have also been prepared for specific application in air pollution control especially in museums and galleries. Due to its antimicrobial and antiseptic properties, silver loaded activated carbon

1360-721: Is not initiated. Activated carbon, in 50% w/w combination with celite , is used as stationary phase in low-pressure chromatographic separation of carbohydrates (mono-, di-, tri- saccharides ) using ethanol solutions (5–50%) as mobile phase in analytical or preparative protocols. Activated carbon is useful for extracting the direct oral anticoagulants (DOACs) such as dabigatran , apixaban , rivaroxaban and edoxaban from blood plasma samples. For this purpose it has been made into "minitablets", each containing 5 mg activated carbon for treating 1ml samples of DOAC. Since this activated carbon has no effect on blood clotting factors, heparin or most other anticoagulants this allows

1428-422: Is not well adsorbed by activated carbon. This should be of particular concern to those using the material in filters for respirators, fume hoods, or other gas control systems because the gas is undetectable to the human senses, toxic to the metabolism, and neurotoxic. Substantial lists of the common industrial and agricultural gases adsorbed by activated carbon can be found online. Activated carbon can be used as

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1496-549: Is particularly ineffective against poisonings of strong acids or bases , cyanide , iron , lithium , arsenic , methanol , ethanol , or ethylene glycol . Activated carbon will not prevent these chemicals from being absorbed into the human body. It is on the World Health Organization's List of Essential Medicines . Incorrect application (e.g. into the lungs ) results in pulmonary aspiration , which can sometimes be fatal if immediate medical treatment

1564-481: Is perfectly capable of producing the equivalent, by adsorption from its environment, liquid water from steam at 100 °C (212 °F) and a pressure of 1/10,000 of an atmosphere . James Dewar , the scientist after whom the Dewar ( vacuum flask ) is named, spent much time studying activated carbon and published a paper regarding its adsorption capacity with regard to gases. In this paper, he discovered that cooling

1632-663: Is referred to as activated coal . Activated coke is derived from coke . Activated carbon is used in methane and hydrogen storage, air purification , capacitive deionization, supercapacitive swing adsorption, solvent recovery, decaffeination , gold purification , metal extraction , water purification , medicine , sewage treatment , air filters in respirators , filters in compressed air, teeth whitening, production of hydrogen chloride , edible electronics, and many other applications. One major industrial application involves use of activated carbon in metal finishing for purification of electroplating solutions. For example, it

1700-487: Is seen as the period when probably either the river system of the Hunze (main stream with supplying tributary streams) was formed or the time when a swamp (fed by streams) arose on the site of the Hunze. However, evidence for this is as yet lacking. Over time, the river was reduced to a stream valley no more than a few kilometers wide. In the 14th century, the northern arm towards Hiddingezijl  [ nl ; zh-min-nan ]

1768-643: Is the main purification technique for removing organic impurities from bright nickel plating solutions. A variety of organic chemicals are added to plating solutions for improving their deposit qualities and for enhancing properties like brightness, smoothness, ductility, etc. Due to passage of direct current and electrolytic reactions of anodic oxidation and cathodic reduction, organic additives generate unwanted breakdown products in solution. Their excessive build up can adversely affect plating quality and physical properties of deposited metal. Activated carbon treatment removes such impurities and restores plating performance to

1836-421: Is used as an adsorbent for purification of domestic water. Drinking water can be obtained from natural water by treating the natural water with a mixture of activated carbon and aluminium hydroxide (Al(OH) 3 ), a flocculating agent . Impregnated carbons are also used for the adsorption of hydrogen sulfide (H 2 S) and thiols . Adsorption rates for H 2 S as high as 50% by weight have been reported. This

1904-419: Is used in smoking filters as a way to reduce the tar content and other chemicals present in smoke, which is a result of combustion, wherein it has been found to reduce the toxicants from tobacco smoke, in particular the free radicals. The structure of activated carbon has long been a subject of debate. In a book published in 2006, Harry Marsh and Francisco Rodríguez-Reinoso considered more than 15 models for

1972-463: Is used to determine the degree of exhaustion of a carbon in use. However, this practice should be viewed with caution, as chemical interactions with the adsorbate may affect the iodine uptake, giving false results. Thus, the use of iodine number as a measure of the degree of exhaustion of a carbon bed can only be recommended if it has been shown to be free of chemical interactions with adsorbates and if an experimental correlation between iodine number and

2040-736: The Kropswolderbuitenpolder and the Westerbroekstermadepolder north of the Zuidlaardermeer . Additionally, on both sides of the Euvelgunnerweg , thanks in part to the late farmer Thies Dijkhuis, the Hunzezone has been established as a green area between two industrial zones, preserving the existing Hunzeloop. In 2014, Hunzevisie (Hunzevision) 2030 was presented. This plan also expressed

2108-481: The Saale Glaciation (the penultimate ice age; 236,000 to 124,000 B.C.) during the last phase of the hif period , when the ice flow of the land ice changed direction from northeast-southwest to northwest-southeast. Possibly the cutout was caused by an ice lobe. It was previously thought that this occurred later and that the valley was created by meltwater runoff. However, the presence of depressions and

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2176-515: The Zuidlaardermeer ) and Ter Apel . Nowadays it is the border between Drenthe and the Province of Groningen . The Stadskanaal ( City canal ), which was dug in the 18th century, largely follows the Semslinie. This canal played a significant role in the large-scale peat harvesting. The areas that were cultivated were called veenkoloniën ( peat colonies ). Due to peat harvesting and drainage

2244-771: The bocht van Hekkum (bend of Hekkum) and the Oude Diepje (Old Deep). At the later Schouwerzijl , the river split into a northern branch (see: Kromme Raken ) which flowed into the Wadden Sea near Pieterburen and a western branch (later part of the Reitdiep) which flowed into the Lauwerszee near Zoutkamp. In 1995, the Groninger landscape, the Drentse landscape, and the Worldwide Fund for Nature (WWF) developed

2312-590: The 19th century peat as a fuel, got competition from coal and peat harvesting became less profitable. In the second half of the 19th century de another important canal was dug, the Verlengde Hoogeveensche Vaart. This resulted in more peat harvesting in the southern points of the bog. In the 20th century peat was no longer the main product from the bog, but activated charcoal , turfstrooisel (a sort of compost) and potting soil became important products. No new canals were dug and products from

2380-638: The 50-mesh sieve (0.297 mm) as the minimum GAC size. The most popular aqueous-phase carbons are the 12×40 and 8×30 sizes because they have a good balance of size, surface area, and head loss characteristics. Extruded activated carbon (EAC) combines powdered activated carbon with a binder, which are fused together and extruded into a cylindrical shaped activated carbon block with diameters from 0.8 to 130 mm. These are mainly used for gas phase applications because of their low pressure drop, high mechanical strength and low dust content. Also sold as CTO filter (Chlorine, Taste, Odor). Bead activated carbon (BAC)

2448-596: The Hunze is called the Selwerderdiepje . From Wierumerschouw, the Reitdiep , starting in the mid-17th century, became the largely straightened lower course of the Hunze. The section from Groningen to Wierumerschouw is the excavated lower course of the Drentsche Aa . Around the year 1400, the Hunze was dammed at Roodehaan and redirected through the newly dug Schuitendiep to Groningen . A portion of it

2516-611: The Westerbroekstermadepolder nature reserve, as it crosses from the province of Drenthe into the province of Groningen. It ultimately joins the Winschoterdiep at Waterhuizen  [ fr ; nl ; pl ; zh-min-nan ] . Between the Winschoterdiep and the Damsterdiep , the river had silted up significantly, making it difficult to recognize it as such. North of the (old) city of Groningen ,

2584-827: The Zuidlaardermeer, it is also referred to as the Oostermoerschevaart, named after the Oostermoer dike. The term 'moer' indicates marsh and fen . West of the Zuidlaarderdiep, the Hunze used to be connected to the Drentsche Aa through a valley that cut through the Besloten Venen. Originally, the river meandered through this swampy area. This marshy terrain is the reason why there is actually no location in Drenthe that directly borders

2652-623: The ambition to allow the Hunze to flow back into the Wadden Sea. In 2023, the municipality of Groningen also presented a Hunze Vision, aligning with the desire of other parties to restore the river's connection to the Wadden Sea. Groningen envisions a series of projects spanning a total of 30 years. The intention is for anyone wishing to develop or build in the Hunze area to incorporate river restoration into their plans. 53°11′01″N 6°39′18″E  /  53.1836°N 6.6550°E  / 53.1836; 6.6550 Activated charcoal Activated carbon , also called activated charcoal ,

2720-627: The bog was being largely transported to factories via narrow gauge railways . From there it was transported by ship, tram engine , train or truck. After the Amsterdamse Veld in southeast Drenthe was stripped of its peat, the harvesting of peat and other products from the bog stopped. A remaining part of the bog and surroundings including the Amsterdamse Veld are now part of the Bargerveen Nature Reserve ,

2788-515: The bog. In the Middle Ages some places at the edges of the bog were drained for growing rye . The drainage caused soil settling and the area became more vulnerable to floodings. Between 1360 and 1500 parts in the northeast were washed away by the Dollart . In the 16th century large-scale peat harvesting began. The Frisian method, using canals , was introduced. At first most peat harvesting

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2856-433: The carbon to liquid nitrogen temperatures allowed it to adsorb significant quantities of numerous air gases, among others, that could then be recollected by simply allowing the carbon to warm again and that coconut-based carbon was superior for the effect. He uses oxygen as an example, wherein the activated carbon would typically adsorb the atmospheric concentration (21%) under standard conditions, but release over 80% oxygen if

2924-571: The carbon was first cooled to low temperatures. Physically, activated carbon binds materials by van der Waals force or London dispersion force . Activated carbon does not bind well to certain chemicals, including alcohols , diols , strong acids and bases , metals and most inorganics , such as lithium , sodium , iron , lead , arsenic , fluorine , and boric acid. Activated carbon adsorbs iodine very well. The iodine capacity, mg/g, ( ASTM D28 Standard Method test) may be used as an indication of total surface area. Carbon monoxide

2992-465: The case of hydrogen gas extracted for use in a hydrogen fuel cell . Gas storage in activated carbons is an appealing gas storage method because the gas can be stored in a low pressure, low mass, low volume environment that would be much more feasible than bulky on-board pressure tanks in vehicles. The United States Department of Energy has specified certain goals to be achieved in the area of research and development of nano-porous carbon materials. All of

3060-538: The city of Groningen, two large bends of the old course are still discernible between Ooster - and Noorderhoogebrug . Structures are also still found on the eastern side of the Selwerderhof cemetery. North of the Van Starkenborghkanaal , the contours of the clay area around Adorp are still visible. From there, the river meandered northward, and the old meanders can still be identified, such as

3128-402: The contaminants involved. Activated carbon is also used for the measurement of radon concentration in air. Biomass waste-derived activated carbons were also succuesfully used for the removal of caffeine and paracetamol from water. Activated carbon (charcoal) is an allowed substance used by organic farmers in both livestock production and wine making. In livestock production it is used as

3196-449: The degree of exhaustion has been determined for the particular application. Some carbons are more adept at adsorbing large molecules. Molasses number or molasses efficiency is a measure of the mesopore content of the activated carbon (greater than 20 Å , or larger than 2 nm ) by adsorption of molasses from solution. A high molasses number indicates a high adsorption of big molecules (range 95–600). Caramel dp (decolorizing performance)

3264-469: The desired level. Activated carbon is used to treat poisonings and overdoses following oral ingestion . Tablets or capsules of activated carbon are used in many countries as an over-the-counter drug to treat diarrhea , indigestion , and flatulence . However, activated charcoal shows no effect on intestinal gas and diarrhea, is ordinarily medically ineffective if poisoning resulted from ingestion of corrosive agents, boric acid, or petroleum products, and

3332-470: The equivalent figure before activation is about 2–5 square metres (22–54 sq ft). A useful activation level may be obtained solely from high surface area. Further chemical treatment often enhances adsorption properties. Activated carbon is usually derived from waste products such as coconut husks; waste from paper mills has been studied as a source. These bulk sources are converted into charcoal before being activated. When derived from coal , it

3400-406: The filter media. Activated carbon filters are used to retain radioactive gases within the air vacuumed from a nuclear boiling water reactor turbine condenser. The large charcoal beds adsorb these gases and retain them while they rapidly decay to nonradioactive solid species. The solids are trapped in the charcoal particles, while the filtered air passes through. Activated carbon is commonly used on

3468-506: The following processes: The Dutch company Norit NV , part of the Cabot Corporation , is the largest producer of activated carbon in the world. Haycarb , a Sri Lankan coconut shell-based company, controls 16% of the global market share. Activated carbons are complex products which are difficult to classify on the basis of their behaviour, surface characteristics and other fundamental criteria. However, some broad classification

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3536-470: The goals are yet to be satisfied but numerous institutions, including the ALL-CRAFT program, are continuing to conduct work in this field. Filters with activated carbon are usually used in compressed air and gas purification to remove oil vapors, odor, and other hydrocarbons from the air. The most common designs use a 1-stage or 2 stage filtration principle in which activated carbon is embedded inside

3604-578: The high surface-area structures of activated carbon are revealed. Individual particles are intensely convoluted and display various kinds of porosity ; there may be many areas where flat surfaces of graphite -like material run parallel to each other, separated by only a few nanometres or so. These micropores provide superb conditions for adsorption to occur, since adsorbing material can interact with many surfaces simultaneously. Tests of adsorption behaviour are usually done with nitrogen gas at 77 K under high vacuum , but in everyday terms activated carbon

3672-508: The laboratory scale to purify solutions of organic molecules containing unwanted colored organic impurities. Filtration over activated carbon is used in large scale fine chemical and pharmaceutical processes for the same purpose. The carbon is either mixed with the solution then filtered off or immobilized in a filter. Activated carbon, often infused with sulfur or iodine, is widely used to trap mercury emissions from coal-fired power stations , medical incinerators , and from natural gas at

3740-497: The old Hunzeboezem, even though the small river near Gasselternijveen and Spijkerboor comes very close to both villages. This proximity is likely the result of rerouting and straightening the original meanders near these villages. At Meerwijck , where the Hunze exits the north side of the Zuidlaardermeer, there is a bicycle and foot ferry. From this point onward, the river is known as the Drentsche Diep, flowing through

3808-644: The one at Hoetsmansmeer in Groningen . These finds are attributed to nomads from the Mesolithic . Eventually these people left because of the growing swamp. Near Valthe - Ter Apel and Nieuw-Dordrecht remnants of roads through the bog were found, dating from the Neolithic to the Iron Age . From a military point of view the swamp had an important function as a protective barrier, especially between 1580 and 1850. The swamp played an important role during

3876-660: The plan, Hunzevisie , with the aim of restoring nature in the Hunze Valley and reconstructing the original river course as much as possible. The province of Drenthe and the municipalities of Aa en Hunze, Borger-Odoorn, and Tynaarlo are jointly restoring the old meanders of the Hunze in the Drenthe part of the small river. During this work, the remains of an old floodgate were found near the hamlet of De Hilte  [ nl ; pl ; zh-min-nan ] in October 2014. In Groningen, examples of realized nature reserves include

3944-589: The proper flow rate will result in vodka with an identical alcohol content and significantly increased organic purity, as judged by odor and taste. Research is being done testing various activated carbons' ability to store natural gas and hydrogen gas . The porous material acts like a sponge for different types of gases. The gas is attracted to the carbon material via Van der Waals forces . Some carbons have been able to achieve binding energies of 5–10 kJ per mol . The gas may then be desorbed when subjected to higher temperatures and either combusted to do work or in

4012-470: The remaining swamp became a lot drier. This was bad for the military function of the eastern branch. Therefore, dikes were built near Bourtange to keep water there. Also colonists from Germany , who grew buckwheat , arrived in the Dutch part of the bog. In order to make the soil suitable to grow buckwheat the peat had to be burned. Because of the inconvenience it brought, it was banned in 1925. During

4080-471: The so-called GAC rule encountered strong opposition across the country from the water supply industry, including the largest water utilities in California. Hence, the agency set aside the rule. Activated carbon filtration is an effective water treatment method due to its multi-functional nature. There are specific types of activated carbon filtration methods and equipment that are indicated – depending upon

4148-645: The steep straight boundary on the west side of the Hunze Valley make this illogical. Later, the valley did serve to drain meltwater. The valley originally had a width of 15 kilometers and a depth of 50 meters. During the Saalian and subsequent periods, including the Eemian (until 114,000 BC; an interglacial period) and the Weichselian (until 9,700 BC), a significant portion of the valley was predominantly filled with sand. The Eemian (between 124,000 and 114,000 B.C.)

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4216-512: The structure, without coming to a definite conclusion about which was correct. Recent work using aberration-corrected transmission electron microscopy has suggested that activated carbons may have a structure related to that of the fullerenes , with pentagonal and heptagonal carbon rings. Activated carbon is carbon produced from carbonaceous source materials such as bamboo, coconut husk, willow peat , wood , coir , lignite , coal , and petroleum pitch . It can be produced (activated) by one of

4284-453: The wars between Groningen and Münster In places with passages through or along the bog, strongholds were built. Bourtange , Oudeschans , Nieuweschans , Valtherschans and Emmerschans are examples of these places. Initially cultivation only occurred at the edges of the swamp. The harvested peat was a source of fuel. During the second half of the Middle Ages the monasteries of Aduard and Essen played an important role in cultivating

4352-406: The wellhead. However, despite its effectiveness, activated carbon is expensive to use. Since it is often not recycled, the mercury-laden activated carbon presents a disposal dilemma. If the activated carbon contains less than 260 ppm mercury, United States federal regulations allow it to be stabilized (for example, trapped in concrete) for landfilling. However, waste containing greater than 260 ppm

4420-520: Was canalized in many places by cutting off meanders and digging sections. At the beginning of the 21st century, parts were transformed into nature reserves, with plans to partially remold the Hunze. The Hunze begins east of Gasselte and west of Drouwenerveen , where the Voorste and Achterste Diepje meet. The Voorste Diep is one of the water gaps that cut through the Hondsrug. From that point to

4488-400: Was diked off and only the western arm remained, which in the course of time was excavated to become the Reitdiep  [ fr ; nl ] . Particularly on the east side of the city of Groningen, parts were excavated to realize a better drainage and waterborne transport. From the middle of the 18th century on, the valley was further narrowed by land reclamation. In the 20th century, the water

4556-434: Was done at the river Hunze near the city of Groningen . The peat could be transported to the city via this small river. In the 17th century, Westerwolde came under control of the city of Groningen and the peat harvesting became more large-scaled Johan de la Haye and Johan Sems designed a line right through the western 'leg' of the bog, de Semslinie . De Semslinie is a straight line between Wolfsbarge (a village near

4624-670: Was later used for the dug Winschoterdiep . This gave the city direct access to the peat areas in East Groningen , enabling it to control the turf trade. The extension of the Schuitendiep within the city is appropriately named Turfsingel , the storage place for peat . On aerial photos and in certain areas of the landscape, the old river valley can still be recognized. The river flowed from Waterhuizen  [ fr ; nl ; pl ; zh-min-nan ] to Oosterhoogebrug and can still be traced, for instance, near Oude Roodehaan . In

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