Chemical-physical treatment plant

A chemical-physical plant (CP plant) is used to dispose of emulsions, oil-water mixtures, rinsing liquids, used oil, acids and bases. The aim of the process is to break down the liquid into its components. Delivery Emulsion, for example, is delivered to the plant by suction trucks. In the first step, the solid material is filtered out and then treated in a high-temperature hazardous waste incinerator. The emulsions are then pumped into a storage tank and the exhaust air is dissipated through a filter. Separation of oil and water Emulsion is separated into water and oil by adding hydrochloric acid. The acidic mixture of oil and water is further treated in an emulsion cascade, allowing the oil to float to the surface before it is conveyed into the holding tank for decanting. The water is transferred into a different holding tank to remove any remaining oil before being discharged into the public sewer. Cleansing (oil) The oil is pumped into the holding tank of the decanter where it is separated into sludge, water and oil using a heat exchanger. The sludge is burned in a high temperature hazardous waste incinerator, while the water is pumped into a holding tank to be further treated before being released into the public sewer. The oil is conveyed into storage tanks, from where it can be picked up for either thermal recycling or refining. Neutralization The acidic water from the holding tank is conveyed into the separating plant where it is neutralized with the use of chemicals. Before the neutralized water can be released into the sewer, it is analysed at the on-site laboratory to ensure that indirect discharge thresholds are not being exceeded. De-watering of sludge Sludge is formed when acidic water is treated and this is then dewatered using a membrane filter press. Depending on its composition, the dry sludge will be either recycled thermally or disposed of. Before the filtered water can be released into the sewer, it is analysed to ensure that discharge thresholds are not being exceeded.

Mechanical-biological treatment-stabilisation plants

Mechanical-biological stabilisation/treatment (MBS/MBT) plants are used to treat household and commercial waste in order to gain an organically stable fraction that can be disposed of safely. Since 1 June 2005, it is no longer allowed in Germany to dispose of untreated waste in landfills. Currently, Germany has 45 MBS/MBT plants in operation with an overall capacity of 5 million tonnes per year. The aim of an MBS/MBT plant is to treat and stabilise waste in such a way that prevents or minimizes any damage done to the environment due to greenhouse gas emissions and highly contaminated landfill leachate. In addition, it is the aim to recover valuable secondary raw materials such as metals and to produce refuse-derived fuel (RDF) of high calorific value. So MBS/MBT plants not only reduce the volume of the landfill fraction and greenhouse gas emissions but they also produces RDF that can be used as a substitute for fossil fuels. Nehlsen developed, built and operated its first MBS/MBT plant in 1998. Today, three modern MBS/MBT plants have resulted from this first pilot project and are operated at an annual capacity of 163,000 tonnes. Want to learn more? Click here for details of completed projects. The main treatment steps of a typical MBS/MBT pant are described in the following paragraphs. 1. Mechanical pre-treatment Firstly, the waste is delivered to a fully encapsulated plant where rejects and secondary raw materials such as metal, wood and plastic are extracted before the waste is fed into a mechanical shredder. The waste is then reduced in size and homogenised before being separated into two fractions: the organic fraction is treated biologically and the fraction containing high calorific material is turned into RDF, which can be used in a waste-to-energy (WtE) plant for the production of steam, heat or electricity. 2. Biological stabilisation/treatment In this step, the organic fraction is dried for 8 days using an in-vessel system, which reduces the weight of the drier and more stabilised material by 25%. There are a number of in-vessel systems available, such as containers or tunnels, which should be chosen according to the waste composition and the local conditions. After the drying process, further material of high-calorific value is then mechanically separated from the material. 3. Encapsulated intensive rotting and open rotting process The Nehlsen concept is based on the encapsulated intensive rotting process, where air is added to the biologically dried waste fraction to speed up the process of achieving biological stability. As a result the rotting time and the floor space required are reduced. The advantage of the fully automated encapsulated intensive rotting system is also, that dust and odour are collected and cleaned in the waste gas purification system. In order to break down the organic material quickly, the intensive rotting process is optimised by controlling the amount of air and water added during the 2-week process. The material then undergoes a 2 - 8 weeks open post-rotting process before being deposited in a landfill. 4. Refuse-derived fuel production Nearly half of the original input material becomes refuse-derived fuel (RDF), a substitute for fossil fuel that can be used in combined heat and power plants in order to produce electricity and steam. This high-calorific material undergoes various mechanical treatment steps such as cutting, sorting, classifying and compacting, in order to achieve the various qualities customers require. For more information on RDF-CHP plants please click here. 5. Air cleaning technology To comply with the required legal limits, the waste gas from the mechanical and biological process is treated and cleaned in a waste gas purification system. Highly polluted waste gas is cleaned by using regenerative thermal oxidation plants (RTO), while the less polluted waste air is treated using biofilters.

Plastic treatment plant

Plastic treatment plant In this treatment plant mixed plastic, such as crisps packets, yoghurt containers or plastic bags, are refined into agglomerate that is then used as a reducing agent for pig iron in the steel production process. Screening and sifting The refining process starts in the rotating drum, where the packaging is freed from contaminants. The plastic is shredded and ferrous and non-ferrous metals such as iron and aluminium are extracted using a metal separator. An air separator is used to sort light and heavy plastics. Agglomeration Pressure and friction heat are used to compact light plastics during the agglomeration process producing granular agglomerates of different sizes. These are again freed from ferrous and non-ferrous metals and before it is conveyed to a sieve. Screening & sizing The agglomerate is separated into three different sizes using sieves. The agglomerate with a size exceeding 1mm is collected in a bunker and can be used in thermal recycling. The medium-sized fraction between 1 – 8 mm is placed into the silo via a conveyor screw. The fraction that is greater than 8 mm is shredded and also conveyed into the silo. Loading & utilisation The agglomerate is stored in silos, then placed in bags and transported to the steel plant. The plastic agglomerate, together with hot air, is injected into the steelwork’s furnace creating gasses that draw oxygen out of the iron ore. Normally, heavy oil is used for this process but using plastic agglomerates helps to protect the environment by preserving valuable primary resources.

Pressing of bales

This technology is used for single material streams – such as paper, foil or polystyrene – that do not require treatment, but can pressed into bales for easy transportation straight away. Our presses are able to compress voluminous materials such as foil into easy-to-handle bales using metal bands for safety. That way more material can be loaded on our trucks and transported to the recycling plants, which both reduces costs and protects the environment.

Recycling at -120° C - Cryogenic separation technology

To be able to re-use contaminated packaging, Nehlsen has developed a technology that can separate harmful residues, such as chemicals or oil, from sought-after raw materials like metal and plastic. We can also recycle oil filters and composite material made of plastic/metal and rubber/aluminium. At the present time the cryogenic plant can treat around 9,000 tonnes a year and we are receiving material from across the whole of Germany, and also from the Netherlands, Belgium, Luxemburg and other parts of the EU. To be able to use the contaminated metal and plastic packaging as secondary raw materials, it must be cleared of harmful residues. This process happens in a low temperature tube, that is twelve metres long, with a diameter of one and a half metres. The material is conveyed through the pipe and cooled to approximately minus 120°C by a special quick-freeze process using liquid nitrogen. The brittle and friable residues, along with any adhering substances are then mechanically separated in a hammer mill. After automatic sorting, just the clean plastics and metals are left, ready to be reutilised. After being packed into practical multi-compartmented big bags and containers, the recycled raw materials are sent to our customers. With the aid of the cryogenic plant we are able to achieve purity levels between 60-70%. These metals are then used commercially under the product name of CyroTall, and the plastics under the name CyroPlast.

Sorting plant for commercial and packaging waste

In sorting plants, different types of consumer goods packaging waste and commercial waste are separated. Sorting and screening On arrival, the waste is crudely separated and freed from large anomalies. The sorting process starts in a rotating drum where smaller contaminants are separated from the material. The rotating drum with its different sized holes allows the material to fall onto different conveyor belts. Larger items are sorted manually and put into their relevant boxes. Separation, sifting & sorting The small-sized fraction first passes a magnetic separator to remove ferrous metal and then a separator for non-ferrous metals removes items such as aluminium and tin. The medium-sized fraction is divided into light and heavy fractions by an air separator. The ballistic separator then sorts the secondary raw materials according to their size and weight, before another separator removes the metals and divides them into ferrous and non-ferrous fractions to further improve the quality of the secondary raw material streams. Near-infrared technology Secondary raw material streams pass near-infrared devices before they reach the manual separation station. These devices use compressed air to extrude materials such as paper, foil or different types of plastics (PE, PP and PET), which are then moved into different storage boxes via conveyor belts. Pressing & Loading After manually checking the quality of the secondary raw materials they are pressed into bales, loaded onto vehicles and then supplied to manufacturing industry.

Treatment of refuse-derived fuels (RDF)

processed in a special treatment plant for substitute fuels to ensure that they are specifically tailored for their use in either combined heat and power plants or the cement industry. Shredding and separation A mechanical gripper is used to load the refuse-derived fuels into the shredder. Ferrous and non-ferrous metals, such as iron and aluminium, are first separated and then the remaining material is sorted according to its size and weight by means of a ballistic separator. Near-Infrared technology Both the small-sized and heavy fractions are conveyed into a bunker for later use in thermal recycling. The lighter large-sized fraction is further shredded and sorted using near-infrared devices. Compressed air is used to extrude polyvinyl chloride, which is then collected in a bunker, compressed and recycled. Milling & loading The refuse-derived fuel fraction is again separated from ferrous and non-ferrous metals and then milled. The material is grinded by a millstone and then pressed through a sieve to produce a grainy material of defined quality. Utilisation The refuse-derived fuel can now be used in either combined heat and power or cement plants as a substitute for primary raw materials.

waste to product services.

waste to product services.