Water can have a wide variety of contaminants. A off-the-shelf solution is therefore only the second best choice. Depending on the type and level of load, we develop individual systems with which your wastewater safely adheres to all the required limit values. Due to our experience, based on many years of project work, we also master complex tasks. In addition to our own developments, the technologies we use include:
Neutralization
Reaction of acid and lye with formation of salt and water. Most commercial and industrial wastewater must be neutralized before discharging into public sewage plants or preflood.
Acidic wastewater is neutralized with alkaline (e.g. lime milk, sodium hydroxide solution, soda solution), alkaline wastewater with acids (e.g. hydrochloric acid, sulphuric acid, carbonic acid). The use of flue gas has been developed in recent years as a particularly economical method for neutralizing alkaline wastewater.
Neutralization, however, is not only the adjustment to pH 7, but also the adjustment to special pH values, e.g. for precipitation of heavy metal hydroxides.
Biological processes
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By means of bacteria dissolved and finely dispersed organic components are degraded into inorganic products in various treatment steps. In principle, biological wastewater treatment is differentiated into aerobic and anaerobic processes.
aerobic processesIn the aerobic processes, the bacteria used primarily reduce organic carbon and ammonium compounds, but also sulphur and phosphorus compounds under constant ventilation. In use are both fixed bed methods and suspended bed methods. The aerobic processes are characterized by a high degree of odour neutrality, whereby an increased energy expenditure is required for aeration.
anaerobic proceduresAnaerobic processes, under oxygen deprivation, are also used for particularly high loads. For this purpose, rotting bacteria are primarily used. The advantage of additional biogas production is one of a relatively high odor nuisance. |
Sedimentation
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In sedimentation, the sinking behaviour of flakes is used due to gravity. The flocs produced in a previous treatment step settle in sediment container to the ground. From here, the settled sludge is fed to further treatment steps or removed from the plant for disposal. |
Counterflow lamella clarifier
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For all wastewaterthat that can be cleared by sedimentation, the counter-current lamella clarifier is the first choice. By using a high number of fins, the sedimentation area is enormously increased in the smallest space. This means space-saving and cost-effective wastewater treatment with particularly high efficiency. Lamella clarifiers are used in almost all areas of water treatment. |
Filtration
Filtration refers to the retention of particles from a gas or liquid with a filter medium. A distinction is made between surface filtration and deep filtration. Both filtration methods are used for water and wastewater treatment.
Surface filtration
The use of filter screens and backwash filters are always surface filters in which the particles are retained on the surface of the filter medium. Another typical example of surface filtration is sludge dewatering by means of a sieve bedside press or chamber filter press. In these processes, a filter cake is built up, which supports the filtration and thus leads to a better filtration result.
Depth filtration
During depth filtration, the particles are retained within the filter medium. Grainy media such as filter sand are often used as filter media. The particles to be filtered flow through the gaps of the filter medium until they come into contact with the medium and are held to its surface.
Flotation
In a flotation tank, wastewater is introduced with undissolved or insoluble constituents. Air is supplied to the wastewater by means of lances or high-speed stirrers. The dispersed particles bind to the air bubbles and are transported to the surface.
The resulting surface foam is discharged by means of a clearer. For the stabilization of the surface foam and for a better connection of the air bubbles to the undissolved constituents a variety of auxiliaries are used.
Dissolved air flotation
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Dissolved Air Flotation is a process for removing fine suspended solids, oils and fats from water and wastewater streams. Here, a gas is dissolved under pressure in the water to be clarified. The gas, which bubbles out when the pressure is reduced, adheres to the suspended particles and floats them to the surface. Usual materials are steel coated, stainless steel and polypropylene. |
Ultrafiltration
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Ultrafiltration is a filtration process in which the finest particles can be separated from a pre-filtered water stream. The wastewater is conveyed by means of high-pressure pumps through pressure pipes. In the pressure pipes, membranes are arranged, in different design variations. The size of the membrane can be designed in such a way that the specific particles to be filtered can no longer pass through it (e.g. 0.1 microns).
The purified filtrate current from the ultrafiltration, the permeate, then contains only particles with a size < of 0.1 microns. In the waste water stream with the retained particles, the retentate, their concentration increases. Thus, ultrafiltration is also suitable for concentrating media. |
Reverse osmosis
Reverse osmosis is a process used to concentrate and retain dissolved ingredients in liquids. Natural osmotic process is reversed with the help of high pressures of up to 30 bar (In case of Seawater-desalination up to 80 bar). The reverse osmosis filter module is designed to allow only the filtrate to penetrate the membrane and retain the dissolved ingredients, the retentate.
Ion exchanger
Ion exchangers are used in full desalination to exchange cations and anions dissolved in water for H+ and OH ions. When softened, Ca2+ and Mg2+ ions normally are exchanged against Na+ ions. Ion exchangers are synthetic resins (organic polymers) in which various exchange-active groups are incorporated to which ions accumulate. During the replacement process, the ions of the solution to be treated are exchanged for attached ions of the same electrical charge on the resin. Basically, a distinction is made between cation exchangers and anion exchanges. Within these species, there are further differentiations with respect to the exchange-active groups:
• slightly acidic / strongly acidic
• weakly basic / medium basic / strongly basic
The terms “ion exchanger” and “resin” are used interchangeably in the language of water treatment.
Sludge drainage
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In a treatment plant, the conversion of dissolved wastewater ingredients into a solid form, as well as their sedimentation, creates a sludge that must be further dewatered from an economic point of view. |
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