DANATIVARA Co.’s wastewater treatment plants Specialize in the treatment of wastewater.
Clean water is one of mankind’s most valuable resources. That’s why we treat it with a great deal of care and respect. We optimize processes to reduce the volume of water used, take all possible measures to prevent contamination and use highly effective methods – some of which we developed ourselves – to treat contaminated water.
Water – a crucial role in chemistry
Water is absolutely crucial to chemistry – it is a key component in products, a solvent, a cleanninig and cooling agent, a source of energy in the form of steam and, of course, plays an essential role in the everyday lives of the people who work with us.
Three-quarters of this water is used for cooling purposes in the production facilities. During this process, the cooling water does not come into contact with products. After we have carried out suitable independent checks, we can therefore feed this cooling water directly back into the source via a separated system. Wastewater containing inorganic loads and few or no organic contaminants that does not require treatment can also be fed straight back into the source, as can uncontaminated rainwater.
Only around ten percent of the water used actually comes into contact with products and subsequently requires treatment. This includes acidic, alkaline and organically loaded wastewater from the production facilities, laboratories and technical service centers as well as sanitary and kitchen wastewater.
This water is thoroughly treated in our own biological wastewater treatment plant at D.T.A physical/chemical pre-treatment measures are carried out upstream-where the water is contaminated. Substances that could impede biological treatment or that cannot be eliminated using biological methods are removed in the production plants themselves. The treated wastewater then flows into the source.
The wastewater treatment process
Contaminated municipal and industrial wastewater can be treated together extremely efficiently. Today ‘s state-of-the-art wastewater treatment is carried out in a number of stages depending on the specific substances contained in the water:
- Mechanical removal of coarse matter and sand (screen, grid chamber)
- Neutralization (acidic and alkaline wastewater is neutralized to avoid any impact on the subsequent biological treatment process)
- Pre-clarification to simultaneously separate out undissolved substances and substances are consumed by bacteria. New bacteria are created.
Secondary clarification to separate the biological sludge from the treated water. A proportion of this biological sludge is fed back into the biological sludge from the treated water. A proportion of this biological sludge is fed back into the biological stage in order to maintain a constant sludge concentration. The rest of the sludge is transported to the sludge treatment section.
Due to the nature of production, the wastewater is usually strongly acidic (ph value approx. 1.5). to protect the bacteria the treatment plant, lime milk is added to the wastewater according to the ph level. This precipitates inorganic substances (including calcium, aluminum and iron comsubstances (including calcium, aluminum and iron compounds) and a part of the organic materials as well.
In the next stage, pre-clarification, the precipitation products of the neutralization process and other solids sink to the bottom and are removed mechanically. The resulting sludge is collected along with sludge from the other treatment stages (see below) and transferred to the sewage sludge treatment system.
The mechanically pre-treated and neutralized and neutralized wastewater is stored in buffer tanks, where the concentration and volume of the wastewater stream are equalized. This improves the degradation performance in the subsequent biological treatment.
Treatment in tower biology
The concept – the processes involved in the biological treatment of wastewater are comparable to the natural self-cleaning capacity of rivers and lakes. Bacteria feed on the substances contained in the wastewater and use the oxygen dissolved in the water to transform these into carbon dioxide, water and biomass carried out in a confined area and on a much shorter timescale than it would occur in nature The performance of the bacteria depends on their specialization – this develops after a period of time and is determined by the substances contained in the water.
The bacteria must also be well supplied with oxygen and the tower biology system achieves this extremely effectively. The process engineers at DTA CO. environment have succeeded in finding a particularly Energy-efficient method of introducing the atmospheric oxygen needed for biological degradation into the mixture of wastewater and bacterial sludge. Using injectors that operate on a principle similar to a water jet pump, compressed air is blown into the towers.
These injectors are a key component of tower biology. The conventional large, Open clarifiers which have depths of three to seven meters and different aeration Systems are replaced by covered towers 30 meters high.
The high liquid column means that the oxygen is used far more efficiently in the towers, thus generating less waste air. The waste air, which also contains expelled organic substances, is collected and incinerated in a thermal waste gas treatment plant. This prevents any odors being released into the ambient air, Intermediate clarification – the wastewater treated in the tower biology flows over cyclones that degasify the wastewater/sludge mixture and enters the suspended, elevated intermediate clarifier in which activated sludge and water are separated. The majority of the activated sludge is feedback into the towers using centrifugal pumps. A smaller amount is removed as unwanted surplus sludge and passed to the sewage sludge treatment system.
Nitrification, denitrification – in order degrade nitrogenous molecules as ammonium compounds, further strains of bacteria are required in addition to those already used to break down carbon compounds. In an initial stage, nitrifying bacteria use oxygen to convert the ammonium compounds into nitrate at temperatures over ten degrees Celsius. In an upstream process, into molecular nitrogen and passed the ambient air.
As this process can only be carried out in the absence of oxygen (anoxia) and in the presence of carbon compounds, 80 percent of the wastewater flowing out of the towers is pumped into a separated tank. This tank contains very little atmospheric oxygen and ample carbon compounds sourced from the untreated site wastewater that flows through the tank before being fed into the towers. This process is known as upstream denitrification.
Each year, this method is used to eliminate over 800 metric tons of nitrogen load from the wastewater. A significant proportion of the nitrogen load is also disposed of with the surplus sludge.
Phosphate eliminated – during the neutralization process with time milk, a large proportion of the phosphate is precipitated and separated along with the sludge produced at the pre-clarification stage. Phosphates are also precipitated through the addition of aluminum and iron salts at the biological treatment stage.
The advantages of tower biology – compared to open, shallow basin biology, tower biology offers a range of advantages:
The injector ensures that the atmospheric oxygen introduced is used to full effect.
The reduction in the volume of waste air cuts costs for waste air incineration The enclosed design and waste air treatment prevent odors being released into the surrounding area.
The injector system results in energy savings of up to 70 percent.
The wastewater and activated sludge can be thoroughly mixed without the need for additional mechanical mixing equipment.
Tower biology contains no moving parts-as a result, the plant is extremely low maintenance and reliable.
The tower design ensures safe, easy monitoring of any leakage. It is impossible for any wastewater to seep into the subsoil unnoticed.
Tower biology requires around 50 to 70 percent less space than conventional biological wastewater treatment plants.
Flotation is a further stage in the treatment of the wastewater. In this process, gas bubbles attach to the flakes of sludge in the wastewater. As they are less dense than the substance around them, they then rise to the surface of the liquid and form a foam layer, or float, which is then removed.
Treatment in basin biology
The water produced from intermediate clarification in the tower biology tanks id then treated further along with the municipal wastewater and the surrounding communities. This is carried out in open activated sludge tanks as a second biological process stage. Surface aerators are responsible for adding the oxygen and the mixing. Before being added to the tanks, the municipal wastewater is mechanically treated in a separated pre- treatment plant using screens, grit chamber and settling tank.
Finally, the activated sludge is separated in three secondary clarifiers and the treated wastewater is fed into the source. The surplus sludge from the secondary clarification is fed into the sewage sludge treatment system.
Sewage sludge treatment
The sewage sludge generated in the mentioned system (industrial and municipal pre-clarification sludge and surplus sludge) is concentrated, equalized and de-watered using membrane filter presses. The filter cake is
then disposed of in the sewage sludge incineration plant. The ash that is left after incineration is deposited at site