Water
Conductivity of Steam/Water: simplest method for determining water quality and is proportional to ionic concentration : 0,2 micro Siemens/cm
TOC (Total Organic Carbon): carbon in organic compound (carbon has 4 electrons in outer electron shell)
TIC (Total Inorganic Carbon):carbon in inorganic compound (like carbonate, minerals and salts)
Hard/soft water:
The hardness or softness of water is determined by the mineral content of both calcium and magnesium: Soft water has less than 17 parts per million. Slightly hard water has 17 to 60 parts per million
Härtegrad des Wassers in mmol/l ≈ [Ca-Wert in mg/l] / 40 + [Mg-Wert in mg/l] / 24,3.
Temperature affects the equilibrium, as CaCO3 is less soluble in hot water than in cold water. The solubility of carbonates decreases with increasing temperature, and therefore clarification occurs.
Purified water is water that has been mechanically filtered or processed to remove impurities and make it suitable for use. Distilled water has been the most common form of purified water, but, in recent years, water is more frequently purified by other processes including capacitive deionization, reverse osmosis, carbon filtering, microfiltration, ultrafiltration, ultraviolet oxidation, or electrodeionization
Osmosis is water moving through a semipermeable membrane from lower to higher concentrations. This has to do with chemical potential. The two sides strive for equal salinity. The salt cannot pass through the membrane, so the water has to diffuse from a little salt to a lot of salt. In reverse osmosis, the pressure is applied towards the concentrated aqueous solution and the water molecules are forced to cross the membrane towards the freshwater.
Boiler feed water (Kesselspeisewasser): The most pure (expensive) water
It will be desalted by using ion exchange resins (Deionat). Then, it will be degassed using steam through a stripper. Oxygen, nitrogen and carbon dioxide will be removed. Uncondensable gases can cause problems in the process. They will accumulate and they might be corrosive. The solubility of gas obeys Henry’s law, that is, the amount of a dissolved gas in a liquid is proportional to its partial pressure. Therefore, placing a solution under reduced pressure makes the dissolved gas less soluble.
This sort of water is usually used with a high pressure, since the boiler shows a better efficiency.
boiler feed water is quite expensive
Clarification for Water & Wastewater Treatment:
Primary clarification: also known as sedimentation, is the first step in the water treatment process for removing suspended solids (TSS), oil and grease. During this step, solids floating at the surface and other large particles from the water or wastewater flow are removed before biological treatment. Sludge is settled to the bottom of the clarifier basins and collected by a rake and removed by a sludge removal system. Meanwhile, oil and grease float to the surface and is skimmed off. A typical primary clarifier removes 60 percent of suspended solids and 30 to 40 percent of Biological Oxygen Demand (BOD).
The residence time is too long, since the oil and grease floats are too small. The smaller the particle size of the disperse phase, the lower the rate of rise/sink (Stokes’ law) due to the bigger the density difference. Therefore longer residence time.
Secondary clarification: follows the biological treatment process with the main goal of returning activated sludge, which is the biomass of microorganisms. Microorganisms can take the waste and become bigger. Waste sludge is removed and thickened prior to the digestion process.
