In the field of water technology many technologies can be applied. Understanding of the differences and interactions gives us the possibility to combine such technologies for the best overall solutions.
Most technologies are about separation or conversion.
In our case it’s basically water + at least 1 other ‘unwanted’ substance.
It is about technologies to exploit differences in chemical, physical and biological properties.
Here you can think about differences in size, shape, mass, density, biodegradability and chemical affinity.
Some technologies have our main attention:
Biological treatment
Based on biodegradability of organic matter.
Membrane filtration
Based on size difference, particles can be separated.
Furthermore, we have listed several other interesting principles, processes and technologies below.
Screening
Based on size difference. Big particles and rubbish will be separated.
Filtration
Based on size difference. Particles can be separated. We distinguish many types of filters, like: media filtration, disc filtration and membrane filtration.
Settling, sedimentation, clarification, sludge thickening
Based on gravity and density difference. Particles will settle to the bottom, to be separated as (thickened) sludge. The overflow is treated water.
Flotation, fat separator, DAF
Based on upward force and density difference. Particles will float on the top, to be separated as sludge. The underflow is treated water.
Centrifugation, cyclonic separation, sludge decantation
Based on centrifugal power (much higher then gravity) and density difference. Particles will ‘settle’ to the outside wall (to be separated as sludge). The overflow is treated water or centrate.
Ion exchange, cation/anion, softener, mixed bed
Based on ion exchange (on a resin). Targeted ions will be exchanged. Continuous outflow of purified water. Periodically the resin will be regenerated.
Activated carbon filtration
Based on adsorption (on activated carbon). Targeted compounds will be adsorbed and so removed from the water. Continuous outflow of purified water. Periodically the carbon can be regenerated.
Sand filtration, media filtration
Based on size difference. Particles can be removed. A granular bed of fine sand or grint will entrap the particles. Purified water is the result. Periodically the filter bed will be backwashed/ cleaned.
Coagulation, flocculation, precipitation
Based on addition of coagulants. Targeted ions and colloids can be coagulated or precipitated. Based on addition of flocculants those and other (small) flocs are ‘glued’ together to get larger separable flocs.
Press, filter press, screw press, belt press
Based on pressure difference a sludge can be dewatered on a ‘perforated’ plate or screw. Dewatered sludge is separated (for disposal). The water (centrate) could be returned to WWTP for example.
Drying, belt dryer
Based on evaporation difference a (dewatered) sludge can be dried. On a ‘perforated’ belt for example. Dried sludge is separated (for disposal). The water (vapor) often is emitted to the sky, or treated (odor).
Evaporation
Based on evaporation difference a water can be purified (from salinity). Evaporated/ condensated flow is the purified water.