After usage and appliation of water, the focus will now be on waste water treatment. We start with an indroductory chapter about waste water treatment, afterwards we will deal with biological treatment and membrane filtration.
Which ways of waste water disposal are differenciated?
Direct discharge (into surface waters) and indirect discharge (into sewage treatment plant)
conditioned and unconditioned
hot or cold
For waste water discharge into sewage, there are a variety of limiting values. Those depend on
kind of discharging: direct or indirect
the amount of water which will be discharged into sewage
the temparature of the water
Limiting values have to be met, because
it is important that the ecosystem of the surface waters as well as the ecosystem of the sewage treatment plant won`t be disturbed damageable.
it is important that sewage treatment plant operators earn a lot of money to add new jobs
One of the important limiting values is the pH-value. If it is too high,
pipelines may be destroyed and microorganisms in the sewage treatment plant may be disturbed
water in the sewage treatment plant is foaming and the microorganisms will be extinguished
chemicals for water-purification can`t act any more
Another important limiting value: Temperature. Which of the following statements is correct?
It has to be hot enough in sewage treatment plant
If it is too hot, pipelines and bacteria in the plant will be destroyed.
Heavy metals: They have to be limited
because heavy metals can access into groundwater and accumulate in the food chain.
That is not true. Heavy metals do not disturb the ecosystem.
Waste water purification takes place within three steps:
mechanical cleaning, biological cleaning, chemical cleaning
biological cleaning, chemical cleaning, digestion tower
all three steps are chemical with different kind of chemicals applicated.
Mechanical cleaning, that is
Solids and particulate material fill be filtered
Microorganisms in water will be destroyed
some special agents will be evaporated
Biological cleaning, that is
microorganisms convert organic load. Therefore, oxygen is brought into the water as compressed air.
soil-removal by usage of biodegradable chemicals.
Chemical cleaning, that is
to precipitate dissolved minerals by usage of non-dissolving salts. In addition, the water will be disinfected by ozone, chlorine or high temperatures
dirt particles will be dissolved be special chemicals