Electroplating uses electrochemical processes to apply metallic coatings such as chrome, nickel and gold to components.
The resulting wastewater contains these very heavy metals, which need to be removed in the company's wastewater treatment plant before the wastewater can be discharged.
The wastewater treatment in our example is common in the electroplating industry: The wastewater, which consists of various partial streams and contains heavy metals, is adjusted to a higher pH value in a precipitation station. This is achieved by adding milk of lime. Due to the higher pH, fine heavy metal hydroxide flocs are formed. A flocculant is added to increase the size of these flocs.
A lamella separator was used to separate these flocs. Two problem situations led to interruptions in operation several times a year:
Accidental occurrence of oily contaminants of unknown origin which interfered with floc formation. As a result, it was not possible to meet the legal requirements for the effluent to be discharged.
Clogging of the lamellas in the lamella separator meant that the lamella packs had to be replaced at least once a year.
The plant operator was urgently looking for a solution that would enable safe and controlled operation of the treatment plant and reduce the high maintenance costs.
The search for a suitable technology led to the Tangential Separator (TS).
The TS is an innovative precipitation/flocculation unit. It has a simple and robust design, is easy to operate and is (almost) maintenance free.A pilot test over several weeks was successful.
TROUBLE-FREE SINCE INSTALLATION
The initial order and construction of the full scale plant was for a capacity of 50 m3/h. The plant has operated without any problems. A year later, further tangential separators were installed and the complete treatment plant was expanded to 120 m3/h.
ADVANTAGES OF THIS APPLICATION IN ELECTROPLATING
Rugged
Safe
Efficient flake separation- Easy to operate
Quick adjustment to changing feed conditions
Quantity and
Quality
Blockage resistant
Overflow proof
Space saving
Less expensive than lamella separators (investment + operation)
Virtually maintenance free
Easy to clean
Optimal pre-thickening before chamber filter press
Scalable
No breakdowns since installation
FLUE GAS SCRUBBING
Like all industrial incinerators in Germany, a chemical company's hazardous waste incinerator is equipped with a system to desulphurise, denitrify and detoxify its flue gases.
The flue gases are first filtered, then "scrubbed" in two stages, and finally "denitrified" and filtered again before being released into the environment. Mercury, cadmium, lead and other heavy metals accumulate in the scrubbing solution.
The flue gas scrubbing water produced in this way is treated by first raising the pH of the flue gas scrubbing water, which is very acidic at pH 0, to pH 9.3 by adding milk of lime.
A gypsum is formed from the calcium in the milk of lime and the sulphur dioxide in the flue gas, and contains heavy metal hydroxides which precipitate as fine flakes due to the high pH.
The addition of flocculants causes the formation of larger flakes that are easier to separate from the treated flue gas scrubbing water.
So much for the theory...
Although the flocs were successfully formed, they could not be completely separated. As a result, the specifications for filterable substances and heavy metals in the effluent could not be reliably met.
The search for a suitable technology led to the TS.
The TS is an innovative solid/liquid separation device. It has a simple and robust design, is easy to operate and is (almost) maintenance free.
RELIABLE FLUE GAS QUALITY
All requirements for the treated flue gas wash water were reliably met.
A pilot test over several weeks was so successful that the pilot plant was "passed on" for further testing at other sites!
