Emulsion splitting plant

Coalescence

Demulsification plants have in the wastewater engineering the task emulsions to split into its components. Usually these are emulsions of light substances (i.e. substances with a lower density than water, such as oil or gasoline) in water.

At the end of the process , the tiny light-weight droplets coalesce to form a coherent phase , which can then be separated and disposed of or recycled .

Procedure

There are a number of different methods with the help of which emulsification can be achieved, also in combination. The electrical charge of the droplets often plays a role here. In thermal processes, the higher boiling points of light materials are used. To support the process, the emulsions may have to be specially conditioned .

In certain processes, one speaks of “breaking” the emulsion.

In detail it concerns the following:

• Adsorption :
  • of hydrophobic silica
  • on kieselguhr
  • of activated carbon

• Biological processes:
  • Activated sludge process

• Chemical processes:
  • Addition of acids ( hydrochloric acid , sulfuric acid )
  • Addition of salts of polyvalent metals ( aluminum , iron , magnesium salts )
  • Addition of organic breakers ( demulsifiers / cationic surfactants : tertiary or quaternary polyamines or polyamide - Amine )
  • UV - oxidation (with hydrogen peroxide )

• Electrical procedures:
  • Electroflotation (with oxygen and hydrogen from electrolysis ; see also flotation)
  • Electrocoagulation
  • Electrophoresis

• Filtration :
  • Membrane filtration ( microfiltration , ultrafiltration )

• Flotation with previous flocculation / coagulation :
  • Pressure relaxation flotation (with air)
  • Electroflotation (with oxygen and hydrogen from electrolysis ; see also electrical processes)

• Mechanical process:
  • Coalescence separator
  • Centrifugation ( decanter )

• Thermal processes:
  • Heat to aid other processes
  • Thin film evaporator
  • Immersion torch
  • Circulation evaporator

literature

• W. Baumann, B. Herberg-Liedtke: Chemicals in metal processing. Data and facts on environmental protection. Springer, Berlin etc. 1996. pp. 228–236 ( limited preview in Google book search).
• B. Bilitewski et al: waste management. Manual for practice and teaching. 3. Edition. Springer, Berlin etc. 2000. pp. 341–345 ( limited preview in Google book search).
• R. Gräf, J. Dirschka: Expertise for lightweight material separators. Separation systems for the separation of substances of low density from the water phase. expert-Verlag, Renningen-Malmsheim 2002. pp. 36–38 ( limited preview in the Google book search).
• L. Hartinger: Handbook of waste water and recycling technology for the metalworking industry. Hanser, Munich and Vienna 1991. pp. 255–265 ( limited preview in Google book search).
• Entry Oil demulsification in PetroWiki