Evaporation process of pharmaceutical wastewater

Evaporation process of pharmaceutical wastewater

 With the development of pharmaceutical industry, pharmaceutical wastewater has gradually become one of the important pollution resources.

Pharmaceutical wastewater has great differences due to different products and production processes. As a result, pharmaceutical wastewater is usually characterized by complex components, many kinds of organic pollutants, high concentration, high COD and BOD and large fluctuations.

The main sources of pharmaceutical wastewater are:

Source of fermentation biopharmaceutical wastewater

1.The drainage during production is characterized by high concentration and large temperature change.

2.Auxiliary process drainage is characterized by low pollutant concentration, large water volume, strong seasonality and large differences among enterprises.

3.Flushing water container equipment flushing water, filter equipment flushing water, ground flushing water, etc. It is characterized by high concentration of pollutants, mainly suspended solids. If it is not properly controlled, it will become an important pollution source.

Source of chemical pharmaceutical wastewater:

1.Mother liquor, including various crystallization mother liquor, phase inversion mother liquor, adsorption residue liquid, etc.

2.Washing wastewater includes washing water of filtration machinery, reaction vessel, catalyst carrier, resin, adsorbent and other equipment.

3.Recovery of residual liquid, including solvent recovery residual liquid, early recovery residual liquid, by-product recovery residual liquid, etc.

Common treatment methods of pharmaceutical industry wastewater include: physicochemical method, chemical method, biochemical method and other combined processes.

Physicochemical methods mainly include: coagulation sedimentation method, air flotation method, adsorption method, point solution method and membrane separation method;

Chemical methods mainly include: Fenton oxidation, catalytic point decomposition and ozone oxidation.

Biochemical methods mainly include: ordinary activated sludge method, biological filter and biological rotary table.

Pharmaceutical wastewater has complex components and different processes produce different wastewater. Generally, after mixing, it enters the evaporation system for desalination treatment after being pretreated by neutralization, flocculation and sedimentation, and then enters the back-end biochemical treatment unit.

Due to the complexity, high salt and high COD of pharmaceutical wastewater, MVR evaporation process is not suitable for desalination. Generally, two effect forced circulation evaporation process is adopted for desalination.

Material selection of evaporation equipment

Generally, pharmaceutical wastewater contains salt such as sodium chloride, ammonium chloride, nitrate, etc. chloride ions are highly corrosive. According to the corrosivity of pharmaceutical wastewater solution, TA2 is used for the part contacting materials, TA2 / 2205 is used for the part contacting secondary steam, and 316L is used for the part contacting condensed water.

Multi effect evaporation process

Because the boiling point temperature of pharmaceutical wastewater increases during crystallization, and the solubility increases with the increase of temperature, the two effect forced circulation evaporation crystallization process is adopted.

Material flow direction:

Raw material → preheater → effect 1 → effect 2 → thickener → centrifuge → solid wet salt

Steam flow direction:

Raw steam → 1-effect heater → 2-effect heater → main condenser

Distilled water flow: 1-effect heater → 2-effect heater / main condenser → distilled water tank → distilled water pump → reuse / discharge


High efficiency demister

With the evaporation, the concentration of organic matter in the wastewater increases, the viscosity increases, and the material is easy to bubble during evaporation. A zigzag channel demister with baffles / wire mesh demister is installed in the separator. This device effectively prevents the phenomenon of material liquid entrained by liquid droplets, separates the mist in the gas, improves the operating conditions, optimizes the process indicators, improves the quality of secondary steam, reduces the corrosion of the equipment, so as to prolong the service life of the equipment and ensure the normal operation of the equipment. In order to ensure the stable operation of the equipment and prevent the influence of foam on evaporation, the system is equipped with a special defoamer dosing system.

Technical structure of evaporator

Ammonium chloride and sodium chloride have large solubility, high degree of supersaturation, and small primary nucleation crystal form. FC is used in the crystallizer, which can greatly eliminate the supersaturation of sodium chloride solution, make the crystal of the solution in the metastable region, and facilitate the growth of crystal form. The system is designed for negative pressure evaporation to reduce the evaporation temperature as much as possible.

Operating parameters of multi effect evaporation

  • daily operation time: 24h
  • steam consumption for evaporating 1t water: 600kg / h (4-6bar)
  • circulating water volume for evaporating 1t water: ~40m³/H (temperature 35 ℃, outlet temperature 43 ℃) inlet pressure 0.3MPa
  • Compressed air:~ 10m ³/h (0.6Mpa)
  • operating power of evaporating 1t water:  ~28kw
  • evaporation parameters of various effects

Heating steam temperature: 106

I Effect evaporation temperature: 90 ℃

II effect evaporation temperature: 60 ℃

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