Membrane treatment technology mainly includes microfiltration, ultrafiltration, nanofiltration and reverse osmosis.
Among them, nanofiltration can concentrate metal ions, salts and so on. In wastewater, reverse osmosis can intercept metal ions and organic additives through the membrane, and let water molecules pass through the membrane to achieve the purpose of separation and concentration.
The wastewater containing heavy metals enters the treatment system, and is pretreated with compound chemicals as needed to reduce the influence of other ions on the membrane system, and then separated and concentrated by nanofiltration membrane and reverse osmosis membrane.
The system is equipped with multiple sets of nanofiltration devices, which can not only help to meet the requirements of concentration multiple, but also switch to meet the requirements of discharging heavy metal ions in the effluent.
Sources and treatment principles of heavy metal wastewater;
Heavy metal wastewater mainly comes from wastewater discharged by mining, smelting, electrolysis, electroplating, pesticides, medicines, paints, pigments and other enterprises. The types, contents and existing forms of heavy metals in wastewater from different production enterprises are different. Because heavy metals cannot be decomposed and destroyed, they can only transfer their existing positions and transform their physical and chemical forms.
For example, after chemical precipitation treatment, heavy metals in wastewater are transformed from dissolved ions into insoluble substances and precipitated, and then transferred from water to sludge; After ion exchange treatment, heavy metal ions in wastewater are transferred to ion exchange resin, and then transferred from ion exchange resin to regenerated waste liquid after regeneration.
Therefore, the principles of heavy metal wastewater treatment are: first, the most fundamental thing is to transform the production process. Do not use or use less toxic heavy metals. Secondly, reasonable technological process, scientific management and operation are adopted to reduce the content of heavy metals and the amount lost with wastewater, so as to minimize wastewater discharge.