Wastewater treatment plant/sewage treatment machine/water treatment machine

Wastewater treatment, or sewage treatment, is a water purification process to achieve the quality requirements on drainage or recycling. Wastewater treatment system is widely used in construction, agriculture, transportation, energy, petrochemical, environmental protection, urban landscape, medical, food and other fields, and is increasingly more influential in people’s daily lives.

According to waste sources, wastewater treatment is generally classified into production sewage treatment and domestic sewage treatment. The former one includes industrial, agricultural and medical sewage, while the latter one is the one generated in daily life, referring to a complex mixture of various forms of inorganic and organic compounds, including: floating and suspending solids; colloidal and gelatinous diffusates; and pure solution.

The pollution may either be due to natural cause or human activities. Currently, the more harmful one is the man-made pollution, which can be further classified into chemical pollution, physical pollution and biological pollution. The main pollutant sources are: 1) the discharge of untreated industrial wastewater; 2) the discharge of untreated sewage; 3) extensive use of farmland fertilizers, pesticides, herbicides; 4) industrial waste and garbage stacked on riverside; 5) soil erosion; 6) mine effluent.

raw water → pretreatment  equipment → effluent treatment equipment → RO system

Modern wastewater treatment may go to different depths. It can be graded into primary, secondary and tertiary treatment. The degree of treatment is determined by the water quality and whereabouts of the water after treatment.

1. Primary Treatment
The primary treatment mainly removes suspending solid pollutants, and most physical treatment completes and stops at this step. After the primary treatment, BOD can be generally removed by 30%, which falls behind the discharge standards. The primary treatment is a pretreatment for the secondary one.

2. Secondary Treatment
The secondary wastewater treatment removes colloidal and dissolved organic pollutants (BOD, COD substances) in the waste water, with a removal rate of up to 90%, so as to meet discharge standards for organic pollutants. The suspended solid removal rate reaches 95%, and the discharged water is much cleaner.

3. Tertiary Treatment
The tertiary treatment performs further processing on hardly degradable organics, nitrogen and phosphorus-soluble inorganic substances that can lead to eutrophication of water. The main methods are nitrogen and phosphorus removal, coagulation sedimentation, sand filtration, activated carbon adsorption, ion exchange and electrodialysis.