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8 Types of Effectively Wastewater Treatment Chemicals

What are wastewater treatment chemicals?

Wastewater treatment chemicals are chemical compounds used in the process of wastewater treatment to remove pollutants and impurities in wastewater before being discharged into the environment. These chemicals have the effect of oxidation, precipitation, sedimentation of organic and inorganic substances that make wastewater meet the standards that allow waste discharge or reuse.
The types of chemicals commonly used in wastewater treatment include: acids, bases (alkalis), iron salts, chlorine, detergents, polymers… Each type of chemical has a different mechanism of action, suitable for wastewater treatment stages.

Benefits of chemicals in wastewater treatment:

  • Effective removal of organic matter, impurities, unpleasant odors in wastewater
  • Reduce pathogenic microorganisms, pathogens in wastewater
  • Precipitation, sedimentation of solids in water
  • Minimize pollutants, toxic to the environment
  • Adjust pH, temperature, DO of wastewater to meet discharge requirements
  • Cost savings compared to other manual wastewater treatment methods

hóa chất xử lý nước thải wastewater chemical

Stages of chemical use in wastewater treatment

The wastewater treatment process consists of many different stages, each stage will use the right chemicals to achieve the highest treatment efficiency.
Specifically:
Stage 1 – Pretreatment: Use strong electrolytes, strong acids / alkalis to adjust the pH, temperature, salinity of wastewater; strong detergents to remove grease, dirt residue.
Stage 2 – Primary wastewater treatment : Using precipitators such as iron / aluminum salts, polymers to precipitate suspended, floating solids; Chlorine to kill bacteria, kill pathogens and unpleasant odors.
Stage 3 – Secondary wastewater treatment : Use acidity / alkalinity adjustment chemicals to ensure proper pH for the microorganisms to decompose the remaining organic matter; supplement nutrients to create ideal conditions for microbial activity.
Stage 4 – Advanced wastewater treatment: Use strong oxidizing chemicals such as chlorine, ozone to remove the remaining organic matter, heavy metals. Then add some neutrals, final disinfection before discharge.

Chemicals commonly used in wastewater treatment

Depending on the stage of wastewater treatment, the chemicals applied will be different. However, some common and commonly used chemicals are:
  • Chlorine: Used in the stages of preliminary, primary and advanced treatment for bleaching, oxidation, disinfection. Chlorine is a powerful biocide, breaking down the molecular structure of organic substances.
  • Precipitation Agent:
  • Iron salts: Precipitate with sulfur to remove odors, decolorize wastewater. Or use at the primary treatment stage.
  • Aluminum polymer: Effective precipitation of suspended solids, dirt residue. Used in primary and secondary treatment.
  • Acid / Alkali: Adjust the pH of wastewater at the appropriate acid / alkali level facilitating chemical reactions to take place. Commonly used acids / alkalis: sulfuric acid, hydrochloric acid, lime powder, soda…
  • Detergents: Surfactants such as SDS are used to remove greasy, greasy adhesives. Then need to neutralize, treat waste detergents so as not to pollute the environment.
  • Nutrients: Provides a source of nitrogen, phosphorus necessary for microbial activity during the secondary processing stage.
  • Ozone: Used for deodorizing, coloring, disinfecting wastewater at advanced treatment stage. Ozone has the ability to oxidize and decompose organic compounds.

Technology of wastewater treatment by chemicals

Chemical wastewater treatment technology is increasingly developed, requiring the chemicals used to be highly efficient, low cost and environmentally friendly. Some trends in chemical application are being considered:
  • Use catalysts / catalysts to increase reactivity, wastewater treatment speed. For example, gold catalysts combine reducing NO3- to N2 in water with high nitrate.
  • Research on nanotechniques (application of ferromagnetic nanomaterials) to adsorb and treat pollutants instead of toxic chemicals.
  • Use of microbial preparations enhances the ability to decompose biological contaminants in wastewater. For example, microorganisms decompose phenols in industrial water.
  • Build complete processing systems that integrate many different processing technologies such as membrane filtration, adsorption of charcoal / incense, treatment with chemicals,….. to improve efficiency, save chemical, energy costs.
  • Using natural compounds such as plant extracts, mushroom essences, bacteria are capable of treating polluted wastewater to replace toxic chemicals.
The chemicals used in wastewater treatment have made great contributions to ensuring water quality, environmental protection and public health. However, the chemicals also pose risks of health harm and pollution if not managed well. Therefore, special attention should be paid to safety requirements, strict control of the treatment process to ensure the chemicals are operated properly and do not cause harm.
Thereby, it can be seen that chemicals play a key role in the wastewater treatment process, helping to remove contaminants and ensuring the quality of wastewater to meet the permitted standards. To optimize the treatment process, there should be a harmonious coordination between many technological solutions and the selection of suitable and safe chemicals.

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