Metallurgical industry wastewater treatment technology

Metallurgical industry wastewater contains heavy metals such as chromium, lead, copper, iron, nickel, zinc... which can accumulate in living animals, indirectly causing many problems for human health. such as stomach diseases, respiratory diseases and cancer.

Each metal or alloy that needs to be produced has its own method, so the wastewater of each metallurgical plant will be different in both quality and quantity. Wastewater treatment technology in the metallurgical industry also has differences, however, they all have some basic things in common as below.

Characteristics of wastewater from the metallurgical industry

The amount of wastewater from metallurgical plants is very large, including: :

1. Cooling water for blast furnaces, compressors, rolling mills, molds... can be used and recirculated, with little pollution.
2. Water cools slag and cleans blast furnace gases containing ammonium, cyanide, sulfur compounds, phenol, heavy metals...
3. Wastewater from the floor and ore sorting process contains gravel, rock, and dissolved inorganic salts.
4. Wastewater from non-ferrous metallurgy technology contains acids, heavy metals and suspended solids.
5. Wastewater from plating and painting industries... contains metals and fluxes.
6. In addition, there is also a part of domestic wastewater containing oil and grease, toilet wastewater...

Wastewater treatment technologies applied in the metallurgical industry

Wastewater treatment technology containing metals includes:

1. Ion exchange technology: Ion exchange method uses ionite which is a synthetic organic resin, a polymer based on hydrocarbons and ion exchange functional groups.
2. Electrochemical technology: This technology allows separating metal ions from wastewater, suitable for wastewater with high metal concentrations, however, the electricity cost is large.
3. Chemical precipitation method: In a suitable pH environment, metal ions in wastewater will react with substances introduced into the wastewater, creating precipitated compounds.
4. Biotechnology: This method takes advantage of the activities of some types of microorganisms to treat wastewater, is suitable for treating wastewater with heavy metal concentrations less than 60mg/l and requires a large treatment area. .

In the case of metallurgy containing heavy metals, the most common technology is chemical technology applying chemical precipitation method, combined with coagulation.

Precipitation method: Use chemicals such as milk of lime, soda and caustic soda to adjust the pH to a weak alkaline or alkaline value, so that the metal precipitates.
Flocculation method: Flocculation chemicals such as aluminum alum and iron alum are added to promote the formation of floc. In addition, there is also an anionic polymer glue aid and a slow-speed agitator system, so that the flocs move, collide and stick together to form large flocs that settle to the bottom.

Diagram of wastewater treatment system for basic metallurgy industry

Wastewater from metallurgy and metal processing industries contains high levels of heavy metals, which need to be treated at the source to recover metals, before being sent to a centralized wastewater treatment plant. In addition, the waste stream also contains toxic substances such as cyanide, fluoride, phenol, and sulfite, so it is necessary to separate treatment channels.

Below is a diagram of the basic metallurgical industry wastewater treatment system:

1. Wastewater tank: Contains and regulates wastewater flow.
2. Reaction tank: The most important component in the treatment system, in the tank there are neutralizing chemicals or reducing chemicals, which react with metal-containing compounds, creating metal hydroxide or precipitated metal salts.
3. Sedimentation device: The mixture of water and precipitate is passed through the sedimentation tank to separate the precipitate. A sedimentation agent or colloid can be added.
4. Sludge treatment: Based on characteristics and composition, sludge is separated as input materials for other production industries or landfilled.

The company specializes in consulting and installing the best water treatment systems

With many years of experience in industrial wastewater treatment, ECLIM - Vietnam E&C Environmental Services Joint Stock Company is ready to help your business consult, test and evaluate effective metallurgical wastewater treatment systems. with commitment:

1. Reasonable investment costs, optimal operating costs.
2. Ensuring the aesthetics of the project, minimizing odors arising during the treatment process.
3. The quality of treated water meets national technical standards on industrial wastewater.
4. Free consultation on procedures and legal documents for standard discharge permits.

We look forward to having the opportunity to work with you, contact us via hotline 0941 113 286