Industrial wastewater is polluted water that becomes contaminated with different pollutants from the industrial production process.
This waste sludge contains heavy metals, chemicals, and biological waste. These contaminants harm the environment, human health, and aquatic life. So, it needs to be appropriately treated.
Wastewater treatment depends on the types of contaminants present in the water. Effective wastewater treatment is essential not only to protect the environment but also to comply with regulations and support the sustainable growth of industries.
In this article, we will provide you with a complete overview of industrial wastewater—its sources, contaminants, types, and the processes involved in its treatment.
Characteristics Of Industrial Wastewater
There are three main characteristics of wastewater. These are
1. Physical Characteristics
- Cloudiness
- Smell
- Temperature change
- Colour
2. Chemical Characteristics
- pH value
- Alkalinity of water
- Sulfates
- Chlorides
- Total Organic Carbon (TOC)
- Total Oxygen Demand (TOD)
- Nitrogen
- Hydrogen ion concentration
3. Biological Characteristics
- Oxygen Demand for Nitrification
- Microbial diversity
- Biochemical oxygen demand
Contaminants Of Industrial Wastewater
- Hydrochloric acid, nitric acid
- Ammonia, fluoride, sulfate, magnesium sulfate.
- Ash, sand
- Heavy metals (Zinc, Silver, Arsenic, Vanadium)
- Organic solids (Alkanes, Benzene, Alcohols)
- Inorganic solids (Carbides, Carbonates, and Cynides )
- Petroleum contaminants (Fuel, Oils)
- Cooking oils, animal fats, motor oil, lubricants
- Synthetic dye
Types Of Industrial Wastewater
1. Inorganic Industrial Wastewater
Inorganic industrial wastewater contains metal ions and inorganic salts. It is generated by coal, steel, electroplating, and circuit board manufacturing companies.
It contains suspended solids, minerals, and harmful solutes like cyanides and acids. Sedimentation, chemical, and ultrafiltration methods are used to remove impurities.
2. Organic Industrial Wastewater
Organic Industrial Wastewater is a waste product of textiles, pharmaceuticals, and electroplating companies. It contains organic compounds and contaminants.
- Chloroform
- Naphthalene
Other contaminants are fat, metals, oils, and dye.
Various methods are used to remove impurities, including filtration, tertiary treatment, wet air oxidation, and biological treatment.
Sources Of Industrial Wastewater
Depending on the water source, industrial wastewater is defined by category and subcategory. Some sources are explained in brief here.
a) Textile Industries
Textile industries are the most common source of industrial wastewater. Many processes use water in these industries, such as dyeing, bleaching, and printing. The result is water contaminated with
- Chemicals
- Dyes
- Heavy metals
- Fluoride
- Iron
- Nitrate
- Lead.
Treatment is essential for the textile industry’s wastewater before it is discharged into other sources.
Several treatment processes include ion exchange, membrane filtration, ozonation, evaporation, and electrochemical oxidation.
b) Dairy waste
Dairy waste contains high amounts of organic matter, such as fat, proteins, lactose, detergents, and salts. It has a high concentration of such contaminants.
- Chemical oxygen demand (COD)
- Biological oxygen demand (BOD)
- Total suspended solids (TSS)
The primary treatment process can remove these impurities.
c) Oil And Gas Industry
The wastewater of the oil and gas industries contains various organic and inorganic components. These contaminants are
- Hydrocarbons
- Heavy metals
- Carbon compounds
- Sulfur compounds
- Toxic organic pollutants.
If these impurities are not appropriately treated, they can harm the environment. Physical, chemical, and biological treatments can separate these impurities.
d) Paper and pulp industries
In the paper and pulp industries, a large amount of water is used in various processes.
These processes use water
- Wood debarking
- Pulp manufacturing
- Bleaching
- Paper manufacturing.
The wastewater of the paper and pulp industries contains such types of contaminants.
- chlorinated organic compounds
- suspended solids
- biological oxygen demand (BOD)
- chemical oxygen demand (COD)
- toxicity
These impurities can harm the environment and aquatic life. Primary, secondary, and tertiary processes can remove these impurities.
e) Mine minerals
Mining mineral industry water contains such contaminants.
- Sulfide
- Toxic chemicals
- Heavy metals
- Radioactive compounds
These can pollute wetlands and groundwater and affect aquatic and human life’s food chain.
These contaminants are removed by neutralization, settling, filtration, and chemical treatment.
f) Food industry
Food industries are also responsible for industrial wastewater. The contaminants come from domestic processes such as sanitation, cooking, cleaning machinery, and food and vegetable processing. This water is rich in organic materials.
Membrane technology, coagulation, and flocculation processes can remove such impurities.
Effects Of Industrial Wastewater
Industrial wastewater has several harmful effects. These are
- Water Pollution
- Effect on water quality
- Land Pollution
- Air Pollution
- Dangerous for human and animal health
- Damages food chain
- Decreases level of oxygen in surface water source
- Eutrophication
- Infectious diseases
- Impact on the marine ecosystem
Industrial Wastewater Treatment Process
Industries generate different types of wastewater, which require specific treatments to remove contaminants. Treating this water is essential, not just to meet regional regulations but also to make better use of water resources.
Effluent treatment plants (ETPs) help clean and purify this industrial wastewater. After treatment through ETP plants, cleaned water may be reused by industries or discharged into another source.
Some industries have their own wastewater treatment systems, including ETPs. These treatment systems partially remove pollutants before discharging the water into municipal treatment plants. Municipal water systems can further clean and treat industrial wastewater for reuse, reducing water wastage.
The processes of treatment of industrial wastewater are
1. Primary Treatment
Primary treatment is the first step in industrial wastewater treatment. This treatment involves removing suspended solids, large particles, and debris from the wastewater and preparing it for further treatment.
The processes used in primary treatment
- Screening
- Grit Removal
- Sedimentation
- Filtration
2. Secondary Treatment
Secondary treatment mainly removes suspended solids and soluble organic substances. Anaerobic microorganisms break down the organic contaminants without oxygen. Biofiltration removes additional sediments, and the oxidation process decomposes contaminants.
These processes are performed in secondary treatment.
- Aerobic Treatment
- Anaerobic Treatment
- Biofiltration
- Rotating biological contactors (RBCs)
3. Tertiary Treatment
Tertiary treatment is a water disinfection process. The tertiary treatment removes bacteria, viruses, and other microorganisms.
The processes of tertiary treatment
- Disinfection (UV light treatment, UV treatment, chlorination, advanced oxidation process [AOP])
- Dechlorination
- Membrane process (ultrafiltration, nanofiltration, reverse osmosis (RO), ceramic membrane filtration)
- Chemical Treatments (Acid and alkalis, flocculation, and precipitation)
- Activated carbon
- Sand filter processes
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Conclusion
Increasing industrialization damages the ecosystem and produces different types of waste. Biodegradable and non-biodegradable waste are equally harmful to environmental health.
Water treatment plants equipped with state-of-the-art technology can overcome this problem. Industrial wastewater processes should be subject to strict regulations, and industrial sectors should also introduce the best treatment methods and technologies.
Read More About: What Are Sewage Treatment Plants?
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