Industrial wastewater treatment

Industrial wastewater treatment is the process of purifying and removing contaminants from water that has been used in industrial processes. It aims to eliminate harmful substances, such as chemicals, heavy metals, and pollutants, from the wastewater before it is discharged into the environment or returned for reuse.

This treatment is essential to protect ecosystems, public health, and comply with environmental regulations.

In this article, we are going to focus on industrial wastewater and its treatment.

What is Industrial waste water?

Industrial wastewater refers to the contaminated water generated during various industrial activities, such as manufacturing, mining, and chemical production. It contains a wide range of pollutants, including chemicals, heavy metals, organic compounds, and solids, which can be harmful to the environment and human health.

This wastewater is a byproduct of industrial processes and often carries high concentrations of pollutants that must be treated before disposal or reuse.

Industrial wastewater can vary significantly in composition, depending on the specific industry and processes involved. Effective treatment is essential to meet environmental regulations, prevent water pollution, and protect ecosystems.

Purpose of Industrial wastewater treatment

The primary purpose of industrial wastewater treatment is to protect the environment by removing or reducing pollutants and contaminants from water that result from industrial processes. This treatment process helps prevent the release of harmful substances into natural water bodies, minimizing the impact on aquatic ecosystems.

Another key purpose is to ensure compliance with environmental regulations and standards set by governmental authorities. Industrial facilities are often required to treat their wastewater to meet specific discharge limits and prevent violations that could lead to legal consequences and fines.

Additionally, industrial wastewater treatment promotes responsible water resource management by enabling the safe and efficient reuse of treated water within industrial operations. This not only conserves water but also reduces the demand on freshwater sources, making it an environmentally sustainable practice.

In summary, industrial wastewater treatment serves the essential purposes of environmental protection, regulatory compliance, and sustainable water resource management in the industrial sector.

Industrial Wastewater treatment technologies

We have main 5 processes :

1. Physical treatment
2. Chemical treatment
3. Biological treatment
4. Advanced treatment
5. Disinfection
6. Disposal and reuse

Generally, the industrial wastewater has to undergo main 4 treatments i.e., Physical treatment, Chemical treatment, Biological treatment, and finally Disposal and reuse.

We can skip the advanced treatment, only if the toxic materials and the impurities have been removed properly. And then we can simply jump from Biological treatment to Disposal and Reuse.

Physical treatment

In the physical treatment we try to remove the large, floating  particles by physical means only, here we use no chemical. In this physical treatment, we have screening, sedimentation, and filtration.

• Screening: This is the first step in the treatment of industrial wastewater. Large particles get trapped at the first only and are kept aside so that the waste water is free from large suspended particles further. It helps in reducing the load on other systems for treatment process.
• Sedimentation: In this process, the wastewater is allowed to rest, so that waste particles settle down at the bottom of the tank, and the water above moves further. The major role that plays here is gravity. Because the large particles settle down due to the effect of gravity and finally form the sludge
• Filtration: When the water from sedimentation tank moves further, it still contains some particles which are not properly settled down, so to remove those particles as well, we go for the filtration. Here the water passes through a medium so that suspended particles are removed completely. Here, we use many filtration techniques, like sand filtration, multimedia filtration, and membrane filtration.

Chemical treatment

In this treatment, we use chemicals to remove the contaminants. Here we have: coagulation and flocculation, precipitation, chemical oxidation.

• In coagulation and flocculation, the particles which do not settle down properly in sedimentation tank due to their small size. So, we add chemicals, called coagulants which help them to settle down. Some chemicals that are used here are aluminum sulphate ( commonly called alum), lime, sodium aluminate etc. Coagulants help in neutralizing the charge on particles which help them to flocculate together into a denser particle. And then they settle down at the bottom of the tank
• Precipitation: is the formation of solid particles from dissolved substances in a liquid solution. This is the common method used in wastewater treatment. Here we use some chemicals e.g. lime to precipitate out metals,
• Talking about chemical oxidation, we use chemicals like chlorine or ozone to oxidize the organic pollutants e.g., chlorine helps in disinfection by killing harmful microorganisms.

Biological treatment

Here, we have activated sludge process, bio filters, anaerobic digestion

• In activated sludge process, we use  aerobic means to decompose the waste material. Here , we use microorganisms to consume the organic matter. It is effective in removing organic pollutants.
• Biofilters consists of a bed of  microorganisms, such as fungi or bacteria, that digest and remove these pollutants from water. Often used for volatile organic compounds (VOCs). Wastewater passes through some biological filters where again the microorganisms break down the pollutants.
• For anaerobic digestion, we don’t use no oxygen. Here, every breakdown happens in the absence of oxygen and the by-product produced from anaerobic digestion is biogas.

If the concentration of toxic materials is high, and the impurities aren’t removed properly from the above mentioned treatments, then we go for the advanced treatment.

Advanced treatment

Here we have membrane bioreactors, reverse osmosis and advanced oxidation process.

• In Membrane Bioreactors,  we combine the biological treatment with the membrane filtration so that we get a high quality affluent. It provides excellent solids removal and can produce high-quality effluent, making it suitable for industries
• In Reverse osmosis, we use a semi permeable membrane to remove salts, heavy metals and contaminants. It’s commonly used in industries requiring high-purity water, such as electronics manufacturing.
• And for Advanced oxidation process, we use powerful oxidants e.g. UV light and hydrogen peroxide to disintegrate the organic compounds.

Disinfection

Here we have Chlorination, UV Disinfection, and Ozonation

• Chlorination: Here chlorine is added to wastewater to kill bacteria, viruses, and other pathogens. It is effective but should be used carefully due to the harmful disinfection byproducts.
• Ultraviolet (UV) Disinfection: Here we use UV light to disinfect water without adding chemicals. UV disrupts the DNA of microorganisms, preventing their reproduction.
• Ozonation: Ozone is a powerful disinfectant and oxidizer. It effectively inactivates pathogens and breaks down organic contaminants, leaving no harmful residuals.

Disposal and reuse

Whatever the effluent we are getting at the end of treatment, we have to dispose off that properly, so that it won’t contaminate our environment.

When it comes to disposing of the waste the processes involves collecting, transporting, processing and disposing off the solid waste material.

First the waste is collected from various sources that is from different industries and then the collected waste is transported to a larger transverse station as it’s streamline the waste management. After that waste is transported from that station to disposal facility which includes the use of trucks, trains etc. In processing, waste is reduced by its volume by recycling, and composting. Then the final step is solid waste handling where the methods of disposal are land filling and  incineration. In land filling, the waste is filled in lands for composting purpose. The modern landforms have liners and systems to collect methane gas. In incineration energy is used to reduce its volume and generate energy.

We should also try to reuse nearly all waste water so as to minimize our discharge. Also we should use the treated industrial wastewater in non-potable purposes, like cooling and irrigation.

How to check the quality of the treated Industrial Waste Water

Now after treating the water completely, we have to check the quality of treated water.

So there are 2 parameters for quality checking

1. Physical parameter
2. Chemical parameter

Physical parameter checking

In physical parameter we have: turbidity, color, taste and odour, temperature, and conductivity check.

Turbidity means when there are suspended particles present in the water and they can be detected by the naked eye. It is measured in mg per litre or PPM. The permissible limit for turbidity is 5 to 10 PPM.

Color is measured by instrument called tintometer or else can be detected with the naked eye. The permissible limit is 5 to 20 PPM.

Taste and odour is due to the dissolved oxygen present in water. limit is 1-3 TON.

Temperature the temperature of water should be between 10 to 20 degree Celsius. If the temperature is greater than 25 degree then it is highly objectionable. The temperature can be measured with the normal thermometers. And increase in temperature of 10 degree Celsius doubles the biological activity

Chemical parameter checking

Chemical parameters here we have: total solids, pH, alkalinity, hardness, and presence of different chemical compounds

Total solids is equal to suspended solids + dissolved solids. The permissible limit is 500 -1000 PPM

PH  is the log of reciprocal of hydrogen ion concentration. Permissible limit is 6.6 to 8.5.

Alkalinity it is the quantity of ions present in water that will utilize the hydrogen ions. it is expressed in terms of equivalent of calcium carbonate

Presence of different chemical compounds :

Chlorine content chlorine and water is mostly from the natural mineral deposit aur irrigational discharge permissible value is 250 PPM

Sulfate it is due to the industrial influent and leads to legs effect and area the permissible value should be less than 250 PPM

Lead and arsenic it leads to accumulation of toxins in body tissues and the permissible value is Nil

Ferrous and manganese leads to discoloration of cloth and appearance of stain on clothes. permissible value of ferrous is less than 0.3 PM and manganese should be less than 0.05 PPM

Conclusion

Industrial wastewater treatment is a critical aspect of ensuring environmental sustainability in the era of rapid industrialization. And because of this there are many challenges to treat the industrial waste water as it demands energy consumption, treatment technologies, chemical processes, and all the advanced technologies.

We should adopt sustainable practices and invest in innovative technologies so that industries will minimize the environmental waste. Industrial wastewater treatment is not just a regulatory requirement but an opportunity for innovation, ensuring a better future for all.

There will slight changes in the treatment processes according to the requirement. You may view a typical water treatment by clicking the below button.

Saadiya Mushtaq @saadiyamushtaq

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