Industrial water treatment facts for kids

Kids Encyclopedia Facts

Industrial water treatment is all about making water ready for different jobs in factories and plants. It also involves cleaning up water after it's been used so it can be reused or safely returned to nature.

When water first comes into a factory, it often needs to be cleaned very carefully. This is because different industrial jobs need water of a specific quality. Industrial water treatment covers all these steps. It includes cleaning up used water from factories, treating water for steam boilers, and preparing water for cooling systems.

Why Treat Water in Factories?
Main Goals of Water Treatment
Cleaning Up Used Factory Water
Common Water Treatment Processes
- Boiler Water Treatment
- Cooling Water Treatment
Modern Water Treatment Technologies
See also

Why Treat Water in Factories?

Treating water helps factories run better and saves money. It also lowers risks. If water isn't treated properly, it can cause problems for pipes and machines.

For example, steam boilers can get covered in a hard layer called scale, or they can rust. This scale makes it harder to heat the water, so the factory uses more fuel. Cooling towers can also get scale and rust. If their warm, dirty water isn't treated, harmful germs like bacteria can grow. This can lead to serious illnesses, like Legionnaires' disease.

Water treatment is also important for making products. For example, in making computer chips or drinks, the water must be very clean. If the water isn't good enough, the products might be faulty.

Sometimes, water that has been used in one part of a factory can be cleaned and used again in another part. This saves money because the factory buys less new water. It also reduces the amount of dirty water that needs to be thrown away. Plus, if the used water is warm, reusing it can save energy by keeping the heat.

Main Goals of Water Treatment

Industrial water treatment aims to solve four main problems:

Scaling: This is when minerals in the water form hard deposits.
Corrosion: This is when metal parts rust or wear away.
Microbes: These are tiny living things like bacteria that can grow in the water.
Wastewater disposal: This is about safely getting rid of used water.

Boilers usually don't have problems with microbes because the high heat kills them.

Understanding Scaling

Scaling happens when minerals dissolved in water turn into solid deposits. This can happen because of the water's chemistry or its temperature. These deposits can be like fine dirt or build up in layers on metal surfaces. Scale is a problem because it acts like an insulator. This means heat can't transfer as well, and more energy is wasted trying to heat the water. Scale also makes pipes narrower, so more energy is needed to pump water through them.

Understanding Corrosion

Corrosion happens when metal surfaces react with water or other substances, like iron rusting. Over time, this can damage factory equipment. The rust can cause problems similar to scale. But corrosion can also lead to leaks, which can be very dangerous in systems that are under high pressure.

Controlling Microbes

Microbes can grow easily in untreated cooling water. This water is often warm and contains nutrients from the air. Cooling towers act like giant air filters, collecting dust, insects, and spores. Without treatment, this can become a "microbial soup." Many outbreaks of Legionnaires' Disease have been linked to cooling towers that weren't managed properly. Because of this, many countries have strict rules for cooling tower operations.

Some industrial processes, like tanning leather or making paper, use heavy metals such as chromium. Even if most of the metal is used up, a small amount can remain in the water. This can be harmful if it gets into drinking water, so even tiny amounts must be removed.

Cleaning Up Used Factory Water

Getting rid of used water from factories can be difficult and expensive. Many factories, like oil refineries and chemical plants, have their own facilities to clean their wastewater. This ensures that the treated water meets local and national rules before it's released into sewage treatment plants, rivers, lakes, or oceans.

Common Water Treatment Processes

Two very important types of industrial water treatment are boiler water treatment and cooling water treatment. If water isn't treated correctly, solids and bacteria can build up in pipes and boilers.

Steam boilers can suffer from scale or corrosion if the water isn't treated. Scale makes the machinery weaker and more dangerous. It also means more fuel is needed to heat the water because the scale blocks heat. Dirty water can also become a breeding ground for harmful bacteria like Legionella, which is a risk to public health.

In low-pressure boilers, corrosion can be caused by oxygen dissolved in the water, or by the water being too acidic or too alkaline. So, water treatment needs to remove dissolved oxygen and keep the boiler water at the right pH (acidity/alkalinity) levels. Without good water treatment, a cooling water system can get scale, rust, and dirt buildup. It can also become a place where harmful bacteria grow. This makes the system less efficient, shortens its life, and makes operations unreliable and unsafe.

Boiler Water Treatment

Boiler water treatment focuses on removing or changing substances that could harm the boiler. Different treatments are used to prevent scale, corrosion, or foaming.

Water is often treated before it even enters the boiler to remove impurities. Then, inside the boiler, treatments help stop the water from dissolving the boiler's metal. They also keep impurities in forms that are less likely to cause problems before they can be removed from the boiler. A special device called a Deaerator is used to reduce oxygen and nitrogen in the water that feeds the boiler.

Cooling Water Treatment

Water cooling is a way to remove heat from machines and industrial equipment. Water is often better at transferring heat than air. In most places, water is good because it can hold a lot of heat and can cool things by evaporating.

Sometimes, water is cheap enough to be used once and then thrown away. But often, it's recycled in closed loops to prevent evaporation and keep things cleaner. If water is recycled using evaporation, some dirty water must be removed to get rid of impurities that become more concentrated.

Water cooling systems have some downsides. They can speed up corrosion. They also need regular maintenance to prevent heat transfer problems from biofouling (slime from living things) or scale buildup. Chemicals added to prevent these problems might make the wastewater toxic. Water cooling is commonly used for cooling automobile engines and large industrial places like nuclear and steam electric power plants, hydroelectric generators, petroleum refineries, and chemical plants.

Modern Water Treatment Technologies

New technologies have changed how industrial water is treated. While mechanical filters like reverse osmosis are widely used to remove contaminants, other methods are also important. These include ozone generators, wastewater evaporation, electrodeionization, and bioremediation.

Ozone treatment involves injecting ozone gas into used water. This can reduce or remove the need for other chemicals that might be dangerous, like chlorine.

Chemical Treatment Methods

Chemical treatments add chemicals to industrial water to make it suitable for use or for safe disposal. These methods include:

Chemical precipitation: Making dissolved substances turn into solids that can be removed.
Chemical disinfection: Killing germs using chemicals.
Advanced Oxidation Processes (AOPs): These use strong oxidizers like Fenton's reagent, Ozone, or Hydrogen peroxide to break down harmful substances in wastewater. AOPs are good for treating dangerous wastewater because they can break down many different pollutants.
Ion exchange: Swapping unwanted ions (charged particles) in the water for less harmful ones.
Chemical neutralization: Adjusting the water's pH to make it less acidic or alkaline.

Physical Treatment Methods

Physical treatment separates solids from industrial wastewater. This can be done through Filtration or Dissolved air flotation.

Filtration: Uses Membranes or filters, like sand filters, to separate solids from liquids.
Dissolved air flotation: Pressurized air is pumped into the wastewater. This air forms tiny bubbles that stick to suspended dirt, causing them to float to the surface. They can then be skimmed off.

Biological Treatment Methods

Biological treatment is used for wastewater that contains biodegradable elements (things that can be broken down by living organisms). It's common in city and factory wastewater treatment plants. It usually involves adding common, environmentally friendly bacteria and other tiny organisms to clean the water. This is a sustainable method that has been used successfully for over a hundred years.

Slow sand filters use a biological process to clean raw water for drinking. They work with a complex biological film that grows naturally on the sand's surface. This slimy film, called the hypogeal layer or Schmutzdecke, is found in the top few millimeters of the sand. As water flows through this layer, the film cleans it. The sand underneath supports this biological cleaning layer.

The Schmutzdecke contains bacteria, fungi, tiny animals, and even insect larvae. As the film gets older, more algae and larger organisms like snails might appear. When water passes through this layer, tiny particles get trapped, and dissolved organic material is absorbed. The bacteria, fungi, and other organisms then break down these contaminants.

Slow sand filters are typically 1 to 2 meters deep. They clean water at a rate of about 0.2 to 0.4 cubic meters per square meter per hour. Filters become less effective as the biofilm gets thicker and slows down the water flow. To fix this, the biofilm and a thin top layer of sand are removed. Water is then put back into the filter to allow a new biofilm to grow. Another method is "wet harrowing," which involves stirring the sand and flushing out the biolayer.

Ultraviolet Light Treatment

Ultraviolet (UV) light disinfection has become popular for water treatment in the last 20 years. This is because it can clean water without using harmful chemicals. The UV-C part of the light spectrum (wavelengths from 200 nm to 280 nm) is used for disinfection. UV-C light goes into cells and damages their genetic material, making them unable to reproduce or cause harm.

Process Water Treatment

Process water is water used in many factory operations, such as coating, plating, rinsing, spraying, and washing. City water or groundwater often contains dissolved minerals that make it unsuitable for these processes. These minerals can affect product quality or increase manufacturing costs. A good water treatment system for incoming water can solve these problems. It creates the right water conditions for specific industrial processes.