Industrial Wastewater Treatment Technology
Water is used across many industrial processes, including fabricating, processing, washing, cooling or transporting products and equipment.
This means that the wastewater is highly varied in strength, composition and contaminants, which can make treatment challenging. However, there are a variety of new technology options that can help solve these issues.
Industrial wastewater treatment technology is a process used to clean and recycle waste water from factories, power plants, oil refineries and other facilities. The treatment process reduces the concentration of solids in the liquid before filtration, minimizes the amount of chemicals needed to coagulate and flocculate the particles and controls the quality of the final water that is discharged.
Sedimentation is an important component of many water treatment systems because it reduces the concentration of solids in suspension and therefore the number of coagulating and flocculating agents needed to treat the wastewater. It can be used before coagulation, or after coagulation to control the amount of coagulating agents needed, or as a pretreatment to subsequent filtration processes.
There are several types of sedimentation tanks that can be used in the water treatment process. These tanks vary in size and shape, but they all offer support to the particles as they settle.
Horizontal flow tanks are the most common type of tank used for sedimentation. These rectangular tanks allow the water to flow horizontally, collecting sediment before it leaves the tank’s far end.
Inclined settling tanks are another option for sedimentation. These tanks have inclined plates at the bottom of the tank to help collect and separate sediment.
Often, these tanks will need additional mechanical assistance to get the most out of the sedimentation process. This can include a sand bed or an additional ballasting agent.
The density of the floc particles can also be increased by using a ballasting agent, such as Bentonite or fine sand. This can increase the settling rate by three or more times, as the floc particles become more dense and are able to settle faster.
Filtration is a technology used in the treatment of industrial wastewater. It involves separating a solid from a fluid through a porous material that holds the solid and allows the fluid to pass through it. It can be a chemical, biological or physical process.
A porous material, such as paper, cloth or cotton-wool, is the filter medium, and the liquid passes through its pores to become a filtrate. The filtrate may be treated by a series of chemicals and processes before it is recirculated or reused.
There are a number of different filtration methods, including pressure filtration and suction filtration. In the latter, a pressure difference is created in the receiver by means of a vacuum pump. This technique is safe, but it is limited to a pressure difference of about 1 bar because the filter cannot exceed the atmospheric pressure.
Another type of filtration is centrifugal separation. This is most effective for removing suspended noncolloidal particles (size up to 1 mm). The denser the solids, the more quickly they are separated by centrifugal devices.
Other filtration techniques involve the use of membranes with pores of a specific size. These pores permit a variety of particles to pass through the membrane while retaining some other particles, such as soft solids and dissolved matter.
A membrane with pores as small as 0.3 microns is called nanofiltration. This is an alternative to thin sand and trickling filters for potable water and wastewater treatment, as it can remove large amounts of pollutants while also reducing energy costs and minimizing pump and piping investment. Its main disadvantage is the difficulty in controlling pore size distribution and repeatability, which can lead to membrane fouling.
Adsorption is a wastewater treatment technology that involves the removal of pollutants from waste water. This process is commonly used in industrial settings and is a highly efficient, inexpensive method of treating wastewater.
The process of adsorption occurs when a substance is absorbed onto the surface of an adsorbent. The process involves the reduction of the conformational entropy of the adsorbate and requires a high level of attraction between the solute molecules and the surface of the adsorbent.
Various types of adsorbents are used for this purpose. These include activated carbon, zeolites, and other adsorbents.
Active carbon is the most common type of adsorbent for wastewater treatment. It is a highly effective adsorbent that removes many organic substances from wastewater. It also has low energy and maintenance costs, is simple to operate, and can be regenerated after use.
Other adsorbents are used for less concentrated organic pollutants and when selectivity is important. These include zeolites, which can be used to adsorb iron, manganese, and other metals from wastewater.
Some adsorbents can be chemically impregnated with additional functional groups to improve their adsorption capacity and stability. This is especially useful for removing chemical substances such as sulphides, nitrates and ammoniacs.
Another form of adsorption is membrane emulsification filtration (MEUF). This method uses a membrane-based adsorbent to filter heavy metals in wastewater. It is most efficient at low concentrations and can reduce the amount of space needed for the adsorption column.
The effectiveness of adsorption is determined by the molecular weight, concentration of the to-be-removed substance, other organic components in the waste, and the set-up design. For adsorption with active carbon, realistic load factors range from 10 to 30%.
In many industries, wastewater streams may contain a variety of pollutants that need to be removed before being discharged to the municipal sewer system or into surface water. This can be done with the help of a number of industrial wastewater treatment technologies, including the removal of total suspended solids (TSS), BOD / COD (biological oxygen demand / chemical oxygen demand), metals, and other contaminants.
Disinfection is a critical step in any wastewater treatment technology, as it removes any remaining pathogenic microorganisms that can cause disease. Various disinfection methods, such as ultraviolet (UV) light, ozone, chlorine, and chlorine dioxide are used to inactivate or kill any remaining microorganisms in the treated wastewater before it is released into the environment.
Depending on the type of wastewater that is being treated, different levels of disinfection can be achieved. Several factors, such as the type of disinfectant used and its dosage, affect the effectiveness of the disinfection process.
Bioremediation is another common industrial wastewater treatment technology that utilizes biological resources such as plants, bacteria, algae and fungi to reduce environmental pollution. This process is often considered a “low-tech/no-tech” solution because it does not require the use of chemicals or large amounts of energy.
Biologically-based wastewater treatment systems have the advantage of being less expensive than mechanically-based technologies, and they tend to be less complex to design and operate. However, they do have limitations, including the need to use a lot of land to grow the appropriate vegetation and the potential for hydraulic overloading or excessive plant growth. For this reason, many communities prefer mechanically-based wastewater treatment technologies. It is also important to remember that some contaminants, such as metals, acids and alkalis, are resistant to biological processes.
Ion exchange is a chemical process that removes unwanted dissolved ions from water and wastewater. The process is often used for water softening, but it can also be used in a number of other processes.
Ion exchangers consist of porous beads containing permanently fixed ions of a particular type that have a mobile counterion of opposite charge. The ion exchangers are placed in contact with an aqueous solution, where the ions are then replaced by the desired ions.
The ion exchange resins have a finite number of individual exchange sites that each become full with prolonged use. The resins then need to be recharged or regenerated, which is done by flushing them with a salt brine solution.
In this regeneration process, the ions that coat the resin bed are replaced with sodium ions. These sodium ions are then flushed out with the wastewater, which is why it’s important to monitor this process and ensure that the ion exchangers are working properly.
Using ion exchange to treat wastewater can be a valuable industrial wastewater treatment technology, but it’s important to understand the costs and maintenance requirements of the technology before implementing it. The costs will vary depending on the location and scale of the facility, as well as the amount of pollutants that need to be removed.
The ion exchange process is highly efficient at removing unwanted dissolved ions from wastewater. However, it is not able to remove all of the contaminants that are present in the wastewater. This can result in significant waste that needs to be disposed of or recycled.