Due to the increasingly stringent control of volatile organic compounds (VOCs) in atmospheric regulations, many flexographic printing plants are turning to water-based ink technologies to reduce the volatilization of organic materials. As the production of water-based inks has increased, the flexographic printing industry has also begun to explore alternatives to handle the waste generated in the ink.
It is a misunderstanding that these inks and the waste water for their cleaning are simply discharged to the sewer as their consumption. Regulations in different regions make regulations for wastewater from industrial equipment. According to what system discharges the wastewater, determine what regulations and restrictions apply.
Wastewater related to water-based inks are color contamination (pigments and dyes), binders (alkaline lysates, emulsions, or colloidal dispersions of chemicals), auxiliary solvents (alcohols, glycols, and glycol ethers) and filling. Additives (waxes, plasticizers and defoamers). Colored waste water can also become an aesthetic problem. This is usually a matter of quality of certain chemicals and pigments exceeding the maximum allowable amount of emissions in the region and the environment.
To discharge water directly into the environment, the factory must have permission to specify the release of allowable pollutants. This license is called the National Pollutant Emissions System (NPDES), and sometimes the State's Wastewater Discharge System (SPDES). These permits have very strict limits on the extent of sewage that can be discharged, and should monitor the discharge of effluent, regularly test the water's receptors, and maintain and report the records made.
Designed exposure systems can only treat sanitary wastewater. Industrial wastewater cannot be discharged into exposure pools or exposure systems. The discharge of industrial wastewater into the exposure system can lead to groundwater pollution and also require high-cost cleaning. In areas where wastewater can only be treated by exposure systems, wastewater treatment is not an option. In some very strict areas, treated industrial wastewater cannot be discharged into the exposure system.
Polluted to a public sewage treatment plant (POTW for short) is the most common wastewater treatment program in a printing plant. Some wastewater treatment plants require all companies to dispose of the treated wastewater to achieve local discharge permits, and some have agreements to allow the wastewater treatment plant to accept the printing wastewater according to local regulations. Effluent discharged to the wastewater treatment plant should comply with local regulations or allowable limits specified by the equipment.
Most flexographic printing shops are located in cities where water and drainage are not strained, and these rules are generally not available in the countryside. Industrialization has widened the limits of treatment and the capacity of sewage treatment plants in many urban areas. However, regardless of the type of system that the printing plant will discharge, it is best to treat a large amount of wastewater at the first site.
Wastewater treatment
The most practical method of treating post-production wastewater using a flexographic printing plant for water-based inks is:
Chemical separations are performed using a continuous or batch process. After adjusting the pH, the solids (pigment and resin) precipitated into sludge by flocculation. The paper sludge is then separated from the water by paper filtration, dewatered and discarded. If filtered presses can remove moisture further, discard the dewatered mud.
The continuous discharge treatment is similar to the chemical separation process described above.
Microfiltration, ultrafiltration, microwave and reverse osmosis. This process is like a mammal's kidney. The wastewater passes through organic and inorganic membranes and can process from 0.1 to 5,000 liters of water per hour. This process basically removes water (or any material with the same molecular weight or less). Ammonia was removed with a post-membrane carbon filter. This treatment method does not have to cost the secondary treatment on the membrane. Clean water can be used in other areas (for example as part of the production of corrugated paper).
Bioabsorption treatment with activated brown carbon; desalination and reactivation of carbon with partial flow or total flow (plus slope reactors, floatation, filtration, softening, reverse osmosis, rotating drum surfaces, etc.).
Oxidation technology provides oxidation and ozone/UV oxidation through the molecularization system.
The quality and quantity of waste water to be treated usually determine what method is used at a particular production site. For almost all manufacturers of flexographic plates that produce wastewater, chemical separations are more appropriate, less expensive solutions for reducing short-term or no wastewater problems in the short-to-medium term. The process from the belt filter to the filter process is selected according to the quantity and quality of the wastewater treatment. The quality of the treated water is determined by local discharge restrictions. It is also whether the printing plant plans to reuse the water for cleaning or for use. Other purposes to decide.
Many printers choose to handle only their wastewater treatment, and waste ink disposal as another part of waste management, some also choose to directly add waste ink directly to the wastewater. This generally increases the amount of suspended solids in the water and requires a more efficient and more expensive method of treating the sludge produced in the chemical treatment. Finally, there will be more wastewater that needs to be treated.
Although many companies have provided simple filtration methods for the treatment of wastewater, removal of solids, and some colors, most of the wastewater is produced by inks, water, and cleaning fluids during flexo printing and cleaning. To effectively treat this waste water, it is necessary to first break the emulsion by chemical separation and then physically filter the resulting material.
There are many chemicals that can be used to break this emulsion and then perform the following treatments:
· Neutralization - Adjust the pH to bring it back to the neutral range.
· Absorption - Absorbs selected chemicals and suspended solids from water.
· Condensation - accumulates in condensation.
• Buried - Non-toxic industrial landfills are best suited for handling chemical solids.
· Physical filtration - use a belt filter or filter compressor.
Most commercially available separating agents work best at pH values ​​of 6.5 to 9, and when the wastewater exceeds this range, it is best to perform pretreatment monitoring and adjust the pH to be able to withstand the effective performance of the agent. It may be necessary to adjust the pH of the discharged sewage before it can be discharged to meet the emission standards.
Water seems to be cheap and freely available and used. If the entire cost of water acquisition, use, and disposal is fully taken into account, it is often found how expensive it is. The cost of water from a municipal system is $125 per million gallons, and the cost of water for wells is $1,000 per million gallons. The cost of water treatment (or effluent discharge) is from $600 to over $4,000 per million gallons. By reducing the amount of water used, factories can reduce water use costs and the cost of emissions. Reducing the amount of water includes reducing dosage and recycling. From the point of view of environmental protection, reducing the amount of these two programs is usually better than recycling.
It is useful to determine where and how much to use. Design a factory water diagram (flow chart for water use), regularly check how much water goes in and out, and then find out how to improve it. Use this diagram to make a program to maintain water usage. It is advisable to install the meter at the main point of use, read the meter at regular intervals, and calculate the water used. According to all aspects of operation, make a factory water budget for tracking and compliance.
Train personnel in the factory to reduce the use of water. By training the press operator to do the following points, the amount of water used in the cleaning process can be reduced.
· Recycle the ink as much as possible into the container.
• Clean the printer parts thoroughly and clean them with water.
· (Ink drying before) rapid cleaning of the inking device can increase cleaning efficiency.
· Use low-flow nozzles.
Use equipment that restricts water flow.
The cleaning of the press can be changed to the following three-step cleaning process with the purpose of using waste water.
The first step: Most of the ink is removed with dirty water.
Step 2: The remaining ink in the first step is cleaned with less dirty water.
Step 3: The remaining ink is rinsed with water.
The water used in the first step is too dirty to be used. The water in the second step can be used for the first step, the water in the third step is used for the second step, and the third step uses clear water. Some companies find filtered wastewater.
It is a misunderstanding that these inks and the waste water for their cleaning are simply discharged to the sewer as their consumption. Regulations in different regions make regulations for wastewater from industrial equipment. According to what system discharges the wastewater, determine what regulations and restrictions apply.
Wastewater related to water-based inks are color contamination (pigments and dyes), binders (alkaline lysates, emulsions, or colloidal dispersions of chemicals), auxiliary solvents (alcohols, glycols, and glycol ethers) and filling. Additives (waxes, plasticizers and defoamers). Colored waste water can also become an aesthetic problem. This is usually a matter of quality of certain chemicals and pigments exceeding the maximum allowable amount of emissions in the region and the environment.
To discharge water directly into the environment, the factory must have permission to specify the release of allowable pollutants. This license is called the National Pollutant Emissions System (NPDES), and sometimes the State's Wastewater Discharge System (SPDES). These permits have very strict limits on the extent of sewage that can be discharged, and should monitor the discharge of effluent, regularly test the water's receptors, and maintain and report the records made.
Designed exposure systems can only treat sanitary wastewater. Industrial wastewater cannot be discharged into exposure pools or exposure systems. The discharge of industrial wastewater into the exposure system can lead to groundwater pollution and also require high-cost cleaning. In areas where wastewater can only be treated by exposure systems, wastewater treatment is not an option. In some very strict areas, treated industrial wastewater cannot be discharged into the exposure system.
Polluted to a public sewage treatment plant (POTW for short) is the most common wastewater treatment program in a printing plant. Some wastewater treatment plants require all companies to dispose of the treated wastewater to achieve local discharge permits, and some have agreements to allow the wastewater treatment plant to accept the printing wastewater according to local regulations. Effluent discharged to the wastewater treatment plant should comply with local regulations or allowable limits specified by the equipment.
Most flexographic printing shops are located in cities where water and drainage are not strained, and these rules are generally not available in the countryside. Industrialization has widened the limits of treatment and the capacity of sewage treatment plants in many urban areas. However, regardless of the type of system that the printing plant will discharge, it is best to treat a large amount of wastewater at the first site.
Wastewater treatment
The most practical method of treating post-production wastewater using a flexographic printing plant for water-based inks is:
Chemical separations are performed using a continuous or batch process. After adjusting the pH, the solids (pigment and resin) precipitated into sludge by flocculation. The paper sludge is then separated from the water by paper filtration, dewatered and discarded. If filtered presses can remove moisture further, discard the dewatered mud.
The continuous discharge treatment is similar to the chemical separation process described above.
Microfiltration, ultrafiltration, microwave and reverse osmosis. This process is like a mammal's kidney. The wastewater passes through organic and inorganic membranes and can process from 0.1 to 5,000 liters of water per hour. This process basically removes water (or any material with the same molecular weight or less). Ammonia was removed with a post-membrane carbon filter. This treatment method does not have to cost the secondary treatment on the membrane. Clean water can be used in other areas (for example as part of the production of corrugated paper).
Bioabsorption treatment with activated brown carbon; desalination and reactivation of carbon with partial flow or total flow (plus slope reactors, floatation, filtration, softening, reverse osmosis, rotating drum surfaces, etc.).
Oxidation technology provides oxidation and ozone/UV oxidation through the molecularization system.
The quality and quantity of waste water to be treated usually determine what method is used at a particular production site. For almost all manufacturers of flexographic plates that produce wastewater, chemical separations are more appropriate, less expensive solutions for reducing short-term or no wastewater problems in the short-to-medium term. The process from the belt filter to the filter process is selected according to the quantity and quality of the wastewater treatment. The quality of the treated water is determined by local discharge restrictions. It is also whether the printing plant plans to reuse the water for cleaning or for use. Other purposes to decide.
Many printers choose to handle only their wastewater treatment, and waste ink disposal as another part of waste management, some also choose to directly add waste ink directly to the wastewater. This generally increases the amount of suspended solids in the water and requires a more efficient and more expensive method of treating the sludge produced in the chemical treatment. Finally, there will be more wastewater that needs to be treated.
Although many companies have provided simple filtration methods for the treatment of wastewater, removal of solids, and some colors, most of the wastewater is produced by inks, water, and cleaning fluids during flexo printing and cleaning. To effectively treat this waste water, it is necessary to first break the emulsion by chemical separation and then physically filter the resulting material.
There are many chemicals that can be used to break this emulsion and then perform the following treatments:
· Neutralization - Adjust the pH to bring it back to the neutral range.
· Absorption - Absorbs selected chemicals and suspended solids from water.
· Condensation - accumulates in condensation.
• Buried - Non-toxic industrial landfills are best suited for handling chemical solids.
· Physical filtration - use a belt filter or filter compressor.
Most commercially available separating agents work best at pH values ​​of 6.5 to 9, and when the wastewater exceeds this range, it is best to perform pretreatment monitoring and adjust the pH to be able to withstand the effective performance of the agent. It may be necessary to adjust the pH of the discharged sewage before it can be discharged to meet the emission standards.
Water seems to be cheap and freely available and used. If the entire cost of water acquisition, use, and disposal is fully taken into account, it is often found how expensive it is. The cost of water from a municipal system is $125 per million gallons, and the cost of water for wells is $1,000 per million gallons. The cost of water treatment (or effluent discharge) is from $600 to over $4,000 per million gallons. By reducing the amount of water used, factories can reduce water use costs and the cost of emissions. Reducing the amount of water includes reducing dosage and recycling. From the point of view of environmental protection, reducing the amount of these two programs is usually better than recycling.
It is useful to determine where and how much to use. Design a factory water diagram (flow chart for water use), regularly check how much water goes in and out, and then find out how to improve it. Use this diagram to make a program to maintain water usage. It is advisable to install the meter at the main point of use, read the meter at regular intervals, and calculate the water used. According to all aspects of operation, make a factory water budget for tracking and compliance.
Train personnel in the factory to reduce the use of water. By training the press operator to do the following points, the amount of water used in the cleaning process can be reduced.
· Recycle the ink as much as possible into the container.
• Clean the printer parts thoroughly and clean them with water.
· (Ink drying before) rapid cleaning of the inking device can increase cleaning efficiency.
· Use low-flow nozzles.
Use equipment that restricts water flow.
The cleaning of the press can be changed to the following three-step cleaning process with the purpose of using waste water.
The first step: Most of the ink is removed with dirty water.
Step 2: The remaining ink in the first step is cleaned with less dirty water.
Step 3: The remaining ink is rinsed with water.
The water used in the first step is too dirty to be used. The water in the second step can be used for the first step, the water in the third step is used for the second step, and the third step uses clear water. Some companies find filtered wastewater.
Shengruisi Packaging Co., Ltd. , http://www.symakeuppackaging.com