Achieving Water Authority Compliance with Printing Wastewater Treatment
Wastewater treatment systems help printers remain in compliance with EPA and local standards, while significantly reducing the cost of treatment, labor and disposal
The printing industry must meet EPA and local wastewater requirements for effluent, including those under the Clean Water Act. Failing to do so can result in severe fines that quickly escalate.
Whether for books, magazines, specialty cards, corrugated paper, or packaging, the use/changeover of printing inks of assorted colors on various media is a source of considerable wastewater when the printing equipment must be cleaned and maintained. Invariably, the combined colors turn the wash water into an inky black wastewater.
Printing ink usually consists of dyes, pigments, resins, binders, solvents and additives.
Decorative metallic inks, often used in holiday cards, party plates or napkins, can also utilize heavy metals such as cobalt, iron, zinc and copper.
Under the Clean Water Act alone, the EPA has identified 65 pollutants and classes of pollutants as “toxic pollutants”, of which 126 specific substances have been designated “priority” toxic pollutants.
For the printing industry, this means installing a wastewater treatment system that effectively separate the contaminants from the water so it can be legally discharged.
However, traditional wastewater treatment systems can be complex, often requiring multiple steps, a variety of chemicals and a considerable amount of labor. Even when the process is supposedly automated, too often technicians must still monitor the equipment in person. This usually requires oversight of mixing and separation, adding of chemicals, and other tasks required to keep the process moving. Even then, the water produced can still fall below mandated requirements.
Although paying to have such wastewater hauled away is also an option, it is expensive. In contrast, it is much more cost effective to treat the wastewater at its source, so the treated effluent can be legally discharged and the resulting sludge passes a TCLP (Toxicity Characteristics Leaching Procedure) test and can be disposed of as non-hazardous waste in a local landfill.
Fortunately, complying with EPA and local wastewater regulation has become much easier with a variety of more fully automated wastewater treatment systems. Such systems not only reliably meet regulatory wastewater requirements, but also significantly reduce the cost of treatment, labor and disposal when the proper Cleartreat® separating agents are also used.
Cost-Effective, Automated Wastewater Treatment
In contrast to labor-intensive multiple step processes, automated wastewater treatment can help to streamline production, usually with a one-step process, while lowering printing costs.
An automated wastewater treatment system can eliminate the need to monitor equipment in person while complying with EPA and locally mandated requirements. Such automated systems separate suspended solids, emulsified oil and heavy metals, and encapsulate the contaminants, producing an easily de-waterable sludge in minutes. The water is typically separated using a de-watering table or bag filters before it is legally discharged. Other options for de-watering include using a filter press or rotary drum vacuum. The resulting solids are non-leachable and are considered non-hazardous, so it will pass all required testing.
These systems are available as manual batch processors, semi-automatic, automatic and can provide a legally dischargeable effluent. A new, fully customized system is not always required. In many cases, it can be faster and more cost effective to add to or modify a manufacturer’s current wastewater treatment systems when this is feasible.
However, because every waste stream is unique to its application, each wastewater treatment solution must be suited to or specifically tailored to the application. The first step in evaluating the potential cost savings and effectiveness of a new system is to sample the wastewater to determine its chemical make-up followed by a full review of local water authority requirements. The volume of wastewater that will be treated is also analyzed, to determine if a batch unit or flow-through system is required. Other considerations include the size restrictions so the system fits within the printer’s available footprint.
An example of successful automated wastewater treatment involves one of the largest independent corrugated manufacturers, which processes over 8 million sq. ft. of corrugated packaging and displays per day. The corrugated manufacturer required more efficient treatment of wastewater that is generated from the washdown of its flexographic printing presses that use various inks in the manufacturing process.
For this, the corrugated manufacturer turned to an EconoFlow fully automated wastewater system as well as Cleartreat separating agent from Sabo Industrial Corp., a New York-based manufacturer, distributor and integrator of industrial waste treatment equipment and solutions, including batch and fully automated systems, Cleartreat separating agents, bag filters, and accessories.
The system included a high-volume flow-through mix unit, ground level feed hopper, bag filter housing for solids removal, self-indexing dewatering table, and final polishing vessels. Sensors ensure proper material flow and operation, and onscreen audio-visual alerts indicate if anything requires attention.
However, instead of typical labor-intensive in-person monitoring of equipment, to correct a problem the mix chambers’ motors are controlled electronically by Human Machine Interface (HMI) and can be remotely adjusted, along with the mix motor speed, and powder feed by a Sabo Industrial technician. The industrial wastewater equipment provider can utilize the equipment’s integrated webcams as needed to view the mixing chambers for flocculant formation, floc structure, color and water clarity. Remote access also enables viewing alert conditions on the touchscreen and provides the ability to reset the machine, if needed.
Despite all the advances in automating wastewater treatment equipment any such system requires effective separating agents which agglomerate with the solids in the wastewater so the solids can be safely and effectively separated out.
Because of the importance of separating agents for wastewater treatment, Sabo Industrial uses a special type of bentonite clay in a line of wastewater treatment chemicals called ClearTreat. This line of wastewater treatment chemicals is formulated to break oil and water emulsion, provide heavy metals removal, and promote flocculation, agglomeration and suspended solids removal.
Bentonite has a large specific surface area with a net negative charge that makes it a particularly effective adsorbent and ion exchange for wastewater treatment applications to remove heavy metals, organic pollutants, nutrients, etc. It has the ability to swell 16 times its normal weight when introduced and mixed with wastewater. As such, bentonite is essential to effectively encapsulate the materials. This can usually be achieved in one-step treatment, which lowers process and disposal costs.
In contrast, polymer-based products do not encapsulate the toxins, so systems that use that type of separating agent are more prone to having waste products leach back out over time or upon further agitation, which can result in compliance violations.
As a point of comparison, if a treated polymer floc is shaken in a container, it will rehydrate and go right back into a wastewater solution. However, Cleartreat floc, if shaken in a container will remain separated as floc and crystal-clear water.
After using separating agents, typically a valve is opened and the treated effluent or floc-ed waste stream is pumped through a bag filter, de-watering table, rotary drum vacuum, or other type of filtration. The floc or sludge stays in the bag and the clear water passes through.
When the bag finishes de- watering, the pumps are usually left on because bentonite is hydrophobic, which means that it continues to shed water when removed from water. So, over time it will become extremely hard and pass any TCLP test. In fact, copper lead, and zinc become virtually undetectable in the treated wastewater and encapsulated sludge.
In the case of a special event paper goods producer, the wastewater generated was from washing the ink chambers used in the manufacturing process. Because metallic inks were involved, this involved a certain amount of cobalt, zinc, iron, copper for coloring. Previously, the paper goods producer had the wastewater hauled away at significant expense.
In search of a more cost-effective solution, the producer turned to treating wastewater at its source. For the application, Sabo Industrial supplied the separating agent, as well as a 250-gallon mixing chamber and a self-indexing dewatering table, which requires a minimal footprint compared to traditional wastewater systems.
The main focus is removing metals such as zinc, copper, and cobalt as well as suspended solids. The treatment method first requires a pH adjustment. Next 10 lbs. of Cleartreat is added at a 0.5% introduction rate. Then the batch is transferred to the self-indexing dewatering table for filtering, where filter paper is automatically advanced by a control probe. The treated water is captured in the tank underneath the dewatering table and is a legally dischargeable effluent.
The treated sludge, capable of passing a TCLP test, is automatically deposited in a waste dumpster. Critically, the encapsulation process prevents the release of the ink and contaminants from the sludge. Even when applying pressure, the ink will not break out onto the paper. Compared to hauling, treating the waste stream at the source is a much less expensive alternative.
Today’s advanced more automated wastewater treatment systems, along with the most effective Cleartreat separating agents, can provide the printing industry with an easy, economical alternative so manufacturers remain compliant with local ordinances and the EPA. Although there is a cost to these systems, they do not require much attention and can easily be more affordable than paying fines or hauling.