Machine shops, metal fabricators, and finishing operations must meet EPA and local wastewater requirements for effluent, including those regulations listed under the federal Clean Water Act. Under that 1972 legislation, the Environmental Protection Agency identifies 65 pollutants and classes of pollutants as “toxic pollutants”, of which 126 specific substances have been designated “priority” toxic pollutants. Failing to manage those effluants properly can result in severe fines — fines that can escalate quickly.
Typically, metal working and fabricating operations rely on washing to get rid of any residue, lubricant, oil, or acid before, during, and after various process steps. Significant amounts of wastewater are generated as a result, including coolant, acid, alkaline, or etching wastewater compounds and rinses. This also may include wastewater related to processes such as metal refining, machining, grinding, quenching, tube forming, stamping, tumbling, plating, electroplating, powder coating, and scrap metal recovery.
For the operators, this means installing a wastewater treatment system that effectively separates the contaminants from the water, so it can be legally discharged into sewer systems or even re-used.
However, standard wastewater-treatment systems can be complex, often requiring multiple steps, a variety of chemicals, and a considerable amount of labor. Even when supposedly automated processes, technicians often must monitor the equipment in person. Usually this requires oversight of mixing and separating, adding of chemicals, and other tasks necessary to keep the process moving. Even then, the water produced may not meet the mandated requirements.
Although paying to have wastewater hauled away is an option too, it is extraordinarily expensive. It is much more cost-effective to treat the industrial wastewater at its source, so treated effluent can go into a sewer and treated 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 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 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 costs at metal industry facilities.
An automated wastewater treatment system can eliminate the need to monitor equipment in person while complying with EPA and locally mandated requirements. Such systems separate suspended solids, emulsified oil and heavy metals, and encapsulate the contaminants, producing an easily de-waterable sludge in minutes, according to metal industry consultants at Sabo Industrial Corp., a New York-based manufacturer, distributor and integrator of industrial waste-treatment equipment, including batch and fully automated systems, Cleartreat separating agents, bag filters, and accessories.
The water typically is then separated using a de-watering table or bag filters before it is discharged into sewer systems or further filtered for re-use as process water. 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 will pass all required testing.
These systems are available as manual batch processors, semi-automatic, automatic and can be designed as a closed loop system for water reuse or provide a legally dischargeable effluent suitable for the sewer system. 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 facility’s current wastewater treatment systems when this is feasible.
However, because every wastewater stream is unique to its industry and 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, say metal industry consultants at Sabo Industrial.
The volume of wastewater that will be treated is analyzed too, to determine if a batch unit or flow-through system is required. Size restrictions are another consideration, so that a new system fits within the plant's available footprint.
Separating agents — Despite the advances in automating wastewater treatment equipment, any such system requires effective separating agents that agglomerate with the solids in the wastewater, so the solids can be safely and effectively separated.
Because of the importance of separating agents for wastewater treatment, Sabo Industrial uses a special type of bentonite clay in its line of wastewater treatment chemicals, called ClearTreat. These wastewater treatment chemicals are formulated to break oil and water emulsions, provide heavy metals removal, and to 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. As such, bentonite is essential to effectively encapsulate the materials. Usually this can be achieved in a 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.
Today’s automated wastewater-treatment systems along, with the effective Cleartreat separating agents, can provide machine shops and metal fabricators with an easy, cost-effective alternative so they remain compliant with local ordinances and the EPA. Although there is a cost to these systems, they do not require much attention and easily can be more economical than paying fines or hauling.
Del Williams is a technical writer based in Torrance, California.