Environmental Compliance Issues Solved by Reuse of Industrial Process Wastewater
A manufacturing plant for heavy duty trucks that utilizes an e-coat paint process requires approximately 13Mgal of fresh water per year and has ISO 9001 and ISO 14001 certifications. The wastewater from the e-coat paint process contains nickel, zinc, phosphates, surfactants, suspended solids, and other contaminants that require treatment by a chemical treatment process. The plant's discharged wastewater makes up 7% of all the water that is discharged to the small, local POTW.
While the plant was meeting the current discharge permit limits, the POTW notified the customer that new permit limits were being developed for molybdenum and surfactants. To meet these new permit limits, the plant would need to invest over $1 million in capital investment to upgrade their existing wastewater treatment system and increase labor to operate it. In addition, their incoming water purification system needed to be upgraded to increase the quality of the influent water.
The ProChem Solution
As an alternative to this costly system upgrade for treating influent, effluent, and discharging the wastewater, ProChem, Inc. suggested that the customer explore a wastewater reuse system to reduce their environmental footprint and reduce the pressure of permit-driven modifications.
After completing bench- and pilot-scale testing, ProChem, Inc. was able to offer a wastewater reuse program that would reduce the volume of water that was discharged from the plant by an average of 75%. ProChem seamlessly integrated the wastewater reuse system into the customer's existing wastewater treatment system and modified the existing chemical treatment program. These modifications were designed for a phased implementation to ensure that there was no impact to the manufacturing process:
- Treatment chemistry modification: To limit the concentrations of salts and eliminate chemical compounds that would negatively impact the reuse system.
- Wastewater Reuse System installation: To accept treated wastewater from the pretreatment system, filter salts and other contaminants from the water, and then return the pure water to the plant for reuse in several plant processes (paint booths, humidification systems, cooling tower).
- Better quality water: The water from the reuse system is an improvement over the water provided by the city, which reduced the costs to pretreat the water coming into the plant process.
- Lower capital costs: The wastewater reuse system required lower capital investment than the modifications that were proposed for their existing treatment system.
- Lower operating costs: The wastewater reuse system is highly automated and utilizes the existing operators for the wastewater treatment system. The operating costs are also 75% lower than the estimated cost for the additional labor that would have been required to operate the proposed treatment system modifications.
- Reduced sludge disposal: The modified chemical treatment program resulted in 50% reduction in off-site disposal of sludge from the wastewater treatment system.
- Zero permit violations: By reducing the frequency of discharge from five days to one day per week, the pressure on the POTW is reduced, and the plant has had zero permit violations since the implementation of the wastewater reuse system.
- Reduced chemical usage: The goal of the wastewater pretreatment system during the reuse phase of operation requires the removal of solids and some dissolved solids. The wastewater is not treated to permit limits at this phase, which results in reduced consumption of coagulants, pH adjustment chemicals, and flocculants.
- Environmental position: The wastewater reuse system was a major step towards fulfilling the customer's goal to have an environmental position for resource conservation and environmental compliance.