One of the largest facilities in its area and one of the largest in that company, a heavy duty truck engine and cab manufacturing facility chooses to recycle their industrial wastewater.
Corporate mandate to reach zero discharge may have been a large motivating factor, but the success of the industrial wastewater recycling program and the cost savings prove to be the wins for this facility. They are now reusing up to 8.4 million gallons of their industrial process water per year, which translates to a 60% - 80% reuse rate. And they have plans to improve that rate to 100%. With ProChem's help, that is a real possibility.
The EHS Manager in this facility faced several challenges with the wastewater they previously discharged. Surfactant issues and foaming at the regional water authority, where the wastewater was received, and also molybdenum contamination of land-applied sludge were reported. The EHS Manager was proactive in identifying the facility's contribution to these issues and in finding a solution. ProChem and the EHS Manager worked together to find the solution that was best for the facility. Multiple technologies were evaluated, including vacuum distillation, ion-exchange, and membrane filtration with nanofilter/reverse osmosis system. The membrane filtration with nanofilter/RO technology would ultimately become the best option for meeting the corporate goal of zero discharge through a closed loop industrial water reuse system.
The proposal to the facility's management included incentives such as directing capital funds to recycling industrial wastewater instead of meeting increasingly stringent and recurring environmental regulations. The recycled water could be routed to the cooling towers because it would actually be of higher quality than what is purchased from the city, reducing the need for chemical pretreatment, increasing cooling efficiency, and extending the equipment's life. More specifically, the membrane filtration (with nanofiltration/RO system) technology offers the following benefits:
- Produces acceptable process water with little organic, microbiological, or inorganic contamination
- Requires minimal operating labor (because ProChem water reuse systems are automated)
- Produces minimal concentrate (waste), which is simple to treat through a conventional precipitation system
- Comes with a reasonable price tag and overall low operational costs
Additionally, adopting industrial water recycling in the facility would eliminate the need to store untreated wastewater due to the flow restrictions from the water authority. Their permit restricts them to 36,307 gallons per day, causing the facility to store an excess of 240,000 gallons.
After implementing the industrial water reuse system, the plant-wide use of water has been reduced from 62 million gallons per year to 26 million gallons per year. Over a 9 year period, plant water use has been reduced by 57.6%. The facility is saving a projected $90,000 on the purchase and disposal of wastewater alone.
The facility uses recycled industrial water in several different applications:
- The e-coating system within the manufacturing process (15,000 to 20,000 gallons per day)
- Humidification (500 to 1,000 gallons per day)
- Parts wash system (12,000 gallons per day)
- Cooling tower (4,000 to 6,000 gallons per day)
The EHS Manager and ProChem are currently working on challenges such as:
- Installing solids removal methods for e-coat discharge to reduce the impact on conductivity/TDS and TSS
- Expanding the storage capacity for reuse water to address losses associated with shutdown periods
- Eliminating stormwater influent to the wastewater treatment process that reduces the water reuse efficiency.
- Adding a high-pressure reverse osmosis system to address the lower conductivity requirement for the e-coat process but also allowing improved reuse rate (>90%)
This facility's EHS Manager is a proponent of industrial water reuse/recycling and despite the remaining challenges still in front of them before reaching their ultimate goal, they are experiencing great benefit from the system:
- Lower operating costs
- Improved feed water quality
- Reduced environmental liability and risk
- Reduced chemical usage
- Decrease in water purchases and disposal costs
- Major step towards fulfilling the company's desired environmental position