The Context
An aerospace manufacturer producing flight-critical components—including gears, transmissions, and rotorcraft drive systems for military and commercial aircraft—operates in a highly regulated environment where consistency and reliability are essential.
Like many in the industry, their metal finishing operations generate cyanide-bearing wastewater. Their treatment system relied on traditional batch alkaline chlorination to destroy amenable cyanides prior to discharge.
The Challenge
Despite having a standard treatment process in place, the facility began experiencing intermittent failures in meeting cyanide discharge limits.
Further analysis revealed the issue: complexed cyanides, specifically iron and nickel cyanide, which are not effectively treated through conventional chlorination.
This created a difficult operating environment:
- Final effluent samples were failing compliance intermittently, making the issue unpredictable
- The facility began receiving non-compliance notices and fines from their local POTW
- Operators were forced to analyze every batch, increasing workload and slowing operations
- When treatment failed, the only option was to dispose of wastewater off-site via tanker trucks
- Annual disposal costs escalated into the tens of thousands of dollars, approaching $100,000
Because the issue was inconsistent, the team had no reliable way to predict or prevent failures—creating both financial and operational risk.
Acculabs’ Approach
Identifying the Root Cause
Acculabs worked with the customer to isolate the source of the problem, confirming that complexed cyanides were passing through the existing chlorination process untreated.
Introducing Targeted Treatment
The solution centered on implementing the Acculabs #707 EZ-TREAT process, designed specifically to precipitate complexed cyanides that cannot be oxidized through traditional methods.
Process Integration & Optimization
Rather than replacing the existing system, Acculabs integrated the #707 process into the current treatment flow:
- Maintaining chlorination for amenable cyanides
- Adding a controlled precipitation step for complexed cyanides
- Adjusting pH and dosing to ensure consistent removal
Acculabs provided guidance on dosing, sequencing, and control to ensure the process could be executed reliably within the existing batch system.
Stabilizing the Operation
With the process in place, the focus shifted to consistency—ensuring that variability in incoming waste streams no longer translated into compliance risk.
Impact
- Cyanide levels were reduced from 72 mg/L to less than 0.023 mg/L, well below discharge limits
- The facility achieved consistent compliance, eliminating intermittent failures
- Non-compliance notices and fines were eliminated
- Reliance on costly off-site disposal was removed, avoiding tens of thousands of dollars in annual costs
- Operators no longer needed to test and troubleshoot every batch, simplifying day-to-day operations
- The treatment process became predictable and repeatable, even with variable waste streams
Most importantly, the customer moved from a reactive, high-risk situation to a stable and controlled wastewater treatment operation—restoring confidence in their ability to meet regulatory requirements without disruption.
