DATA AND MEASUREMENTS
A metals manufacturing company had a wastewater treatment facility , with an agreed discharge consent from the local water authority. They were experiencing regular quality failures of their treated wastewater, meaning there was additional delays and expenses to their process. to discharge their wastewater. It was uncertain if the failures were due to ineffective water treatment processes, poor sampling technique or inadequate testing protocols. They believed they were getting false failures as there was no obvious contaminants in their manufacturing process that could explain the regular failures.
An initial investigation uncovered several key issues:
- Treated wastewater regularly failed to meet discharge criteria. No clear causation of failure.
- Water treatment and analysis took at best 3 days to complete. Treatment failures caused significant rework and testing.
- Countermeasures included transferring of wastewater to IBCs, or diluting with fresh mains water. This require significant labour and resources.
- There was a high risk of delays to water treatment causing stoppages to production.
- The water treatment equipment did not have a structured maintenance program and was found to contain significant quantities of solid matter, reducing the capacity of the facility by 50%.
- The quality control test produced significant quantities of hazardous waste with no protocol for disposal.
Identified the following:
- Review of local water authority discharge consent agreement.
- Review of processes generating wastewater.
- Review of water treatment processes.
- Review of company’s sampling methods and analysing techniques.
- Review of historic analytical
- Review of company’s maintenance procedures and schedule.
- The quality control test method was evaluated using reliability and repeatability studies. This revealed that the test failures and variation was inherent to the test method and not due to operator variation.
- A cause and effect analysis showed that the matrix elements in the wastewater was acting as an interference causing a false positive result and only by diluting the water was the effect removed. This dilution also reduced the sensitivity of the test rendering it unusable.
- Liaised with the local water authority on best practice for water treatment, testing and discharge.
- The water treatment aeration process was improved to an industrial standard.
- An alternative test method which was not sensitive to the contaminant type in the water was identified, verified and implemented.
- Control charts were introduced to monitor the water quality to within defined sigma limits in line with the regulatory compliance.
- A maintenance cleaning program was implemented to minimise the deposition of solid matter and keep the equipment running at design capacity.
- The full environmental testing capability was brought in house. This improved the feedback time allowing processed wastewater to be discharged sooner.
- The improvement to wastewater treatment facility reduced the water consumption by 50%.
- The Process equipment running at its design operational capacity.
- Quality monitoring provided greater process control to ensure regulatory compliance.
- A safer test method with no hazardous waste generated.
- The risk of wastewater delaying production operations was significantly reduced.