When a prominent plastics manufacturer encountered issues with settleability and organics reduction in their wastewater plant’s secondary treatment system, they consulted several membrane system providers to determine the feasilbility of using a membrane bioreactor (MBR) to solve the problems. They narrowed the field to two manufacturers, and had each conduct a pilot study to determine which could achieve their objective: over 99% reduction in 5-day biological oxygen demand (BOD5). One pilot used a pressure-driven external module with high cross-flow velocities, while the other used a submerged vacuum-driven unit; the latter was able to achieve the target BOD with less energy and foaming and, therefore, was selected for the full-scale plant. The MBR was installed and placed on-line in June of 2014, running extremely well for about 6 months. In mid-December, a major spill in the production plant killed nearly all of the biomass in the aeration tanks, and shortly thereafter flow through the membranes slowed dramatically. Initially, the cause was believed to be silicone in the wastewater (fiber analysis showed higher-than-normal Si levels), but further testing revealed the real culprit to be the extracellular polymeric substances (EPS) produced by the dying biomass population. The membranes were manually cleaned to remove much of the EPS “slime” coating the fiber surfaces, and chlorine cleanings were dramatically increased. Over time, the membranes recovered to about 80% of their original flux. This presentation describes the membrane pilot and full-scale systems, details the membrane fouling and troubleshooting sequences, and explains the system recovery and lessons learned.
This presentation is available to AMTA Members only.
- Dave Holland
- Aqua-Aerobic Systems, Inc.
- AMTA/NWMOA/WEF Technology Transfer Workshop, Vancouver, WA
- AMTA/NWMOA/WEF Technology Transfer Workshop
- Industrial MBR, COD Reduction, EPS Membrane Fouling