Energy from Waste Plant - Process Water Drainage Design

Process Water Drainage Design – Energy From Waste Plant (Orsted Rensscience EfW)

Beta Design Consultants were appointed by the client to review the existing system for the closed loop process water drainage. The facility was one of a kind, processing municipal waste (black bin bags) for more than 25000 properties using the anaerobic digestion process.

The Anaerobic Digestion process deals with municipal waste – requiring carefully designed process drainage

Process waste liquids were collected from various locations within the plant, channelled through gravity open drains into an underground system that ends at a sump for pumping back into the system after removing sedimentation.

The existing system was reviewed by Beta Design Consultants engineers and assessed based on performance. Our engineers carried out extensive research in the process area, observing flow and blockages and talking to client process engineers and maintenance operatives on site to understand the bottlenecks, diagnose the shortcomings of the existing layout before proposing any improvements.

Grit separation to extract sediments upstream introduced at various positions in the system

The proposed intervention addressed various issues, through the following approach.

1. Widening the channels to standardize flow and reduce flow peaks.
2. Changing drain covers to composite type durable and easy to handle type improving maintenance and effectiveness in catching solid waste.
3. Introducing grit separation equipment at strategically chosen locations after conducting market research to identify suitable equipment for the flow and layout. This resulted in considerable improvement of the system flow as sediments and grit were extracted early on reducing risk of blockages in the system and also reducing wear and tear in the existing facilities.
4. Introducing improved grit/sediment collection baskets from stainless steel at more frequent locations to improve maintenance and reduce sediments load downstream and on the manholes and the sump.
5. Introducing high performance concrete HPC as a material for use around all the “aco drains” as these channels were subject to corrosive liquids resulting in the degradation of the surround concrete. Using the durable HPC concrete surround would not only protect the aco drains and their covers but also reduce risk of tripping and accumulation of solids on sides of drains.
6. Conducting section by section trials on the proposals to ensure the performance in reality is consistent with the desk-based findings.

High Performance Concrete used as surround concrete on the sides of the ACO drains