Written by Tom Welch
Version also published in TPO Magazine, October 2020
The Bissell Point Wastewater Treatment Plant, owned by Metropolitan St. Louis Sewer District (MSD), is the largest wastewater treatment plant in metropolitan St. Louis, MO. Schwing Bioset had previously provided six (6) KSP 25 piston pumps with 50 HP power packs and a live bottom receiving station at the facility that have been in service since 1993. The piston pumps conveyed 25% dry cake solids to the multiple hearth incinerators, but due to the high amount of additional silt that makes its way through the plant via inflow and infiltration during wet weather events, the dry solids content can soar to over 40%. While this nearly 30-year-old equipment continues to perform admirably, MSD was seeking a solution for the biosolids produced at its satellite plants and wanted to utilize the excess incineration capacity at Bissell Point.
Due to the long and successful history with the current equipment at Bissell Point, MSD purchased a larger KSP 45 piston pump and piping system to transport the received solids into the facility, as well as a push floor truck receiving station with over 50 cubic yards of capacity from Schwing Bioset. The new system is able to handle a high volume of biosolids and complements the existing equipment.
Schwing Bioset worked closely with Donohue and Associates to design and provide the new biosolids receiving station for the WWTP. The new receiving station, designed utilizing push floor technology, allows dewatered biosolids to be received from other Metropolitan St. Louis Sewer District facilities so that disposal costs can be minimized by allowing the biosolids to be incinerated. Push floor technology was chosen over the incumbent live bottom as a more efficient and lower maintenance system that also improves material flow characteristics.
The push floor bunker design consists of two hydraulically-driven push frames that reciprocate along the bunker floor. The action of the frames breaks material bridging and feeds solids into the extraction conveyor, and rectangular bunkers allow multiple trucks to back up to and unload into the bunker simultaneously. The bin also includes a retractable bi-fold cover integral to the system when not receiving biosolids, which assists in containing odors and prevents rain, snow, and other tramp materials from falling into the bunker.
As plant staff are already familiar with the equipment and its operation, integration into existing operations has gone smoothly and the new equipment provides MSD flexibility in their management of biosolids from within their service area into the future.