Last night brought a lot of excitement to the $271 million Piscataway WRRF Bioenergy Project, which centers on the addition of the thermal hydrolysis and anaerobic digestion processes to produce Class A biosolids. In the words of our friends at WSSC Water, “Last night, a bundle of innovation was born.”
This quip refers to the next phase of operational start-up requiring initial seeding of the anaerobic digester. The anaerobic digestion process harnesses natural bacteria to treat wastewater biosolids. At WSSC, these biosolids will first flow through the new thermal hydrolysis process (THP) followed by the anaerobic digesters (ADs). When initially commissioned, anaerobic digestion facilities require seeding with biologically active sludge to produce the population of methanogenic and acid-forming bacteria required for the anaerobic digestion process to work effectively. To accelerate the process of acclimation of the bacteria to the new environment, the preference is to seed with biologically active sludge that has gone through similar processes, in this case THP.
DC Water, located less than 15 miles from the WSSC Piscataway WRRF, also incorporated THP and anaerobic digestion at their Blue Plains AWWTP facility with the Main Process Train project, which was completed by PC in 2015. As a fully established facility, DC Water was happy to provide “bugs” that are “trained” to jump start the anaerobic digestion process. Beginning last night, tanker trucks containing this biologically active sludge began rolling into WSSC’s bioenergy facility and this sharing of special resources will continue over the next five days. Click here to watch last night’s excitement.
Once the seeding process is complete, initiation of full-time operation of the THP processes will begin. In preparation for this, the WSSC operations team has concurrently begun pre-dewatering activities, processing the indigenous biosolids produced by the Piscataway WRRF and storing the dewatered cake in the new cake storage silos. The volume of biosolids processed will ramp up from 4 dry tons per day to 16 dry tons per day over a 30-day period. Once this is complete, the facility will operate for another 60 days solely processing Piscataway WRRF biosolids before bringing biosolids from WSSC’s four other facilities to the site for processing through the new systems.
The Piscataway WRRF Bioenergy Project utilizes cutting-edge green technology to transform the way WSSC handles biosolids from all five of their water resource recovery facilities, significantly reducing the volume and creating Class A biosolids. The process will also reduce operating costs by more than $3 million per year and reduce greenhouse gas emissions by 15% by capturing and cleaning the digester gas to help power the facility through the CHP facility.
