Posted on January 9, 2013
City of St. Petersburg upgrades biosolids treatment to Class AA/EQ using Schwing Bioset’s patented Bioset process.
St. Petersburg, FL – Until recently, the city of St Petersburg, Florida’s Southwest Water Reclamation Facility relied solely on anaerobic digesters to stabilize their biosolids. However, the 20+ year old digesters had not only aged to a point of disrepair, but were beginning to cause odor complaints from the neighbors. Hence, the city felt the pressure to take corrective action quickly.
Not only would rehabilitating the existing digesters entail a sizeable expense, but in the end, the digesters would still only be producing a Class B product that needed to be hauled off to land sites. In the past this was not an issue, but the new F.A.C. 62-640 rule in Florida is going to make Class B biosolids harder to reuse in a beneficial manner.
Schwing Bioset brought in their mobile Bioset System to the St Petersburg facility in June of 2011 for a 5-day trial. Demonstrating their ability to use a natural process that eliminates pathogens by elevating pH and temperature, they proved their ability to create a Class AA/EQ product from the facility’s biosolids that would meet the 62-640 rule in Florida.
After successfully providing Class AA within 24 hours of setting up the equipment for the trial, the city engaged in an active discussion with Schwing Bioset to extend their trial to a full year. In this time, Schwing Bioset would be contracted to install all equipment, make sure operators were trained properly, and modify the city’s existing operation for a year-long period. Presently the equipment is operating successfully, the digesters are off line, the odor complaints have been eliminated, and the plant is producing Class AA/EQ biosolids that are being beneficially reused locally.