Caught Up in Time
Missouri city complies with regulations with new sewage treatment infrastructure
City officials in Sullivan, Mo., were notably proud in 1988 when their new aerated wastewater treatment lagoon began operation. Within five years, however, the plant was essentially obsolete due to the reclassification of the effluent-receiving stream by the state’s regulatory agency and apprehensions about the stability of the site’s underpinning geology.
“If those concerns had existed a decade earlier, state regulators would not have approved the lagoon plant’s design and operating permit,” said City Engineer Robert Schaeffer, P.E., CFM. “These were unexpected issues for a city that just a few years earlier had made a relatively large investment in the new facility.”
The city commissioned a study to review the problem and present solutions. The study identified a series of needed upgrades and concluded that Sullivan would require a different, more advanced wastewater treatment process.
Jacobs Engineering was selected from competitive proposals to serve as design consultants for the replacement plant and related upgrades. From the eight process alternatives evaluated in the study, the city selected the Sanitaire’s ICEAS continuous-flow sequencing batch reactor (SBR) system, which utilizes a modified activated sludge biological treatment. The automated process is an enhanced variant of the activated sludge process that earned preferred specification based on the earlier study’s cost-benefit analyses of immediate and long-range considerations. The design option offered acceptable initial cost, ability to handle the varied flow and the flexibility to be operated to achieve nutrient removal with minimal operator interaction.
“The SBR technology has become increasingly common here in Missouri and is easy to operate,” according to PK Mathai, P.E., the Jacobs project engineer.
The major difference between the conventional activated sludge process and a conventional SBR cycle exists in the elimination of primary settling, aeration and secondary clarification in costly separate basins. SBRs perform these stages sequentially in the same basin, which also reduces the plant footprint and contingent construction costs. The advanced Sanitaire ICEAS continuous-flow SBR takes the process farther by using continuous flow without the batch interruptions during the settling and decanting required in a conventional SBR operating cycle. Instead, the ICEAS system uses a time-controlled continuous repetition of three sequential phases: aerate, settle and decant. Flow equalization, oxidation, nitrification/dentrification, phosphorous removal and solids separation occur in a controlled manner within the same tank. The new-generation Sanitaire ICEAS system thereby simplifies the entire process flow.
Now equipped to leave earlier concerns about stringent wastewater regulations behind, the city of Sullivan can again be proud of its new sewage treatment infrastructure. With an intelligently designed Sanitaire ICEAS system with lifetime efficiency in mind, the city benefits from not only simplified cost-saving operations, but also reliable results for the ongoing removal of nitrogen and phosphorous.