Utility Partners and the Town of St. Johnsbury entered into a public private partnership to provide utility management services on January 1, 2011. This full-service agreement includes the operation, maintenance, and repair of the wastewater treatment facility and sewer pumping stations. St. Johnsbury has 7,700 residents that appreciate outstanding opportunities for education, commerce and healthy living. The wastewater treatment facility is permitted to treat up to 1.60 MGD, though the actual flow can reach more than 3.0 MGD during rain events. It is operated eight hours per day, five days per week, with continuous emergency protection from a call-out system. Our staff performs laboratory testing and analysis required to insure the NPDES requirements are met.



 

Influent enters the headworks of the facility and is pumped through two low-lift screw pumps before going through a girt removal and screening process. The flow is then diverted into two primary clairifiers where a period of settlement occurs. After that primary treatment, the flow travels through a series of rotating biological contactors. A RBC is a type of secondary treatment process that consists of a series of closely spaced discs mounted on a rotating shaft. Microorganisms grow on the surface of the discs where degradation of pollutants in the wastewater takes place. Flow then travels on to two secondary clariifers. The facility utilizes a SCADA system for automation and Ultra-Violet (UV) system for disinfection. Flow also passes through two parallel chlorine contact chambers for disinfection before it is neutralized with sodium bi-sulfite and discharged into the Passumpsic River.

Solids that settle in the clarifiers are pumped to multiple anaerobic digesters. Here the sludge is stabilized and pathogens are removed. Methane gas produced by the digester is used to heat the treatment facility buildings and accelerate the sludge digestion process. The condensed sludge is transported by staff to local agricultural pastures for land application where it is used as a fertilizer.

St. Johnsbury, VT

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