History of the Plant
The original Waynesboro Wastewater Treatment Plant was constructed in 1954. It employed the latest technology at the time for secondary sewage treatment. Most plants prior to that time provided only primary treatment which included settling out and digestion of solids and disinfection of the liquid prior to discharge. The Secondary treatment process provided a higher degree of treatment through additional biological treatment by means of a trickling filter. The trickling filter utilizes a 67 – foot depth of stone media over which the settled sewage was distributed. A growth of microorganisms formed on the media which removed pollutants as the flow “trickled” over the stones.
In 1968, an expansion of the original plant was completed which effectively doubled the capacity from 2 MGD (million gallons per day) to 4 MGD. The process was the same, but a new digester and vacuum filter were added.
The digesters also utilize microorganisms to treat the sludge settled out in the clarifiers. The sludge was then dewatered on the vacuum filter or dried on the open sand beds.
In the summer of 1988, in response to much stricter limits set by the Virginia Water Control Board, the City began construction of major additions to the plant to upgrade it to an advanced waste treatment facility. Stone media in trickling filters was replaced with plastic media which provides more surface area for microorganism growth resulting in greater pollutant removal by these units. Rotating biological contactors were added to provide nitrification of the wastewater. This process utilizes a different type of microorganism growing on rotation discs to reduce the amount of ammonia which can be toxic to fish in the South River. Sand filters were also added to further polish the treated wastewater and ensure meeting the low pollutant levels mandated by the State. A belt press was installed to provide better and more reliable dewatering of sludge.
The original plant utilized chlorine for disinfection of the effluent. It is known, however, that chlorine can combine with other compounds to form toxic substances. Rather than adding dechlorinating chemicals to the water, the City chose to employ ultraviolent disinfection to the new addition. Ultraviolet light produced by special submerged bulbs kill all organisms without adding anything to the water. Cascade aeration steps following ultraviolet disinfection sere to increase the dissolved oxygen in the effluent.
In order to meet regulations set forth in the Chesapeake Bay Preservation Act, The City of Waynesboro is about to expand our treatment operations once more. By December 2010, we will have upgraded to a 6 MGD facility with a 5 stage biological nutrient Removal process and Ultraviolet disinfection.