Wastewater Treatment Process

The Jackson Pike (JP) plant was placed into service in 1937. Since that time, it has been modified, expanded, and improved many times. The historical narrative, presents milestones in history highlighting significant improvements. 

It is located on State Route 104 just south of Greenlawn Avenue and is visible from I-71. The plant features a conventional activated sludge process and meets all treatment requirements of the National Pollutant Discharge Elimination System (NPDES) permit. Clean effluent is returned to the Scioto River. 

The average daily design capacity at Jackson Pike is 68 million gallons daily  (MGD) with a peak flow capacity of 150 MGD. A unique flow diversion structure to the north of the plant can direct flows through an interconnecting sewer to the Southerly plant when JP reaches its maximum capacity. 

Wastewater flow that reaches JP enters a set of mechanical course and fine screens before it is pumped to a vortex grit removal system. From here, flow is split between A-Plant and B-Plant using a flow control system. The A-Plant and B-Plant are nearly identical except that A-Plant was constructed originally, and B-Plant was added later when more capacity was needed.

Biosolids are treated and stabilized through anaerobic digestion to Class B standards, which reduces pathogens, minimizes odor, and decreases volume A portion of the solids are taken to the Composting Facility where they are composted to Class A, exceptional quality standards and marketed to the public and other outlets as Com-Til mulch.

Jackson Pike is implementing an electrical cogeneration system (photo below) to utilize methane rich gas produced by the digesters to generate electricity for multiple uses in the plant. This includes heating of the digestion process and buildings, and generating electricity to offset much of the electrical demands of running the plant.

Located on U.S Route 23 just north of Pickaway County, this plant was placed into service in 1967 to meet the needs of the growing service area. It has been modified, expanded, and improved many times.

Like Jackson Pike (JP), the Southerly plant features a conventional activated sludge process and follows all treatment requirements of the National Pollutant Discharge Elimination System (NPDES) permit. Clean effluent is returned to the Scioto River (photo left). 

The average daily design capacity of the Southerly WRP is 114 MGD and can treat up to 330 MGD through full treatment and an additional 110 MGD through a Chemically Enhanced Primary Treatment system (CEPT). In addition to flow from its service area, Southerly can also receive flow diverted from JP through a flow diversion system and the interconnector sewer (photo below). 

Wastewater flow that reaches Southerly enters a set of mechanical coarse and fine screens before it is pumped to a vortex grit removal system. Next, flow is split between three trains: west, center, and east. Each train is nearly identical with the exception that west and center trains have rectangular primary clarifiers, and the east train has circular shaped primary clarifiers. 

Biosolids are treated and stabilized through anaerobic digestion to Class B standards, which reduces pathogens, minimizes odor, and decreases volume. A portion of the solids are taken to the Compost Facility where they are composted to Class A, exceptional quality standards and marketed to the public and other outlets as Com-Til mulch.

Like Jackson Pike, the Southerly plant is implementing an electrical cogeneration facility that will use methane gas to fuel boilers for process and building heat, and generate electricity for plant use. 

This facility is the centerpiece of the City’s biosolids beneficial use program. It is also the longest-standing outlet for Columbus, taking about 40% of the City’s biosolids annually. Currently, the facility can receive up to 200 wet tons per day of biosolids from the two water reclamation plants after they are separated and treated from the incoming wastewater. 

First placed into operation in 1980, the Compost Facility is one of the oldest composting facilities of its kind in the nation, and our only outlet which produces Class A, exceptional quality biosolids as defined in Section 3745-40 of the Ohio Administrative Code (OAC). The final compost, marketed as “Com-Til,” is our only biosolids product available for public use including lawns, gardens, tree nurseries, roadsides, and local farmers.  

• Two perforated air pipes are placed longitudinally on a one-foot-thick foundation of wood chips and spaced a few feet apart.
• Piles are constructed using a mixture of biosolids and bulking agents, which consists of wood chips and pre-cured compost. The average solids concentration of sludge introduced into the process is approximately 21%.
• A special turning machine mixes the biosolids and bulking agents in batches to achieve a uniform texture and size. After two passes with the machine, the pile is erected and covered with a two-foot-thick insulation layer of unscreened cured compost.
•  The composting process officially begins. Air is pulled through the piles by blowers for approximately 21 days. During this period of active composting, the internal pile temperature reaches and is maintained at approximately 60-65 degrees C (140 degrees F to 149 degrees F). Temperature probes are used to monitor the process and adjust blower speed to maintain this temperature.
• Air pulled through the compost piles is sent to biofilters for odor control treatment.
• At the end of the 21-day aeration cycle, active composting is complete. The pile is then torn down and the material moved to another part of the site to undergo curing for 21-28 days, where it is restacked in piles that are unaerated.
• Once the curing is complete, the pile is torn down and the compost sent to a rotary screen where larger pieces are removed and returned to the beginning of the compost process.
• The screened compost is stored in piles and is sold wholesale to businesses and the public, and is also resold to the public by mulchers and soil blenders under our trademark name.  

All composting operations are performed outdoors on paved surfaces and operate under any weather conditions. The Compost facility can accept biosolids during rain, snow, and cold weather and operates 7 days each week. 

The Compost facility serves as an educational resource to residents. Tours are offered to all interested including students at the nearby Ohio State University, local environmental groups, City colleagues, and fellow utilities seeking to learn about the program as biosolids composting grows in popularity. Additionally, the Compost Facility runs a robust donation program, offering up to 10 cubic yards to community gardens free of charge. More information regarding the Compost Facility, including sales, donations, and yard waste can be found at our website at Columbus.gov/Com-til.