Water and Sewer Division

All About Wastewater

Galion’s Wastewater Treatment Plant (WWTP) went on line in 1986. The plant is a 2.7 million gallon per day (MGD) design activated sludge plant with lagoon tertiary treatment.  Design population for the year 2000 was 17,173. Treatment processes include screening, grit removal, pre-aeration, primary clarification, single-stage activated sludge, secondary clarification, tertiary lagoon, chlorination and dechlorination. Storm flows in excess of 6.8 MGD, after primary clarification, are diverted around the treatment. Flows in excess of 8.5 MGD are passed through chlorination and tertiary lagoon treatment. Primary clarifier sludge and waste activated sludge are combined in a gravity thickener and then pumped to an anaerobic digester where they are held until processed with N-Viro technology to a Class A Exceptional Quality Sludge (EQS) product.

            Flows enter the plant through one of three sewers. An 18” gravity sewer serves a small section in the south and south west section of town. The south east intercept sewer serves the east side of Galion. The southeast interceptor has two lift stations.  In 1995, two old, leaking, tree-root obstructed 24” sewers were combined into a new 36” sewer. This new sewer (Cherry Street) was laid from Portland Way South to the treatment plant. At the plant terminus, two new above ground lift stations were installed.

Tidd Drive lift station is another  station in the sewer collection system. It is a small below ground station with two pumps. This station serves a low area on the end of a sewer and only handles several dozen homes. Our final station is referred to as Sherman St. lift station.  This is a small, submersible pump station serving a half-a-dozen homes.  These homes, originally, were connected to a large trunk main.  The sewer to those homes had no grade and perhaps even a negative grade.  During higher flows, the trunk sewer backed up into this small sewer causing problems.  The installation of the lift station was the solution.  

       All lift stations, except Sherman St., have telemetry to the plant.  Telemetry transmits real time wet well levels, pump operations and alarm conditions.  Information for the in-system stations call in every hour. Alarm conditions are called in as they occur. The Cherry Street lift station data is transmitted continually to the plant computer because it is wired into the plant data system.

            All plant flows go through one of two bar screen channels.  Screenings and grit are landfilled.   A peristaltic pump and refrigerated sampling station is located between the bar screens and the grit pumps. This is our raw sample site.  Flow next goes to the grit removal tanks via one of two 66” diameter screw pumps. 

            Plant flows are pumped up to the grit tanks, the highest elevation in the plant. From this point on, all flows, except for recycle and sludge flows, are by gravity.  The two primary clarifiers are 60’ in diameter with a side water depth (SWD) of 10’.   In this process most of the larger solids are removed.

            Secondary treatment consists of activated with secondary clarification. There are four 281,000 gallon aeration tanks. For simplicity, all tanks are usually operated unless one is taken out of service for maintenance.  Secondary clarifiers are the same diameter as the primary clarifiers, however, they have a 12 foot side water depth.

            Tertiary treatment is provided by two lagoons in series with chlorination located in between. The first lagoon is relatively small with the 2.8 million gallon capacity providing about one days detention time at design flow.

            Disinfection is by gaseous chlorine feed by a controller paced off of plant flow. A back up manual chlorine feeder is available.  The following lagoon has a volume of 6.2 million gallons. Two floating aerators are used during the summer months to provide additional DO but also to help dissipate chlorine residuals. The effluent automatic sampling station provides continual monitoring of DO, pH and chlorine residuals. All information is transmitted to the plant computer for monitoring and record retention.          

            The sludge handling train consisted of gravity thickening of primary clarifier and waste activated sludge before pumping to anaerobic digestion. Two anaerobic digesters were operated in series. Sludge can be stored in holding tanks if needed. 

            The N-Viro International Corporation (NVIC) Advanced Alkaline Stabilization with Subsequent Accelerated Drying (AASSAD), “N-Viro Soil” process is a patented process for the treatment and recycling (reuse) of bio-organic wastes, utilizing certain alkaline by-products produced from the lime, utility and other industries. The N-Viro process has been commercially utilized for the treatment of wastewater treatment sludge and pharmaceutical and livestock wastes. N-Viro Soil, produced according to process specifications, is an “Exceptional Quality Sludge”  (EQS) product under Section 503 Sludge Regulations which exempts it from further federal regulation. The product is registered in most states as an agricultural product and covered under worldwide product liability insurance.

            The N-Viro process involves mixing the wastewater sludge with alkaline reagents and then subjecting the mixture to a controlled period of storage, mechanical turning, and accelerated drying. The N-Viro process stabilizes and pasteurizes the wastewater sludge, reduces odors to acceptable levels, immobilizes various toxic components and generates N-Viro Soil, a product which has a granular appearance similar to soil and has multiple commercial uses. The alkaline admixture used in the N-Viro process consists of byproduct dusts from cement or lime kilns, certain fly ashes and certain other mineral by-products.  Our particular process utilizes cement kiln dust and fly ash.  Our product is given away as a soil amendment.  Area farmers utilize the product to help increase soil pH and to add organic material to the soil.

Definitions

Activated Sludge - Microorganisms feed on the sewage breaking down the organic material into inert solids, water and various gasses. We maintain the proper mix of "food" to organisms, air and pH.  (return to previous location)

Anaerobic digestion - All accumulated solids eventually end up in the digester for further treatment. Anaerobic digesters are sealed with no addition of oxygen to the tank. With mixing, strict control of temperatures and pH ranges, solids are reduced to their inert component so they can be processed further or disposed of. (return to previous location)

Clarification - A tank in which flow velocities are slowed to the point that the heavier solids will settle out of the water by gravity. Those solids are removed from the bottom of the tanks and pumped to other processes for further treatment. (return to previous location)

Chlorination - Disinfection. Chlorine is applied to the treated effluent before it is released to the stream to kill harmful bacteria. (return to previous location)

Dechlorination - Small amounts of chlorine are harmful to some of the smaller organisms found in the stream. We must reduce the chlorine levels before discharge to the stream to prevent any harmful effects. (return to previous location)

DO - Dissolved oxygen. A measurement of the amount of oxygen available in a sample for biological activity. (return to previous location)

EQS - Exceptional Quality Sludge. This designation is applied to sludge treatment processes that meet the most stringent treatment standards from the USEPA. This designation also has the least restrictions as to reuse. (return to previous location)

Grit - Sand, stone and other mostly non-organic material that settles easily and that can cause excessive wear in equipment if not removed. (return to previous location)

N-Viro - A patented process in which wastewater solids are treated to a very high degree so they can be safely reused. (return to previous location)

Pre-aeration - a process that "freshens" the sewage by adding dissolved oxygen. This process makes the sewage easier to treat in later processes.(return to previous location)

Screening - an accumulation of rags, paper products, and other products that are intercepted before passage into the treatment plant to protect pumps and other mechanical devices. (return to previous location)

Sludge - Any accumulation of solids collected or removed in a plant during the process of treating the water. (return to previous location)

Tertiary - A more advanced form of treatment. In our plant, two large, settling lagoons at the end of all other processes. (return to previous location)