Ohio Wastewater Plant Built with the Future in Mind
North Royalton, OH has a new wastewater treatment plant that was designed with the future in mind. Recently expanded to have a capacity of 3.3 million gallons a day (mgd), the municipality's Plant A in suburban Cleveland now is equipped with multiple advanced treatment processes, including several supplied by U.S. Filter Corporation.
To keep up with growth the wastewater district could have added capacity a little at a time with a series of expansion projects. Instead, the community elected to look further ahead and build new facilities that would be good for the next 20 years. And while that meant higher upfront costs, North Royalton's plan will prove to be the more cost-effective choice over a 20-year period.
This commitment to the future by the municipality has been made by the efforts of the city's engineering department, the local council, and Mayor Gary P. Bama. Funded entirely by local money, the plan addresses not only plant capacity, but extends to the treatment processes designed by the engineering firm selected for the project, Montgomery Watson of Pasadena, CA.
N/AE="1">North Royalton's Process Arrangement
At the point of its discharge to the East Branch of the Rocky River, the plant's treated effluent, filtered and disinfected with an ultraviolet (UV) light system, averages only two milligrams per liter (mgl) of suspended solids, and five mgl CBOD5. It also meets the required ammonia nitrogen and phosphorus limits.
On the solids side of the plant, dewatered sludge is processed into EQS (Exceptional Quality Sludge) biosolids in an agitated open bay composting system. The compost facility that has been built is large enough to handle biosolids from North Royalton's two treatment plants, as well as from other communities, far into the future. This will eliminate transportation and landfill costs, and the district plans to market the nutrient-rich material to homeowners, gardeners and businesses.
At the start of the treatment train, USFilter Internalift screw pumps lift wastewater from the influent basin to an upper screw pump chamber. That chamber is equipped with an overflow box, designed so that water flow in excess of 14 mgd is bypassed to a flow equalization basin. Three pumps in this section each have a capacity of seven mgd.
Following screening the wastewater passes to rectangular clarifiers supplied by <%=company%>, which is headquartered in Waukesha, WI. These basins are equipped with chain and scraper sludge removal systems, as well as scum removal mechanisms.
After biological treatment in the activated sludge section of the process train, and secondary clarification, the waste stream flow passes to a Hydro-Clear pulsed bed sand filtration system. This is a product of the <%=company%> (Rothschild, WI), another unit of USFilter. The system consists of six cells in concrete tanks, and employs an innovative underdrain and pulsing mechanism which enables the filter to cope with varying incoming solids loads.
The filtered effluent, now clear, is disinfected with ultraviolet light, and passes through a post-aeration step before discharge to the river. In dry weather as much as 95% of the flow in the East Branch of the Rocky River can be the treated wastewater from the plant. And Cleveland Metro Parks authority officials are appreciative of the high quality of the water discharged to the river, which flows through their property.
N/AE="2">Making the Biosolids Product
To convert waste activated and primary sludge into a clean, marketable biosolids product, the North Royalton process scheme first uses a sludge thickening step that employs an Envirex gravity belt thickener. This process also uses a polymer addition for sludge conditioning. To introduce this chemical a compact Poly-Blend GEN 2 polymer feed unit was acquired from <%=company%> (Bradley, IL).
Sludge odors are controlled by a packed bed scrubber that was developed by another USFilter group, <%=company%>, located in Tallevast, FL, supplied its Triplex scrubber. This has three modules, each containing its own integral packed bed, sump, and re-circulation system.
Following this step the sludge is dewatered to about 20% on belt presses. Each day, two 16-yard hoppers of dewatered sludge are trucked about half a mile to the composting facility, and mixed with sawdust. Sludge from North Royalton's Plant B also is delivered to this site.
In the open-bay IPS composting system from CPC Products group, Sturbridge, MA, yet another USFilter unit, the sludge-sawdust mix is stored and agitated in 215-ft-long concrete-walled bays for approximately 24 days. The agitators ride on rails on top of the bay walls, mixing and aerating the compost, and moving it toward the end of the bay. From there it is transferred to storage areas where thermocouples monitor its temperature. To ensure pathogen kill, aeration blowers are used to maintain a temperature of 55°F automatically. Four to six of the 10 bays built at the plant are in use at any one time.
The expanded North Royalton Plant A has been running for just over a year now. By the year 2117, its service area is anticipated to have a population that will have grown well beyond the current number of 22,000. But with the forward thinking that went into its recent upgrade and expansion, the plant is expected to be capable of meeting the effluent and recyclable biosolids requirements of that time.
About the Author: Warner Jenkins is superintendent of the North Royalton municipal wastewater treatment Plant A in Royalton, OH.