Case Study: Delphos, Ohio

MBR Coupled with 2nd Generation ATAD Provides Exceptional Quality Effluent and Biosolids

Delphos, OH - ThermAer™ easily maintains thermophilic temperatures even under the low MBR volatile solids loading conditions producing Class A biosolids.

Delphos, Ohio, is located at the intersection of Lincoln Highway, the country's first coast-to-coast highway, and the historic Miami-Erie Canal. Prior to 2006, Delphos utilized aerobic digestion to treat their biosolids. The resulting Class B biosolids were liquid land applied. Annual hauling and application costs were between $200,000 and $300,000. The greenfield WWTP improvement project enabled Delphos to treat its high organic influent and upgrade from a Class B liquid biosolids to a Class A dewatered biosolid material. Delphos retained the services of Floyd Browne Group and CT Consultants, regional engineering firms, to aid in the selection of process equipment and the design of this award winning facility. A comprehensive investigation of various technologies and process equipment, including lime stabilization, drying and standard aerobic digestion led Delphos to select the Thermal Process Systems' ThermAer to provide them Class A biosolids and substantial volume reductions.

Out-of-basin pumps complete with VFDs allow for variations of mixing intensity.

Upstream of the ThermAer, Delphos utilizes a membrane bioreactor (MBR) for wet-stream biological treatment. The MBR is an activated sludge process that allows for secondary treatment, clarification, and filtration typically installed in conventional activated sludge facilities. Solids (WAS) from the MBR are taken across a gravity belt thickener to remove excess water and increase the solids to approximately 4 - 6% TS. These thickened solids are pumped to one of the two ThermAer reactors at the facility. Microbial activity of the thermophilic bacteria maintains an internal temperature of around 145°F; no supplemental heating is required. An isolation time, based on the operating temperature, ensures the required pathogen kill and VS destruction to meet USEPA 503 regulations for Class A biosolids.

Jet aeration and positive displacement blowers provide mixing and oxygen to the reactor. Monitoring of the oxidation reduction potential (ORP) controls the mixing intensity and air supply to match real time conditions as dictated by the oxygen demand. Following feed events, oxygen supply is increased to counteract the deficit created in order to reduce the mass and minimize the formation of mercaptans and other reduced sulfur compounds.

Blowers provide the oxygen required by the system as indicated by the ORP.

Nitrification and denitrification are inhibited at the higher ThermAer temperatures. Therefore, a heat exchanger reduces the temperature to around 95°F during the transfer from the ThermAer reactors to the storage nitrification/denitrification reactor (SNDR™). An optimal environment is created to facilitate these microbial reactions. The aeration is controlled by adjusting the pH setpoints (typically in the range of 6.5 to 6.8) to remove ammonia from the filtrate and produce a final biosolid material that is very stable and easily dewatered at a reasonable cost. Furthermore, up to an additional 10% total solids reduction can be realized with the SNDR operation. Lower temperatures and pH combined with the reduced concentration of ammonia results in lower chemical consumption and therefore reduced costs associated with the dewatering process. Combination gravity belt thickener/belt press units dewater the biosolids to a final concentration of approximately 25% TS. Local farmers haul and apply the biosolids to crop fields. Additionally, a small amount of the biosolids is retained at the WWTP for use by residents of the community.

The city council was adamant the new WWTP be odor free. As such, a BioflitAer™ odor control unit was selected to treat the off-gas from the ThermAers and SNDR solids digestion process.

The ThermAer system installed at Delphos offers the following:

Class A Biosolids
2008 Average Total Solids Reduction = 49%
2008 Average Volatile Solids Reduction = 67%
Final cake - 25% solids
Reduction of hauling/land application fees resulting in savings of up to $200,000 a year

Class A Biosolids, on average, consist of:

Ammonia as N - 5,900 mg/kg
Phosphorus - 40,600 mg/kg
Total N - 39,800 mg/kg

Brochures

ThermAer: Your Class A Solution for Biosolids Management
Check out our new brochure! Your best solution for biosolids management.
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BiofiltAer: The Engineered Biofiltration System
Read about the advantages of BiofiltAer, an aerobic all-natural biofiltration odor control unit.
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Case Studies

Delphos, OH
MBR Coupled with 2nd Generation ATAD Provides Exceptional Quality Effluent and Biosolids
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Yorkville, IL
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Events

Kansas WEA
Capitol Plaza Hotel
Topeka, KS
August 30 - September 2
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Atlantic Canada Water and Wastewater Assoc.
Delta Brunswick
Saint John, New Brunswick
September 12-14
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Virginia WEA
Hampton Roads Convention Center
Hampton, VA
September 21-22, 2010
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2010 WEFTEC
New Orleans Morial Convention Center
New Orleans, LA
October 2-6, 2010
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$109 / dry ton, Amazing!
In 2004, the City of Bowling Green, Ohio, installed Ohio's first TPS ThermAer Process expanding the plant capacity from 6 MGD to 10 MGD. This energy efficient process offered superior solids reduction and an odor-free operation. Doug Clark, Water Pollution Control Superintendent, calculated 2009 treatment costs at a remarkable $109 per dry ton. In addition, 38% total solids are coming off the centrifuge.

TPS Thermaer Process