City of Massillon Wastewater Treatment Plant

The City of Massillon has been a trusted client of CTI Engineers since the Ohio offices opened in 1995. With a major plant upgrade completed in 2000, Massillon has trusted CTI to keep the wastewater treatment plant on the cutting edge of technology since the beginning.


At the beginning of the new millennium, the city's plant had reached its maximum capacity of 12.5 MGD and expansion was necessary to perform for western Stark County for the next 20 years. CTI was chosen to project future Stark County sewer service needs, identify and recommend measures to eliminate inflow and infiltration issues that would often overwhelm the system, and expand the facilities within a tightly confined site within the Ohio and Erie Canal National Heritage Corridor.

CTI prepared the update design to expand the plant from 12.5MGD to 15.8MGD with improvements to the flow equalization and aeration system.

The project included the addition of two concrete basins with a combined volume of 5.6 million gallons for equalization of both diurnal flows and wet weather flows. Basins were equipped with non-clog, stainless steel, coarse bubble diffusers for aeration and with tipping buckets for periodic flushing and cleaning. The brush aerators in the existing oxidation ditches were removed and replaced with vertical, slow speed mixers and fine bubble, ceramic disc diffusers.

To provide air for the aeration system, a new blower building was added, containing three 8,100-cfm, 350-hp centrifugal blowers driven through VFDs for capacity control. Also provided in the blower building were three 7,200-cfm, 200-hp centrifugal blowers, driven through VFDs, for equalization basin aeration. An automatic DO control system was provided to adjust air supply to meet actual aeration system demands.

Construction Costs:

$30 Million




Services by CTI

Sanitary Sewer Flow Monitoring

Infiltration/Inflow Analysis

Facility Plan Update

O&M Manual/Startup

Industrial Wastewater Pretreatment Program Assistance

Operator Training

Operations Assistance


Construction Services





Their latest upgrade tackled an EPA compliance problem with a system that was the first of its kind in Ohio. Massillon recruited CTI in a joint venture with OBG to install an Integrated Fixed-Film Activated Sludge (IFAS) treatment system.

The IFAS system is a suspended growth process incorporating an attached growth media within a suspended growth reactor. This technology facilitates the creation of additional biomass within the treatment facility to meet more stringent effluent standards and increased volume of loading, without increasing or adding tank capacity.

This system was chosen to enable biological nutrient removal (BNR) and reduce the need for chemical precipitation.

Following new regulations from the Ohio EPA and the Tuscarawas River Total Maximum Daily Load (TMDL) report, the plant was required to upgrade its existing liquid and solids handling treatment facilities to meet an average monthly concentration (1mg/L) for their final effluent limit for Total Phosphorus (TP).

To achieve capacity expansion and BNR, the Facility Plan and associated TP Removal Study recommended retrofitting the existing biological process to an IFAS system.

By expediting the project design and taking advantage of Ohio Environmental Protection Agency’s Harmful Algae Bloom (HAB) loan opportunity for phosphorous reducing projects, the City procured a 0% loan for the portions of the project attributable to phosphorous removal. This reduced interest rates for the project from 2.14% to 0.32%, amounting to a savings of approximately $7 million over the life of the loan.

Integrated Fixed-Film Activated Sludge

Based on site and process restrictions, this plug flow type activated sludge system was retrofitted into the existing aeration tanks and new process tanks were built in and around the footprint of the previous first and second stage screw pumps (between the primary clarifiers and the existing aeration tanks).

Each tank consists of three treatment compartments, each including the following steps:

  • Anaerobic (1 zone per train)
  • Anaerobic/Anoxic Swing (1 zone per train)
  • Anoxic (1 zone per train)
  • Anoxic Effluent Channel

The existing three aeration tanks were retrofitted into three plug flow reactors and include the following steps:

  • Oxic (1 zone per train)
  • Internal Recycle (IR) Wells (1 well midway down each Oxic Zone, the other at the effluent channel)
  • De-oxygenation zone (1 zone per train)
  • Effluent Channels

Construction Costs:

$26 Million


Ohio EPA Harmful Algae Bloom (HAB) Loan

Services by CTI

Total Phosphorus Removal Study

Facility Plan Update

Pre-purchase bidding of select treatment components

Design of IFAS secondary treatment system with intermediate pumping, fine screens and tertiary filter improvements

Geotechnical Investigations

Process Model Development

Pre-purchase bid development and documents


Regulatory Assistance

Bidding Assistance

Construction Administration

IFAS media loading