City Of Lansing Wastewater Treatment Plant

FACILITY BASIC INFORMATION

• Plant Name: Lansing Wastewater Treatment Plant (WWTP)
• Location: Lansing, Ingham County, Michigan
• Operating Authority: City of Lansing Public Service Department
• Design Capacity: 40 MGD (Secondary Treatment), 165 MGD (Peak Wet Weather with Retention)
• Current Average Flow: ~19 MGD
• Population Served: Approx. 134,000 residents (City of Lansing + wholesale customers)
• Service Area: City of Lansing, Lansing Township, parts of Delta Township
• Receiving Water Body: Grand River
• NPDES Permit Number: MI0023591
• Original Construction: 1930s (Significant expansions in 1970s and 2000s)

TARGET AUDIENCE

• Municipal consulting engineers evaluating wet weather flow management

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• Wastewater treatment plant operators and superintendents
• Environmental regulators (EGLE/EPA) monitoring Grand River water quality
• Engineering firms specializing in CSO abatement and separation
• Municipal decision-makers studying regional service models

1. INTRODUCTION

The City of Lansing Wastewater Treatment Plant (WWTP) serves as the cornerstone of water quality protection for Michigan’s capital city and the downstream Grand River watershed. Located on Sunset Avenue, this complex facility operates as a conventional activated sludge plant with advanced wet-weather handling capabilities. While the plant treats an average daily flow of approximately 19 million gallons per day (MGD), its operational significance is defined by its massive hydraulic range, capable of managing peak wet weather flows up to 165 MGD through integrated retention and high-rate treatment strategies.

Operated by the City of Lansing Public Service Department, the facility has gained national recognition for its role in the city’s 30-year, $370+ million Combined Sewer Overflow (CSO) Control Program. Successfully completed in late 2023, this infrastructure initiative has virtually eliminated untreated overflows into the Grand River, positioning the Lansing WWTP as a model of regulatory compliance and environmental stewardship in the Great Lakes region. With robust solids handling, renewable energy generation via biogas, and ultraviolet disinfection, the plant exemplifies the transition from simple waste treatment to resource recovery.

2. FACILITY OVERVIEW

A. Service Area & Coverage

The Lansing WWTP serves a regionalized sanitary district covering approximately 55 square miles. The primary service area is the City of Lansing, but through inter-governmental agreements, the plant also accepts flow from Lansing Township and significant portions of Delta Township. The collection system is complex, consisting of over 500 miles of sanitary and combined sewers. The demographic served includes a mix of dense urban residential zones, heavy industrial corridors (including automotive manufacturing support), and state government institutional facilities.

B. Operational Capacity

The plant is designed for substantial hydraulic variability—a necessity given the historical combined nature of the collection system.

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• Average Daily Flow: 18-20 MGD
• Secondary Treatment Design Capacity: 40 MGD
• Peak Primary Treatment Capacity: 80 MGD
• Peak Hydraulic Capacity (with Retention): 165 MGD

During dry weather, the plant operates at approximately 50% of its secondary design capacity, allowing for optimal biological treatment efficiency. During storm events, the facility utilizes on-site retention basins (20 million gallons capacity) to store excess flow for subsequent treatment, or provides primary treatment and disinfection for flows exceeding secondary capacity but within permit limits.

C. Discharge & Compliance

Treated effluent is discharged into the Grand River, the longest river in Michigan, which eventually flows into Lake Michigan. The discharge is regulated under the National Pollutant Discharge Elimination System (NPDES) administered by the Michigan Department of Environment, Great Lakes, and Energy (EGLE). The plant adheres to strict limits on Carbonaceous Biochemical Oxygen Demand (CBOD5), Total Suspended Solids (TSS), Ammonia Nitrogen (NH3-N), Phosphorus, and E. coli. The facility has maintained an exemplary compliance record, particularly regarding the elimination of dry-weather overflows and the management of wet-weather excursions.

3. TREATMENT PROCESS

The Lansing WWTP utilizes a conventional activated sludge process supplemented by robust preliminary treatment and advanced disinfection. The process train is designed to handle high inorganic loads typical of urban runoff while maintaining biological stability.

A. PRELIMINARY TREATMENT

Raw influent enters the headworks via the main interceptor sewers. The preliminary stage is critical for protecting downstream pumping and biological equipment.

• Screening: Mechanically cleaned coarse bar screens remove large debris (rags, wood, plastics). Screenings are washed, compacted, and conveyed to dumpsters for landfill disposal.
• Grit Removal: Following screening, flow enters aerated grit chambers. Velocity is controlled to allow inorganic heavy solids (sand, gravel, coffee grounds) to settle while keeping organic matter in suspension. The grit is pumped out, cyclonically separated, washed, and disposed of.

B. PRIMARY TREATMENT

Flow moves to the primary clarifiers, which are large rectangular sedimentation tanks. Here, the velocity of the wastewater is significantly reduced.

• Sedimentation: Gravity settles approximately 60-70% of Total Suspended Solids (TSS) and 30-35% of Biochemical Oxygen Demand (BOD).
• Scum Removal: Surface skimmers remove fats, oils, and grease (FOG), which are pumped to the solids handling train.
• Primary Sludge: Settled solids are scraped to hoppers and pumped to the anaerobic digesters.

C. SECONDARY TREATMENT

The biological core of the plant uses the Activated Sludge process to degrade dissolved organics and nutrients.

• Aeration Basins: Primary effluent is mixed with Return Activated Sludge (RAS) to form mixed liquor. The basins utilize fine-bubble diffused aeration to provide oxygen for microorganisms. The plant operates in a plug-flow configuration, which is efficient for BOD removal and aids in preventing sludge bulking.
• Secondary Clarifiers: The mixed liquor flows to circular secondary clarifiers. The biological floc settles out, leaving clear supernatant at the top.
• RAS/WAS Strategy: A portion of the settled sludge is returned to the aeration tanks (RAS) to maintain the microbial population. The excess (Waste Activated Sludge or WAS) is removed to control the Mean Cell Residence Time (MCRT) and pumped to solids processing.

D. WET WEATHER / TERTIARY MANAGEMENT

Lansing’s approach to wet weather is a defining feature. Flows exceeding the secondary capacity (typically >40 MGD) can be diverted to:

• Retention Basins: A massive 20-million-gallon retention basin system allows the plant to store peak surges. This water is held and returned to the head of the plant for full treatment once flows subside.
• Flow Equalization: This prevents hydraulic washout of the biological mass in the secondary system during storm events.

E. DISINFECTION

Prior to 2007, the plant used chlorination. It has since upgraded to high-intensity Ultraviolet (UV) disinfection.

• Technology: The UV system alters the DNA of pathogenic bacteria (E. coli), rendering them unable to reproduce.
• Operation: The UV system operates seasonally (typically May 1 to October 31) as mandated by Michigan water quality standards for recreational water bodies, though year-round disinfection requirements are becoming more common in the industry.

F. SOLIDS HANDLING

The Lansing WWTP functions as a resource recovery facility through its solids processing.

• Thickening: Primary sludge and WAS are thickened (using gravity belt thickeners or gravity thickening) to reduce water content before digestion.
• Anaerobic Digestion: Thickened sludge is stabilized in anaerobic digesters heated to mesophilic temperatures (~98°F). This process reduces volatile solids by 40-50% and produces methane-rich biogas.
• Dewatering: Digested biosolids are dewatered using high-solids centrifuges or belt filter presses to produce a “cake” material.
• Disposal: The resulting Class B biosolids are typically hauled for land application on agricultural fields as a soil amendment, returning nutrients to the earth.

4. INFRASTRUCTURE & FACILITIES

A. Physical Plant

The site spans several acres along the riverfront. The architecture reflects multiple eras of expansion, from the original 1930s structures to modern concrete tankage. The site includes a dedicated administration building, a fully equipped laboratory for process control and compliance testing, and extensive maintenance workshops.

B. Energy Systems & Biogas

The Lansing WWTP is a significant energy user, but also an energy producer. The facility utilizes Cogeneration (Combined Heat and Power – CHP). Methane gas produced in the anaerobic digesters is captured and scrubbed. It is then used to fuel engine generators that produce electricity to power plant operations. The waste heat from these engines is captured via heat exchangers to maintain the temperature of the digesters and heat buildings during Michigan winters. This circular energy loop significantly reduces the plant’s reliance on the grid and lowers its carbon footprint.

C. Odor Control

Given the plant’s proximity to residential areas and the river trail, odor control is paramount. The headworks and primary sludge handling areas—typically the primary sources of odors—are enclosed. Foul air is extracted and treated through chemical scrubbers or biofilters before release to the atmosphere.

5. RECENT UPGRADES & MAJOR PROJECTS

CSO Control Program Completion (1990s – 2023)

Total Investment: >$370 Million
The most significant infrastructure project in the plant’s history is the completion of the Combined Sewer Overflow (CSO) Control Program. While largely a collection system project, its impact on the plant is fundamental.

• Scope: Separation of stormwater and sanitary sewers across the city. Construction of the retention basins at the WWTP site.
• Outcome: Lansing became one of the first major cities in Michigan to effectively eliminate raw sewage overflows into its river. This project ensures that all wet weather flows entering the system receive at least primary treatment and disinfection, or are stored for full secondary treatment.

Digester & Solids Handling Improvements

Project Scope: Rehabilitation of digester covers, mixing systems, and heat exchangers.
Drivers: Aging infrastructure and the need to maximize biogas production for energy recovery.
Results: Improved volatile solids reduction and increased gas production for the cogeneration system.

Future/Ongoing: Tertiary Filtration Study

With EGLE potentially tightening phosphorus limits for the Grand River watershed, the City monitors technologies for tertiary filtration (such as disc filters or cloth media) to polish effluent further, although current biological removal remains effective.

6. REGULATORY COMPLIANCE & ENVIRONMENTAL PERFORMANCE

A. Permit Requirements

The facility operates under NPDES Permit No. MI0023591. Key parameters include:

• CBOD5: Monthly average limits typically < 25 mg/L.
• TSS: Monthly average limits typically < 30 mg/L.
• Phosphorus: Strict 1.0 mg/L monthly average (often lower in practice to minimize algal blooms).
• Ammonia: Seasonal limits to prevent toxicity to aquatic life.
• E. Coli: < 130 counts/100ml (30-day geometric mean) during disinfection season.

B. Environmental Stewardship

The plant participates in the Industrial Pretreatment Program (IPP). This program monitors and permits industrial users (like metal finishers or manufacturers) to ensure they do not discharge toxins that could upset the biological treatment process or pass through to the river. Lansing has been proactive in monitoring for PFAS (Per- and Polyfluoroalkyl Substances), working with the state to identify upstream sources and reduce influent concentrations.

7. OPERATIONAL EXCELLENCE

A. Staffing

The plant is staffed 24/7/365. It requires highly skilled professionals, including:

• Operations: State of Michigan certified operators (Class A, B, C, D).
• Maintenance: Millwrights, electricians, and instrumentation technicians.
• Laboratory: Chemists and lab technicians conducting daily process control and permit reporting analysis.

B. Technology

The plant utilizes a SCADA (Supervisory Control and Data Acquisition) system for real-time monitoring. This allows operators to visualize tank levels, dissolved oxygen concentrations, and pump status from a central control room, enabling rapid response to flow changes during storm events.

8. CHALLENGES & FUTURE PLANNING

• Aging Infrastructure: Like many Midwest utilities, Lansing must balance operational costs with the capital need to replace concrete and mechanical assets dating back 40-50 years.
• Workforce Development: As senior operators retire, recruiting certified wastewater professionals remains a priority challenge.
• Emerging Contaminants: Regulations regarding PFAS and microplastics are evolving. The plant is positioning itself to adapt to future discharge limits that may require advanced treatment technologies like Granular Activated Carbon (GAC) or membrane filtration.
• Climate Resilience: Increasing intensity of rainfall events in the Great Lakes region places higher stress on the wet-weather retention systems, necessitating constant evaluation of hydraulic capacity.

10. TECHNICAL SPECIFICATIONS SUMMARY

12. FREQUENTLY ASKED QUESTIONS

Technical Questions

1. What is the peak capacity of the Lansing WWTP?
While the secondary biological treatment capacity is rated for 40 MGD, the plant can manage hydraulic peaks up to 165 MGD by utilizing its 20-million-gallon retention basin system and primary treatment bypass strategies for wet weather flows.

2. Does the Lansing plant generate its own power?
Yes. The plant utilizes anaerobic digestion to produce methane gas (biogas), which fuels engine generators to produce electricity and heat for plant operations.

3. How does the plant handle Combined Sewer Overflows (CSO)?
Lansing has separated the vast majority of its sewers. Any remaining combined flow is directed to the plant where it is captured in retention basins. The City recently completed a 30-year CSO Control Program ensuring no untreated sewage enters the river.

4. What disinfection method is used?
The plant uses Ultraviolet (UV) disinfection, which eliminates the safety hazards associated with storing chlorine gas and prevents the formation of chlorinated disinfection byproducts in the effluent.

Public Interest Questions

5. Where does the water go after treatment?
The treated, clean water (effluent) is discharged into the Grand River. The quality of this water often exceeds the quality of the river water itself.

6. Does the plant smell?
While wastewater treatment naturally produces odors, the Lansing WWTP utilizes enclosed structures and air scrubbers to treat foul air before it leaves the buildings, minimizing impact on the surrounding neighborhood.

7. How is biosolids waste handled?
After treatment and dewatering, the leftover solids (biosolids) are typically transported to agricultural land where they are applied as a nutrient-rich fertilizer, subject to strict EPA and state regulations.