City Of Kalamazoo Water Reclamation Plant

1. INTRODUCTION

The Kalamazoo Water Reclamation Plant (KWRP) is a cornerstone of environmental infrastructure in Southwest Michigan, serving as a regional hub for wastewater treatment. Unlike typical municipal facilities that handle predominantly domestic sewage, KWRP is distinguished by its unique influent profile, which includes a substantial industrial loading from the pharmaceutical (Pfizer) and paper manufacturing sectors. Operated by the City of Kalamazoo, this 53.3-MGD design capacity facility functions as a specialized utility, employing advanced High-Purity Oxygen (HPO) activated sludge processes to manage high biological oxygen demand (BOD) loads.

Situated on the banks of the Kalamazoo River, the plant has evolved from a primary treatment facility commissioned in the 1950s to a sophisticated tertiary treatment complex. It plays a critical role in the remediation and protection of the Kalamazoo River watershed. Today, the facility is aggressive in its modernization efforts, balancing the maintenance of legacy infrastructure with the integration of modern SCADA automation, energy-efficient solids handling, and stringent nutrient removal strategies required by the Michigan Department of Environment, Great Lakes, and Energy (EGLE).

2. FACILITY OVERVIEW

A. Service Area & Coverage

The KWRP operates as a regional authority, accepting wastewater from a sprawling collection system that extends well beyond the city limits. The “Kalamazoo Regional Water and Wastewater System” includes 1,200 miles of collection piping and over 60 lift stations. The service area encompasses:

• Primary Municipality: City of Kalamazoo
• Customer Communities: 18 surrounding jurisdictions, including the City of Portage, Comstock Township, Cooper Township, Oshtemo Township, Texas Township, and the Village of Richland.
• Demographics: The facility serves a population exceeding 200,000. Uniquely, industrial users contribute a significant percentage of the organic loading, necessitating a robust Industrial Pretreatment Program (IPP).

B. Operational Capacity

The plant is designed to handle substantial hydraulic and organic loads:

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• Design Average Flow: 53.3 Million Gallons per Day (MGD)
• Peak Hydraulic Capacity: Approximately 90 MGD
• Current Average Daily Flow: Fluctuates between 25 and 30 MGD.
• Capacity Utilization: While hydraulic utilization is roughly 50-60%, the organic loading capacity is often utilized at higher rates due to high-strength industrial waste streams.

C. Discharge & Compliance

Treated effluent is discharged into the Kalamazoo River. The facility operates under a National Pollutant Discharge Elimination System (NPDES) permit issued by Michigan EGLE. The Kalamazoo River is a sensitive receiving water body with strict Total Maximum Daily Load (TMDL) requirements, particularly regarding phosphorus, to prevent eutrophication and algal blooms downstream. The plant consistently achieves high compliance rates, often discharging effluent significantly cleaner than permit limits require.

3. TREATMENT PROCESS

The KWRP utilizes a complex treatment train capable of handling high-strength industrial waste. The process flow is categorized into Preliminary, Primary, Secondary (High-Purity Oxygen), and Tertiary treatment.

A. PRELIMINARY TREATMENT

Raw wastewater enters the facility via large interceptors. The headworks aims to protect downstream equipment:

• Screening: Automated mechanically cleaned bar screens remove large debris (rags, plastics, wood). Screenings are washed, compacted, and sent to a landfill.
• Grit Removal: Following screening, flow enters aerated grit chambers where velocity is reduced, allowing inorganic solids (sand, gravel, coffee grounds) to settle while organic matter remains suspended.
• Flow Measurement: Parshall flumes measure the influent flow rate for pacing chemical dosing and process control.

B. PRIMARY TREATMENT

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The physical separation of settleable solids occurs in rectangular primary clarifiers.

• Clarification: The velocity of the wastewater is slowed in large rectangular tanks. Solids settle to the bottom as primary sludge, while grease and oils float to the surface as scum.
• Chemical Enhancement: Ferric chloride or alum is frequently added at this stage to precipitate phosphorus and enhance the settling of suspended solids. This Chemical Enhanced Primary Treatment (CEPT) is crucial for meeting the river’s strict phosphorus limits.
• Removal Efficiency: Primary treatment typically removes 30-40% of BOD and 50-60% of Total Suspended Solids (TSS).

C. SECONDARY TREATMENT (High-Purity Oxygen)

This is the most distinct technical feature of the KWRP. Unlike conventional aeration basins that use atmospheric air, KWRP utilizes a High-Purity Oxygen (HPO) Activated Sludge system (UNOX type design).

• Cryogenic Oxygen Generation: The plant has on-site cryogenic air separation capabilities to generate pure oxygen.
• Closed Reactors: The aeration basins are covered (closed-tank reactors). Pure oxygen is introduced into the headspace and mechanically mixed into the mixed liquor.
• Why HPO? HPO systems maintain higher Dissolved Oxygen (DO) levels and support a higher biomass concentration (MLSS). This is specifically engineered to treat the high-strength BOD loads from the local pharmaceutical and paper industries, providing a smaller physical footprint and faster reaction rates than conventional air systems.
• Secondary Clarification: Mixed liquor flows to circular secondary clarifiers where the biological floc settles. Clean water flows over the weirs, while settled biomass is either returned (RAS) or wasted (WAS).

D. TERTIARY TREATMENT

To meet stringent NPDES limits for suspended solids and phosphorus:

• Gravity Sand Filtration: Secondary effluent is pumped to rapid gravity sand filters. These filters trap remaining fine suspended solids and particulate phosphorus that escaped secondary clarification.
• Backwashing: Filters are automatically backwashed based on head loss or time, with backwash water returned to the headworks.

E. DISINFECTION

The final step before discharge:

• Chlorination: The filtered water flows through chlorine contact tanks where Sodium Hypochlorite is added to neutralize pathogenic bacteria (E. coli).
• Dechlorination: Before entering the Kalamazoo River, Sodium Bisulfite is added to remove residual chlorine, which is toxic to aquatic life.
• Seasonality: Per Michigan regulations, disinfection is typically required from May 1st through October 31st, though year-round monitoring is maintained.

F. SOLIDS HANDLING

KWRP operates a robust solids processing division, functioning partly as a resource recovery center.

• Thickening: Primary sludge and Waste Activated Sludge (WAS) are thickened using Dissolved Air Flotation (DAF) or gravity belts to reduce volume.
• Dewatering: Thickened sludge is conditioned with polymer and processed through centrifuges or belt filter presses to create a “cake” with higher solids content (typically 20-25%).
• Incineration: The plant utilizes Multiple Hearth Incineration technology to thermally reduce the biosolids volume. This reduces the final disposal mass by over 90%, leaving only inert ash.
• Disposal: The resulting sterile ash is disposed of in landfills.

4. INFRASTRUCTURE & FACILITIES

A. Physical Plant

The site covers extensive acreage along the riverfront. It includes the distinctive cryogenic plant structure (for oxygen generation), the incineration complex with emissions stacks, and an administration building housing the SCADA control center and NELAC-certified laboratory.

B. Odor Control

Given the plant’s proximity to urban areas and the nature of the industrial influent, odor control is a priority. The facility utilizes:

• Chemical Scrubbers: Located at the headworks and sludge processing areas to treat hydrogen sulfide (H2S).
• Biofilters: Employed in specific zones to treat organic odors using biological media.
• Activated Carbon: Polishing units for air exhausted from high-concentration areas.

5. RECENT UPGRADES & MAJOR PROJECTS

The City of Kalamazoo maintains a rolling Capital Improvement Plan (CIP) to address aging infrastructure. Recent and ongoing projects include:

Major Electrical Distribution Upgrade (2019-2023)

• Project Scope: Replacement of the plant’s main electrical substation and distribution gear, much of which dated back to the 1980s.
• Budget: Approx. $15 – $20 Million.
• Funding: Financed largely through State Revolving Fund (SRF) loans.
• Technical Highlights: Installation of redundant power feeds, modern switchgear, and integration with the plant’s SCADA system for improved energy management and reliability.

Secondary Treatment & Aeration Improvements

• Scope: Rehabilitation of the HPO tanks and oxygen generation equipment.
• Drivers: Ensuring the reliability of the pure oxygen system, which is critical for treating industrial loads.
• Outcome: Improved oxygen transfer efficiency and reduced energy consumption for the cryogenic plant.

Biosolids Handling & Incinerator Upgrades

• Scope: Upgrades to the incinerator emissions scrubbers to meet new EPA Sewage Sludge Incineration (SSI) Maximum Achievable Control Technology (MACT) standards.
• Significance: Allows the plant to continue using thermal reduction (incineration) as a disposal method while meeting strict air quality standards.

6. REGULATORY COMPLIANCE

A. NPDES Permit Parameters

The facility operates under strict limits set by Michigan EGLE (Permit MI0023299). Key parameters include:

• CBOD5: Monthly average limits typically < 15 mg/L.
• TSS: Monthly average limits typically < 20 mg/L.
• Phosphorus: 1.0 mg/L (monthly average), with goals often set lower (0.5 mg/L) due to watershed constraints.
• Ammonia Nitrogen: Seasonally variable limits to prevent toxicity.
• E. Coli: Daily maximum and 30-day geometric mean limits during disinfection season.

B. Industrial Pretreatment Program (IPP)

KWRP manages one of Michigan’s most complex IPPs. The plant monitors and regulates discharges from major pharmaceutical manufacturers and paper mills. This includes surcharge programs for high-strength waste (BOD/TSS) and strict local limits for metals and specific organic compounds to prevent pass-through or interference with the biological process.

7. CHALLENGES & FUTURE PLANNING

A. Aging Infrastructure

Like many Midwestern facilities, KWRP faces the challenge of replacing assets installed during the EPA grant boom of the 1970s and 80s. The current Capital Improvement Plan focuses heavily on “state of good repair” projects—replacing pumps, valves, and electrical gear before failure.

B. Emerging Contaminants (PFAS)

Michigan is a frontline state for PFAS regulation. KWRP is actively involved in source tracking to identify and reduce PFOS/PFOA entering the collection system, particularly from industrial plating or landfill leachate sources. The plant utilizes its IPP authority to mitigate these contaminants at the source, as conventional wastewater treatment does not remove PFAS.

C. Workforce Development

As senior operators retire, the facility is focused on knowledge transfer and recruiting Class A licensed operators. The increasing technical complexity of the HPO system and incineration units requires specialized training beyond standard wastewater operations.

8. TECHNICAL SPECIFICATIONS SUMMARY

9. FAQ

Technical/Professional Questions

1. Why does KWRP use High-Purity Oxygen (HPO) instead of conventional aeration?
The HPO system was selected to manage the high industrial organic loading (high BOD) from pharmaceutical and paper industries. Pure oxygen allows for a higher biomass concentration and faster oxygen transfer rates in a smaller tank volume compared to conventional air systems.

2. How does the plant achieve low phosphorus limits?
KWRP uses a dual approach: Chemical precipitation (typically utilizing ferric chloride or alum) in the primary and/or secondary stages, followed by tertiary sand filtration to remove particulate phosphorus.

3. Does the plant generate energy?
While the plant focuses on incineration for volume reduction rather than anaerobic digestion for biogas production, heat recovery systems are often employed within incineration processes to improve thermal efficiency.

4. How are biosolids handled?
Sludge is thickened, dewatered, and then incinerated. The resulting ash is landfilled. This method significantly reduces the volume of material requiring final disposal.

Public Interest Questions

5. What is the “weird smell” sometimes near the plant?
Wastewater treatment naturally generates odors, primarily hydrogen sulfide (rotten egg smell). KWRP has installed extensive odor control scrubbers and carbon filters. However, atmospheric inversions or maintenance on scrubbers can sometimes allow odors to escape briefly.

6. Does the plant treat PFAS?
Conventional wastewater plants do not destroy PFAS. KWRP focuses on the Industrial Pretreatment Program (IPP) to stop PFAS at the source—identifying industrial users contributing PFAS and requiring them to treat it before discharging to the city sewer.

7. Who runs the plant?
The plant is owned and operated by the City of Kalamazoo Department of Public Services, but it functions as a regional utility serving 18 surrounding townships and cities.