What is a Package Wastewater Treatment Plant?

Introduction

A package wastewater treatment plant (package WWTP) is a pre-engineered, factory-assembled treatment system designed to provide complete biological wastewater treatment in a self-contained unit. Unlike conventional treatment plants — which are designed and built from scratch with concrete tanks, steel structures, and site-specific equipment — package plants arrive at the site largely pre-built, substantially reducing installation time and cost.

Package plants range from systems treating a few hundred gallons per day for a remote lodge or campground, to large modular systems treating 1-5 MGD for small municipalities. They're the right answer when you need a treatment plant quickly, affordably, and without a large engineering budget.

How Package Plants Work

Most package wastewater treatment plants use extended aeration activated sludge — the same biological process as a full-size plant, just engineered into a compact footprint.

Typical process train:

1. Influent screening/bar screen — removes rags, solids, debris
2. Aeration basin — extended aeration; SRT 15-30 days for nitrification
3. Secondary clarifier — separates mixed liquor; returns sludge
4. Effluent disinfection — UV or chlorination
5. Sludge management — sludge holding/aeration; pumping to hauler or digester

The entire process is integrated into stainless steel tanks, fiberglass vessels, or packaged in a modular trailer/container configuration. All pumps, blowers, controls, and piping are pre-installed and factory-tested.

Plug-and-play installation: Gravity wastewater in one end, treated effluent out the other. Connect power, influent, and effluent — commission and start.

Types of Package Treatment Plants

Extended Aeration Package Plants

The most common type. Uses simple activated sludge with long SRT for reliable nitrification. Smith & Loveless and Norweco are major manufacturers.

Sequencing Batch Reactor (SBR) Package Plants

Single basin serves as both aeration and clarification in a fill-and-draw cycle. Very compact. Aqua-Aerobic Systems, Fluidyne, and Premier Tech Aqua offer SBR package systems.

Membrane Bioreactor (MBR) Package Plants

Submerged ultrafiltration membranes replace the secondary clarifier. Produces very high quality effluent (suitable for reuse). Higher capital and O&M cost than conventional package plants. Kubota and Veolia offer MBR packages; Kovalus (formerly Koch) supplies the membranes.

Trickling Filter Package Plants

Plastic media tower with recirculation. Robust, tolerant of flow variability. Several manufacturers offer packaged trickling filter systems (RWL Water's package treatment assets were acquired by Fluence).

Lagoon + MBBR Package Upgrades

For communities with existing lagoons needing nitrification, MBBR carrier media packs installed in existing lagoon cells provide a package solution.

Package Plant Applications

Best suited for:

• Small communities, subdivisions, and planned unit developments (< 0.5 MGD)
• Resort communities, campgrounds, parks (seasonal loading)
• Industrial facilities needing on-site pretreatment
• Emergency/temporary treatment while a permanent plant is constructed
• Rural areas where centralized sewer is not feasible
• International and disaster relief applications

Less suitable for:

• Very tight nutrient limits (< 3 mg/L TN, < 0.1 mg/L TP) without additional upgrades
• Flows > 5 MGD where site-built is more cost-effective
• Communities with high inflow/infiltration (I/I) causing wet-weather peaks

Regulatory Considerations

Package plants require the same NPDES discharge permit as any other wastewater treatment system. State regulatory agencies vary in their willingness to approve package plants for specific applications:

• Some states have approved technology lists — verify your system is on the list
• Extended aeration with nitrification is generally well-accepted
• MBR package plants are increasingly accepted for reuse applications
• Some states require individual system approval (pilot testing, performance data)
• General permits for small package systems exist in some states

Important: Even a "package" plant requires a licensed professional engineer to design the site infrastructure, connections, and site-specific modifications. The manufacturer provides the treatment equipment; the PE designs the system.

Package Plant vs. Conventional Plant: When to Choose Each

Package Plant Costs

Rule-of-thumb capital costs (2024 pricing):

• 0.1 MGD extended aeration: $500K - $1.5M installed
• 0.5 MGD extended aeration: $1M - $3M installed
• 1.0 MGD package plant: $2M - $5M installed

Costs vary significantly by:

• Site conditions and land costs
• Permit requirements (influent screening, UV/chlorination, nutrient limits)
• Sludge handling/disposal approach
• Geographic location and contractor market

Leading Package Plant Manufacturers

• Aero-Mod, Inc. (an Axius Water company) — SEQUOX/SEQUOX+ packaged BNR plants with ClarAtor clarification; extended aeration and activated sludge packages
• Fluidyne — ISAM integrated package treatment and SBR systems
• Smith & Loveless — OXIGEST and FAST extended aeration systems; one of the oldest and largest package plant manufacturers
• Norweco — widely used for small systems; Singulair residential and small community systems
• Anua International — trickling filter and extended aeration packages
• Premier Tech Aqua — BioFiltro packages and decentralized treatment; note its Rewatec SBR line was discontinued in North America (effective January 2023)
• BioMicrobics — small/residential and cluster systems
• Jet Inc. — extended aeration packages for small communities