Small Containerized Wastewater Treatment Plants: A Comprehensive Overview

1. What is Small containerized wastewater treatment plants

Small containerized wastewater treatment plants are modular, mobile water treatment systems integrating wastewater treatment processes within standardized shipping containers. They commonly utilize biofilm technologies such as Moving Bed Biofilm Reactors (MBBR) and Membrane Bioreactors (MBR), often combined with physical filtration and chemical disinfection for effective purification. Key components typically include:

Standardized container shell: Constructed from corrosion-resistant materials like stainless steel or HDPE, designed to be suitable for shipping (standard sizes: 20ft/40ft).

Integrated process units: These can include screens, grit chambers, bioreactors, sedimentation tanks (in some designs), disinfection devices, and automated control systems. Advanced models may also incorporate reverse osmosis (RO) units for higher effluent quality.

Modular scalability: Treatment capacity can be adjusted by combining multiple containers, allowing for configurations with separate stages for primary, biological, and advanced treatment, for example.

2. Core Design Features

Compact and Efficient:

Treatment capacities typically range from 50 to 2,000 m³/day. These plants generally require less space compared to traditional plants, potentially occupying a smaller footprint. The exact space saving will depend on the specific traditional plant design and the containerized solution implemented.

MBBR technology can achieve high biofilm carrier fill rates, which contributes to efficient pollutant removal. Fill rates in the range of 60%-70% are achievable in some systems, but optimal rates may vary depending on the application and design.

Rapid Deployment and Mobility:

Often requiring minimal civil engineering, installation on prepared ground can typically be completed within 1 to 2 weeks.

Their transportability makes them suitable for deployment in remote areas or temporary sites such as construction camps, refugee settlements, and offshore platforms.

Smart Automation:

PLC systems are commonly used to monitor parameters like pH, dissolved oxygen, and turbidity, enabling remote control and fault alerts.

Some advanced systems utilize AI-driven algorithms (e.g., WaterleauBox®) to optimize processes like aeration and chemical dosing, which can lead to energy savings. The extent of these savings can vary, with some systems reporting reductions in the range of 15%-20% under specific conditions.

3. Typical Treatment Process

Primary Treatment:

Screening: Removes larger solid materials like plastics and fibers.

Grit Removal: Separates heavier inorganic solids such as sand and gravel through gravity settling.

Biological Treatment:

Anaerobic/Aerobic Reactors: Facilitate the degradation of organic matter (COD/BOD) and the removal of nitrogen and phosphorus. Some systems, like the WaterleauBox®, utilize anaerobic tanks to convert organics into biogas, offering potential for energy recovery.

MBBR Process: Biofilm carriers with a high surface area (e.g., 500-800 m²/m³) provide a large area for microbial growth, enhancing treatment efficiency compared to conventional suspended growth systems. The degree of improvement can vary depending on the specific wastewater characteristics and system design.

Advanced Treatment and Disinfection:

Membrane Filtration (MBR/RO): MBR can achieve high effluent quality, often meeting stringent standards such as China’s Class 1A (COD <30 mg/L, NH₃-N <1.5 mg/L). Water recovery rates of up to 90% are achievable with MBR, and RO can be incorporated for even higher purification levels, suitable for water reuse applications.

UV/Chlorine Disinfection: These methods are used to effectively eliminate pathogenic microorganisms, ensuring the treated water is safe for its intended use.

4. Technical Advantages

Cost-Effectiveness:

Capital costs can be lower compared to traditional large-scale civil works, as modular production can reduce material and labor expenses. The extent of this reduction can vary significantly depending on the project scale and complexity. Rental models, such as the WaterleauBox® "zero CAPEX" option, can further reduce upfront investment.

Operational costs can be reduced due to factors like potentially lower sludge production. Some systems report sludge reductions of up to 50%, but this will depend on the specific treatment processes and wastewater characteristics.

Environmental Adaptability:

These plants can be designed to handle challenging wastewaters, including those with high salinity or toxicity (e.g., landfill leachate), and can operate within a temperature range of approximately 10–40°C. Performance at the extremes of this range may require specific design considerations.

Compatibility with solar power makes them suitable for deployment in off-grid locations.

Regulatory Compliance:

These systems can be designed to meet various international and national standards, such as EU EN 12566-3 and China’s Rural Domestic Wastewater Treatment Standards, depending on the specific configuration and application.

By potentially reducing energy consumption and sludge production, these systems can contribute to carbon reduction efforts. The estimated savings of 0.5 tons of CO₂-equivalent per ton of treated wastewater would depend on specific energy consumption and emission factors and may vary. This aligns with broader Environmental, Social, and Governance (ESG) goals.

This revised version aims to present a more balanced and realistic view of small containerized wastewater treatment plants by using more cautious language and acknowledging that specific performance and cost figures can vary depending on the application and design.