MBR Design Checklist – Design Tools

Phase 1: Feasibility & Preliminary Assessment

Wastewater Characterization

Analyze influent BOD, COD, TSS, nitrogen, phosphorus, and other relevant parameters. Assess seasonal variations and peak flows.

Effluent Quality Requirements

Define discharge standards or reuse criteria. Determine required removal efficiencies for BOD, TSS, nitrogen, and phosphorus.

Site Assessment

Evaluate available space, utilities (water, power, gas), soil conditions, climate, and access for equipment installation and maintenance.

Regulatory Compliance Review

Verify local discharge limits, building codes, environmental regulations, and any special requirements for the project location.

Cost-Benefit Analysis

Estimate capital and operational costs. Compare MBR with alternative treatment technologies. Evaluate payback period and lifecycle costs.

Phase 2: System Configuration & Design Parameters

Select MBR Configuration

Decide between submerged (immersed) or external (side-stream) MBR based on flow rate, space constraints, and fouling characteristics.

Determine Design Flux

Select target flux (typically 15–30 L/m²·h for UF). Consider membrane material, fouling propensity, and operational flexibility.

Set Sludge Retention Time (SRT)

Define SRT based on treatment objectives (typically 10–20 days). Longer SRT improves nitrification but increases tank volume.

Define Hydraulic Retention Time (HRT)

Calculate HRT (typically 6–12 hours) based on wastewater characteristics and biological treatment requirements.

Establish MLSS Concentration

Set target MLSS (typically 8,000–12,000 mg/L). Higher MLSS improves treatment efficiency but increases fouling risk.

Select Membrane Type & Material

Choose between microfiltration (MF) and ultrafiltration (UF); polymeric (PVDF, PES) or ceramic. Consider cost, fouling resistance, and lifespan.

Phase 3: Detailed Engineering & Sizing

Calculate Bioreactor Volume

Use HRT and peak flow to determine bioreactor volume. Use the Sizing Calculator for assistance.

Calculate Membrane Area

Determine required membrane area based on peak flow and target flux. Include safety margin (typically 10–20%).

Size Aeration System

Calculate air requirements for biological treatment and membrane scouring. Specify blower capacity and air distribution system.

Design Pumping System

Size permeate pump, return sludge pump, and waste sludge pump. Account for head loss and system redundancy.

Plan Cleaning Strategy

Define physical cleaning (backflush, relaxation, air scouring) and chemical cleaning (frequency, chemicals, procedures).

Create Process Flow Diagram (P&ID)

Develop detailed P&ID showing all equipment, piping, instrumentation, and control points. Reference Flow Diagram Templates.

Phase 4: Equipment Specification & Procurement

Select Membrane Modules

Specify membrane supplier, model, configuration (hollow fiber, flat sheet, tubular), and quantity. Use Membrane Database for comparison.

Specify Blower & Aeration Equipment

Select blower type (centrifugal, rotary), capacity, and control system. Specify diffusers and air distribution piping.

Specify Pumps & Motors

Select permeate, return sludge, and waste sludge pumps with appropriate capacity and head. Include variable frequency drives (VFD) for energy efficiency.

Design Control & Instrumentation

Specify sensors (pressure, flow, level, temperature), control logic, SCADA system, and alarms for safe and efficient operation.

Plan Sludge Handling & Disposal

Design excess sludge handling system (thickening, dewatering, disposal). Estimate sludge production and disposal costs.

Phase 5: Construction & Installation

Prepare Construction Site

Clear site, prepare foundation, install utilities (water, power, drainage). Ensure compliance with safety and environmental regulations.

Install Bioreactor Tank

Install or construct bioreactor vessel. Verify structural integrity, waterproofing, and safety features.

Install Membrane Modules

Install membrane modules according to manufacturer specifications. Verify proper seating, connections, and support.

Install Mechanical Equipment

Install blowers, pumps, motors, and piping. Perform pressure tests and leak checks. Verify alignment and vibration isolation.

Install Instrumentation & Controls

Install sensors, transmitters, control panels, and SCADA system. Perform calibration and functional testing.

Phase 6: Commissioning & Startup

Pre-Startup Safety Review

Conduct comprehensive safety inspection. Verify all equipment is properly installed and functioning. Review emergency procedures.

Fill & Flush System

Fill bioreactor with water. Flush all piping and membrane modules to remove air and debris.

Seed Bioreactor with Microorganisms

Inoculate with activated sludge from an existing plant or use acclimation period. Monitor MLSS buildup and biological activity.

Gradual Flow Ramp-Up

Gradually increase influent flow over several days/weeks. Monitor system response and adjust operational parameters.

Optimize Operational Parameters

Fine-tune aeration, flux, sludge wasting, and cleaning cycles. Monitor TMP, effluent quality, and energy consumption.

Operator Training & Documentation

Train operators on system operation, maintenance, troubleshooting, and emergency procedures. Provide comprehensive manuals and documentation.