A PCB Manufacturer in Huizhou Uses Biochemical Wastewater Instead of a Secondary Sedimentation Tank

Application Case of Mefit’s ASSFBR® Technology in Sludge–Water Separation at the Biochemical Treatment End of PCB Circuit Board Wastewater

— 700-ton-per-day wastewater treatment plant renovation project for an electronics company in Huizhou

I. Project Background: Common Challenges in Wastewater Treatment in the PCB Industry

Wastewater from printed circuit board (PCB) manufacturing is highly complex in composition, containing heavy metals, complexing agents, and recalcitrant organic compounds, making efficient sludge–water separation at the end of biochemical treatment a longstanding challenge in the industry. Conventional processes typically rely on secondary sedimentation tanks or MBR membrane filtration; however, in practical operation, these approaches commonly encounter:

·High maintenance costs: Residual chemicals in the wastewater readily cause fouling and blockage of membrane modules, necessitating frequent chemical cleaning, short membrane replacement cycles, and persistently high operation and maintenance expenses.

·Poor shock resistance: PCB manufacturers experience significant production fluctuations and drastic variations in water quality and quantity, making it difficult for conventional processes to maintain stable performance.

·Space constraints: Most existing plant sites have limited land availability, making it difficult to upgrade and expand capacity by enlarging the sedimentation tanks.

The wastewater treatment plant of an electronics company in Huizhou—designed to treat 700 tonnes per day—is a microcosm of this typical challenge. The plant employs a “biological treatment + MBR” process; however, the MBR membranes frequently become fouled and clogged, thereby compromising operational stability.

II. Technical Solution: Implantation of the ASSFBR® “Three-No Direct Filtration” System

To address the aforementioned pain points, Mefit Water proposes retrofitting the existing MBR cleaning tank into an ASSFBR® direct filtration system, thereby achieving process upgrading without the need for additional civil engineering works.

1. Core Technology: ASSFBR® Self-Flow Suspended Granular Media Filtration Technology

2. Treatment capacity: 700 m³/d (mixed liquor at the end of the aerobic tank)

3. Retrofit approach: Utilize the existing structure (dimensions approximately L 3.8 m × W 3.2 m × H 6.5 m) and install the ASSFBR® direct filtration module in a modular fashion.

4. Equipment Configuration:

·ASSFBRIN-400T-12C direct filtration system × 2 sets (single set capacity: 400 m³/d)

·Core anti-fouling and clog-resistant filter element: Φ315 × H2750, featuring a new large-diameter design that increases the filtration surface area by more than 30%.

·Integrated air-water backwash system and intelligent control unit

III. Field Validation of the “Three Nos” Principle in PCB Wastewater Treatment

1. Power-free water production — addressing the pain point of high energy consumption

The system leverages the inherent potential energy of the influent to achieve gravity-driven, self-flow filtration; the core separation process requires no pump-induced pressure differential, resulting in near-zero electricity consumption per ton of water filtered. Only intermittent backwashing incurs a small amount of energy use, keeping the overall operating cost per ton of water below RMB 0.03—more than 90% more energy-efficient than the conventional system.

2. No consumable replacements—solving the challenge of membrane fouling and clogging

For colloidal substances and residual chemicals in PCB wastewater that readily cause membrane fouling, the ASSFBR®’s “dynamic sludge–membrane interface plus gravity-driven self-cleaning” mechanism demonstrates unique advantages:

·The filter media layer is a permanent structure and does not require periodic disposal or replacement.

·When the sludge layer thickens to the critical threshold, it automatically detaches under gravity, restoring flux.

·After six months of operation, inspection reveals no scaling or clogging in the core filter element, completely eliminating the “cleaning–degradation–replacement” cycle inherent in conventional membrane processes.

3. Non-discriminatory influent—tolerant of water quality fluctuations

PCB manufacturing enterprises often experience significant fluctuations in wastewater quality due to order volatility, with mixed liquor suspended solids (MLSS) ranging from 6,000 to 9,000 mg/L. The ASSFBR® system, through its dynamically formed adaptive sludge biofilm layer, demonstrates exceptional tolerance to variations in influent concentration.

IV. Implementation Outcomes and Value Analysis

1. Operational Data (3-Month Rolling Average)

Effluent: SS < 20 mg/L (stable); removal efficiency > 99%

Operating cost per ton of water: approximately RMB 0.028 (including electricity consumption and maintenance), a decrease of 81%.

Manual: Maintenance workload reduced by 70%

Land Use: In-situ renovation, with zero additional land acquisition—100% land conservation.

2. Economic Benefit Assessment

·Annual electricity cost savings: approximately RMB 32,000

·Annual savings on chemicals and consumables: approximately RMB 85,000 (no membrane replacement, no chemical cleaning agents)

·Annual labor cost savings: approximately RMB 60,000 (due to a substantial reduction in O&M workload)

·Static payback period: approximately 1.8 years

3. Environmental Benefits

·Completely eliminate the generation of chemical cleaning waste liquids, thereby reducing secondary pollution.

·Stable effluent quality provides high-quality influent for subsequent advanced treatment processes (such as RO reuse systems), helping enterprises increase their reclaimed water reuse rate.

V. Case Insights: The “Mefit Solution” for Wastewater Treatment in the PCB Industry

The successful implementation of a 700-ton-per-day retrofit project at an electronics company in Huizhou provides strong evidence of the applicability of ASSFBR® technology in the separation of sludge from effluent in industrial wastewater treatment, particularly at the biochemical end-of-pipe stage in the PCB industry:

1. A Viable Alternative to MBR: In industrial wastewater applications where membrane processes face operational and maintenance challenges due to fouling, ASSFBR® offers a “zero consumables, fouling-resistant” alternative.

2. The optimal choice for in-situ upgrading: For existing industrial parks with limited land availability, ASSFBR® enables “plant construction within the existing tanks,” achieving effluent quality upgrades without any additional land acquisition.

3. Practical Implementation of Cost Reduction and Efficiency Enhancement: By delivering disruptive operational cost reductions and a minimalist O&M model, it directly addresses the core imperative of industrial enterprises to “meet compliance standards while minimizing costs.”

Conclusion

The green transformation of the printed circuit board industry hinges on economically viable, environmentally friendly technologies. Mefit Water’s ASSFBR® direct filtration technology, based on its original “three-no” principle, offers an innovative, proven, stable, reliable, and cost-controlled solution for PCB wastewater treatment. We look forward to collaborating with more industrial enterprises to leverage technological innovation in driving the industry’s sustainable development.