2026-10-29
A major photovoltaic (PV) manufacturing hub with a total planned capacity of 10GW operates an integrated recirculated water system handling 1,700 m³/h across wafer texturing, high-purity water preparation, and precision cleaning processes. PV wafer processing demands stringent water clarity: suspended silicon powder, colloidal particles, and mineral precipitate carryovers severely foul downstream Reverse Osmosis (RO) membranes. This deterioration reduces ultrapure water quality, damages wafer etching and texturing performance, and depresses solar cell production yield.
The plant’s original pretreatment section relied on conventional single-layer quartz sand filters. Over three years of rapid production expansion, these legacy units exhibited severe capacity bottlenecks, lack of gradient filtration, and outdated manual controls—failing to support the site's expanded water recycling demands. Furthermore, with strict regional water reclamation regulations, the plant struggled with low recycling rates, facing urgent pressure to upgrade to an automated, multi-layer deep filtration system to protect RO membranes, increase water reuse, and lower operational overhead.
Frequent Down-time & RO Membrane Damage: Single-layer sand media allowed fine silicon dust and colloidal particulates to bleed through into the RO feed. Downstream RO membranes required full chemical cleaning every 28 days, forcing an 8-hour system shutdown per cycle. This halted wafer texturing lines, stranded large batches of work-in-progress, caused severe output loss, and significantly shortened RO membrane service life.
Lack of Individual Backwashing: Legacy sand filters could not backwash individually; all tanks had to shut down simultaneously. During backwashing, raw water bypassed protection, causing turbidity spikes that continuously eroded downstream precision equipment.
High Maintenance & Low Water Reclamation: System operation required two dedicated maintenance technicians to manually replenish and replace sand media inside filter vessels. Backwashing lacked intelligent control, wasting vast amounts of water and holding the plant’s water reuse rate at just 62%—well below the mandated 75% regional benchmark, resulting in heavy water consumption surcharges.
LEFILTER’s engineering team conducted on-site surveys of piping layout, water quality profiles, and civil conditions. To handle the 1,700 m³/h flow rate, LEFILTER supplied four LF-DM Series Multi-Media Filters in a parallel arrangement for direct, on-site replacement without modifying civil foundations or major piping structures.
3-Stage Gradient Media Structure: Heavy-duty carbon steel vessels with internal/external epoxy corrosion-resistant coatings withstand weak acidic/alkaline wash water. Inside, a triple-layer gradient bed—anthracite coal, refined quartz sand, and garnet—progressively intercepts coarse silicon dust, colloidal particles, and metal precipitates. This design maintains outlet turbidity below 3 NTU and SDI under 3, easily meeting RO feed requirements.
Non-Stop Air-Water Joint Backwashing: Equipped with differential pressure transmitters, the system automatically triggers backwash per vessel when head loss reaches 0.12 MPa. While one vessel undergoes a 35-second air-water joint backwash, the remaining three units continue full-capacity filtration, ensuring uninterrupted supply to wafer processing lines.
Smart PLC & DCS Integration: Features an independent PLC control cabinet with a standard Modbus interface for seamless integration into the plant’s central DCS. Operators can monitor differential pressure, backwash frequency, and real-time turbidity remotely, while receiving instant acoustic/optical alarms for any abnormal conditions.
Rapid Delivery: Leveraging standardized, large-scale manufacturing capacity, LEFILTER completed design verification, media filling, pressure testing, and factory dispatch in just 8 days, perfectly matching the client’s scheduled shutdown window.
Operating continuously for over 12 months, the LF-DM multi-media filtration system has delivered outstanding performance across all metrics:
Superior Particulate Capture & Membrane Life Extension: Achieved a 93% interception rate for silicon dust and colloidal solids. Downstream RO membrane chemical cleaning cycles were extended from 28 days to 90 days, eliminating multiple line shutdowns and preventing substantial output losses.
Automated Maintenance & Reduced Labor: Automated, vessel-by-vessel backwashing eliminated manual media handling inside vessels. Dedicated site labor was reduced by 50%, saving significant annual maintenance and media replacement costs.
Significant Water Savings: Smart pressure-differential backwashing reduced flush-water consumption by 62%. The plant’s water recycling rate increased from 62% to 78%, saving over 81,000 tons of purified water annually, complying with environmental targets, and eliminating excess water usage surcharges.
Yield Improvement: Stable process water quality led to a marked drop in wafer surface defects, boosting overall PV cell manufacturing yield by 2.8%.
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