限外ろ過膜のファウリング - 原因、影響、対策 (インダストリアルガイド)

This hands-on guide explains 限外ろ過膜のファウリング, how to diagnose it fast, and how to recover performance without risking downstream RO. You’ll find symptom maps, a recovery playbook, a prevention program, printable checklists, and FAQs engineers can act on.

Focus process:
UF dead-end & crossflow trains

You’ll learn:
12 root causes → recovery → prevention

Who is it for:
Plant engineers, O&M teams, integrators

Tip: Your Table of Contents plugin will auto-build from the H2/H3 headings below.

1) Snapshot: symptoms & fast triage

症状	What it usually means	First checks (10–15 min)
Flux decline at same feed	Cake/gel layer growth; temperature drop; instrument drift	Normalize to 25 °C; verify flow & TMP sensors; review last 24 h turbidity/SDI
TMP rise by stage	Colloids, biofilm or scale; backwash/CIP cadence too low	Check backwash logs, air scour function, and chemical inventory/strength
Filtrate quality drift	Integrity loss or channeling	Run integrity/pressure hold test; inspect vents for air binding
Frequent alarms after CIP	Residual chemical release (“sponge effect”)	Rinse and neutralize to spec; confirm zero oxidant before RO

安全第一だ： De-pressurize, lockout/tagout pumps, wear PPE, follow the membrane OEM chemical limits, and verify zero oxidant before sending filtrate to RO.

2) What UF is & where fouling happens

Ultrafiltration separates colloids and microorganisms while allowing salts to pass. In a modern plant the UF stage typically sits before RO/EDI to stabilize SDI/turbidity or after clarification/polishing in food & beverage. Fouling forms on the fiber surface (cake/gel layer), within the pores (pore blocking), or as biofilm when nutrients and warm temperatures align.

3) Ultrafiltration membrane fouling — 12 likely root causes

Water & chemistry

• Low feed temperature → higher viscosity, lower flux at same TMP.
• High SDI/colloids or shock loads from pretreatment upsets.
• Algae/microbial spikes from warm raw water or long residence times.
• Chemical carry-over (coagulants, polymer, oxidants) binding on fibers.

Hydraulics & operations

• Overfeed flow/pressure trying to “chase production.”
• Insufficient crossflow velocity or air scour effectiveness.
• Backwash/CIP intervals too long for the load; skipped soaks.
• Incomplete post-CIP rinsing; pH not neutral when restarting.

Hardware & integrity

• Damaged elements, partial fiber breaks, or poor potting repairs.
• Air binding from bad vents causing localized dryness and scale.
• Instrumentation drift (flow, pressure, turbidity) hiding true TMP/flux.
• Strainers/guards missing or overloaded, letting debris reach modules.

4) Downstream impact (why UF fouling hurts RO & polishing)

• RO stress: SDI creep pushes RO into faster fouling cycles and higher OPEX.
• Chemical shock: retained NaOH/NaOCl can oxidize polyamide if not rinsed to non-detect.
• Quality variability: sporadic fiber leaks cause microbiological risk downstream.

5) Recovery playbook (gentle → aggressive)

Step A — Physical cleaning

• Optimize forward flush and backwash timing; confirm valves and sequences.
• Air scour where supported; verify blower delivery and distribution.
• Reset to OEM-recommended flux (critical flux margin) before chemistry.

Step B — Chemical cleaning (CIP)

• Alkaline clean for organics/biofilm: NaOH with surfactant; optional low-dose NaOCl if OEM allows.
• Acid clean for inorganics/scale: citric or other approved acid with anti-scalant dispersant.
• Method: recirculate 20–40 min → soak 10–30 min → recirculate → thorough rinse to neutral pH & zero oxidant.

Step C — Escalate when TMP isn’t restored

• Repeat targeted chemistry; extend soak; raise temperature within OEM limits.
• Rotate elements or replace modules that no longer recover.

6) Operating mode & design notes: dead-end vs crossflow

Mode	Pros	Watch-outs for fouling
Dead-end	Simpler, lower pumping energy	Higher fouling tendency; needs tighter pretreatment and more frequent backwash/CIP
Crossflow	Surface shear lowers cake buildup; steadier TMP	Higher recirculation energy; design for velocity windows and CFD-informed manifolds

7) Integrity management: dealing with hollow-fiber breaks

If integrity tests fail or filtrate quality drifts, isolate the suspect train, plug identified fibers per OEM practice, then re-test. When the percentage of plugged fibers approaches the OEM limit, plan module replacement to avoid hidden bypass and persistent 限外ろ過膜のファウリング.

8) Monitoring & control checklist

Interval	What to record	Why it matters
Every shift	Feed temp, turbidity/SDI, filtrate quality, feed/retentate/filtrate flows, TMP by stage	Builds a baseline to detect early fouling
毎日	Backwash/air scour success and durations; chemical inventory	Prevents spacing out cleans
ウィークリー	Integrity test, sensor calibration check, vent/strainer inspection	Validates true performance

9) Prevention program (what “good” looks like)

• Keep velocity within design windows; avoid running at maximum TMP for long periods.
• Set alarm bands for TMP rise rate and filtrate turbidity; trigger clean/soak automatically.
• Jar tests each season change; track raw-water biology and switch chemistry accordingly.
• Spare parts: seals, strainers, gauges, oxidant/pH test kits, and at least one spare module per skid.

10) Quick BOM & spares list

• Hollow-fiber UF modules (per OEM code), O-rings/seals, strainers/guard filters
• CIP chemicals: alkaline (NaOH + surfactant), acid (citric or approved), neutralizers
• Oxidant, ORP and pH strips/meters; turbidity & SDI kits; calibration liquids

11) FAQs

What does a rising TMP mean?

It signals resistance at the membrane interface or inside pores. Trend TMP at constant temperature and normalized flux to confirm 限外ろ過膜のファウリング versus instrumentation drift.

How do I pick acid vs. alkaline cleaning?

Start with a short alkaline clean for organics/biofilm. If TMP is still high, follow with an approved acid clean for scale. Always rinse to neutral pH and zero oxidant before sending filtrate to RO.

How often should I clean?

Use trend-based intervals. Many plants backwash every 20–60 minutes and perform a short CIP every 8–24 hours of operation, tightening cadence during high-load seasons.

Can I run oxidant through UF?

Only under OEM-approved concentration, pH and temperature limits. Residual oxidant must be non-detect before permeate is allowed to reach RO to avoid polyamide damage.

12) Next steps (RFQ & helpful links)

Share your feed analysis and demand curve—our team will size velocity windows, backwash/CIP cadence, and recommend hygienic tanks & piping for reliable UF performance.

見積依頼

Internal resources:  UF cleaning & maintenance - RO troubleshooting guide - DI water storage tank & loop design - Stainless-steel tanks & housings

External references:  Water Quality Association - US EPA Water Research

著者 Stark Water Process Engineering Team (process design, O&M, commissioning). Peer-reviewed by: QA/Compliance. Last updated: 20 Oct 2025.

This guide is for trained professionals. Always follow your membrane OEM limits and site safety procedures.