{"id":66424,"date":"2025-11-07T16:04:32","date_gmt":"2025-11-07T08:04:32","guid":{"rendered":"https:\/\/stark-water.com\/?p=66424"},"modified":"2025-11-07T16:04:35","modified_gmt":"2025-11-07T08:04:35","slug":"uf-feed-water-quality-key-parameters","status":"publish","type":"post","link":"https:\/\/stark-water.com\/nl\/blog\/uf-feed-water-quality-key-parameters\/","title":{"rendered":"UF Feed-Water Quality \u2014 Key Parameters Explained (2025 Guide)"},"content":{"rendered":"<p><strong>Last updated:<\/strong>&nbsp;November 7, 2025 \u00b7&nbsp;<strong>Reading time:<\/strong>&nbsp;12\u201315 minutes \u00b7&nbsp;<strong>Audience:<\/strong>&nbsp;UF\/MBR\/RO operators, process engineers, EPCs<\/p>\n\n\n\n<p>Understanding&nbsp;<strong>UF feed-water quality<\/strong>&nbsp;helps you prevent fouling, stabilize flux, and protect downstream RO\/NF. This guide summarizes the parameters that matter\u2014particles\/colloids (turbidity, TSS, SDI), organics (TOC\/DOC, UV254\/SUVA), oils, Fe\/Mn, hardness, conductivity\/TDS, pH, and silica\u2014plus sampling notes, practical cues, and acceptance ranges to tune for your project.<\/p>\n\n\n\n<figure class=\"wp-block-image size-large\"><img fetchpriority=\"high\" decoding=\"async\" width=\"1024\" height=\"640\" src=\"https:\/\/stark-water.com\/wp-content\/uploads\/2025\/11\/UF_feed_water_quality_dashboard-1024x640.png\" alt=\"UF feed-water quality dashboard: NTU, TSS, SDI, TOC\/DOC, UV254\/SUVA, oil, Fe\/Mn, hardness, EC\/TDS, pH, silicaFrom routine tests to a defensible pretreatment plan.\" class=\"wp-image-66435\" title=\"\" srcset=\"https:\/\/stark-water.com\/wp-content\/uploads\/2025\/11\/UF_feed_water_quality_dashboard-1024x640.png 1024w, https:\/\/stark-water.com\/wp-content\/uploads\/2025\/11\/UF_feed_water_quality_dashboard-300x188.png 300w, https:\/\/stark-water.com\/wp-content\/uploads\/2025\/11\/UF_feed_water_quality_dashboard-768x480.png 768w, https:\/\/stark-water.com\/wp-content\/uploads\/2025\/11\/UF_feed_water_quality_dashboard-1536x960.png 1536w, https:\/\/stark-water.com\/wp-content\/uploads\/2025\/11\/UF_feed_water_quality_dashboard-18x12.png 18w, https:\/\/stark-water.com\/wp-content\/uploads\/2025\/11\/UF_feed_water_quality_dashboard-600x375.png 600w, https:\/\/stark-water.com\/wp-content\/uploads\/2025\/11\/UF_feed_water_quality_dashboard.png 1920w\" sizes=\"(max-width: 1024px) 100vw, 1024px\" \/><figcaption class=\"wp-element-caption\">UF feed-water quality dashboard: NTU, TSS, SDI, TOC\/DOC, UV254\/SUVA, oil, Fe\/Mn, hardness, EC\/TDS, pH, silica\nFrom routine tests to a defensible pretreatment plan.<\/figcaption><\/figure>\n\n\n\n<h2 class=\"wp-block-heading\">Why UF Feed-Water Quality Matters<\/h2>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>Fouling control:<\/strong>\u00a0particulate\/colloidal, organic\/biofouling, oil\/grease, metals, and silica can all shorten run length.<\/li>\n\n\n\n<li><strong>Operations:<\/strong>\u00a0clean data lets you set flux, backwash\/CIP frequency, chemical windows, and protect downstream RO\/NF recovery.<\/li>\n\n\n\n<li><strong>Documentatie:<\/strong>\u00a0log units, methods, sampling points, and stabilization times for traceability.<\/li>\n<\/ul>\n\n\n\n<h2 class=\"wp-block-heading\">UF feed-water quality Particles &amp; Colloids \u2014 Turbidity, TSS, SDI<\/h2>\n\n\n\n<h3 class=\"wp-block-heading\">Turbidity (NTU)<\/h3>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Optical measure of suspended\/colloidal matter; quick and continuous.<\/li>\n\n\n\n<li><em>Rule-of-thumb cue:<\/em>\u00a0UF feed\u00a0<strong>\u2264 5 NTU<\/strong>\u00a0for stable operation; many drinking-water sites target \u2264 1 NTU.<\/li>\n<\/ul>\n\n\n\n<h3 class=\"wp-block-heading\">Total Suspended Solids (TSS, mg\/L)<\/h3>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Gravimetric mass of solids retained on a glass-fiber filter (laboratory standard). More specific than turbidity for fine solids.<\/li>\n\n\n\n<li>Use when turbidity is unstable or dominated by color\/fines that distort optics.<\/li>\n<\/ul>\n\n\n\n<h3 class=\"wp-block-heading\">Silt Density Index (SDI)<\/h3>\n\n\n\n<p>Quantifies fouling tendency using a&nbsp;<strong>47 mm \/ 0.45 \u00b5m<\/strong>&nbsp;membrane at&nbsp;<strong>30 psi<\/strong>. Record initial time&nbsp;<em>t<sub>i<\/sub><\/em>&nbsp;to collect 500 mL, then time&nbsp;<em>t<sub>f<\/sub><\/em>&nbsp;at test end; compute SDI for total time&nbsp;<em>T<\/em>&nbsp;(min):<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>SDI = ( 1 \u2212 t_i \/ t_f ) \u00d7 ( 100 \/ T )    \u2190 common practice: T = 15 minutes (SDI\u2081\u2085)\n<\/code><\/pre>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Lower is better; for UF\/RO pretreatment,\u00a0<strong>SDI\u2081\u2085 &lt; 5<\/strong>\u00a0is a typical design cue (project-specific).<\/li>\n\n\n\n<li>Stir\/feed recirculation during the test to avoid settling artifacts; temperature affects viscosity\u2014log it.<\/li>\n<\/ul>\n\n\n\n<h2 class=\"wp-block-heading\">UF feed-water quality Organics &amp; Biofouling Risk \u2014 TOC\/DOC, COD\/BOD, UV254\/SUVA<\/h2>\n\n\n\n<h3 class=\"wp-block-heading\">TOC &amp; DOC (mg\/L)<\/h3>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>TOC<\/strong>\u00a0is total organic carbon (dissolved + particulate);\u00a0<strong>DOC<\/strong>\u00a0is the \u22640.45 \u00b5m fraction.<\/li>\n\n\n\n<li><em>Cue:<\/em>\u00a0UF feed\u00a0<strong>TOC > 2 mg\/L<\/strong>\u00a0flags higher biofouling likelihood\u2014tighten backwash\/CIP or add coagulant\/oxidant control as permitted.<\/li>\n<\/ul>\n\n\n\n<h3 class=\"wp-block-heading\">UV254 &amp; SUVA<\/h3>\n\n\n\n<p>UV absorbance at 254 nm tracks humic\/aromatic organics.&nbsp;<strong>SUVA<\/strong>&nbsp;(specific UV absorbance) characterizes organic type:<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>SUVA (L\u00b7mg\u207b\u00b9\u00b7m\u207b\u00b9) = UV254 (cm\u207b\u00b9) \u00d7 100 \u00f7 DOC (mg\/L)<\/code><\/pre>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>SUVA > 4<\/strong>\u00a0\u2192 humic-rich;\u00a0<strong>SUVA &lt; 2<\/strong>\u00a0\u2192 algal\/low-aromatic organics.<\/li>\n\n\n\n<li><em>Cue:<\/em>\u00a0<strong>UV254 > 0.5 cm\u207b\u00b9<\/strong>\u00a0suggests notable biofouling tendency; plan for enhanced cleaning or upstream coagulation.<\/li>\n<\/ul>\n\n\n\n<h3 class=\"wp-block-heading\">COD \/ BOD<sub>5<\/sub><\/h3>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>COD<\/strong>\u00a0is fast chemical oxygen demand;\u00a0<strong>BOD<sub>5<\/sub><\/strong>\u00a0is 5-day biological oxygen demand.<\/li>\n\n\n\n<li>For UF operations, trend TOC\/DOC + UV254 first; use COD\/BOD to interpret pollution episodes.<\/li>\n<\/ul>\n\n\n\n<h2 class=\"wp-block-heading\">Oils &amp; Hydrocarbons (O&amp;G)<\/h2>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Even trace oil can create persistent fouling on UF fibers\/sheets. Keep below the method detection limit and install oil alarms where relevant.<\/li>\n\n\n\n<li><em>Cue:<\/em>\u00a0aim\u00a0<strong>&lt; 0.05 mg\/L<\/strong>\u00a0(site-specific; verify method).<\/li>\n<\/ul>\n\n\n\n<h2 class=\"wp-block-heading\">Iron &amp; Manganese<\/h2>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Oxidized Fe\/Mn are well retained by UF but deposit as solids; sources include raw well water, corrosion, coagulant residuals.<\/li>\n\n\n\n<li>Control oxidation state upstream; maintain filters\/backwash so particulates don\u2019t overload UF.<\/li>\n<\/ul>\n\n\n\n<h2 class=\"wp-block-heading\">Hardness, Conductivity\/TDS &amp; pH<\/h2>\n\n\n\n<h3 class=\"wp-block-heading\">Hardness (as CaCO<sub>3<\/sub>)<\/h3>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Soft \u2264 60 mg\/L, moderate 60\u2013120, hard 120\u2013180, very hard > 180 mg\/L (design context for downstream scaling control).<\/li>\n<\/ul>\n\n\n\n<h3 class=\"wp-block-heading\">Conductivity \/ TDS<\/h3>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Conductivity (\u00b5S\/cm) correlates with dissolved salts (TDS). Track temperature or convert to 25 \u00b0C.<\/li>\n<\/ul>\n\n\n\n<h3 class=\"wp-block-heading\">pH<\/h3>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Controls corrosion\/scaling chemistry and coagulant performance. Note any seasonal drift; calibrate probes regularly.<\/li>\n<\/ul>\n\n\n\n<h2 class=\"wp-block-heading\">Silica \u2014 Reactive vs Colloidal<\/h2>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>Reactive (dissolved) silica<\/strong>\u00a0passes UF and limits RO recovery;\u00a0<strong>colloidal silica<\/strong>\u00a0is retained but fouls the surface if poorly controlled.<\/li>\n\n\n\n<li>Use filtration (\u22640.45 \u00b5m) to separate dissolved vs colloidal fraction for accurate diagnosis.<\/li>\n<\/ul>\n\n\n\n<h2 class=\"wp-block-heading\">Quick Acceptance Cues (Tune Per Project)<\/h2>\n\n\n\n<figure class=\"wp-block-table\"><table class=\"has-fixed-layout\"><thead><tr><th>Categorie<\/th><th>Parameter<\/th><th>Typical cue<\/th><th>Opmerkingen<\/th><\/tr><\/thead><tbody><tr><td>Particles<\/td><td>Turbidity<\/td><td>\u2264 5 NTU (\u2264 1 NTU for high-spec)<\/td><td>Stabilize upstream filters\/backwash<\/td><\/tr><tr><td>Particles<\/td><td>SDI<sub>15<\/sub><\/td><td>&lt; 5<\/td><td>47 mm \/ 0.45 \u00b5m, 30 psi, temperature logged<\/td><\/tr><tr><td>Organisch<\/td><td>TOC<\/td><td>&lt; 2 mg\/L<\/td><td>Higher values \u2192 biofouling risk; combine with UV254\/SUVA<\/td><\/tr><tr><td>Organisch<\/td><td>UV254<\/td><td>&lt; 0.5 cm\u207b\u00b9<\/td><td>Humic\/aromatic indicator<\/td><\/tr><tr><td>Organisch<\/td><td>SUVA<\/td><td>2\u20134 L\u00b7mg\u207b\u00b9\u00b7m\u207b\u00b9<\/td><td>&gt;4 humic-rich; &lt;2 algal-type<\/td><\/tr><tr><td>Oil<\/td><td>O&amp;G<\/td><td>Not detected (target &lt; 0.05 mg\/L)<\/td><td>Install oil alarms where applicable<\/td><\/tr><tr><td>Metals<\/td><td>Fe\/Mn<\/td><td>Low\/controlled<\/td><td>Prevent oxidized solids overloading UF<\/td><\/tr><tr><td>Ions<\/td><td>Hardness<\/td><td>Context only<\/td><td>Sets downstream scaling limits (RO\/boiler\/cooling)<\/td><\/tr><tr><td>Ions<\/td><td>Conductivity\/TDS<\/td><td>Trend<\/td><td>Normalize to 25 \u00b0C<\/td><\/tr><tr><td>Chemistry<\/td><td>pH<\/td><td>Stable, project window<\/td><td>Affects coagulants, scaling, corrosion<\/td><\/tr><tr><td>Silica<\/td><td>Reactive vs colloidal<\/td><td>Split &amp; trend<\/td><td>Colloids foul UF; dissolved limits RO recovery<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n<p><strong>Disclaimer:<\/strong>&nbsp;These are practical cues. Final limits depend on the UF module\/vendor, flux, backwash\/CIP strategy, and your downstream process targets.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">Sampling &amp; QA\/QC (Operator Workflow)<\/h2>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Sample at the UF feed tank or inlet after stabilization; purge lines to avoid dead-leg water.<\/li>\n\n\n\n<li>Duplicate runs for TOC\/DOC and UV254; log filter pore size (\u22640.45 \u00b5m) wherever \u201cdissolved\u201d is referenced.<\/li>\n\n\n\n<li>Maintain a spreadsheet with time, flow\/pressure, temperature, NTU, TSS, SDI, TOC\/DOC, UV254\/SUVA, O&amp;G, Fe\/Mn, hardness, EC\/TDS, pH, and silica.<\/li>\n<\/ul>\n\n\n\n<h2 class=\"wp-block-heading\">Visuals &amp; Downloadables<\/h2>\n\n\n\n<ul class=\"wp-block-list\">\n<li><a href=\"https:\/\/stark-water.com\/nl\/stark-water-tools\/\">UF Feed Dashboard (online tool, coming soon)<\/a><\/li>\n\n\n\n<li><a href=\"https:\/\/stark-water.com\/nl\/downloads\/uf-feed-quality-checklist.pdf\/\">UF feed quality checklist (PDF)<\/a>\u00a0<em>(placeholder path)<\/em><\/li>\n\n\n\n<li><a href=\"https:\/\/stark-water.com\/nl\/oplossingen\/\">Water Treatment Solutions<\/a>\u00a0-\u00a0<a href=\"https:\/\/stark-water.com\/nl\/case\/\">Case Studies<\/a>\u00a0-\u00a0<a href=\"https:\/\/stark-water.com\/nl\/blog\/\">Blog<\/a><\/li>\n<\/ul>\n\n\n\n<h2 class=\"wp-block-heading\">Referenties en verder lezen<\/h2>\n\n\n\n<p>General resources for water quality methods and health context:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li><a href=\"https:\/\/www.epa.gov\/water-research\" target=\"_blank\" rel=\"noreferrer noopener\">U.S. EPA \u2014 Water Research<\/a><\/li>\n\n\n\n<li><a href=\"https:\/\/www.who.int\/water_sanitation_health\" target=\"_blank\" rel=\"noreferrer noopener\">WHO \u2014 Water Quality Resources<\/a><\/li>\n\n\n\n<li><a href=\"https:\/\/www.usgs.gov\/special-topics\/water-science-school\" target=\"_blank\" rel=\"noreferrer noopener\">USGS \u2014 Water Science School<\/a><\/li>\n<\/ul>\n\n\n\n<h2 class=\"wp-block-heading\">Turn Lab Numbers into a Pretreatment Plan<\/h2>\n\n\n\n<p>Upload your UF feed dataset (NTU\/TSS\/SDI, TOC\/DOC, UV254\/SUVA, O&amp;G, Fe\/Mn, hardness, EC\/pH, silica). We\u2019ll return a fouling-risk scorecard and a tuned operating window (flux, backwash\/CIP).<\/p>\n\n\n\n<p><a href=\"https:\/\/stark-water.com\/nl\/request-a-quote\/\">Een offerte aanvragen<\/a><\/p>\n\n\n\n<h3 class=\"wp-block-heading\">About the Author<\/h3>\n\n\n\n<p>Stark Water&nbsp;\u2014 Process engineers focused on UF\/RO pretreatment design, membrane fouling control, and compliance-driven operations.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">FAQs \u2014 UF Feed-Water Quality<\/h2>\n\n\n\n<h3 class=\"wp-block-heading\">1) SDI\u2081\u2085 vs SDI\u2085 or SDI\u2081\u2080 \u2014 how do I adjust?<\/h3>\n\n\n\n<p>Use the same formula&nbsp;<em>SDI = (1 \u2212 t_i\/t_f) \u00d7 100 \/ T<\/em>&nbsp;with your chosen total time&nbsp;<em>T<\/em>&nbsp;(5, 10, or 15 min). Report the time in the subscript.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">2) When should I run TSS instead of turbidity?<\/h3>\n\n\n\n<p>When turbidity is dominated by color or fines that skew optics. TSS provides gravimetric confirmation of particulate loading.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">3) TOC\/DOC vs COD\/BOD \u2014 which should I prioritize?<\/h3>\n\n\n\n<p>For UF fouling, trend TOC\/DOC and UV254 first. Use COD\/BOD to interpret pollution events or permit compliance.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">4) What SUVA ranges imply organic character?<\/h3>\n\n\n\n<p>SUVA &gt; 4 indicates humic-rich water; SUVA &lt; 2 suggests algal or low-aromatic organics. Pair with DOC.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">5) How do I screen for trace oil?<\/h3>\n\n\n\n<p>Use O&amp;G methods with low detection limits; install upstream oil alarms if industrial discharges are possible.<\/p>","protected":false},"excerpt":{"rendered":"<p>Last updated:&nbsp;November 7, 2025 \u00b7&nbsp;Reading time:&nbsp;12\u201315 minutes \u00b7&nbsp;Audience:&nbsp;UF\/MBR\/RO operators, process engineers, EPCs Understanding&nbsp;UF feed-water quality&nbsp;helps you prevent fouling, stabilize flux, [&hellip;]<\/p>","protected":false},"author":1,"featured_media":66440,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"site-sidebar-layout":"default","site-content-layout":"","ast-site-content-layout":"default","site-content-style":"default","site-sidebar-style":"default","ast-global-header-display":"","ast-banner-title-visibility":"","ast-main-header-display":"","ast-hfb-above-header-display":"","ast-hfb-below-header-display":"","ast-hfb-mobile-header-display":"","site-post-title":"","ast-breadcrumbs-content":"","ast-featured-img":"","footer-sml-layout":"","theme-transparent-header-meta":"","adv-header-id-meta":"","stick-header-meta":"","header-above-stick-meta":"","header-main-stick-meta":"","header-below-stick-meta":"","astra-migrate-meta-layouts":"default","ast-page-background-enabled":"default","ast-page-background-meta":{"desktop":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"tablet":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"mobile":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""}},"ast-content-background-meta":{"desktop":{"background-color":"var(--ast-global-color-4)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"tablet":{"background-color":"var(--ast-global-color-4)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"mobile":{"background-color":"var(--ast-global-color-4)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""}},"_joinchat":[],"footnotes":""},"categories":[208],"tags":[],"class_list":["post-66424","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-industrial-water-treatment-guides"],"acf":[],"_links":{"self":[{"href":"https:\/\/stark-water.com\/nl\/wp-json\/wp\/v2\/posts\/66424","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/stark-water.com\/nl\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/stark-water.com\/nl\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/stark-water.com\/nl\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/stark-water.com\/nl\/wp-json\/wp\/v2\/comments?post=66424"}],"version-history":[{"count":2,"href":"https:\/\/stark-water.com\/nl\/wp-json\/wp\/v2\/posts\/66424\/revisions"}],"predecessor-version":[{"id":66437,"href":"https:\/\/stark-water.com\/nl\/wp-json\/wp\/v2\/posts\/66424\/revisions\/66437"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/stark-water.com\/nl\/wp-json\/wp\/v2\/media\/66440"}],"wp:attachment":[{"href":"https:\/\/stark-water.com\/nl\/wp-json\/wp\/v2\/media?parent=66424"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/stark-water.com\/nl\/wp-json\/wp\/v2\/categories?post=66424"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/stark-water.com\/nl\/wp-json\/wp\/v2\/tags?post=66424"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}