Harn R/O Systems Blog

How to Complete a Silt Density Index (SDI) Test and Why it's Important

Posted by Julie Nemeth-Harn on Jun 21, 2017 4:14:56 PM

Silt Density Index Test

It is important to check on the level of semi-colloidal suspended solids in the feedwater to RO systems. The level can be estimated (not measured absolutely) by the Silt Density Index or SDI test which measures the blocking rate of a 0.45 micron filter pad under controlled pressure conditions. This test was originally developed by DuPont and there are several variations using different test times of 5, 10 & 15 minutes. The method used for testing feedwater quality into an RO/NF system is always the 15 minute test – which is the most sensitive.

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Topics: water quality, ro calculations, silt density index

Are You Getting The Most Value Out of Your Scale Inhibitor?

Posted by Julie Nemeth-Harn on Jun 7, 2017 11:23:50 AM


There exists a potential for calcium, barium, strontium, fluoride and silica compounds to precipitate in the concentrate or brine channels of the reverse osmosis membranes. Precipitation occurs when the solubility limits of these various salts and silica is exceeded. As pure water is forced through the membrane under pressure, the salt concentration on the brine side of the membrane increases since the solvent (pure water) is being transported through the membrane, which acts as a barrier to the salts. As the salt concentration increases, the least soluble salts will 

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Topics: membrane treatment system, membrane treatment, water treatment, scale inhibitor

How to Calculate Percent Recovery and What Affects it in a Membrane Treatment System?

Posted by Julie Nemeth-Harn on Jun 5, 2017 2:08:06 PM


Recovery is the amount of water permeated per unit time - usually in gallons per minute (gpm) and expressed as a percentage of the raw water feed flow rate. The design recovery is calculated as follows:

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Topics: membrane treatment system, membrane treatment, water treatment, ro calculations

4 Reasons You Need to Replace Your Conventional Water Treatment Plant with a Membrane Water Treatment System

Posted by Julie Nemeth-Harn on Mar 29, 2017 11:44:55 AM

Water quality and purification processes improved over time, while demand for drinkable water has increased. Today’s membrane treatment plants can be tailored to the overall composition of water to be processed, and the membrane treatment methods used can reduce more possible contaminants. Where the desired outcome is stable, clean water with an appreciable return on the investment, upgrading to a membrane water treatment system is backed by cutting edge industry science.
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Topics: membrane treatment system, water treatment, water quality, water purification process

How to Save Money and Avoid Issues in Your Membrane Water Treatment Plant by Using a Pilot During the Design Process

Posted by Julie Nemeth-Harn on Mar 15, 2017 10:46:00 AM
Pilot systems are the most cost-effective method of testing membrane plant designs. The basic idea is that a pilot system can be implemented at a fraction of the cost of the full system, and then full implementation follows after the design has been optimized and potential obstacles have been worked out.
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Topics: membrane treatment system, water treatment, pilot systems, reverse osmosis pilot

Improve Your Existing Water Treatment Process with a Membrane System

Posted by Julie Nemeth-Harn on Feb 23, 2017 11:00:00 AM

Membrane filtration systems are helping water treatment providers simplify and automate their processes while significantly improving water quality. Replacing or augmenting conventional treatment with membrane processes helps avoid heavy use of chemical processes and methods and can provide a superior finished water quality.

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Topics: membrane treatment system, water treatment

Membrane Water Treatment: A Simpler and More Cost- Effective Process Than You May Think

Posted by Julie Nemeth-Harn on Feb 8, 2017 10:15:00 AM

Membrane filtration can be explained as a method of allowing certain materials to permeate a surface while blocking others. For water, this means allowing clean water to flow through the membrane while eliminating sediments and other materials or pathogens. Membrane filtration is a multiple-step process which is considered to be one of the most cost-effective water treatments available.

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Topics: reverse osmosis, membrane treatment, water treatment

Is the ISO 9001 Certification Still Relevant for Manufacturers?

Posted by Julie Nemeth-Harn on Jan 26, 2017 11:30:00 AM

The ISO 9001 first debuted in 1987 with the goal of helping organizations satisfy customer and stakeholder needs as well as statutory and regulatory requirements relating to their product or service. This certification has evolved over time, with regular revisions requiring associated companies to expend resources in order to maintain their certification.  

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Topics: florida manufacturers, iso 9001

Use Variable Frequency Drives to Save Energy in Membrane Plants

Posted by Julie Nemeth-Harn on Jan 18, 2017 11:45:00 AM

Variable frequency drives (VFD) are becoming the popular choice for many industrial processes that need to make use of motors with changing speeds. In membrane plants, these motors are used to feed the pressure and flow of the water as it moves through the various areas of the treatment cycle.

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Topics: water treatment, membrane plants, vfd

The Power of Automation in a Membrane Water Treatment Plant

Posted by Julie Nemeth-Harn on Jan 12, 2017 9:45:00 AM

From IT computer server rooms to automotive factories, improved productivity is a reality thanks to modern automation technologies. Membrane water treatment plant operations can be supervised by the same intelligent controls, easy-to-use human interfaces, and industrial SCADA (Supervisory Control and Data Acquisition) systems that are used in other industries.

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Topics: water treatment, design-build