ASTM D4993-08(2014)
Standard Practice for Calculation and Adjustment of Silica 40;SiO241; Scaling for Reverse Osmosis

Standard No.

ASTM D4993-08(2014)

Release Date

2008

Published By

American Society for Testing and Materials (ASTM)

Latest

ASTM D4993-08(2014)

Scope

5.1 In the design and operation of reverse osmosis installations, it is important to predict the SiO₂ scaling properties of the concentrate stream. Because of the increase in the concentration of SiO₂ and the change in pH, the scaling property of the concentrate stream will be quite different from that of the feed solution. This practice permits the calculation of the scaling potential for the concentrate stream from the feedwater analysis and the reverse osmosis operating parameters.

5.2 Scaling by SiO₂ will adversely affect the reverse osmosis performance. This practice gives various procedures for the prevention of scaling.

5.3 The presence of certain metals, for example, Al⁺³, may significantly alter the solubility of SiO₂ via formation of insoluble metal silicates. This practice does not address this phenomena.

1.1 This practice covers the calculation and adjustment of silica (SiO₂) for the concentrate stream of a reverse osmosis system. The calculations are used to determine the need for scale control in the operation and design of reverse osmosis installations. This practice is applicable for all types of reverse osmosis devices (tubular, spiral wound, and hollow fiber).

1.2 This practice is applicable to both brackish waters and seawaters.

1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.

1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

ASTM D4993-08(2014) Referenced Document

• ASTM D1067 Standard Test Methods for Acidity or Alkalinity of Water
• ASTM D1129 Standard Terminology Relating to Water
• ASTM D1293 Standard Test Methods for pH of Water
• ASTM D3739 Standard Practice for Calculation and Adjustment of the Langelier Saturation Index for Reverse Osmosis
• ASTM D4194 Standard Test Methods for Operating Characteristics of Reverse Osmosis Devices
• ASTM D6161 Standard Terminology Used for Crossflow Microfiltration, Ultrafiltration, Nanofiltration, and Reverse Osmosis Membrane Processes
• ASTM D859 Standard Test Method for Silica in Water

ASTM D4993-08(2014) history

• 2008 ASTM D4993-08(2014) Standard Practice for Calculation and Adjustment of Silica 40;SiO241; Scaling for Reverse Osmosis
• 2008 ASTM D4993-08 Standard Practice for Calculation and Adjustment of Silica (SiO₂) Scaling for Reverse Osmosis
• 1989 ASTM D4993-89(2003) Standard Practice for Calculation and Adjustment of Silica (SiO₂) Scaling for Reverse Osmosis
• 1989 ASTM D4993-89(1998)e1 Standard Practice for Calculation and Adjustment of Silica (SiO₂) Scaling for Reverse Osmosis