Arsenic Removal
Granular ferric hydroxide adsorption
Arsenic in water occurs mainly as inorganic arsenite (As(III)) and arsenate (As(V)); the form present depends on the water chemistry and redox conditions. LennSORB 102 is a granular ferric hydroxide adsorbent developed for arsenic removal. Its product datasheet states that it adsorbs both arsenate and arsenite and that its capacity depends on the water composition and operating conditions. The datasheet also documents compliance with DIN EN 15029 and certification to NSF/ANSI Standard 61. See the LennSORB 102 product datasheet for product details and conditions of use.
Process design and operation
The treatment system typically uses an adsorber vessel containing LennSORB 102 media supported by a gravel layer. Design depends on the feed-water analysis, flow rate and required treated-water quality. Phosphate, silicate, pH, turbidity and temperature are among the water-quality parameters that can affect adsorption performance and media capacity.
Other arsenic treatment options
Adsorption is one of several treatment approaches. Depending on the water chemistry, flow and treatment objectives, engineers may also evaluate iron coagulation and filtration, anion exchange, or membrane processes such as nanofiltration and reverse osmosis. Arsenite (As(III)) can be more difficult to remove than arsenate (As(V)) with some processes, so oxidation may be considered where appropriate. LennSORB 102’s product datasheet specifically states that the media adsorbs both forms.
Water analysis should consider arsenic speciation, pH, and competing ions. For anion exchange, sulfate can compete for resin capacity. The process choice should also account for the residual stream produced, such as spent media, sludge, regenerant or membrane concentrate.
Monitor treated-water arsenic and the filter’s operating conditions to determine when the bed needs replacement. Backwashing and other operating steps should follow the selected filter design and product guidance. Spent media may contain concentrated arsenic; handle and dispose of it in accordance with applicable local requirements and product guidance.
Arsenic removal system design
Lenntech can design a project-specific arsenic-removal system using water-analysis and flow data. Supply options described by Lenntech include individual equipment for on-site assembly or a prebuilt system on skids. Control equipment, technical documentation, installation supervision and operational training can also be discussed for a project.
LennSORB 102 product datasheet
For information about a project or a quotation, contact Lenntech using the feedback form or call +31 152 610 900.