Arsenic and Flouride Removal

There are several technologies available capable of removing fluoride and arsenic from drinking water, although not all of them are practical for smaller filtration systems.

Conventional methods vs. Seccua filtration

The EPA published a handbook in 2003 describing technologies available to remove arsenic from a water source. It compares the pros and cons of each technology, and provides a generally unbiased view of the challenges in implementing them.

For smaller systems, the most common methods of treatment are Reverse Osmosis (RO) and Activated Alumina (AA). A condensed comparison table, taken from the report, is shown below. It’s easy to see that traditional methods for arsenic removal require compromises, and that in 2003 Coagulation Assisted Direct Filtration (CADF) was complicated to operate, although it was a viable alternative if the technology were evolved to make it easier to maintain.

In contrast to arsenic removal, fluoride is only removed in rare cases because it’s usually not cost effective with the above technologies. RO provides a very significant outlet waste stream (15-75% of the input water exits without being filtered) while the AA systems are very labor intensive and creates a caustic waste stream that must be discharged.

Seccua filtration, via pre-treatment, coagulation and filtration of the precipitate, was shown to be more efficient and effective from a capital investment and Operations and Maintenance (O&M) standpoint from during Seccua’s studies.

Technology Type

Sorption Processes

Membrane Processes

Precipitative Processes

Name

Activated Alumina

Reverse Osmosis

Coagulation-Assisted Direct Filtration (Closest technology to Seccua Filtration)

Acronym

AA

RO

CADF

System Size (capacity range where technology is still affordable)

25-10,000 people

25-10,000 people

500-10,000 people

Removal Efficiency

95%

>95%

90% (depending on Arsenic and coagulation concentrations)

Total Water Loss

1-2%

15-75%

1-2%

Pre-Oxidation Required

Yes

Likely

Yes

Optimal Water Quality Conditions

pH 5.5 – 6 or 6 – 8.3
< 250 mg/L Cl-
< 2 mg/L F-
< 360 mg/L SO4 2-
< 30 mg/L Silica
< 0.5 mg/L Fe+3
< 0.05 mg/L Mn+2
< 1,000 mg/L TDS
< 4 mg/L TOC
< 0.3 NTU Turbidity

No Particulates

pH 5.5 – 8.5

Operator Skill Required

Low when used in non-regenerated mode

Medium

High (for non-Seccua products)

Waste Generated

Spent Media, Backwash Water

Reject Water

Backwash Water, Sludge

Other Considerations

  • Possible pre & post pH adjustment.
  • Pre-filtration may be required.
  • Modified AA available.

High water loss (15-75% of feed water)

Possible pre & post pH adjustment.

Seccua filtration: The best solution for Arsen Removal

Seccua is taking Arsenic and Fluoride removal to the next level with its advanced, compliant and easy-to-operate filtration systems.

Simple removal of Arsenic and Fluoride

Seccua Filtration has proven to simply remove Arsenic from drinking water to below detection level and Fluoride to below the strict levels of U.S. EPA drinking water guidelines. In a combined process of direct coagulation and filtration through a Seccua Virex Pro. Due to the ultimately fine pores of the Seccua Filtration systems, Arsenic and Fluoride can be filtered out after a simple pre-treatment step. The use of older, more expensive technologies like activated aluminum beads is therefore obsolete. During studies performed on ground-water in Oklahoma, a Seccua Virex Pro Connect system with an up-front dosage of coagulant was able to achieve the following performance:

  • Average Fluoride influent: 4.1 mg/L
  • Average Arsenic influent: 0.015 mg/L
  • Average Arsenic effluent: Non detectable
  • Average pH in: 9,15
  • Average pH out: 7,25

The average effluent Fluoride is not listed above as different levels of fluoride removal can be targeted. The results of fluoride removal were excellent and can achieve up to 75%. During the study the Fluoride concentrations targeted were at 3.0 mg/L and 1.5 mg/L effluent, which the data showed both are very achievable. Also shown in the above chart, an auxiliary benefit of this treatment is that it reduces the pH of the system from above a pH of 9 to the low 7 range.

Seccua Arsenic Removal

Easy-to-operate Filtration systems to remove Arsenic

Seccua is on the leading edge of Ultrafiltration. We have certified pathogen removal, integrated membrane testing, data logging and web based remote access. Our system is fully automated, including an integrated, state-of-the-art membrane integrity test. It detects membrane damages smaller than the size of pathogens.

Together with its ability to monitor the signal of a turbidity meter in the filtrate line of the system, it performs a continuous, daily indirect integrity test, triggering the integrated, direct membrane test whose results are reported via the data logger.

Nano-pore Ultrafiltration-technology for Arsenic and Fluoride removal

The nano-pores of the Seccua ultrafiltration provide removal characteristics that meet and exceed regulatory requirements for application of membrane filtration in drinking water treatment. Our system has proven to fully remove virus, cyst and bacteria, tested also against U.S. EPA Standards. As the only one of its kind, our system continuously measures the actual degree of fouling of the membrane – based on a function of flow and differential pressure. The systems automatically react to varying feed water conditions and adjust the frequency of its cleaning cycles accordingly. This allows us to treat difficult contaminant issues as we see here and to successfully use ultra filtration in conjunction with coagulation/flocculation.

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