Arsenic’s evil reputation is manifested in its old alchemy symbol: a coiled serpent ready to strike. Considering arsenic’s eminence as the preferred homicidal agent of detective novels, it is not surprising there is a great deal of anxiety over its possible presence in water, among other substances, we use on a daily basis.I am an evil, poisonous smoke…but when from poison I am freed Through art and sleight of hand, then can I cure both man and beast From dire disease oft times direct them; but prepare me correctly, and take great care That you faithfully keep watch over me; For else I am poison, and poison remain that pierces the heart of many a one
– Valentini 1694
Overview
Arsenic is a naturally occurring contaminant in groundwater that poses significant long‑term health risks. While low‑level exposure has no proven biological benefit, elevated concentrations can cause toxicity affecting the skin, liver, and nervous system, and are linked to increased cancer risk with prolonged ingestion.
Due to these health concerns, arsenic is tightly regulated. The U.S. Environmental Protection Agency (USEPA) established a maximum contaminant level (MCL) of 10 µg/L (0.010 mg/L) for drinking water to protect public health.
The Pureflow Solution
The Pureflow system for arsenic filtration is an improved design for the water treatment industry. A highly adsorptive, NSF approved, media and chemical pretreatment system combine to provide a simple, safe, compact filtration system requiring minimal attendance by maintenance personnel.
The removal of arsenic occurs by its adsorption onto an iron precipitate that is formed in the pretreatment process. The multi-media filter includes a highly adsorptive active media that adsorbs the iron and arsenic in, essentially, oxidized forms. The Filter media is cleaned by back washing the filter with processed water. The backwash to filtration ratio is less than 5%.
Well water containing arsenic is chemically treated with an oxidant (such as chlorine) at the first static mixer. If dissolved iron (in sufficient concentration) is not present in the raw water, ferric salt is also fed ahead of the second static mixer. The iron is oxidized to a processable form, and a free chlorine residual is provided to the water distribution system.
The filter media does not contain greensand or activated alumina, and, therefore, does not require costly regenerating chemicals such as potassium permanganate or acid / caustic solutions. Backwash water is usually discharged to the sewer system. An optional backwash water reclaim system is available to reclaim approximately 99% of the backwash water.
The chemical pretreatment is manually set and automatically operated. The filter effluent is continuously monitored with a chlorine residual analyzer to permit the positive, simple, and automatic adjustment of the chemical feed pump.
A field pilot testing program is available to ensure the proper design and operation of every system. The cost of this program is deductible from the purchase price.
Standard Equipment Features:
- Permanent and disposable media systems
- ASME code pressure vessels up to 250 psi
- Oxidation pretreatment equipment
- Multi-media filter load (NSF 61 Approved) Filter face piping
- Electrically operated butterfly valves Filter flow control valves
- Backwash flow control valves
- Backwash water reclaim & sludge management system available
- Automatic control panel (PLC Based)
- Stainless steel wedge-wire wrapped laterals
- NSF 61 approved interior coatings
- Process analyzers
- Air relief valves
