Iron and Manganese (plus Aluminium and Hydrogen Sulphide)

Both metallic and some non-metallic contaminants can be removed from water by passing the water through a bed of specialised media. These media act in two ways; triggering the precipitation of the contaminant to form an insoluble particle and then physically filtering out the contamination to leave clean water. By selecting the correct media, very specific water problems can be treated easily. We have a number of units which carry out this process:

Birm, Filox & Greensand

A choice of media are available depending upon the exact chemical make-up of the water to be filtered. Each have their strengths and weaknesses and your local water treatment expert will be able to advise as to the best choice.

The media most commonly used are:- 

BIRM, which gives good removal at a relatively low cost. Generally suited to waters that would be considered hard in nature, its performance is adversely affected by the presence of chlorine, organic contaminants and some chemical treatments.

FILOX R, has a much higher level of activity than BIRM, and is more suitable across a greater range of waters. It is chlorine resistant and can be used to help in the removal of hydrogen sulphide (the bad egg smell that is sometimes encountered).

MANGANESE GREENSAND, generally only used in industry for iron and manganese removal, as it requires chemical regeneration (with Potassium Permanganate) to restore its activity.

System Management & Backwashing

In order to remove accumulated deposits from the filter bed, the water flow through the filter is reversed (backwashed). Water is run to drain at a high flow rate to separate the deposits from the filter media. The control valve completes the backwash cycle automatically at the intervals and times set during installation. The backwash and rinse cycle takes approximately 20 minutes, although these can be altered to suit individual conditions.

Specifying and Sizing

BIRM Operating parameters:

Oxygen level = 15% of iron level. pH range = 6.8 - 9.0. Alkalinity greater than 2 x (Sulphate + Chloride), no Hydrogen Sulphide, oil or polyphosphates. Organic matter less than 5ppm. Free chlorine less than 0.5ppm. Temperature 3-45oC (35-110oF).

BIRM, Greensand and Multi-Media Filter Systems include service and drain line flow controllers. NB Backwash flow per vessel is twice the service flow, therefore where possible use two or more small units instead of one large one.

Technical Details and Model Numbers for BIRM systems and Multi

Media Filters.

FILOX-R filter systems for removal of Iron, Manganese & Hydrogen Sulphide

Includes service and drain line flow controllers. NB Backwash flow on all systems is greater than service flow. Operating parameters pH range 6-9* (see FILOX-R data sheet for limitations and pre-tests). Organis Iron below .5ppm, Iron below 27 ppm, Manganese below 11 ppm, Hydrogen Sulphide below 17 ppm, Temperature 3-45o (35-110oF).

NB. To prevent damage to the vessel these filters must be protected from negative pressure from the drain or supply. A vacuum relief valve is recommended on the inlet supply and is supplied with all vessels from 770mm diameter upwards.

Triplex

Problematic waters can be treated with a Triplex system to both raise the pH and remove the Iron and Manganese. First water is passed through an aerator contact assembly which entrains air into the water to encourage initial precipitation of the contaminants. This has the effect of reducing the overall load on the filter media, making the complete removal of the contaminants much more efficient.

The Triplex vessel uses a unique blend containing a pH correction media, an Iron and Manganese removal media, and a physical filter media. This works in three ways and has the combined effect of raising the pH of the water (eliminating the acidity), precipitating any dissolved Iron and Manganese in the water, and finally filtering out this precipitate. Clean treated water is then passed to service ready for use. 

Unlike other Iron and Manganese removal systems, the Triplex filter has an equal backwash and service flow. This means that the load on the borehole pump is minimised, with no requirement for backwash booster pumps. This makes Triplex ideally suited to domestic and light commercial applications with flow rates up to 4m3 per hour.

System Management, Backwashing and Regeneration

The aerator contact assembly is installed between the borehole pump and accumulator on a pressurised system, to ensure a consistent flow through the aerator. This results in the air venturi working effectively at all times. The Triplex filter is installed downstream of the accumulator.

For non-pressurised systems relying on tank level switches to activate the borehole pump, a microswitch inside the filter valve is used to operate the borehole pump for backwashing. Untreated water can be prevented from bypassing to service during backwash by using a close down valve fitted to the standard backwash valve, or by specifically modifying the valve during manufacture of the filter.

Triplex models FT350 to FT750 have a bypass leg fitted to maintain high service flow through the aerator contact assembly, while still maintaining good levels of aeration. In areas of high organic loading, or waters with high levels of manganese, pre-treatment with ozone may be advisable. Alternatively intermittent backwashing with a dilute chlorine solution may be employed.

Special Product Features:

• Improved performance over existing Iron & Manganese filters

• Light media for easier backwashing

• Aeration and degassing in same unit

• Reduces Hydrogen Sulphide

• Raises pH

• Aerator manufactured from plastic parts that can be acid cleaned

• High efficiency aerator venturi

• Easily maintained

• Maximised air/water contact within Aerator pressure vessel

• High flow 1" Couplings

Crystal Right

Crystal Right works by an ion exchange process which removes iron, manganese and hardness. The minimum pH requirement is 6.0 and Crystal Right will raise the pH in these acidic waters. Crystal Right works at its best on clear water, i.e. when the iron/manganese are in a dissolved form. Crystal Right will also remove hardness with no extra treatment. Ammonia, lead, hydrogen sulphide and copper can also be reduced. The media bed can be sanitised with chlorine from time to time. The regeneration process is exactly the same as that used in a water softener and requires regeneration with salt (sodium chloride).

There are two types of Crystal Right. CR100 is used where the pH is between 6 and 7 and will increase the pH. CR200 is used where the pH is 7 or above. Crystal Right has a number of advantages over conventional systems in that pH correction, iron/manganese removal and softening can all be addressed in a single process.

Crystal Right works best on clear water iron and manganese, where a water sample is clear of precipitated iron when freshly pumped The lifetime can be reduced on very low TDS water so we do not recommend its use with a TDS of less than 80 ppm or a hardness of less than 50 ppm. Crystal Right 100 is used where the raw water pH is between 6.0 and 7.0. (if the pH is lower than 6.0 then conventional pH correction will also be needed.) Crystal Right 200 is used where the raw water pH is 7.0 or above, its advantage in this situation is a higher capacity.