Cleaning Water: Making water safe at home, at work and in agriculture


Why is there manganese in ground water?

Manganese is a mineral that naturally occurs in rocks and soil and may also be present due to underground pollution. When manganese is present in water, it is every bit as annoying as iron, perhaps even more so. In low concentrations it produces extremely objectionable stains on everything with which it comes in contact. Deposits collect in pipelines, and tap water may contain black sediment and turbidity due to precipitated manganese. When fabrics are washed in manganese-bearing water, dark brown or black stains are formed due to the oxidation of the manganese.

Manganese correction media

Our first choice media is a silica crystal that works by an ion exchange process which removes iron, manganese and hardness (and reduces ammonia). The minimum pH requirement is 6.0 and it works best on clear water, i.e. when the iron/manganese are in a dissolved form. The media will also reduce hardness with no extra treatment.
The regeneration process is exactly the same as that used in a water softener and requires regeneration with salt (sodium chloride). The media has a number of advantages over conventional systems in that pH correction, iron/manganese removal, ammonia reduction and softening can all be addressed in a single process. It can reduce dissolved iron and manganese even at pH 6 (most other medias cannot).

How does it work?

Water flows into the valve at the top, down through the media and then up through the ‘riser’ tube in the middle of the vessel. As the water travels through the media the manganese is removed leaving clear water. There are timer options that can be set to automatically self clean (backwash) and wash away any of the accumulated manganese. Cleaning can be set for a given time or after a certain amount of water has been used. With our preferred media, salt is also added to regenerate it ready for service. Manganese filters can also be used in conjunction with other filters such as sand filters if the water has high turbidity, or pH correction filters if the pH of the water very low.

How to size

On average 160 litres of water is used per person per day. This normally occurs in two peak periods, one in the morning and one in the evening. A family of four typically uses 700 litres of water per day but may use 300 litres in an hour in the morning. Larger households, farms, stables and irrigations systems all use more water.

When sizing a system the average flow and the peak flow rate need to be taken into account. Try and size a system to run for 3 days without regenerating or a duplex for 12 hours. The vessel size is given as the diameter and the height (in inches). The amount of water produced between regenerations depends on the hardness, sodium and iron/manganese levels. Recommended operating pressure range 20 to 120 psi. Water temperature ranges from 2 to 38°C.

A water quality test report should be obtained to ensure the appropriate equipment is suggested.