Birm is a relatively inexpensive material which can be used for iron and manganese removal by oxidation. It requires a pH of 7 or more for iron removal and pH 8 for manganese removal (it uses dissolved oxygen in the water to oxidise the metal). As it acts as a catalyst it is not consumed so Birm doesn’t require regenerating or topping up. Birm also has the advantage of acting as a filter removing relatively high levels of turbidity. It is advised not to use Birm in combination with chlorination and the water should be free of oil and hydrogen sulphide. If the pH of the water is too low pH correction maybe required. Birm requires DO at least 15% of the iron and manganese content to work.

30% freeboard
Service flow rate: 12m/hr
Backwash rate: 24 m/hr
Density: 1.2 Kg/litre
Alkalinity: greater than twice the combined sulphate and chloride
pH: 6.8 to 9.0
Dissolved oxygen: at least 15% of the iron or manganese content less than 0.5% chlorine, no H2S, oil or polyphosphates