GreensandPlus™ is a black filter media used for removing soluble iron, manganese, hydrogen sulphide, arsenic and radium from groundwater supplies.
The manganese dioxide coated surface of GreensandPlus™ acts as a catalyst in the oxidation-reduction reaction of iron and manganese.
The silica sand core of GreensandPlus™ allows it to withstand waters that are low in silica, TDS and hardness without breakdown.
GreensandPlus™ is effective at higher operating temperatures and higher differential pressures than standard manganese greensand. Tolerance to higher differential pressure can provide for longer run times between backwashes and a greater margin of safety.
Systems may be designed using either vertical or horizontal pressure filters, as well as gravity filters.
GreensandPlus™ is a proven technology for iron, manganese, hydrogen sulphide, arsenic and radium removal. Unlike other media, there is no need for extensive preconditioning of filter media or lengthy startup periods during which required water quality may not be met.
GreensandPlus™ is an exact replacement for manganese greensand. It can be used in CO or IR applications and requires no changes in backwash rate or times or chemical feeds.
* Removes Iron, Manganese, Hydrogen Sulfide, Arsenic and Radium
Iron and Manganese Removal
GreensandPlus™ has a manganese dioxide coating which creates a highly oxidative environment. When a strong oxidant is injected in the raw water stream ahead of a GreensandPlus™ filter, soluble iron and manganese are easily oxidized and the precipitates are trapped by the media (which acts as a catalyst and does not participate in the reaction). The filter is subsequently backwashed and reused, therefore it is not sacrificed in this process.
Hydrogen Sulfide Removal
GreensandPlus™ directly oxidizes sulphide and catalyzes the oxidation reaction. Increased run length and service life of GreensandPlus™ may be realized by pre-feeding a solution of chlorine-containing compounds.
GreensandPlus™ can be used to remove arsenic from groundwater in the presence of iron. Chlorine must be pre-injected to oxidize the iron and convert arsenite to arsenate and keep the media regenerated.
Arsenic combines with oxidized iron and is filtered out in the media. If there is not a sufficient amount of iron present in the raw water, then an iron salt such as ferric chloride can be pre‑injected.
A general guideline is 1 mg/L of iron to remove 20 µg/L of arsenic. This can vary greatly depending on pH, silica, and other competing ions in the water.
GreensandPlus™ can be used to remove radium from groundwater in the presence of manganese, in a similar manner to arsenic removal. In the case of radium, manganese in the raw water is necessary.
If there is not a sufficient amount of manganese present, then manganese sources such as manganous sulphate can be pre‑injected.