Patent ID: 7438814

Claim:
A method for purifying raw water by decreasing the contents of at least one contaminant selected from the group consisting of metals, metalloids, nitrate, and nitrite in said raw water, the method comprising: feeding raw water containing at least one contaminate selected from the group consisting of metals, metalloids, nitrate, and nitrite through horizontally arranged feeding pipes into a basin; flowing said raw water through naturally occurring filter material arranged in said basin; intermittently introducing water containing at least one agent selected from the group consisting of oxygen, oxygen-releasing substances, metabolic substrates, and naturally occurring micro-organisms to the basin through a plurality of satellite wells arranged around at least one extraction well for extracting purified water, wherein said water containing at least one agent selected from the group consisting of oxygen, oxygen-releasing substances, metabolic substrates, and naturally occurring micro-organisms is homogeneously distributed vertically in said basin; creating a constant negative pressure around said at least one extraction well; and extracting said purified water from said at least one extraction well.