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Japanese national phone company NTT has hit on a novel use for recycled
telephone directories. A clay-like waste product is left after the books are
pulped, and researchers at NTT have turned the goo into balls of a microporous
material (MPM) that can absorb phosphorous and nitrogen from water, at half the
cost of activated charcoal. Putting hundreds of MPM balls in a polluted stream
should clear away phosphates and nitrates. After use, the balls can be reused as
fertiliser.