Denitrification in a Box

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Denitrification in a Box

Dr. Andry Ranalvoson, University of Minnesota researcher, created bioreactors for filtering runoff in plastic pallet tanks, saving farming land.

iec92Sh.jpgPlastic boxes were filled with wood chips, gravel, chemicals and pesticides to create an environment for microbes to denitrify water runoff.

Elevated nitrate levels in water create unfavorable conditions for aquatic insects and fish.

Nitrates are used by plants for their growth, however too much nitrates in soil can cause negative effects of the plants.

Denitrification happens in waterlogged soil with enough organic matter which provides energy for bacteria. These boxes provide good conditions for denitrifying bacteria.

The microbes consume carbon from wood chips (organic matter) and nitrates from water and therefore purify.

Natural bacteria, present in the water, uses carbon from wood chips (organic matter) and they breathe the nitrates from the water.

M9FDtkT.jpgDenitrification in these boxes prevents water bodies and soil from getting polluted.

97% of nitrate is removed in some cases. The boxes were most efficient in rainy months in spring and summer and lack of rain and the temperature drop reduced the productivity.

In addition to nitrate reduction, phosphorous levels are regulated by adding corn cobs, crushed concrete, limestone, steel slag and a steady drip of acetate.

Different carbon sources had different effect on nutrients removal - steel slag removed the most nitrogen – 34% and crushed concrete removed most phosphorous – 37%.

These bioreactor boxes could have great impact in improving water quality and soil preservation.

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