bacteria to the rescue

Bacteria to the rescue



    A product of agricultural waste, fertilizers and even human sewage, nitrates pollute water everywhere and pose a health risk. The Hebrew University’s new bio-filter presents a unique method for removing harmful nitrates from drinking water.​

  • Dried biopolymer carriers containing a nitrate-munching bacterium
    • Nitrate is a colorless, odorless, tasteless compound polluting water everywhere. A product of agricultural waste, fertilizers and even human sewage, nitrates pose a health risk - especially for newborns who drink formula prepared with water high in nitrates.
      The compound can be diluted in drinking water, but there is no way to remove nitrates except by expensive reverse osmosis.
      Now a new product from two researchers at the Hebrew University of Jerusalem may have a remarkable effect on the way nitrates are cleaned from drinking water and aquifers, and it even has an application for commercial aquariums, where solutions are badly needed.
      Their inexpensive product, now being developed commercially by the university’s technology transfer company, Yissum, is in the form of biodegradable beads that look like small white Styrofoam balls. The beads contain a nitrate-munching bacterium, which releases nitrate gas as an end-product.
      This bio-filter was introduced at the WATEC conference in Tel Aviv in November as a novel way of purifying water.
      Perfect for aquariums
      Professors Amos Nussinovitch and Jaap van Rijn from the Hebrew University say their approach can denitrify water in a very cost-effective and safe way. “This is big business for marine aquariums, and nitrate removal is an important aspect for water quality control,” says van Rijn, who previously developed Grow Fish Anywhere, which allows for raising fish in pools.
      “The solution can be enlarged for treatment of drinking water. There is a lot of interest right now because there are various methods for trying to remove nitrates, but they are costly. Using our technology is not only effective but also cost-effective.”
      Cross-section of a carrier including a denitrifying bacterium
      Cross-section of a carrier including a denitrifying bacterium
      No more baby blues
      High nitrate levels can lead to algal blooms and to a serious condition, called blue baby syndrome, in infants under six months.
      Still in prototype development, the researchers’ permeable polymer beads can be loaded with either denitrifying bacteria alone or a combination of fermentative and denitrifying bacteria plus a carbon source. These substances reduce nitrate to nitrogen gas, which evaporates. In dry form, the bio-filters can be safely stored for years.
      The bio-filter can deal with both fresh and seawater, and can easily be applied to water purification systems in contaminated bodies of water or in aquariums of up to 200 liters, where it increases the life span of the fish. The solution is currently being tested in larger amounts of water and in water wells.
      Nussinovitch says: “The main issue here is that these beads are good for both drinking water and salty water. We had to prepare beads with the proper porosity, and so that the active materials could diffuse in and out. We also developed a drying method to get as high a porosity as possible and with a shelf-life as long as possible.” Fish and babies everywhere should be happy about the news.