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With continuous and slow oxygen-release characteristic, calcium peroxide (CaO_2) has been a new source of supplying oxygen for aerobic microbes in bioremediation of contaminated groundwater. Batch experiments were conducted to evaluate the oxygen-release rate of CaO_2 react- ing with water, the regulation of high pH, as well as the growth of mixed aerobic microbes in the medium containing CaO_2. The results show that the oxygen-release process of CaO_2 comprises three phases. In the first phase, dissolved oxygen levels of water increased sharply, and average oxygen-release rates increased as the adding weight of CaO_2 increased. However, the rates almost kept invariable in the latter phases and were approximately 0.48 and 0.084 mg O_2·h~ -1 , respectively. As the necessary components of medium, potassium dihydrogen phosphate (KH_2PO_4) and ammonium sulphate ((NH_4)_2SO_4) at a certain ratio could regulate pH caused by CaO_2 from 12.1 to the range of 6.5—8.5, which is helpful for microbial growth. In addition, diauxic growth curve observed in the medium containing CaO_2 suggested that the growth of mixed aerobic microbes could be stimulated by the addition of CaO_2.
With continuous and slow oxygen-release characteristic, calcium peroxide (CaO_2) has been a new source of supplying oxygen for aerobic microbes in bioremediation of contaminated groundwater. Batch experiments were conducted to evaluate the oxygen-release rate of CaO_2 react- ing with water, The regulation of high pH, as well as the growth of mixed aerobic microbes in the medium containing CaO_2. The results show that the oxygen-release process of CaO_2 comprises three phases. In the first phase, dissolved oxygen levels of water increased sharply, and average oxygen-release rates increased as the adding weight of CaO_2 increased. However, the rates are kept invariable in the latter phases and were approximately 0.48 and 0.084 mg O_2 · h ~ -1, respectively. As the necessary components of medium, potassium dihydrogen phosphate (KH_2PO_4) and ammonium sulphate ((NH_4) _2SO_4) at a certain ratio could regulate pH caused by CaO_2 from 12.1 to the range of 6.5-8.5, which is helpful for mic robial growth. In addition, diauxic growth curve observed in the medium containing CaO 2 suggested that the growth of mixed aerobic microbes could be stimulated by the addition of CaO_2.