WATER QUALITY PURIFICATION BY A POROUS CONCRETE BLOCK INCLUDING BACILLUS SUBTILIS NATTO GROUP

Laboratory experiments were carried out on water quality purification by a porous concrete block including Bacillus subtilis natto group. The block is called EcoBio-Block (EBB). The time variations of biochemical oxygen demand (BOD) and chemical oxygen demand (COD) were obtained experimentally under the aerated condition by changing the weight ratio of EBB to water. The time variations of BOD and COD were expressed universally by normalizing the data. The reduction rate of BOD increases with the weight ratio. On the other hand, that of COD takes the maximum value at the weight ratio of 0.01 and decreases after that. The rapid reduction of BOD and COD seen in the early stage may be due to the adhesion or adsorption of organic matter by EBB. The mineralization of organic matter and the nitrification of NH4-N by EBB become active at the later stage and the activity increases with the weight ratio. It was experimentally revealed that EBB has also the very high ability for the water quality purification in the DO-saturated water and it depends strongly on the weight ratio of EBB to water.