| 摘要 |
<p>PURPOSE:To efficiently wash a biological filter apparatus with a reduced amount of washing water by together using air washing and water washing. CONSTITUTION:When a filter bed 2 is clogged by the continuation of biological filtration, the supply of raw water and that of diffusing air are stopped to perform water drainage from a washing waste water pipe 9. Subsequently, air is supplied at flow velocity of 0.3-0.8m<3>/m<2>/min from a washing air pipe 5 as an upward stream to perform the air washing of the filter bed 2 for 2-6min. Subsequently, simultaneously with the air washing at said flow velocity, washing water is supplied at flow velocity of 0.4-0.8m<3>/m<2>/min from a washing water pipe 6 to perform the water washing of the filter bed 2 by an upward stream for 0.5-2min. Thereafter, air is supplied at flow velocity of 0.3-0.8m<3>/ m<2>/min. from the washing air pipe 5 to perform air washing by an upward stream. After the filter bed 2 is allowed to stand for 1-3min, water is drained from the washing waste water pipe 9 and upper water is discharged from the filter bed 2 as washing waste water. As mentioned above, after the filter bed 2 is washed, raw water is supplied from a raw water pipe 3 and air is supplied from the diffusing air pipe 4 to reopen the biological filtering of the raw water passing through the filter bed 2 under the diffusion of air.</p> |
