Analysis of the organic removal effect of BAC and BCF

The respective removal effect of BAC filter bed and BCF filter bed on DOC and BDOC after ozonation is shown respectively in Fig. 29 and Fig. 30. Only a few DOC, which accounts for 4% of raw water is removed by ozonation. For calculation, the removal of DOC and BDOC shown in Fig. 29 and Fig. 30 is in relative terms with ozonation. Analysis of the statistics of Fig. 29 and Fig. 30 is shown in Table 5, in which NBDOC stands for non­biodegradable dissolved organic carbon. As shown in Table 5, the removal effect of BAC on DOC is mainly focused on removing BDOC, among which removal of BDOC accounts for 85% of the degradation DOC, while for BCF filter bed, this proportion can be as high as 98%.

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ozonation effluent efficiencies

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ozonation effluent efficiencies

Figure 30. Results of DOC and BDOC removal in BCF filter

Column

DOC removal

BDOC removal

BDOC/DOC (%)

NBDOC

BDOC

BAC

1.685

0.234

1.451

85

BCF

1.525

0.03

1.495

98

Table 5. Calculation results of DOC and BDOC removal in BAC and BCF filter 3.3.3.3. Quantitative analysis of Оз-BAC adsorption and biodegradation

According to the calculation method in Fig. 24, and considering the analysis of BAC, BCF biological activity and their effects on removing organics, Table 6 shows quantitative calculation results of organic matter removal by adsorption and biodegradation in BAC filter. To intuitively understand how O3-BAC biodegradation and adsorption work, Fig. 31 along with the analysis of Table 6 and Fig. 29, shows a simplified model of O3-BAC removes organics.

Column

DOC removal

BDOC removal

NBDOC

BDOC

Adsorption

0.595

0.234

0.361

Biodegradation

1.09

0

1.09

Total

1.685

0.234

1.451

Table 6. Calculation results of organic matter removal by adsorption and biodegradation in BAC filter

As shown in Fig. 31, it is conducted by the synergy effect of activated carbon adsorption and biodegradation of O3-BAC. Under the system research conditions, BAC bed biodegradation is dominant which accounts for 65% removal of total organics, furthermore, this 65% is mainly organics of BDOC, which indicates that the main organics removed by biodegradation is readily degradable dissolved organics, which can be concluded that biodegradation has a remarkable selectivity. In contrast, activated carbon adsorption plays a supporting role in the system, while via adsorption the quantity of removed difficult biodegradable material is roughly similar to the quantity of the readily one[60].

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Figure 31. Illustration of organic matter removal by BAC filter after ozonation