BAC Filter Research Articles

Study on control of micro-pollutants by BAC filtration

The objective of this research was to evaluate removal efficiency of micro-pollutants in a BAC filter that followed ozonation for long term operation. The experimental results showed that after continuous operation for one year BAC filter still maintained a removal of 15 approximately 20% for COD(Mn) and 20 approximately 30% of removal for UV(254). Correlative analysis based on lots of data found that empty bed contact time (EBCT) instead of flow rate could obviously impact on removal effect of micro-pollutants in BAC filter. And the optimal relationship between EBCT and removal effect of micro-pollutants for BAC filter was logarithm. On the other hand, long term running of BAC filter proved that there was a good removal of chloroform formation potential, but the removal of brominated trihalomethane formation potential decline with further bromization, even there appeared to be formation of bromoform in BAC filter.

A direct repeat sequence associated with the centromeric retrotransposons in wheat.

A high-density BAC filter of Triticum monococcum was screened for the presence of a centromeric retrotransposon using the integrase region as a probe. Southern hybridization to the BAC digests using total genomic DNA probes of Triticum monococcum, Triticum aestivum, and Hordeum vulgare detected differentially hybridizing restriction fragments between wheat and barley. The fragments that hybridized to genomic DNA of wheat but not to that of barley were subcloned. Fluorescence in situ hybridization (FISH) analysis indicated that the clone pHind258 hybridized strongly to centromeric regions in wheat and rye and weakly to those in barley. The sequence of pHind258 was homologous to integrase and long terminal repeats of centromeric Ty3-gypsy retrotransposons of cereal species. Additionally, pHind258 has a pair of 192-bp direct repeats. FISH analysis indicated that the 192-bp repeat probe hybridized to centromeres of wheat and rye but not to those of barley. We found differential FISH signal intensities among wheat chromosomes using the 192-bp probe. In general, the A-genome chromosomes possess strong FISH signals, the B-genome chromosomes possess moderate signals, and the D-genome chromosomes possess weak signals. This was consistent with the estimated copy numbers of the 192-bp repeats in the ancestral species of hexaploid wheat.

Performance of advanced water treatment plant for removing Fe, Mn and organic pollutants from raw water

In the case of treating a source water containing higher concentrations of Fe 2+ , Mn 2+ and organic pollutants, the Fe 2+ was partially removed by pretreatment steps of aeration-sand filtration, while Mn 2+ and organics were removed mainly by an ozonation-BAC process. The performance of the advanced treatment plant and removal mechanisms are studied in this paper. The optimal O 3 dosage and residual O 3 were found to be 4 mg l −1 and 0.4 mg l −1 , respectively, for which the Fe 2+ , Mn 2+ and COD Mn removals reached 98%, 95% and 85.5% respectively. GC/MS analytical results showed that the advanced water treatment plant was very efficient in micro-organic pollutant removal. The total species decreased from 59 in the raw water to 50, 40 and 26 in the effluents of the sand filter, ozonation column and BAC filter, respectively. The priority and potentially hazardous pollutant species decreased from 16 in the raw water to 10, 8 and 5 in the corresponding effluents, respectively.

The effect of various operating conditions and water quality parameters on the removal of perchlorate in a biologically active carbon filter

The removal of μg/L concentrations of perchlorate using biologically active carbon filtration (BAC) was investigated. Previous work has shown that BAC filtration can be a highly effective treatment process for the removal of perchlorate from drinking water. The work presented here demonstrated that perchlorate removal using BAC filtration can be inhibited by dissolved oxygen. It also showed that empty-bed contact time is a key process parameter that affects perchlorate removal in the BAC filter. Finally, it was demonstrated that BAC filtration is robust with respect to electron donor addition failure.

Biodergradability and GAC Adsorbability of Micropollutants by Preozonation

In order to evaluate the effect of preozonation on GAC adsorbability and biodegradability and to discuss the performance of BAC, three kinds of batch experiments have been conducted, using humic acid as the test substance. Conclusively, it is recognized that preozonation evidently improves the biodegradability of humic acid, but the equilibrium adsorption constant k, is not changed. However, the adsorption rate is greatly improved. Based on these results and continuous experiments, the characteristics of the removal mechanism of organics by a BAC filter and a GAC filter are compared.