Advancing Granular Activated Carbon Filtration via Microbial Inoculation: A Multitechnique Environmental Engineering Study

Effect of granular activated carbon pore-size distribution on biological activated carbon filter performance

Can we shape microbial communities to enhance biological activated carbon filter performance?

Removal of precursors of typical nitrogenous disinfection byproducts in ozonation integrated with biological activated carbon (O3/BAC)

Differentiating between adsorption and biodegradation mechanisms while removing trace organic chemicals (TOrCs) in biological activated carbon (BAC) filters

An advanced water treatment system was introduced at the Osaka Municipal Water Works Bureau in March 2000. This system incorporates ozonation and a granular activated carbon (GAC) process into conventional treatment processes, improving tap water quality. The GAC process is the last stage of the process, and it can effectively remove trihalomethane precursors and other toxic organic substances. GAC treats water through a physical adsorption effect inherent in the GAC itself, and an effect by the microorganisms in the GAC layer (called the biological activated carbon (BAC) effect). Sparse reports on long-term changes in the BAC effect make it very difficult to determine the replacement period for BAC. A long-term study of BAC water treatment performance, physical characteristics, and other factors was conducted in Osaka City in order to decide upon BAC replacement standards. 48 water quality items were checked at a demonstration plant and with an experimental device. Three patterns of deterioration in BAC water treatment performance were identified. Physical properties of BAC (5 items including adsorption capacity and hardness) were also studied, and no significant correlation with water treatment performance was found. An optimal BAC replacement standard was decided upon from this and other factors (costs, environmental influence, etc.).

Two different granular activated carbon (GAC) filters were utilized to investigate the removal efficiency of bromate and natural organic matters (NOM) during the transition from fresh GAC to the biological activated carbon (BAC). The removal efficiency of bromate, nitrate, UV254, DOC, and trihalomethane formation potential (THMFP) in GAC filter apparently decreased during the transition from fresh GAC to BAC. The high level of anions and NOM, and high pH value may slow down the bromate reduction in GAC filter, in initial period GAC filter still has a significant reduction of bromate, with a calculated average reduction rate of 71.9%. Moreover, the GAC filter demonstrated a sustainable and effective bromate reduction in long-term operation. Therefore, if suitable GAC was used, the filter can achieve a plausible bromate reduction efficiency with a long bedlife. Backwashing treatment has only a limited improvement on bromate reduction during transition from fresh GAC to BAC.

Application of biofiltration system on AOC removal: Column and field studies

Factors affecting removal of NDMA in an ozone-biofiltration process for water reuse

The objective of this study is to evaluate the adsorption capacity of BAC saturated with natural organic matter (NOM) for micropollutant removal which intermittently enter into water sources and to compare this to sand filtration that has no adsorbability but has biodegradability. The removal of intermittently applied micropollutants was examined with two BAC and sand filters. Two BAC filters which have been operated for 6 and 20 months and a sand filter being used for 6 months for the treatment of reservoir water were used in this experiment. EBCT of these BAC and sand filter were 15 minutes. Bromophenol (highly adsorbable but refractory) and phenol (adsorbable and biodegradable) were used instead of targeted micropollutants. Bromophenol and phenol of about 200 μg·l−1 were applied for 24 hours. The BAC 1, which was used for 20 months had already lost its adsorbability because it was saturated with NOM. BAC 2 filter which was used for 6 months had small adsorption capacity for NOM. As a result, either BAC 2 or BAC 1 removed bromophenol (160 μg·l−1) completely for 24 hours spike, but sand filter did not removed at all. Bromophenol can be removed only by adsorption, therefore bromophenol might be removed through adsorption by BAC. On the other hand, phenol (220 μg·l−1) whose adsorbability is lower than bromophenol, was removed completely by both BAC 1 and BAC 2. These results indicate that micropollutants with similar adsorbability as that of phenol and bromophenol can be removed by BAC even after a long period of operation and saturation with NOM.

Micropollutant removal with saturated biological activated carbon (BAC) in ozonation-BAC process

Performance of biological activated carbon (BAC) filtration for the treatment of secondary effluent: A pilot-scale study

Adsorption and biodegradation of 2-methylisoborneol and geosmin in drinking water granular activated carbon filters: A review and meta-analysis

Biological ion exchange as an alternative to biological activated carbon for natural organic matter removal: Impact of temperature and empty bed contact time (EBCT)

Effects of biological activated carbon filter running time on disinfection by-product precursor removal.

BackgroundBioanalytical tools have been shown to be useful in drinking water quality assessments. Here, we applied a panel of in vitro bioassays to assess the treatment efficiency of two pilot-scale treatments: ozonation and granular activated carbon (GAC) filtration at a drinking water treatment plant (DWTP). The pilot-scale systems were studied alongside a full-scale treatment process consisting of biological activated carbon (BAC) filtration, UV disinfection, and monochloramine dosing. Both systems were fed the same raw water treated with coagulation/flocculation/sedimentation and sand filtration. The endpoints studied were oxidative stress (Nrf2 activity), genotoxicity (micronuclei formations), aryl hydrocarbon receptor (AhR) activation, as well as estrogen receptor (ER) and androgen receptor (AR) activity.ResultsNrf2, AhR, and ER activities and genotoxic effects were detected in the incoming raw water and variability was observed between the sampling events. Compared to most of the samples taken from the full-scale treatment system, lower Nrf2, AhR, and ER bioactivities as well as genotoxicity were observed in all samples from the pilot-scale systems across all sampling events. The most pronounced treatment effect was a 12-fold reduction in Nrf2 activity and a sixfold decrease in micronuclei formations following ozonation alone. GAC filtration alone resulted in sevenfold and fivefold reductions in Nrf2 activity and genotoxicity, respectively, in the same sampling event. Higher bioactivities were detected in most samples from the full-scale system suggesting a lack of treatment effect. No androgenic nor anti-androgenic activities were observed in any sample across all sampling events.ConclusionsUsing effect-based methods, we have shown the presence of bioactive chemicals in the raw water used for drinking water production, including oxidative stress, AhR and ER activities as well as genotoxicity. The currently used treatment technologies were unable to fully remove the observed bioactivities. Ozonation and GAC filtration showed a high treatment efficiency and were able to consistently remove the bioactivities observed in the incoming water. This is important knowledge for the optimization of existing drinking water treatment designs and the utilization of alternative treatment technologies.