Effect Of Granular Activated Carbon Research Articles

Changing bioavailability of per- and polyfluoroalkyl substances (PFAS) to plant in biosolids amended soil through stabilization or mobilization

Biosolids containing per- and polyfluoroalkyl substances (PFAS) could contaminate the receiving environments once they are land applied. In this study, we evaluated the feasibility of controlling the bioavailability of PFAS in biosolids to timothy-grass through stabilization or mobilization approaches. Stabilization was accomplished by adding a sorbent (i.e. granular activated carbon (GAC), RemBind, biochar) to biosolids, while mobilization was achieved by adding a surfactant, sodium dodecyl sulphate (SDS), to biosolids. The results showed that the ΣPFAS concentration in grass shoots grown in biosolids amended soil treated by GAC or RemBind at 2% was only 2.77% and 3.35% of the ΣPFAS concentration detected in shoots grown in biosolids amended soil without a sorbent, respectively, indicating the effectiveness of GAC and RemBind for stabilizing PFAS and reduce their bioavailability. On the other hand, mobilization by adding SDS to biosolids at a dose range of 10–100 mg/kg significantly increased the plant uptake of ΣPFAS by 15.48%–108.57%. Thus, mobilization by adding SDS could be a valuable approach for enhancing the PFAS removal if phytoremediation is applied. Moreover, higher rate of PFAS uptake took place after grass cutting was observed in this study. Thus, proper mowing and regrowth of timothy-grass could lead to efficient and cost-effective removal of PFAS from biosolids amended soil through phytoremediation and leave the site clean to be used for other purposes.

Effect of granular activated carbon and other porous materials on thermal decomposition of per- and polyfluoroalkyl substances: Mechanisms and implications for water purification

Thermal treatment is routinely used to reactivate the spent granular activated carbon (GAC) from water purification facilities. It is also an integral part of sewage sludge treatment and municipal solid waste management. This study presents a detailed investigation of the fate of per- and polyfluoroalkyl substances (PFAS) and one PFAS alternative (GenX) in thermal processes, focusing on the effect of GAC. We demonstrate that the thermolysis of perfluoroalkyl carboxylic acids (PFCAs), including perfluorooctanoic acid (PFOA), and GenX can occur at temperatures of 150‒200 °C. Three temperature zones were discovered for PFOA, including a stable and nonvolatile zone (≤90 °C), a phase-transfer and thermal decomposition zone (90‒400 °C), and a fast decomposition zone (≥400 °C). The thermal decomposition began with the homolysis of a C‒C bond next to the carboxyl group of PFCAs, which formed unstable perfluoroalkyl radicals. Dual decomposition pathways seem to exist. The addition of a highly porous adsorbent, such as GAC or a copolymer resin, compressed the intermediate sublimation zone of PFCAs, changed their thermal decomposition pathways, and increased the decomposition rate constant by up to 150-fold at 250 °C. The results indicate that the observed thermal decomposition acceleration was linked to the adsorption of gas-phase PFCA molecules on GAC. The presence of non-activated charcoals/biochars with a low affinity for PFOA did not accelerate its thermal decomposition, suggesting that the π electron-rich, polyaromatic surface of charcoal/GAC played an insignificant role compared to the adsorbent's porosity. Overall, the results indicate that (1) substantial decomposition of PFCAs and GenX during conventional thermal GAC/sludge/waste treatment is very likely, and (2) the presence or addition of GAC or other highly porous materials can accelerate thermal PFAS decomposition and alter decomposition pathways.

Effects of GAC and UV/H2O2-GAC filtration on the bacterial community and opportunistic pathogens in simulated drinking water systems

The effects of granular activated carbon (GAC) and UV/H2O2-GAC filtration on the bacterial community and opportunistic pathogens (OPs) in simulated drinking water systems were investigated in this study.

Anaerobic digestion of blackwater assisted by granular activated carbon: From digestion inhibition to methanogenesis enhancement

This study investigated the effect of granular activated carbon (GAC) on the digestion of blackwater collected from different collection systems, by monitoring the biochemical methane production (BMP), adsorption of molecules to GAC and their impacts on the microbial community. Without GAC-amendment, BMP reached 35.6, 42.6 and 50.4% in 1L, 5L and 9L water-flushed blackwater, respectively. When 33.3 gL-1 GAC was added to the cultures, methane potential increased up to 53.1% in 1L water-flushed blackwater, while in 5L and 9L water-flushed conditions the BMP drastically decreased to 16.1 and 9.6%, respectively. The concentration of volatile fatty acids (VFA) in 5L and 9L water-flushed blackwater with GAC-amended cultures was not enhanced, in contrast with 1L water-flushed blackwater. Further tests showed 29.8% (±1.9%) of VFA and 86.0% of soluble chemical oxygen demand were removed by GAC adsorption in 9L water-flushed blackwater. A decrease in biomass density in 5L and 9L GAC-amended cultures was also observed, corroborated by a significant decrease in gene copy numbers of methanogenic archaeal communities. This study gives an insight on the effect of GAC on different strengths of blackwater, which is of relevance for further tests of long-time and full-scale application.

Membrane fouling and performance of anaerobic ceramic membrane bioreactor treating phenol- and quinoline-containing wastewater: granular activated carbon vs polyaluminum chloride.

Although anaerobic membrane bioreactor (AnMBR) has been proposed for the treatment of phenolic wastewater, the membrane fouling is still a major obstacle. The effects of dosing of granular activated carbon (GAC) and polyaluminum chloride (PACl) on the treatment performance and membrane fouling of anaerobic ceramic membrane bioreactor were investigated for treating phenol- and quinoline-containing wastewater. The results suggested that the one-off dosing of GAC resulted in a decrease of protein/carbohydrate ratio, which might account for the aggravation of membrane fouling alongside with the decreased flocs size. Nevertheless, the substrate uptake rates (SUR) of phenol and quinoline, and the specific methanogenic activity of sludge at the GAC dosing stage of experimental reactor (R1) were 8.79 ± 0.63mg phenol g-1 MLVSS d-1, 7.01 ± 0.09mg quinoline g-1 MLVSS d-1 and 0.27 ± 0.01g CODCH4 g-1 MLVSS d-1, which were 1.69, 3.59 and 1.93 times higher than that of the control reactor (R2). The dosing of PACl reduced the membrane fouling rate by changing the floc structure of sludge, as well as the component of SMP and EPS. However, the substrate uptake rate of quinoline was declined. This work provides a comprehensive evaluation on the effect of GAC and PACl dosing on membrane fouling and performance of anaerobic ceramic membrane bioreactor treating phenol-and quinoline-containing wastewater.

Effect of granular activated carbon concentration on the content of organic matter and salt, influencing E. coli activity and survival in fluidized bed disinfection reactor.

Granular activated carbon (GAC) is used in water treatment systems, typically to remove pollutants such as natural organic matter, volatile organic compounds, chlorine, taste, and odor. GAC is also used as a key component of a new technology that combines a fluidized bed reactor with radio frequency electric fields for disinfection. So far, the effects of GAC on bacteria in these fluidized bed reactors are unclear. This paper describes a systematic study of the physico-chemical changes in five microbial media compositions caused by different concentrations (23-350 g/L) of GAC, and the effects of these physico-chemical changes on the metabolic activity and survival of a model microorganism (Escherichia coli YMc10) in a fluidized bed reactor. The chemical adsorption taking place in suspensions with specific GAC changed nutritional, osmotic, and pH conditions in the investigated microbial media (LB, diluted LB, PBS, diluted PBS, and tap water), leading to a decay of the metabolic activity and survival of E. coli. Especially media that are poor in organic and mineral compounds (e.g., PBS) with suspended GAC showed a concentration decay of 3.5 Log CFU/mL E. coli after 6 h. Organic compounds depletion and severe pH variation were enhanced in the presence of higher GAC concentrations.

Pretreatment of Textile Dye Carriers with Ozonation and Enhanced Ozonation

The chemical treatability of a nonbiodegradable textile dye carrier by single ozonation and ozonation enhanced by ferrous iron salt (FeSO4 · 7H2O) and granular activated carbon (GAC) addition has been reported. First, the single effects of Fe2+ and Fe3+ salts (100–1,000 mg L-1 at pH = 11) and GAC (1–10 g L-1 at pH = 3) addition have been examined to explain their effects in combination with ozone. Thereafter, t he investigated pollutant has been subjected to oxidative treatment via direct ozonation at pH = 3 (the natural pH of carrier added textile dye-baths) to reduce its chemical oxygen demand (COD) and thereby to improve its biodegradability in terms of the 5-day biochemical oxygen demand (BOD5), which is a useful sum parameter for biological treatability evaluation. A kinetic study was also conducted in which time-dependent changes in COD as well as in outlet partial ozone pressure have b een measured throughout the ozonation process. These have been used to determine kCOD, the bimolecular reaction rate constant for COD abatement that has been found as 81 M-1 min-1 . Finally, it could established that the addition of only 1 mM (56 mg L-1) Fe2+ considerably enhanced COD abatement, speculatively by acting as a redox catalyst, whereas the effect of GAC was rather additive. The biodegradability of the textile dye c arrier (initial BOD5 ≈ 0) increased to 70, 109, and 140 mg L-1 after oxidative treatment with O3, Fe(II)/O3, and GAC/O3, respectively, supporting the possibility of chemical pretreatment with enhanced ozonation process at reasonable ozone doses (0.7 mgO3 mg L -1 CODo).

Using RSSCTs to predict field‐scale GAC control of DBP formation

For this water, the laboratory‐based RSSCTs effectively predicted the field‐scale behavior of three types of GACs for controlling DBPs.The primary objective of this study was to evaluate the use of the rapid small‐scale column test (RSSCT) for predicting the control of disinfection by‐product (DBP) formation by granular activated carbon (GAC). DBP formation was assessed by using a simulated distribution system (SDS) test and measuring trihalomethanes and total organic halide in the influent and effluent of the laboratory‐ and field‐scale columns. It was observed that for the water studied, the RSSCTs effectively predicted the nonadsorbable fraction, time to 50 percent breakthrough, and the shape of the breakthrough curve for DBP formation. The advantage of RSSCTs is that conclusions about the amenability of a GAC for DBP control can be reached in a short time period instead of at the end of a long‐term pilot study. The authors recommend that similar studies be conducted with a range of source waters because the effectiveness of GAC is site‐specific.