Activated Carbon Treatment Research Articles

Nitrogen doped carbon for Pd-catalyzed hydropurification of crude terephthalic acid: roles of nitrogen species.

The purification of crude terephthalic acid was performed by the hydrogenation of 4-carboxybenzaldehyde (4-CBA) over activated carbon (AC) supported Pd catalysts in industry. However, traditional Pd/AC catalysts usually suffer from low hydrogenation activity and poor thermal stability. Herein, nitrogen was incorporated into AC via a simple hydrothermal treatment of AC with urea as the nitrogen resource. The N doped AC contained pyridinic N, pyrrolic N, graphitic N and oxidized N. Wide characterizations revealed that N doping not only effectively improved the dispersion of Pd NPs but also increased the proportion of Pd0. In addition, N doping also enhanced the dissociative adsorption capacity of molecular hydrogen. More importantly, the resistance to sintering of Pd NPs was efficiently suppressed after N doping. As a result, N doped AC supported Pd showed both higher activity and better thermal stability than the N-free one.

Disinfection byproduct formation from algal organic matters after ozonation or ozone combined with activated carbon treatment with subsequent chlorination

Algal organic matter (AOM), including extracellular organic matter (EOM) and intracellular organic matter (IOM) from algal blooms, is widely accepted as essential precursors of disinfection byproducts (DBPs). This study evaluated the effect of ozonation or ozone combined with activated carbon (O3-AC) treatment on characteristic alternation and DBP formation with subsequent chlorination of Chlorella sp.. The effects of pH and bromide concentration on DBP formation by ozonation or O3-AC treatment were also investigated. Results showed that the potential formation of DBPs might be attributed to ozonation, but these DBP precursors could be further removed by activated carbon (AC) treatment. Moreover, the formation of target DBPs was controlled at acidic pH by alleviating the reactions between chlorine and AOM. Besides, the bromide substitution factor (BSF) value of trihalomethanes (THMs) from EOM and IOM remained constant after AC treatment. However, THM precursors could be significantly decreased by AC treatment. The above results indicated that O3-AC was a feasible treatment method for algal-impacted water.

Impaired benthic macrofauna function 4\xa0years after sediment capping with activated carbon in the Grenland fjords, Norway

The sediments in the Grenland fjords in southern Norway are heavily contaminated by large emissions of dioxins and mercury from historic industrial activities. As a possible in situ remediation option, thin-layer sediment surface capping with powdered activated carbon (AC) mixed with clay was applied at two large test sites (10,000 and 40,000 m2) at 30-m and 95-m depths, respectively, in 2009. This paper describes the long-term biological effects of the AC treatment on marine benthic communities up to 4 years after treatment. Our results show that the capping with AC strongly reduced the benthic species diversity, abundance, and biomass by up to 90%. Vital functions in the benthic ecosystem such as particle reworking and bioirrigation of the sediment were also reduced, analyzed by using novel bioturbation and bioirrigation indices (BPc, BIPc, and IPc). Much of the initial effects observed after 1 and 14 months were still present after 49 months, indicating that the effects are long-lasting. These long-lasting negative ecological effects should be carefully considered before decisions are made on sediment remediation with powdered AC, especially in large areas, since important ecosystem functions can be impaired.

Overview of pretreatment methods employed on oil palm biomass in producing value-added products: A review

Oil palm biomass is readily available in Malaysia. However, its high lignin content makes it undesirable for further processing. Pretreatment is employed to reduce the amount of lignin. Many resources exist on pretreatment methods for lignocellulosic biomass, but there are few articles specifically on oil palm biomass. Therefore, this review focuses on pretreatment methods for oil palm biomass, comparing their main strengths and limitations. Furthermore, this review tabulates different pretreatment conditions utilized, combinations of pretreatment methods, the resulting yields, and the potential applicability in producing value-added products. Because the main limitation of pretreatment is the formation of toxic compounds such as furfural and hydroxymethylfurfural, this review also discusses chemical detoxification methods for oil palm biomass residues. According to this review, among all types of oil palm biomass, oil palm empty fruit brunch is the most widely studied, and alkaline pretreatment is the most popular of all pretreatment methods. Combination of pretreatment methods is suitable for biomass with greater lignin content, to increase delignification efficiency. Furthermore, a combination of overliming and activated carbon treatment removes the maximum amount of toxic by-products.

Enhancing inhibition of disinfection byproducts formation and opportunistic pathogens growth during drinking water distribution by Fe2O3/Coconut shell activated carbon.

The effects of biological activated carbon treatment using Fe2O3 modified coconut shell-based activated carbon (Fe/CAC) were investigated on the occurrence of opportunistic pathogens (OPs) and formation of disinfection by-products (DBPs) in simulated drinking water distribution systems (DWDSs) with unmodified CAC as a reference. In the effluent of annular reactor (AR) with Fe/CAC, the OPs growth and DBPs formation were inhibited greatly. Based on the differential pulse voltammetry and dehydrogenase activity tests, it was verified that extracellular electron transfer was enhanced in the attached biofilms of Fe/CAC, hence improving the microbial metabolic activity and biological removal of organic matter especially DBPs precursors. Meanwhile, the extracellular polymeric substances (EPS) on the surface of Fe/CAC exhibited stronger viscosity, higher flocculating efficiency and better mechanical stability, avoiding bacteria or small-scale biofilms falling off into the water. Consequently, the microbial biomass and EPS substances amount decreased markedly in the effluent of Fe/CAC filter. More importantly, Fe/CAC did significantly enhance the shaping role on microbial community of downstream DWDSs, continuously excluding OPs advantage and inhibiting EPS production. The weakening of EPS in DWDSs resulted in decrease of microbial chlorine-resistance ability and EPS-derived DBPs precursors supply. Therefore, the deterioration of water quality in DWDSs was inhibited greatly, sustainably maintaining the safety of tap water. Our findings indicated that optimizing biological activated carbon treatment by interface modification is a promising method for improving water quality in DWDSs.

Genotoxic activities of wastewater after ozonation and activated carbon filtration: Different effects in liver-derived cells and bacterial indicators

Aim of this study was to investigate the impact of advanced wastewater treatment techniques (combining ozonation with activated carbon filtration) on acute and genotoxic activities of tertiary treated wastewater. Concentrated samples were tested in Salmonella/microsome assays. Furthermore, induction of DNA damage was measured in liver-derived cells (human hepatoma and primary rat hepatocytes) in single cell gel electrophoresis experiments, which are based on the measurement of DNA migration in an electric field. These cell types possess phase I and phase II enzymes, which catalyze the activation/detoxification of mutagens. Acute toxicity was determined with the trypan blue exclusion technique. We found no evidence for mutagenic effects of non-ozonated samples in several bacterial tester strains (TA98, TA100, YG7108, YG7104, YG7112 and YG7113) but clear induction of His+ mutants after O3 treatment in two strains with defective genes encoding for DNA repair, which are highly sensitive towards alkylating agents (YG7108 and YG7104). These effects were reduced after activated carbon filtration. Furthermore, we detected a slight increase of mutagenic activity in strain YG1024 with increased acetyltransferase activity, which is sensitive towards aromatic amines and nitro compounds in untreated water, which was not reduced by O3 treatment. A completely different pattern of mutagenic activity was seen in liver-derived cells; non ozonated samples caused in both cell types pronounced DNA damage, which was reduced (by ca. 25%) after ozonation. Activated carbon treatment did not cause a substantial further reduction of DNA damage. Additional experiments with liver homogenate indicate that the compounds which cause the effects in the human cells are promutagens which require enzymatic activation. None of the waters caused acute toxicity in the liver-derived cells and in the bacterial indicators. Assuming that hepatic mammalian cells reflect the genotoxic properties of the waters in vertebrates (including humans) more adequately as genetically modified bacterial indicators, we conclude that ozonation has beneficial effects in regard to the reduction of genotoxic properties of treated wastewaters.

Enhancement in xylonate production from hemicellulose pre-hydrolysate by powdered activated carbon treatment

Xylonic acid can be produced with high-yield from hemicelullosic xylose, which accounts for 25% of the total sugars in lignocellulosic material. The key barrier associated with efficient bio-oxidation of hemicellulosic xylose to xylonic acid is the serious foam formed in downstream air-aerated and agitated bioreaction process, which caused by the high viscosity of concentrated pre-hydrolysate. Powdered activated carbon treatment can selectively absorb the non-sugar compounds with relatively low losses of xylose, which is beneficial for the valuable xylose derivatives production. In this present study, powdered activated carbon was employed for treating the concentrated pre-hydrolysate from diluted acid pretreated corncob. The results indicated that the powdered activated carbon treatment significantly reduced the viscosity of concentrated pre-hydrolysate and the other non-sugar compounds, which enabled scale-up lignocellulosic xylonic acid production using the air-aerated and agitated bioreactor.

Chlorothalonil transformation products in drinking water resources: Widespread and challenging to abate

Chlorothalonil, a fungicide applied for decades worldwide, has recently been banned in the European Union (EU) and Switzerland due to its carcinogenicity and the presence of potentially toxic transformation products (TPs) in groundwater. The spread and concentration range of chlorothalonil TPs in different drinking water resources was examined (73 groundwater and four surface water samples mainly from Switzerland). The chlorothalonil sulfonic acid TPs (R471811, R419492, R417888) occurred more frequently and at higher concentrations (detected in 65–100% of the samples, ≤2200 ngL−1) than the phenolic TPs (SYN507900, SYN548580, R611968; detected in 10–30% of the samples, ≤130 ngL−1). The TP R471811 was found in all samples and even in 52% of the samples above 100 ngL−1, the drinking water standard in Switzerland and other European countries. Therefore, the abatement of chlorothalonil TPs was investigated in laboratory and pilot-scale experiments and along the treatment train of various water works, comprising aquifer recharge, UV disinfection, ozonation, advanced oxidation processes (AOPs), activated carbon treatment, and reverse osmosis. The phenolic TPs can be abated during ozonation (second order rate constant kO3 ∼104 M−1s−1) and by reaction with hydroxyl radicals (OH) in AOPs (kOH ∼109 M−1s−1). In contrast, the sulfonic acid TPs, which occurred in higher concentrations in drinking water resources, react only very slowly with ozone (kO3 <0.04 M−1s−1) and OH (kOH <5.0 × 107 M−1s−1) and therefore persist in ozonation and OH-based AOPs. Activated carbon retained the very polar TP R471811 only up to a specific throughput of 25 m3kg-1 (20% breakthrough), similarly to the X-ray contrast agent diatrizoic acid. Reverse osmosis was capable of removing all chlorothalonil TPs by ≥98%.

Multi-step purification method of water-soluble oligosaccharides produced from hardwood and softwood

Abstract Pressurized hot water pretreatment was performed on softwood (SW) and hardwood (HW) chips following the same conditions (1 h at 170 °C) in order to partly hydrolyse hemicelluloses. The complete characterization of these sugar enriched autohydrolysates (AH) being rather complex, two different purification methods were conducted. Nanofiltration (NF) 1kDa membrane and ultrafiltration (UF) 3 and 5kDa membranes were used to separate oligosaccharides (OS) from undesired compounds and for their molar mass fractionation. Granulated activated charcoal (GAC) adsorption was also used for hydrolysates detoxification. The chemical nature of OS and side charge groups vary significantly depending of the fractions obtained, e. g. xylans' chain length is positively correlated with the degree of acetylation. UF at 5kDa allows for the total separation of galactoglucomannans (GGMs) from xylans, in SW AH, however, this result was not achieved with HW. From the acid soluble lignin (ASL) removal point of view, membrane filtration from 1kDa is more efficient than activated carbon treatment concerning HW AH, on the contrary to SW AH. Regarding the lignin to OS ratio, for both species, GAC leads to a better sugar purity.

Removal of bacterial growth inhibition of anticancer drugs by using complexation materials

AbstractIn the context of batch production of cytotoxic drugs in hospital pharmacies with the need of sterility testing, the objective was to validate the use of Rapid Microbiological Method (RMM), and to develop adequate neutralization method in case of inhibition of bacterial growth. The potential microbiological growth inhibitory effect of three anticancer drugs (5 fluorouracil, irinotecan and oxaliplatin) selected for batch production was assessed on BacT/ALERT® system. Among cytotoxic drugs, only 5FU exhibited inhibitory effect on microbiological growth using rapid microbiological method. To counteract this effect our purpose was to use neutralizing agents complexing the drug i. e. activated carbon or ion exchange resins. The microbiological bactericidal concentration of 5FU was very low (1.10–4 mg/mL) indicating the absolute need to neutralize the whole drug before sterility test. The complexation was validated by High Performance Liquid Chromatography control of the residual 5FU concentration in solution after the use of neutralizing agents. Only activated carbon was able to fully capture 5FU when previously diluted at 5 mg/mL. Conversely, the resins, in the condition of the study, were not able to fully capture 5FU whatever the dilution. The microbiological growth on BacT/ALERT® system after active carbon treatment was successfully confirmed with Staphylococcus aureus. Based on this validation results a method was then developed to routinely be able to perform sterility test of the batches produced and was confirmed on five microbiological species (i. e. S. aureus, Pseudomonas aeruginosa, Bacillus subtilis, Candida albicans, Aspergillus brasiliensis). Our work gives a new insight for considering sterility testing by rapid microbiological method even for drugs exhibiting inhibitory effect on microbiological growth.

Removal of typical pollutants from water sources of Chouara Tannery by the integration of coagulation–flocculation and activated carbon treatment

Removal of typical pollutants from water sources of Chouara Tannery by the integration of coagulation–flocculation and activated carbon treatment

Pilot-scale ozone/biological activated carbon treatment of reverse osmosis concentrate: potential for synergism between nitrate and contaminant removal and potable reuse

Reverse osmosis treatment for potable reuse can reduce the cost for removing nitrate and contaminants from wastewater prior to discharge.

Role of the air-water interface in removing perfluoroalkyl acids from drinking water by activated carbon treatment

Contamination of drinking water by per- and polyfluoroalkyl substances (PFASs) is a worldwide problem. In this study, we for the first time revealed the role of the air-water interface in enhancing the removal of long-chain perfluoroalkyl carboxylic (PFCAs; CnF2n+1COOH, n ≥ 7) and perfluoroalkane sulfonic (PFSAs; CnF2n+1SO3H, n ≥ 6) acids, collectively termed as perfluoroalkyl acids (PFAAs), through combined aeration and adsorption on two kinds of activated carbon (AC). Aeration was shown to enhance the removal of long-chain PFAAs through adsorption at the air-water interface and subsequent adsorption of PFAA-enriched air bubbles to the AC. The removal of selected long-chain PFAAs was increased by 50–115 % with the assistance of aeration, depending on the perfluoroalkyl chain length. Aeration is more effective in enhancing long-chain PFAA removal as air-water interface adsorption increases with PFAA chain length due to higher surface activity. After removing adsorbed air bubbles by centrifugation, up to 80 % of the long-chain PFAAs were able to desorb from the sorbent, confirming the contribution of the air-water interface to the adsorption of PFAAs on AC. Aeration during AC treatment of water could enhance the removal of long-chain PFAAs, and improve the performance of AC during water treatment.

Behavior of PBTC, HEDP, and Aminophosphonates in the Process of Wastewater Treatment

Ten times at intervals of 1–2 months, individual treatment stages of two wastewater treatment plants (WWTPs) were analyzed for the five quantitatively most widely used phosphonates. The total dissolved concentration of the investigated phosphonates in the influents was between 131 µg/L and 384 µg/L. The nitrogen-free phosphonates 2-phosphonobutane-1,2,4-tricarboxylic acid (PBTC) and 1-hydroxyethylidene(1,1-diphosphonic acid) (HEDP) accounted for an average proportion of 83–85%. Diethylenetriaminepenta(methylene phosphonic acid) (DTPMP) contributed with 13–14%, whereas aminotris(methylphosphonic acid) (ATMP) (≤15 µg/L) and ethylenediaminetetra(methylene phosphonic acid) (EDTMP) (≤11 µg/L) contents detected in the WWTP influents were comparatively low. The application of new analytical methods allowed the quantification of phosphonates in the solid fraction of the WWTP influents for the first time. High loads of phosphonates were determined (223–2555 mg/kg), indicating that 20%–80% of the phosphonates are present in the adsorbed state. The removal of total dissolved phosphonate by secondary clarification was between 69.7% and 92.4% (medians: 90.7% and 87.7%). In both WWTPs, HEDP (medians: 89.2% and 86.4%) was slightly better eliminated than PBTC (medians: 87.2% and 82.5%). In the sand filtration stage of a WWTP, the average removal was not further improved. In contrast, an additional removal of dissolved phosphonates could be achieved by activated carbon treatment (median: 96.4%). The proportion of phosphonate-P in the dissolved unreactive phosphorus fraction was consistently between 10% and 40% throughout all treatment stages.

Combined Treatments Consisting of Calcium Hydroxide and Activate Carbon for Purification of Xylo-Oligosaccharides of Pre-Hydrolysis Liquor.

In this study, the effect of a combined treatment consisting of calcium hydroxide (CH) followed by activated carbon (AC) on the purification of hemicellulose in the pre-hydrolysis liquor (PHL) from pulping process has been evaluated. The results show that lignin and furfural of PHL are efficiently removed, and the lignin removal is achieved by forming complexes onto CH particles in the CH treatment process, while acetic acid (acetate) is formed from the hydrolysis of acetyl groups present in the dissolved hemicelluloses in the PHL. The loss of xylo-oligosaccharides (XOS) is moderate, even at a high CH dosage of 0.8% while the xylose concentration is essentially unchanged. For the AC treatment, the optimal treating pH can enhance the interactions between AC and residual lignin and change the zeta potential of AC resulting in improved lignin adsorption onto AC. An increase of AC dosage has the tendency to adsorb more XOSDP>6 than XOSDP2~6. Overall, 66.9% of lignin and 70.1% of furfural removals are achieved under the optimal conditions of CH and AC treatment process, with a 5.9% total xylosugars loss. The present combination of CH and AC treatment process was more effective and selective for purification of xylosugars of PHL.

Study on the reuse of anaerobic digestion effluent in lactic acid production

Abstract A novel process for reuse of anaerobic digestion effluent in lactic acid fermentation was investigated to resolve wastewater pollution in lactic acid industry. A series of experiments were performed and the results showed that anaerobic digestion effluent directly reused did not affect liquefaction of raw materials, but inhibited lactic acid fermentation instead. Further experimental studies proved that excess ammonia-nitrogen, Zn2+, Fe2+, S and Mn2+ in the anaerobic digestion effluent could inhibit lactic acid fermentation and their corresponding critical inhibition concentrations were 100 mg/L, 1 mg/L,1 mg/L, 2.5 mg/L and 1 mg/L, respectively. In this paper, the activated carbon treatment was adopted to process the anaerobic digestion effluent, and these inhibitors had been effectively removed. The removal rate of metal ions reached 75%, and that for ammonia-nitrogen was over 80%. Application of the treated anaerobic digestion effluent in lactic acid fermentation, there was 129.59 ± 3.13 g/L of lactic acid, which was comparable to the control (130.09 ± 2.12 g/L). This new process is of significance to the realization of no-waste manufacturing, energy saving and emission reduction in lactic acid industry. It can be concluded that a cleaner way to produce lactic acid is realized.

Process and development of ozone-biological activated carbon treatment for micro-polluted raw water

The basic principle and process flow of ozone-biological activated carbon treatment of micro-polluted source water were analyzed, and the application of the method at home and abroad was introduced. Some problems that need to be paid attention to when applying the method were put forward. The results show that ozone-activated carbon water purification technology can effectively remove organic matter and ammonia nitrogen in water. It also has good removal effect on inorganic reducing substances, chroma and turbidity in water. Moreover, the mutagenic activity of effluent can be effectively reduced to ensure the safety of drinking water. Some problems which should be attended are prompted when this technique is in application in the paper. It is a water purification technology worth promoting.

Resolving DOAC interference on aPTT, PT, and lupus anticoagulant testing by the use of activated carbon

BackgroundDirect oral anticoagulants (DOACs) affect laboratory coagulations tests. Activated carbon (AC) can be used for adsorption of DOACs during acute human intoxications. ObjectivesThis study evaluates whether AC can also be used to resolve DOAC interference on in vitro clotting tests (prothrombin time [PT], activated partial thromboplastin time [aPTT], and lupus anticoagulant [LA] assays). Patients/MethodsInterference on PT, aPTT, Liquid anti‐FXa, DTI, and LA screening/confirmation (SCT and dRVVT) was determined by spiking citrated plasma from 5 adult controls with 0, 20, 40, 80, 120, or 160 mg/mL AC. DOAC concentrations, PT, and aPTT were compared before and after AC addition to citrated plasma from patients receiving DOACs (n = 29), low molecular weight heparin (n = 10), and coumarin (n = 10) therapy. Samples from 69 LA screened patients were compared before and after AC addition. ResultsA concentration of 20 mg/mL AC had the lowest interference and was selected for further experiments. After AC addition, all DOAC concentrations were below the limit of quantification in the 29 treated patients, except for 2 apixaban samples. AC removed DOAC interference on PT and aPTT but had no impact on results obtained during coumarin or low molecular weight heparin therapy. Of 15 LA samples with interference resulting from DOAC therapy, 14 samples became negative and 1 positive after AC addition. Interference from coumarin therapy was not resolved. All 19 LA negative samples remained negative. AC treatment of the negative pooled plasma was required to avoid false‐negative LA results in 21 known LA‐positive samples. ConclusionsAC selectively removes DOAC interference on PT, aPTT, and LA assays.

Organic micropollutant desorption in various water matrices - Activated carbon pore characteristics determine the reversibility of adsorption

The adsorption of organic micropollutants (OMP) onto activated carbon (AC) in real waters is strongly affected by dissolved organic matter (DOM). This study examines the impact of DOM quantity and composition in terms of OMP desorption from different AC, by using four different water samples. In batch tests, an OMP concentration drop in the influent of an AC treatment system was simulated. These tests were conducted with six AC products with different internal pore structures. The tests were evaluated with respect to the extent of OMP desorption by interpreting corresponding OMP adsorption and desorption isotherms. For each tested AC and each evaluated OMP the isotherms in the different water samples were qualitatively very similar. Thus, despite different DOM composition very similar OMP desorption extents can be expected in different waters. Among the AC products a clear trend can be seen in all waters, namely that increasing pore size results in increasing desorption. The OMP desorption extent was quantified by a simple Freundlich equation-based approach, expressing the relative position of corresponding adsorption and desorption isotherms via the ratio KF, Des/KF, Ads. Plotting KF, Des/KF, Ads of any given substance for the different tested AC in one water over the average AC pore size shows a linear correlation. This confirms that the OMP desorption extent in real waters is strongly impacted by the AC pore structure. Furthermore, it indicates that the average AC pore size might be a good tool to assess the vulnerability of treatment systems towards desorption.

Bitterness of fish protein hydrolysate and its debittering prospects.

Fish processing by-products often generated as discard can enzymatically be processed into a product known as fish protein hydrolysates (FPH). FPH is a good source of amino acid and peptides with bioactivities. FPH can be added to foods to improve nutritive values and bioactivities. However, bitterness in FPH, associated with hydrophobicity, degree of hydrolysis, molecular weight, proline residues, type of enzymes, and amino acid sequences has limited its uses in foods. Thus, FPH is used in foods at low levels. Numerous procedures such as extraction with alcohol, activated carbon treatment, Maillard reaction, cyclodextrin, chromatographic separation, and enzymatic hydrolysis with exopeptidase and plastein reaction have been explored to remove the bitterness of FPH. These methods can lower bitterness and improve its taste. However, changes in structure and loss of some peptides may occur. FPH with less or no bitterness can thereforebe used at higher levels to alleviate nutrition deficiencies in foods. PRACTICAL APPLICATIONS: Fish protein hydrolysate (FPH) is a nutritive ingredient, which can be produced from fish processing by-products. However, bitterness in FPH has limited its potential use as a nutritive ingredient. As a result, it is incorporated into foods at low levels. Nevertheless, application of several reported debittering processes could assist to solve the problem of bitterness in FPH. The debittering can improve sensory property of FPH, thus widening its utilization.