Activated Carbon Column Research Articles

Enzymatic syntheses of glucobioses by a condensation reaction with .ALPHA.-glucosidase, .BETA.-glucosidases and glucoamylase.

Various glucobioses were synthesized enzymatically by two procedures, an incubation of a highly concentrated solution of D-glucose in the presence of glycosidases (batch method reaction), and the other is circulation of highly concentrated D-glucose solution through an immobilized glycosidase column and an activated carbon column connected in series (column method reaction). The composition of disaccharides differed with the difference of reaction methods and with the kind of glycosidases. A similar reaction was also done with glucoamylase and the factors controlling the regioselectivity of the reaction with the differences of enzyme or with the differences of the procedures are discussed.

Biological treatment of potato processing wastewaters

A bench-scale laboratory study was conducted to determine the performance of the single-stage treatment system of powdered activated carbon activated sludge reactors and the two-stage treatment system using activated sludge reactors followed by the biological activated carbon columns. Two activated sludge reactor runs and two biological activated carbon (BAC) column runs were conducted in this study. Hydraulic detention time in the aeration tank was 8, 16, and 32 hours for the activated sludge reactor runs. In run 2,4 g/1 of powdered activated carbon (PAC) were added to the activated sludge reactors to improve organic pollutant removal. The feed COD (chemical oxygen demand) was from 2668 to 3309 mg/1. For the BAC runs, the hydraulic detention time varied from 0.288 to 4.034 hours. Results indicate that 92% of COD was removed in the non-PAC activated sludge reactors, while 96% of COD was removed in the PAC activated sludge reactors. Biomass accumulation in the BAC columns improved the COD removal. Effluents from BAC columns contained 34 to 95 mg/1 COD. The two-stage treatment system of activated sludge followed by BAC process had better treatment performance than the single-stage treatment system of PAC activated sludge process.

GC‐MS analysis of odorous emissions from the dissolved air flotation units treating surplus activated sludge at a wastewater treatment works

Odorous air from the dissolved air flotation (DAF) unit of a wastewater treatment plant was scrubbed through an activated carbon column and air samples analysed by gas chromatographic‐mass spectrometric techniques. Chromatographic profiles of the gases emitted at the DAF units were obtained. Compounds identified included mainly the aliphatic hydrocarbons from C9 to C14. The odorous compounds detected were toluene, meta‐, para‐ and ortho‐xylenes, phenol, dimethyl disulphide and dimethyl trisulphide, alkyl benzenes and chlorinated hydrocarbons such as chloroethylene and chlorobenzenes. Phenol and toluene were found to be the most dominant compounds detected.

Use of an activated carbon column for the synthesis of disaccharides by use of a reversed hydrolysis activity of ?-galactosidase

An activated carbon column was utilized for the synthesis of disaccharides by use of a reversed hydrolysis activity of an immobilized β-galactosidase column in order to shift the equilibrium to the direction of condensation. The yields of lactulose and allo-lactulose from galactose and fructose, and N-acetyl lactosamine and N-acetyl allolactosamine from galactose and N-acetyl glucosamine, were 11.3% and 10.0%, respectively.

Identification of odorous gases originating from refuse waste

The complex mixture of gaseous compounds emitted from refuse wastes was scrubbed through an activated carbon column until odor breakthrough occurred. Refuse air samples were collected at the influent and effluent ports of the column for analysis on a gas chromatograph-mass spectrometer system. Sampling techniques involved the concentration of gaseous volatiles on Tenax GC adsorption tubes prior to thermal desorption onto a capillary fused-silica column for compound separation. Separated compounds were scanned by a quadrapole mass selective detector and compounds were matched against a library of mass spectra and available gas standards. Results indicated that the typical odorous gases emitted from refuse waste consisted mainly of carboxylic acids and some S compounds. Sensory tests revealed that a sweetish odor was associated with the carboxylic acids which eluted from the carbon column first.

Adsorption and Microbiological Mechanisms for Removal of Natural Organics in Granular Activated Carbon Columns

Abstract Performance data for GAC columns treating surface water are analyzed to determine the relative importance of physical adsorption and biological activity, with and without pre-ozonation. Kinetic and equilibrium adsorption parameters for the source water are used in the Homogeneous Surface Diffusion model to predict GAC performance over 83 weeks. The model underestimates removal of TOC for ozonated and unozonated streams by 46% and 28%, respectively, which is attributed to omission of biological removal in the model.

Formation and Fate of Bromoform During Desalination

The objectives of this study were to evaluate the formation and fate of bromoform (one of the regulated trihalomethanes) in pretreatment systems at a pilot-scale desalination facility operated to evaluate various reverse osmosis (RO) systems for desalting seawater. The various RO units being tested at the facility were also assessed with regard to their capabilities for rejecting bromoform. The results show that bromoform is produced in significant quantities when raw seawater is chlorinated, and that the bromoform concentration increases through the various pretreatment processes in use at the facility with the exception of the activated carbon columns. The cellulose triacetate hollow fine fiber RO membranes do not reject bromoform, and bromoform concentrations in the RO permeate are higher than those in the feed water to the RO units. The polyether/urea and polysulfone thin film spiral wound membranes did reject bromoform effectively.

Bilayer film model for the interaction between adsorption and bacterial activity in granular activated carbon columns part I: Formulation of equations and their numerical solutions

AbstractThe diffusion‐reaction film model proposed by Andrews and Tien (1981) for the interaction between adsorption and bacterial activities in carbon columns was generalized. The microbial film was assumed to be composed of two regions of distinctively different microbial activity, depending on the presence or absence of dissolved oxygen. Governing equations were derived to describe the dynamics of the carbon columns in which the interaction between adsorption and bacterial growth and methods for solving these equations were developed.

Bilayer film model for the interaction between adsorption and bacterial activity in granular activated carbon columns part II: Experiment

AbstractExperiments were conducted on the degradation of valeric acid in aqueous solutions by bacteria in attached growth and on the removal of valeric acid from aqueous solutions in granular activated carbon columns. The first type of experiment was intended to obtain results necessary to determine the values of the relevant parameter of biofilm kinetics. These parameters were then used in conjunction with the model developed in Part I to predict the performance of carbon columns for removing valeric acid. Comparisons between experiments and predictions constitute the necessary model validation.

Distribution profiles of chloroform, weak organic acids, and PCBs on granular activated carbon columns from Waterford, New York

Profiles are given for the distribution of chloroform, weak organic acids, and polychlorinated biphenyls (PCBs) on granular activated carbon (GAC) samples from four pilot columns, placed in series and operated for 26 weeks at Waterford, NY. Chloroform and the weak organic acids are found at or near saturation through most of the GAC system, whereas the PCBs are accumulated only at the inlet. The extent of saturation achieved by these compounds is consistent with differences in their mass inputs and GAC capacities. However, irregularities in adsorption of these substances are evident in localized depletions of chloroform and the weak organic acids at the inlet to the system. Displacement of chloroform from the GAC inlet after 26 weeks' operation is confirmed by analysis of breakthrough data for the trihalomethanes.

Removal of hydrocarbons from Nile water

The need to remove hydrocarbons from water supply sources raises questions on the efficiency of the present water treatment processes in removing hydrocarbons. Therefore, the effectiveness of physicochemical processes involving chlorination, chemical coagulation and sand filtration were investigated. The effect of variable filtration media was also examined. In addition, the use of an activated carbon column was considered, and the effect of different retention times was evaluated. Results of this study showed that chemical coagulation using alum and Nalco removed only 32% of the total hydrocarbons and 80% of turbidity. Use of sand and a mixture of anthracite and sand filters showed additional removal of hydrocarbons and turbidity during the continuous filtration process. Increasing the anthracite depth relative to the total effective filtration depth increases the efficiency of the filter. Adsorption on granular activated carbon was shown to be an effective means for the removal of hydrocarbons. Results obtained indicated that the carbon adsorption capacity increases linearly as the retention time increases.

Amylase inhibitors produced by Streptomyces sp. No. 280.

Fourteen kinds of amylase inhibitor (AI) were obtained by active carbon column chromatography and other procedures. The molecular weights of the AIs were estimated to be 310 ~ 1300 by gel filtration. They seem to have 1 ~ 4 glucose residues and one nitrogen per molecule. All the AIs have almost the same inhibitory activitagainst glucoamylase. High molecular weight AIs have much stronger activity toward α-amylase and phosphorylase a than low molecular weight AIs, but the latter have much stronger inhibitory activity toward sucrase and α-glucosidase than the former. Four kinds of AI were hydrolyzed by s-amylase which changed their inhibitory activities.

Effects of Surface Area and Flow Rate on Marine Bacterial Growth in Activated Carbon Columns

The colonization of granular activated carbon columns by bacteria can have both beneficial and potentially detrimental consequences. Bacterial growth on the carbon surface can remove adsorbed organics and thus partially regenerate the carbon bed. However, growth can also increase the levels of bacteria in the column effluents, which can adversely affect downstream uses of the treated water. This study of a sand column and several activated carbon columns demonstrated that considerable marine bacterial growth occurred in both sand and carbon columns and that this growth increased the number of bacteria in column effluents. Activated carbon supported approximately 50% more bacteria than did sand. Bacterial growth on activated carbon was reduced by increasing the flow rate through a carbon column and increasing the carbon particle size. Scanning electron micrographs showed that bacteria preferred to attach in the protected crevices on both the sand and carbon surface. The results of this study indicated that the colonization of activated carbon by marine bacteria was enhanced because of carbon's high surface area, its rough surface texture, and its ability to absorb organic materials.

Theory of Adsorption by Activated Carbon. IV. High-Speed Modeling of Continuous Flow Columns

Abstract An algorithm is developed for integrating the differential equations modeling the operation of a continuous flow activated carbon column. This algorithm is more than an order of magnitude faster in computation than the direct numerical integration of the differential equations, and appears to be just as accurate. Computer memory requirements are small. Results are presented showing the dependence of the breakthrough curves on the parameters of the Langmuir adsorption isotherm, flow rate, influent concentrations, mass transfer rate parameter, and other quantities appearing in the model. The theory is extended to the case of several solutes competing for adsorption sites.

Effects of salts on activated carbon adsorption of fulvic acids

Calcium, magnesium, and sodium significantly influenced the adsorptive capacity of activated carbon for fulvic acids from three sources, including a natural groundwater supply. Adsorptive capacity was evaluated as a function of salt type, salt concentration, and pH and was most sensitive to changes in low concentrations of salt. Chloride, sulfate, bicarbonate, and phosphate exhibited no observable effect on the adsorption of fulvic acid. Calcium significantly influenced the adsorption of peat fulvic acid by an activated carbon column, the addition of calcium greatly enhanced adsorption, and the withdrawal of calcium from a loaded column resulted in substantial desorption. Salts enhanced the adsorption of dihydroxybenzoic acid but had variable effects on the adsorption of EDTA, citric acid, and aspartic acid.

Selected organic pesticides, behavior and removal from domestic wastewater by chemical and physical processes

A study was conducted to evaluate the effectiveness of chemical and physical wastewater treatment processes in removing selected organic pesticides from domestic wastewater. A 3785 m 3 day −1 (1 MGD) nominal capacity pilot plant consisting of biological, chemical and physical units was used for the study. Biologically treated domestic wastewater was subjected to chemical coagulation, multimedia filtration, and activated carbon adsorption. Eight sequences of treatment processes were studied. Influent and effluent samples were analyzed for selected chlorinated hydrocarbon pesticides and chlorophenoxy herbicides using EC-GC. Confirmatory tests such as TLC, extraction of p-value and CPU-MS-GC were applied on selected samples. Results of the study provided qualitative and quantitative evaluation of the performance of the treatment processes studied. Qualitatively characteristic profiles consisting of a limited number of refractory organic residues were detected as peaks on EC chromatograms of extracts from each treatment unit. Thirteen compounds were confirmed in the biologically treated wastewater. These included DDT and its metabolites, aldrin, dieldrin, and 2,4-D alkyl esters and salts. Concentration levels of these compounds in wastewaters were at the ng l −1 (part per trillion) level. Chemical coagulation with alum-lime or lime-ferric chloride was found to effect slight reduction of the organic residues detected on EC chromatograms. Quantitatively only DDT compounds were more completely removed by chemical treatment. Multimedia filters had no discernible effect in removing organic residues from biologically and chemically treated wastewater. Activated carbon columns were found to be the most effective means for removing the refractory organic residues detected. However, breakthrough of some organic residues was noted after usage of the carbon for over 1 year. The overall results of the study showed that application of several sequences of treatment processes on domestic wastewater can produce a high quality effluent which is virtually free from EC detectable organic residues.

Effects of Surface Area and Flow Rate on Marine Bacterial Growth in Activated Carbon Columns

Effects of Surface Area and Flow Rate on Marine Bacterial Growth in Activated Carbon Columns

Success story uncovered

The story behind the cover photograph on the August 1981 JOURNAL AWWA is told. The granular activated carbon columns in the photograph were installed in Lee County, Florida, while the author's firm was general water consultant to the county. These units and a chlorine dioxide feed system were designed and installed to remove taste, odor, and trihalomethanes.

Activated carbon adsorption treatment of spent pickle brine

AbstractA continuous process for recovery of spent pickle brine (SPB) by preliminary filtration on a sand bed to remove suspended solids, followed by adsorption treatment in an activated carbon column to remove color and odor‐causing organic compounds is investigated. Batch isotherm adsorption experiments revealed that the adsorption capacity of the SPB‐activated carbon system is relatively insensitive to temperature variation (about 15% drop for a temperature rise from 0 to 40°C), but quite sensitive to the effect of dilution (about 25% lower for 90% SPB solution). Regenerated activated carbon behaved similarly to fresh carbon with only slightly lowered adsorption capacity. It is estimated that a low capital investment of 0.08 cent per liter of recycled treated SPB is required for a plant with a 190 000 L/d capacity. This cost is much lower than that of fresh salt, and thus will be defrayed by savings on recycled salt.

Theory of Adsorption by Activated Carbon. III. Effects of Equalization Tanks on Time-Dependent Feeds

Abstract Operation of a flow equalization tank and activated carbon column in series was simulated by computer. The flow equalization tank smooths out concentration and flow rate variations in strongly time-dependent feeds; this results in the reduction or elimination of breakthrough of solute in the column effluent due to shock loadings. The effects of various concentration and flow rate pulses on column performance were examined with flow equalization tanks of various sizes. Use of a flow equalization tank is compared with increasing the length of the carbon column.