Personal Research Database

Full Text: 1960-80\Wat Res12, 399.pdf

Abstract: An ammonia determination based on formation of a substituted indophenol with sodium salicylate as phenolic reagent has been developed and compared with other methods. Sensitivity and reproducibility are comparable with results obtained in a method where phenol was used, while a number of the disadvantages inherent to the use of phenol are avoided. The salicylate method is specific for NH₃

N and interferences are generally absent in samples from natural fresh waters. The method can be easily applied for seawater analysis.

Gould, M.S. and Genetelli, E.J. (1978), Heavy metal complexation behavior in anaerobically digested sludges. Water Research, 12 (8), 505-512.

Full Text: W\Wat Res12, 505.pdf

Abstract: Heavy metal interactions with anaerobically digested sludges have been examined by equilibrating sludge solids with solutions containing acetate salts of zinc, nickel copper, and cadmium over the range of pH from 5.0 to 8.0. The partitioning of the metals with the solids suggested chemisorptive behavior. Currently available adsorption isotherms could be used to describe this behavior if modified to incorporate effects due to hydrogen ion concentration. The Freundlich isotherm was superior to the Langmuir and Temkin isotherms.

A comparison of Langmuir inhibition variations and Freundlich results suggests that weakly acidic ligands are involved in heavy metal complexation and that there exists a competition between the metal and hydrogen ions for these sites. Lowering the pH resulted in lower degrees of complexation.

Stability constants were calculated from Langmuir isotherm results and are in the range of values calculated by others for heavy metal complexation with soil organic matter.

? Painter, H.A. and King, E.F. (1978), Effect of phosphate and temperature on growth of activated-sludge and on biodegradation of surfactants. Water Research, 12 (11), 909-915.

Full Text: 1960-80\Wat Res12, 909.pdf

Abstract: Occasional inconsistent and low removals of readily biodegradable surfactants and poor growths of sludge have been traced to sub-optimal concentrations of phosphate in the synthetic sewage used in the EEC method of assessment. The variable concentration of phosphate in this sewage was probably the result of variable amounts present in the organic components, peptone and meat extract. Reduced removal of alkylphenol ethoxylate surfactants at low temperature has been shown not to be related to a phosphate deficiency.

Jørgensen, S.E., Libor, O., Barkacs, K. and Kuna, L. (1979), Equilibrium and capacity data of clinoptilolite. Water Research, 13 (2), 159-165.

Full Text: W\Wat Res13, 159.pdf

Abstract: The equilibrium and capacity data of natural clinoptilolite and clinoptilolite treated with sodium hydroxide were investigated. It was shown that the usual description of the selectivity as function of the equilibrium concentration can be replaced by equation (1), which is independent of the equilibrium concentration. Once constants K, n and Q_o (see the equation) have been determined the equilibrium data can be calculated from equation (1) and the mass balance equation (2).

The practical capacity has been found by pilot plant experiment, and it was demonstrated that if it is expressed as `layer not used’ (Y), it is only dependent upon the flow rate. Once the relation between y and the flow rate is established, it is easy to design a column. This procedure is considerably less cumbersome than the usually applied calculation on the basis of diffusion coefficient.

? Nayar, S.C. and Sylvester, N.D. (1979), Control of phenol in biological reactors by addition of powdered activated carbon. Water Research, 13 (2), 201-205.

Full Text: 1960-80\Wat Res13, 201.pdf

Abstract: A biological reactor containing a pure culture of E. coli was subjected to a variety of feed upsets involving phenol with powdered activated carbon applied as a control mechanism. The amount and rate of addition of the carbon was varied to evaluate the effectiveness of this strategy for maintaining the effluent quality. It was found that the carbon addition greatly reduced the magnitude of concentration transients and permitted operation with an input phenol concentration above 1000 mg 1⁻¹.

Notes: highly cited (> 1000)

Karickhoff, S.W. Brown, D.S. and Scott, T.A. (1979), Sorption of hydrophobic pollutants on natural sediments. Water Research, 13 (3), 241-248.

Full Text: W\Wat Res13, 241.pdf

Abstract: The sorption of hydrophobic compounds (aromatic hydrocarbons and chlorinated hydrocarbons) spanning a concentration range in water solubility from 500 parts per trillion (ppt) to 1800 parts per million (ppm) on local (North Georgia) pond and river sediments was investigated. The sorption isotherms were linear over a broad range of aqueous phase pollutant concentrations. The linear partition coefficients (K_p) were relatively independent of sediment concentrations and ionic strength in the suspensions. The K_p were directly related to organic carbon content for given particle size isolates in the different sediments. On an organic carbon basis (K_{oc = Kp/fraction}) organic carbon), the sand fraction (> 50 m particle size) was a considerably less effective sorbent (50–90% reduction in K_oc) than the fines fraction (> 50 m particles). Differences in sorption within the silt and clay fractions were largely related to differences in organic carbon content. Reasonable estimates of K_oc can be made from octanol/water distribution coefficients, which are widely catalogued or easily measured in the laboratory.

Keywords: Sediments, Sorption, US

El-Dib, M.A. and Badawy, M.I. (1979), Adsorption of soluble aromatic hydrocarbons on granular activated carbon. Water Research, 13 (3), 255-258.

Full Text: W\Wat Res13, 255.pdf

Abstract: Adsorption of benzene, toluene, o-oxylene and ethylbenzene on granular activated carbon proceeds in accordance with the Freundlich model. Adsorption parameters, k and 1/n, reflect the effects of chemical structure, solubility and competitive interactions on the adsorption process. Results obtained add to the validity of the carbon column technique in the removal of soluble aromatic hydrocarbons that affect water quality.

Notes: highly cited

? Owen, W.F., Stuckey, D.C., Healy, J.B., Young, L.Y. and McCarty, P.L. (1979), Bioassay for monitoring biochemical methane potential and anaerobic toxicity. Water Research, 13 (6), 485-492.

Full Text: 1960-80\Wat Res13, 485.pdf

Abstract: Techniques are presented for measuring the biodegradability (Biochemical Methane Potential—BMP) and toxicity (Anaerobic Toxicity Assay—ATA) of material subjected to anaerobic treatment. These relatively simple bioassays can be conducted in most research laboratories without the need for sophisticated equipment. BMP is a measure of substrate biodegradability determined by monitoring cumulative methane production from a sample which is anaerobically incubated in a chemically defined medium. The ATA measures the adverse effect of a compound on the rate of the total gas production from an easily-utilized, methanogenic substrate. These techniques are demonstrated by an analysis of the BMP and ATA of processed samples of peat.

Brown, M.J. and Lester, J.N. (1979), Metal removal in activated sludge: The role of bacterial extracellular polymers. Water Research, 13 (9), 817-837.

Full Text: W\Wat Res13, 817.pdf

Abstract: A combination of flocculation and settling is the mechanism by which metal removal is achieved in activated sludge. Bacterial extracellular polymers appear to play an important role in flocculation; metal cations may also be involved in this process. Extracellular polymers in activated sludge are mainly of a polysaccharide nature, although protein and nucleic acid from autolysis are constituents of the polymer matrix. Precipitated metals may be removed either by independent settling or by physical trapping in the sludge floc matrix. Metals present in the ionic form may be removed from solution by adsorption to sites on bacterial extracellular polymers. Metal ions may also be accumulated in the cytoplasm of a bacterial cell, or adsorbed on to the cell wall.

If activated sludge plants are overloaded with metals, toxic effects on bacteria and other microorganisms may severely inhibit the treatment process, resulting in poor quality effluents. Acclimated bacterial cultures can tolerate much higher metal concentrations than non-acclimated cultures; these are advantageous in the treatment of metal-laden wastes.

McKay, G., Otterburn, M.S. and Sweeney, A.G. (1980), The removal of colour from effluent using various adsorbents. III Silica: Rate processes. Water Research, 14 (1), 15-20.

Full Text: W\Wat Res14, 15.pdf

Abstract: The rate of adsorption of Astrazone Blue, a basic dye, on Sorbsil Silica has been studied. The parameters studied include particle size, initial dye concentration, agitation and dye solution temperature. The rate controlling step is mainly intraparticle diffusion, although a small boundary layer resistance is experienced. The activation energy for the adsorption of Astrazone Blue on silica is 13.2±0.6 kJ kg^-1. The diffusion coefficients vary from 9×10^-9 cm² s^-1 at 20°C to 10×10^-8 cm² s^-1 at 82°C.

McKay, G., Otterburn, M.S. and Sweeney, A.G. (1980), The removal of colour from effluent using various adsorbents. IV. Silica: Equilibrium and column studies. Water Research, 14 (1), 21-27.

Full Text: W\Wat Res14, 21.pdf

Abstract: The adsorption of Astrazone Blue (Basic Blue 69) on silica has been investigated. Adsorption parameters for the Langmuir and Freundlich isotherms were determined. A series of static and fluidised bed experiments were undertaken and the results compared with existing design models for adsorption columns.

? Klieve, J.R. and Semmens, M.J. (1980), Evaluation of pretreated natural zeolites for ammonium removal. Water Research, 14 (2), 161-168.

Full Text: 1960-80\Wat Res14, 161.pdf

Abstract: Clinoptilolite has been widely studied for ammonium removal in the past 2 yr. However, many investigators have reported variations in the measured capacities of samples of clinoptilolite. These studies and the factors believed to influence measured zeolite capacity are reviewed. In addition no studies to evaluate other natural zeolites for ammonium removal have been reported.

In this study samples of clinoptilolite, erionite, mordenite and phillipsite provided by the Anaconda Company were evaluated for ammonium removal from wastewaters. In addition, samples of clinoptilolite were pretreated in various ways to determine whether an improvement in ammonium removal performance could be realized. Total exchange capacities, capacities for ammonium removal from a synthetic waste, packed bed densities and crushing strengths were measured.

Phillipsite was found to have almost twice the weight capacity for ammonium removal from synthetic waste compared to that of clinoptilolite. The volumetric capacity was 26% better than that of clinoptilolite. However, the phillipsite sample was extremely friable and it could not be used for water treatment unless it was strengthened with a binder.

Pretreatment of clinoptilolite with NaOH, HNO₃ and steam did little to improve the zeolite’s performance. However, heat pretreatment (600°C for 1 h) improved the zeolite’s selectivity for ammonium significantly. Ammonium removal capacities were increased by approximately 17% for heat treated zeolite samples although the total exchange capacity of the zeolite was reduced somewhat.

? O’Connor, D.J. and Connolly, J.P. (1980), The effect of concentration of adsorbing solids on the partition coefficient. Water Research, 14 (10), 1517-1523.

Full Text: 1960-80\Wat Res14, 1517.pdf

Abstract: The results of a number of laboratory studies are presented to demonstrate an inverse relationship between concentration of adsorbing solids and partition coefficient. Various functional forms which define the relation are developed and correlated with the data. A power-law dependence of partition coefficient on concentration of solids is shown. The significance of this relationship in assessing the fate of hydrophobic pollutants in natural water systems is discussed.

Notes: IIsotherm

? van Vliet, B.M., Weber, Jr., W.J. and Hozumi, H. (1980), Modeling and prediction of specific compound adsorption by activated carbon and synthetic adsorbents. Water Research, 14 (12), 1719-1728.

Full Text: 1960-80\Wat Res14, 1719.pdf

Abstract: The performance characteristics of two activated carbons and eight synthetic adsorbents are compared. The comparison addresses both the equilibrium capacities and mass transport properties of the adsorbents. A new empirical adsorption isotherm is employed for description of adsorption equilibrium data. A predictive mathematical model is used for forecasting adsorption bed performance from independent batch reactor system data.

Knocke, W.R. and Hemphill, L.H. (1981), Mercury(II) sorption by waste rubber. Water Research, 15 (2), 275-282.

Full Text: 1981\Wat Res15, 275.pdf

Abstract: Studies were connected to assess the capability of waste tire rubber for removing inorganic mercury from solution. Samples of vulcanized tire rubber were ground to a suitable sorbent size and utilized in batch sorption studies. Research parameters included aqueous mercury concentration, rubber sorbent particle size, solution temperature, and hydrogen ion concentration. Alternate sulfur-free rubber materials were also evaluated in an attempt to identify the sorption mechanism. The studies showed tire rubber to be an efficient sorbent material for mercury removal from waste solutions. Of the parameters investigated, pH was determined to be most crucial, with an optimum pH range of 5.5 to 6.0 for good mercury removal. The diffusion of mercury through pores in the rubber sorbent was shown to be the rate limiting step regarding mercury uptake. Finally, sulfur-free rubber materials were shown to be equally efficient for inorganic mercury removal.

McKay, G., Otterburn, M.S. and Sweeney, A.G. (1981), Surface mass transfer processes during colour removal from effluent using silica. Water Research, 15 (3), 327-331.

Full Text: W\Wat Res15, 327.pdf

Abstract: The effects of several variables on the initial rate of Astrazone Blue (Basic) dye removal have been investigated. The surface mass transfer coefficients have been determined and correlated as the dimensionless mass transfer term Sh/Sc^0.33, as a function of agitation, initial dye concentration, silica particle size and temperature.

? Bader, H. and Hoigné, J. (1981), Determination of ozone in water by the indigo method. Water Research, 15 (4), 449-456.

Full Text: 1981\Wat Res15, 449.pdf

Abstract: The concentration of aqueous ozone can best be determined by the decolorization of indigo trisulfonate (600 nm, pH below 4) whenever the ozone cannot be measured directly by its u.v. absorption. The method is stoichiometric and extremely fast. The change of absorbance vs ozone added is −2.0±0.1×104 M⁻¹ cm⁻¹ and is independent of the concentration of aqueous ozone in the range 0.005–30 mg 1⁻¹. The precision of the analysis is 2% or 3 μg 1⁻¹ for low concentrations if a spectrophotometer or a good filter instrument is used. Visual methods can be used to measure 0.01 mgl⁻¹ ozone. Secondary oxidants produced by ozone in natural water, including hydrogen peroxide or chlorite, do not interfere; chlorine can be masked. The reagent solution is stable for 3 months. The method is recommended for kinetic measurements, for studies of ozonation processes and for visual field methods.

? Larson, R.J., Clinckemaillie, G.G. and Vanbelle, L. (1981), Effect of temperature and dissolved-oxygen on biodegradation of nitrilotriacetate. Water Research, 15 (5), 615-620.

Full Text: 1981\Wat Res15, 615.pdf

Abstract: The effect of temperature and dissolved oxygen on the rate of biodegradation of nitrilotriacetate (NTA) was examined in water samples collected from the Rur River. Biodegradation of NTA was first order with respect to NTA concentration over a concentration range of 50–1000 μg l⁻¹. First order rate constants showed a typical temperature dependency (temperature coefficient, Q₁₀ = 2) and biodegradation of NTA was observed over a temperature range of 2–24°C. The effect of temperature on the rate of NTA biodegradation was described by the Arrhenius equation, with calculated activation energies in the range reported for ordinary enzyme reactions. Biodegradation of NTA was also observed at low dissolved oxygen concentrations (0.3 mg l⁻¹), although at reduced rates compared to high oxygen concentrations (13 mg l⁻¹). Biodegradation of NTA was oxygen-dependent, suggesting an obligate oxygen requirement for the initial steps in NTA metabolism by natural microbial communities in surface waters. In general, our results indicate that NTA biodegradation will occur in natural waters under conditions of low temperature and low dissolved oxygen and also at low NTA concentrations.

Elliott, H.A. and Huang, C.P. (1981), Adsorption characteristics of some Cu(II) complexes on alumino silicates. Water Research, 15 (7), 849-855.

Full Text: W\Wat Res15, 849.pdf

Abstract: The adsorption of Cu(II) by aluminosilicates with varying Si/Al ratios was investigated. The presence of complex-forming organic ligands [nitrilotriacetate (NTA) and glycine (Gly)] alters metal electrovalency and, in so doing, modifies Cu(II) adsorption characteristics which can influence its fate, biological activity and transport in aquatic systems. Electrostatic attraction by a positively-charged aluminosilicate surface is an important mechanism whereby anion CuNTA⁻ complexes were adsorbed. Two distinct mechanisms are involved in the adsorption of cationic complexes: (1) an exchange reaction at permanent structural sites and (2) interfacial accumulation in response to the pH-dependent surface charge. The contribution of each mechanism to the total amount of CuGly⁺ adsorbed is related to the Si/A1 ratio. At the critical Si/A1 ratio (Si/A1_iso), the aluminosilicates have zero net pH-dependent surface charge. In the absence of specific adsorption, aluminosilicates for which Si/A1 ≥ Si/A1_iso can only function as cation exchangers. For Si/A1 < Si/A1_iso simultaneous adsorption of anions and cations is possible.

Laxen, D.P.H. and Harrison, R.M. (1981), The physicochemical speciation of Cd, Pb, Cu, Fe and Mn in the final effluent of a sewage treatment works and its impact on speciation in the receiving river. Water Research, 15 (9), 1053-1065.

Full Text: W\Wat Res15, 1053.pdf

Abstract: A scheme for the speciation of metals in freshwaters has been applied to the analysis of the final effluent from a sewage treatment plant and to the receiving river upstream and downstream of the effluent outfall. The treatment plant was selected because of the high influent and effluent concentrations of Cd. The metal speciation patterns in the effluent are interpreted primarily in terms of organic interactions, which appear to be exerting a solubilizing effect on Cd and Cu, but not on the Pb and Fe which are principally associated with the particulate size fraction (> 12 m). The influx of metals with the sewage effluent alters the speciation pattern in the river. A large part of the Cd is added to the smallest size fraction (< 0.015 m). However, the major part of each metal, with the exception of Mn, is associated with the colloidal and particulate size fractions, thus minimising the immediate toxic significance to aquatic life.

Braam, F. and Klapwijk, A. (1981), Effect of copper on nitrification in activated sludge. Water Research, 15 (9), 1093-1098.

Full Text: W\Wat Res15, 1093.pdf

Abstract: The concentration of free copper in activated sludge with copper added is strongly influenced by pH. For example, at pH 6.5 with 9.13×10^-5 mol Cu l^-1, the free copper concentration is 4.0×10^-7 mol l^-1 (pCu = 6.4) and at pH 8.4 this concentration is 10^-8 mol l^-1 (pCu = 8.0). In both cases the activated sludge concentration is 0.7 g MLSS l^-1. The free copper concentration is also affected by the concentration of mixed liquor suspended solids (MLSS).

In batch experiments with constant pH, the effect of copper on the nitrification rate was not regulated by total copper concentration but by copper/sludge ratio or by free copper concentrations. Experiments at different pH showed a linear correlation between nitrification capacity and free copper concentration, suggesting that the pH effect on nitrification below 8.3 is in fact a copper effect.

Activated sludge with copper did not become acclimatized to the copper in a period of three days. Addition of nitrilotriacetic acid (NTA) within one day did cancel the copper inhibition.

The results were compared with the effect of copper on acetate removal by heterotrophic micro-organisms. The nitrifiers proved to be no more susceptible to copper than heterotrophic micro-organisms.

Frenet, M. (1981), The distribution of mercury, cadmium and lead between water and suspended matter in the loire estuary as a function of the hydrological regime. Water Research, 15 (12), 1343-1350.

Full Text: W\Wat Res15, 1343.pdf

Abstract: We examined Hg, Pb, Cd in filtered water and suspended sediments from the Loire Estuary. The metal concentration in both varies widely and is a function of hydrodynamic and hydraulic parameters. We classified them according to geographical repartition, salinity, tidal state etc. A laboratory study, monitored under the same conditions of salinity, showed the affinity of suspended material for Hg, Pb and Cd. The results of the two studies, in vivo and in vitro emphasize the importance of salinity in the metal repartition between water and sediments.

Christensen, E.R. and Delwiche, J.P. (1982), Removal of heavy metals from electroplating rinsewaters by precipitation, flocculation, and ultrafiltration. Water Research, 16 (5), 729-737.

Full Text: W\Wat Res16, 729.pdf

Abstract: Chromium, nickel, copper and zinc can be effectively removed from electroplating rinsewaters by hydroxide precipitation, flocculation and ultrafiltration. Prior to precipitation, chromium is reduced from the hexavalent to the trivalent form by ferrous sulfate and cyanide in copper and zinc rinsewaters are oxidized by sodium hypochlorite. Minimum metal concentrations in the permeate from separate batches of chromium, nickel, copper and zinc rinsewaters were found to be, respectively, 0.17 mg 1^-1 Cr (T), 0.26 mg 1^-1 Ni, 0.30 mg 1^-1 Cu and 1.84 mg 1^-1 Zn. These solubilities are in good agreement with the theoretical solubility curves, except for copper where the formation of stable copper cyanide complexes appears to increase the solubilities at least two orders of magnitude relative to those predicted on the basis of the equilibrium constants for copper hydroxides and oxides. A simple mass balance model, assuming concentrate recycle and constant metal concentration in the permeate, is adequate for the prediction of feed and permeate concentrations as a function of the volume filtered up to a relative volume of about 0.3. Above this value, the feed concentrations are lower than predicted, apparently because of entrapment of metal precipitate in the strainer. Water recoveries are strongly dependent on the specific metal removed and are found to be 24% for Ni with a 0.20 m membrane, 10% for Cr with a 0.80 m membrane, 6.5% for Cu and 3.7% for Zn, both with a 0.45 m membrane.

Aoki, T. and Munemori, M. (1982), Recovery of chromium(VI) from wastewaters with iron(III) hydroxide. I: Adsorption mechanism of chromium(VI) on iron(III) hydroxide. Water Research, 16 (6), 793-796.

Full Text: W\Wat Res16, 793.pdf

Chromium(VI) [Cr(VI)] is adsorbed as HCrO₄^- on iron(III) hydroxide at pH below 8.5. The Cr(VI) adsorption is suppressed by the presence of other anions such as SO₄^2- and SCN^-, and enhanced by the presence of metal ions such as Cd(II) and Pb(II). The suppression is due to the competitive adsorption of other anions, depending upon the stability of their iron complexes. The enhancement is probably due to the increase in adsorption sites as a result of coprecipitation of metal ion with iron(III) hydroxide.

Winfield, B.A. (1982), Cellulose acetate membranes for the reverse osmosis treatment of sewage effluents. Water Research, 16 (6), 797-799.

Full Text: W\Wat Res16, 797.pdf

Abstract: A study has been made of the performance of cellulose acetate reverse osmosis membranes used in the treatment of secondary sewage effluents over a period of three years. The trials have shown that the deterioration in salt rejection performance is less than hydrolysis theory predicts. In addition there is a reduction in the water permeability of the membrane when theory suggests that it should increase. There is no evidence to indicate that microbiological attack of the membrane occurs to a significant extent. Several explanations are given in support of the observed phenomena.

Pandey, M.P. and Chaudhuri, M. (1982), Removal of inorganic mercury from water by bituminous coal. Water Research, 16 (7), 1113-1118.

Full Text: W\Wat Res16, 1113.pdf

Abstract: Sorption of inorganic mercury in water onto bituminous coal and activated carbon was investigated in the laboratory. Some coal samples were observed to be comparable to activated carbon in mercury sorption. Chemical pretreatment of coal, e.g. nitric acid oxidation, sulfonation, and sulfurisation further improved the sorption capacity. Column studies indicated the feasibility of using coal for removing mercury from water supplies or industrial wastewater.

Couillard, D. (1982), Toxicity, assessment of snowmelt water runoff in an urban area. Water Research, 16 (7), 1197-1205.

Full Text: W\Wat Res16, 1197.pdf

Abstract: There is a current paucity of information on the characteristics of water originating from melting snow in urbanized areas. In fact no data exist on the potential chronic toxicity of waters originating from melting snow combined with sewage waters of industrial and domestic activities. Bioassays were conducted on the green alga Selenastrum capricornutum to evaluate the composite effect of all pollutants occurring in waters originated from melting snow in urbanized areas and also to determine the long-term bioavailability of selected toxicants in these waters.

The publication resumes a sampling study of two outfalls (Curotte-Papineau and Meilleur-Atlantique) from collector systems on the island of Montréal, Québec, Canada (see Fig. 1). Both sewer systems are of the combined surface runoff-wastewater type, are self contained and drain watersheds of 11.7 and 22.2 km² area respectively (see Table 1). The sampling program carried out in spring (March–May) 1978, was oriented towards the analysis of flow-quality relationships during two dry and three snowmelt periods. The flow from the intrusion of snowmelt into the sewage networks were due not only to high air temperature and solar radiation conditions but also to a heavy rainfall (9.67 mm; maximum intensity of 4.6 mm h^-1. The principal water quality parameters studied were BOD₅, COD, Cl^-, N_in, P_i, Pb, Cr, Zn, Cn^- and SS (see Table 2).

In addition a bioassay based on the fertility potential [the Selenastrum capricornutum Printz algal assay bottle test; U.S.E.P.A. (1978)] on filtered samples (1.2 m GF/C) of waste water was used to detect any toxological qualities of the outfalls during both dry and snowmelt periods. An analysis of the relationship between chemical quality and the toxological properties of the samples from both sewage networks showed that water collected during a period of snowmelt without rain had a greater potential chronic toxicity and greater mean ratios of B_EDTA/B than combined water collected during a dry climatic period (see Table 3). This toxicity is due mainly to inorganic compounds. However, the increase in water discharge rate during periods of snowmelt accompanied by rain results in an apparent dilution of the aquatic toxicants. The potential chronic toxicity of water during the latter periods is consequently reduced compared with combined waters during dry periods.

Knowledge of relationships between water flow and the chronic toxicity characteristics of waste water from urban snowmelt is necessary in the planning of any future combined water treatment system.

Notes: highly cited

? Pierce, M.L. and Moore, C.B. (1982), Adsorption of arsenite and arsenate on amorphous iron hydroxide. Water Research, 16 (7), 1247-1253.

Full Text: 1982\Wat Res16, 1247.pdf

Abstract: Adsorption isotherms in solutions with ionic strengths of 0.01 at 25°C were measured over the arsenite and arsenate concentration range 10−7−10−3 M and the pH range 4–10. At low concentrations, these isotherms obeyed equations of the Langmuir type. At higher concentrations the adsorption isotherms were linear, indicating the existence of more than one type of surface site on the amorphous iron hydroxide adsorbent. Removal of arsenite and arsenate by amorphous iron hydroxide throughout the concentration range were determined as a function of pH. By careful selection of the relative concentration of arsenic and amorphous iron hydroxide and pH, removals on the order of 92% can be achieved.

Keywords: Adsorption, Arsenate, Arsenite, Iron

Cullen, G.V. and Siviour, N.G. (1982), Removing metals from waste solutions with low rank coals and related materials. Water Research, 16 (8), 1357-1366.

Full Text: W\Wat Res16, 1357.pdf

Abstract: Ion exchange media were produced by contacting brown coal, peat or wood sawdust with a solution of calcium hydroxide, preferably as an aqueous slurry of lime. The resultant calcium loading on the media, which ranged up to 8% for sawdust, 12% for peat and to 19% for brown coal, was exchanged for many metals in solution.

Preliminary work showed the method to be amenable to extraction of copper, nickel, chromium, cadmium, lead, zinc, mercury, cobalt, silver, iron, manganese, vanadium, germanium, gallium, aluminium, antimony and uranium. For most of the metals more than 99% was removed from I g 1^-1 solutions.

In more detailed work, confined to calcium loaded brown coal and solutions having metal concentrations more typical of industrial operations, minimum residual metal concentrations of 0.0005 mg l^-1 mercury; 0.02 mg 1^-1 copper; 0.02 mg 1^-1 zinc; <0.05 mg l^-1 cadmium; 0.1 mg 1^-1 lead and 0.2 mg l^-1 manganese were obtained. These results compare favourably with those reported for other relevant processes and there might be operational advantages in the method.

The method can be applied either by agitating the calcium loaded media in the solution and then filtering, or by passing the solution through packed beds of the media. Where appropriate, dilute solutions can be up-graded for re-use by stripping the metals from the media which can also be re-used. Alternatively, the loaded media can be combusted and the metals recovered from the residues.

The method might be applicable to mine drainage and to effluents from metallurgical processing and electroplating, but more work is required to assess costs.

It is suggested that the method is environmentally preferable to other common effluent treatment procedures because it enables collection and recycling of heavy metal pollutants.

Laxen, D.P.H. and Harrison, R.M. (1983), Physico-chemical speciation of selected metals in the treated effluent of a lead-acid battery manufacturer and in the receiving river. Water Research, 17 (1), 71-80.

Full Text: W\Wat Res17, 71.pdf

Abstract: A scheme for the speciation of metals in freshwaters has been applied to the metals Pb, Cd, Cu, Fe and Mn in the treated effluent of a lead-acid battery manufacturer and the receiving river upstream and downstream of the effluent outfall. The speciation is inferred from measurements of the size-associations of the metals, the lability with respect to anodic stripping voltammetry and Chelex resin and by u.v. irradiation to destroy organic complexing agents. The results are related to chemical and physical interactions within the waters and are discussed in terms of the impact of the effluent discharge upon the receiving river.

Notes: highly cited

? Hoigné, J. and Bader, H. (1983), Rate constants of reactions of ozone with organic and inorganic compounds in water. I. Non-dissociating organic compounds. Water Research, 17 (2), 173-183.

Full Text: 1983\Wat Res17, 173.pdf

Abstract: Rate constants of reactions of ozone with non-ionized solutes, such as aliphatic alcohols, olefins, chlorosubstituted ethylenes, substituted benzenes and carbohydrates, have been determined from the absolute rates with which ozone reacts in the presence of various concentrations of these compounds in water. They have been tested by comparison with the relative rates by which pairs of these solutes are transformed by ozone. Different experimental methods have been developed to determine such rate constants in the range from 10⁻² to 105 M⁻¹ s⁻¹. Interferences between the direct reactions of ozone and reactions due to its preliminary decomposition to secondary oxidants could be eliminated. The kinetics of all the reactions studied are first order with respect to ozone and solute concentration. The rate constants of many types of organic compounds in water are of the same order of magnitude as in organic solvents. Substituted benzenes, however, react in water about 100 times faster. They obey a linear free energy relationship with p = −3.1 when based on δp+ values. Comparisons of rate constants with chemical structures of the reacting groups show that all reactions of ozone are highly selective and electrophilic. The kinetic data allow explanation of the chemical effects of ozone observed in water treatment practice.

Notes: highly cited

? Hoigné, J. and Bader, H. (1983), Rate constants of reactions of ozone with organic and inorganic-compounds in water. II. Dissociating organic-compounds. Water Research, 17 (2), 185-194.

Full Text: 1983\Wat Res17, 185.pdf

Abstract: Comprehensive lists of rate constants of reactions of ozone with acidic and basic organic chemicals dissolved in water, such as amines, amino acids, carboxylic acids and phenols are reported. The second-order rate constants increase with pH as does the degree of deprotonation of the dissolved substances, e.g. from 1 to 100 M- ~ s- ~ for formic acid, from 0.2 to 2 M- ~ s- t for glyoxalic acid and from [03 to l09 M - t s- t for phenolic compounds. All results support the conclusions presented in Part I for the electrophilic reactions of ozone with non-dissociating compounds. They are important for the understanding of the pH dependence of the rate and selectivity of ozonation reactions and for explaining the chemical effects of ozone on impurities in drinking water and waste waters.

Keywords: Water

Cooney, D.O., Nagerl, A. and Hines, A.L. (1983), Solvent regeneration of activated carbon. Water Research, 17 (4), 403-410.

Full Text: W\Wat Res17, 403.pdf

Abstract: Nineteen solvents were evaluated in batch tests involving the desorption of a representative organic adsorbate (phenol) from activated carbon. Three of the better solvents which also possess complete miscibility with water (acetone, dimethylformamide, methanol) were tested further in fixed-bed runs. The effects of solvent temperature and solvent flow rate on phenol desorption were evaluated. In addition, the recovery of phenol adsorption capacity by an activated carbon bed operated cyclically using a sequence of phenol adsorption, desorption with methanol, and rinsing with water was determined. It was found that solvent temperature and flow rate are not critical variables. Solvent volume and type were the most important factors in phenol desorption. A modest volume of methanol restored 88% of the fixed-bed adsorption capacity for phenol after 1 regeneration, and the capacity essentially leveled off after 5 regenerations at a value of 81% of the capacity of fresh carbon. Methanol regeneration is effective, easy to perform and offers convenient solvent recovery. Thus, it is an attractive alternative to thermal regeneration methods.

Salim, R. (1983), Adsorption of lead on the suspended particles of river water. Water Research, 17 (4), 423-429.

Full Text: W\Wat Res17, 423.pdf

Abstract: The effects of the chemical composition and particle size, of suspended particles in river water, on the adsorption of lead onto these particles have been studied. Lead has been determined using the conventional method of anodic stripping voltammetry. Particle sizes have been determined using the Coulter Counter. The organic matter content of the suspended particles has been found responsible for most of the lead adsorbed onto these particles. An attempt has been made to quantify the relationship between the particle size of suspended particles and the amount of lead adsorbed onto these particles. The shape of the calibration graphs of lead from solutions in river water has been explained with reference to the adsorption of lead on suspended particles.

Becker, E.W. (1983), Limitations of heavy metal removal from waste water by means of algae. Water Research, 17 (4), 459-466.

Full Text: W\Wat Res17, 459.pdf

Abstract: It has been suggested by several authors that heavy metals might be removed from aqueous systems by phytoplanktonic algae, whose high capacity for accumulating dissolved metals has previously been described. This paper shows––by comparing results obtained on accumulation factors and growth rates in different models––that metal removal by means of algae is not feasible in practice. It was found that under optimum conditions in a static system the reduction of a given initial metal concentration by 50% requires approx. 14 days, while in a dynamic model a retention time of approx. 19 days is needed to achieve the same reduction. Finally, measurements of nitrogenase activity inhibition caused by various concentrations of mercury and cadmium demonstrate that nitrogen-fixing blue-green algae can be used for biological sewage treatment only at very low heavy metal concentrations in the medium.

Box, J.D. (1983), Investigation of the folin-ciocalteau phenol reagent for the determination of polyphenolic substances in natural-waters. Water Research, 17 (5), 511-525.

Full Text: W\Wat Res17, 511.pdf

Abstract: The methodology associated with the Folin-Ciocalteau phenol reagent was investigated and the performance characteristics of a method using sodium carbonate as the supporting medium were determined. Calibration curves using phenol, tannic acid, or L-tyrosine were linear up to at least 1000 g l^-1. The limit of detection was 6 g phenol l^-1 and the relative standard deviation at 100 g phenol l^-1 was 5.2% and at 1000 g phenol l^-1 was 4.1%. The absorbances obtained with equal amounts of a range of potential standards showed variations when compared with that of phenol: phenol (100%), L-tyrosine (62%), oak gall tannin (58%), tannic acid (48%), chestnut tannin (26%), oak tannin (24%), fulvic acid (5%). The method was applicable to a wide range of monohydric and polyhydric phenolic substances and interferences from inorganic and non-phenolic organic compounds were examined. Interference would be expected above 30 g S^2- l^-1, 300 g Mn(II) l^-1, or 400 g SO₃^2- l^-1. Concentrations of iron >2 mg l^-1 as Fe(II) or Fe(III) formed the insoluble iron(III) hydroxide which increased the absorbance, but centrifugation could be used to remove this source of interference. Other potential sources of intereference (e.g. reducing agents and certain metabolic products) would be expected to have a negligible effect in unpolluted waters. Methods using diazotised sulphanilic acid or 4-aminoantipyrine (4-AAP) were found to be inferior when applied to natural water samples.

Perineau, F., Molinier, J. and Gaset, A. (1983), Adsorption of ionic dyes on wool carbonizing waste. Water Research, 17 (5), 559-567.

Full Text: W\Wat Res17, 559.pdf

Abstract: Wool carbonizing waste is not used although large amounts are available in the countries where wool is processed. Wool carbonizing waste is made up of two components: the plant particles can be considered as sulfo lignins; the short-size wool fibres have undergone chemical modifications. Owing to its physical structure and to the polar as well as apolar properties of its macromolecules, this waste is liable to adsorb ionic organic solutes. The adsorption of ionic dyes on wool carbonizing waste was therefore investigated so as to evaluate its possible use for the decolourization of dyeing effluents. The effect of the solution-substrate reaction time on the adsorption at various temperatures was studied first. Temperature had a marked effect on the adsorption of the acid dye (AB 80) (Fig. 1) whereas the basic dye (BR 22) (Fig. 2) was characterized by its faster diffusion within the wool carbonizing waste particles. These differences can be ascribed to the higher steric hindrance of the AB 80 molecules and to their possible aggregation. The L-type adsorption isotherms corroborated the temperature effect already mentioned as well as the high affinity of the wool carbonizing waste with acid (Fig. 3) and basic (Fig. 4) dyes. The shape of the adsorption isotherms suggests that the adsorption proceeds through ionic bonding; as the dye molecules are oriented flatwise on the surface of the waste, the dye-substrate hydrophobic interactions can be maximum. The amounts adsorbed were 0.744 mmol g^-1 (i.e. 52.5%) for AB 80 at pH 2 and 0.193 mmol g^-1 (i.e. 5.5%) for BR 22 at pH 4. Higher amounts of basic dyes might however be expected to be adsorbed since the adsorption maximum is reached at pH 9 in the case of BR 22 (Fig. 5), as a result of the increasingly electronegative charge of the substrate. The Langmuir and Freundlich equations (Table 1) were used to have a mathematical model for the operation of a waste water processing unit. As shown by the L-type adsorption isotherms, the wool carbonizing waste used is suitable for the processing of low concentration effluents, such as dyeing waste waters: the decolourization of synthetic solutions was therefore considred. The column processing of an AB 80 solution showed the effect of the reaction time on the efficiency of the material used (Table 2). Investigation of the processing of a BR 22 solution in a stirred reactor led to the determination of the optimum carbonizing waste concentration (Fig. 6). as well as of the optimum effluent-substrate reaction time and the number of reactors to be used (Fig. 7). Eventually, the adsorptive power of the wool carbonizing waste used was compared with that of various materials (Table 3): the uptake capacity of wool carbonizing waste is lower than or equal to that of other substrates in the case of basic dyes but it is 6–10-fold higher in the case of acid dyes.

de Mora, S.J. and Harrison, R.M. (1983), The use of physical separation techniques in trace metalspeciation studies. Water Research, 17 (7), 723-733.

Full Text: W\Wat Res17, 723.pdf

Abstract: Size fractionation techniques used in speciation studies of trace metals in natural waters have been reviewed. Centrifugation, filtration, ultrafiltration (UF), dialysis and gel filtration chromatography (GFC) have been considered with respect to trace metal contamination, adsorption effects and size selectivity. Size differentiation during centrifugation is impeded due to density effects on particle settling rates. Filtration is the most commonly used method to fractionate trace metal species, but often only ‘issolved’ and ‘particulate’ fractions are identified. Filters may be decontaminated with dilute nitric acid and adsorption effects may be minimised by preconditioning with a dilute calcium nitrate solution. Several studies concerning the size selectivity of filters indicate that at present only Nuclepore polycarbonate filters are suitable for size spectrum investigations. Those difficulties outlined above are also experienced with UF methods but generally have not been so well resolved. particularly with respect to adsorption. Adsorption during UF causes an overestimation of the molecular size of metal complexes. Dialysis techniques have been utilized with some success in order to isolate trace metal species in true solution but have seen only limited applications in comprehensive speciation schemes. GFC offers considerable potential in physicochemical speciation studies. The major advantage lies with the ability to determine metal concentrations over a continuous size spectrum rather than at discrete size ranges. In contrast to other methods, adsorption during GFC will cause the molecular weight of organometallic complexes to be underestimated. Several examples of the environmental application of each technique have been considered, thereby illustrating the value of examining the size distribution of metal species in natural waters.

Huang, C.P. and Blankenship, D.W. (1984), The removal of mercury(II) from dilute aqueous solution by activated carbon. Water Research, 18 (1), 37-46.

Full Text: W\Wat Res18, 37.pdf

Abstract: The results of preliminary screening tests comparing the total Hg(II) removal capacity of 11 different brands of commercial activated carbon indicated that a very high percent (99–100%) total Hg removal was attained by all types of activated carbon especially at pH 4–5; the percent total Hg(II) removal decreased with pH’s 4–5 except activated carbons Nuchar SA and SN which maintained a relatively high percent (>90%) total Hg(II) removal capacity at all pH values. Experiments were then conducted to reveal the mechanisms of Hg(II) removal by Nuchar SA (a powdered carbon). The results show that total Hg(II) removal was brought by two mechanisms: the adsorption and reduction. In order to investigate the kinetics of these two reactions, volatilization by bubbling N₂ gas at high flow rate was used to remove the Hg(g) product of the reduction reaction. It was noted that both the adsorption and the reduction/volatilization reactions were highly pH-dependent; at pH approx. <3–4 or > approx. 9–10 the extent of reduction/volatilization reaction superceded the adsorption reaction; whereas in the mid-pH region adsorption reaction dominated the total Hg(II) removal. The rate of adsorption reaction is very fast, reaching equilibrium in a few minutes; the rate of reduction/volatilization follows a linear t^0.5 expression. The reduction reaction is more significant with Filtrasorb 400 (H-type carbon) than Nuchar SA (L-type carbon). In the presence of strong chelating agent, ethylenediaminetetraacetate (EDTA), the total Hg(II) removal decreases due partly to the formation of less adsorbably mercuric(II)-EDTA complexes.

Martin, R.J. and Ng, W.J. (1984), Chemical regeneration of exhausted activated carbon-I. Water Research, 18 (1), 59-73.

Full Text: W\Wat Res18, 59.pdf

Abstract: This paper represents the first of a series of reports on the chemical regeneration of exhausted activated carbon following experimental research studies carried out at the University of Birmingham, U.K.

A wide range of regenerants, inorganic and organic, was evaluated in the treatment of carbon samples exhausted with mono-substituted benzene compounds. Organic chemical regenerants with solubilising powers were found to be generally much more effective than inorganic chemical regenerants with oxidising powers. Results showed that the efficacy of organic solubilising regenerants decreased as their molecular weights and sizes increased; it is likely that the smaller the regenerant, the further it could penetrate into the micropores of the carbon and displace the adsorbate. The relationship between the molecular weight of the adsorbate and that of the organic regenerant was observed to be of significant importance; the regenerant chosen should be smaller than the smallest adsorbate to be removed.

Keywords: Activated Carbon, Adsorption, Desorption, Regeneration, Chemicals, Molecular Size, Molecular Structure, Chemical Properties

Gould, M.S. and Genetelli, E.J. (1984), Effects of competition on heavy metal binding by anaerobically digested sludges. Water Research, 18 (1), 123-126.

Full Text: W\Wat Res18, 123.pdf

? Beltrame, P., Beltrame, P.L. and Carniti, P. (1984), Influence of feed concentration on the kinetics of biodegradation of phenol in a continuous stirred reactor. Water Research, 18 (4), 403-407.

Full Text: 1984\Wat Res18, 403.pdf

Abstract: The rate of phenol degradation by activated sludge was studied in a completely mixed continuous-flow reactor with sludge recycle, operated at steady-state conditions at 20°C. Monod kinetics was followed when the influent concentration (C_s°) was kept constant. When using different C_s° levels, the phenol removal rate was found to have an inverse dependence on C_s°. It is suggested that this kinetic anomaly is due to inhibition of the biooxidation by some secondary reaction product(s). A kinetic model based on this concept is able to interpret experimental facts.

Keywords: Phenol Biodegradation, Activated Sludge, Continuous Reactor, Removal Rate, Influent Concentration, Inhibition, Kinetic Model

Netzer, A. and Hughes, D.E. (1984), Adsorption of copper, lead and cobalt by activated carbon. Water Research, 18 (8), 927-933.

Full Text: W\Wat Res18, 927.pdf

Abstract: The phenomena of lead, copper and cobalt adsorption by activated carbon from aqueous solution was studied in detail. Laboratory studies were conducted to evaluate and optimize the various process variables (i.e. carbon type, solution pH, equilibrium time and carbon dose). A quantitative determination of the adsorptive capacity of activated carbon to remove these metals was also determined.

Significant differences were found in the ability of different types of activated carbons to adsorb lead, copper and cobalt from aqueous solution. Solution pH was found to be the most important parameter affecting the adsorption. It was found that there was practically no adsorption of lead, copper and cobalt by activated carbon below a well defined solution pH value for each metal. This critical solution pH value was found to be lower than the pH value associated with the formation of hydrolysis products. Of the ten commercially available activated carbons evaluated in these experiments, Barney Cheney NL 1266 was found to adsorb the largest percentage of lead, copper and cobalt. The adsorption of any single metal (lead, copper and cobalt) was hindered by the presence of the other metals; the metals apparently competed for adsorption sites.

Keywords: Copper, Lead, Cobalt, Aqueous Solution, Removal, Activated Adsorption

Rowley, A.G., Husband, F.M. and Cunningham, A.B. (1984), Mechanism of metal adsorption from aqueous solutions by waste tyre rubber. Water Research, 18 (8), 981-984.

Full Text: W\Wat Res18, 981.pdf

Abstract: The mechanisms of adsorption of cadmium(II), mercury(II) and lead(II) on to shredded rubber from old automobile types have been studied and it is shown that at least two distinct processes can be involved depending upon the metal being adsorbed. Mercury and cadmium uptake are accompanied by displacement of zinc and therefore probably involve an ion exchange type mechanism. Lead adsorption, in contrast, involves no zinc displacement and is not competitive with cadium or mercury uptake, suggesting that a completely separate mechanism and site of binding are used by lead(II).

Keywords: Tyres, Waste, Rubber, Metal Adsorption, Mercury, Cadmium, Lead, Mechanism, Effluents

Jardim, W.F. and Pearson, H.W. (1984), A study of the copper-complexing compounds released by some species of cyanobacteria. Water Research, 18 (8), 985-989.

Full Text: W\Wat Res18, 985.pdf

Abstract: The production of copper-complexing extracellular material by cyanobacteria was studied by using ion specific electrodes. The species studied were Plectonema boryanum and Anabaena cylindrica. The values of the conditional stability constants for the copper complexes (K’), for the two species at pH 6.60 (±0.05) were, respectively 2.8 (±0.8)×10⁶ and 5.9 (±2.0)×10⁷. A strain of P. boryanum that was made tolerant to a concentration of 1×10^-6M copper produced greater amounts of copper-complexing products than the normal strain although the K’ value for the copper complexes was the same. When stressed with copper, P. boryanum and A. cylindrica produced more complexing material than under the usual growth conditions.

Keywords: Cyanobacteria, Extracellular Products, Copper, Stressing, Conditional Stability Constants, Toxicity, Copper Tolerance

Notes: highly cited

Blanchard, G., Maunaye, M. and Martin, G. (1984), Removal of heavy metals from waters by means of natural zeolites. Water Research, 18 (12), 1501-1507.

Full Text: W\Wat Res18, 1501.pdf

Abstract: The natural zeolite clinoptilolite can be used as an ion exchanger for the removal of ammonium ions from drinking waters. These waters may also contain small amounts of heavy metals. The retention possibilities of these cations by the zeolite are presented.

The study of the selectivity of the Na-exchanged clinoptilolite in presence of ammonium ions has been achieved by plotting the exchange isotherms relative to the various cations. This leads to the following order of decreasing efficiency of the zeolite.

Tan, T.C., Chia, C.K. and Teo, C.K. (1985), Uptake of metal ions by chemically treated human hair. Water Research, 19 (2), 157-162.

Full Text: W\Wat Res19, 157.pdf

Abstract: The uptake capacity of chemically treated human hair waste for the various metal ions can be arranged in the following decreasing order: Hg²⁺ (Hg⁺), Ag⁺, Pb²⁺, Cd²⁺, Cu²⁺ (Cu⁺), Cr⁶⁺, Ni²⁺, Cr³⁺. The uptake capacity is significantly affected by the presence of other metal ions. Anionic effect was found to be more pronounced for a mixed ions system than for a single ion system.

Keywords: Keratinous Waste, Human Hair, Metal Ion Adsorption

McKay, G., Bino, M.J. and Altamemi, A.R. (1985), The adsorption of various pollutants from aqueous solutions on to activated carbon. Water Research, 19 (4), 491-495.

Full Text: W\Wat Res19, 491.pdf

Abstract: The ability of activated carbon. Filtrasorb 400, to adsorb various pollutants from aqueous solutions has been studied. The pollutants investigated are phenol, p-chlorophenol, sodium dodecyl sulphate, mercuric ions and chromic(III) ions. The saturation adsorption capacity of the activated carbon for the pollutants is 213, 434, 361, 35 and 138 mg g^-1 for phenol, p-chlorophenol, sodium dodecylsulphate, chromium(III) and mercuric(II) respectively. Equilibrium isotherm analyses were undertaken using Langmuir and Freundlich equations.

Keywords: Adsorption, Activated Carbon, Water Pollution, Equilibrium Isotherms, Phenol, p-Chlorophenol, Sodium Dodecyl Sulphate, Mercuric Ions, Chromium(III) Ions

Narkis, N. and Ben-David, B. (1985), Adsorption of non-ionic surfactants on activated carbon and mineral clay. Water Research, 19 (7), 815-824.

Full Text: W\Wat Res19, 815.pdf

Abstract: A series of non-ionic surfactants of nonyl-phenol ethoxylates, with n = 4−23;0 ethylene oxide groups and dinonyl-phenol ethoxylate were studied in dilute aqueous solution. Their removal efficiencies and mechanisms by adsorption on powdered and granular activated carbon and on Na-montmorillonite clay were investigated. The powdered activated carbon proved to be the most efficient with 94–100% non-ionic surfactants removal by addition of 40–80 mg activated carbon. Various models of adsorption isotherms such as Langmuir, BET and S-type were used to determine Q⁴, the limiting adsorption capacity. The relationships between Q^o and parameters affecting the adsorption of non-ionic surfactants such as n, HLB and CMC were determined. The cross-sectional area ₀ occupied by surfactant molecules on the adsorbent was calculated. Adsorption has been proven to be a potential advanced physicochemical treatment method for the effective removal of non-ionic surfactants present in effluents intended for reuse.

Keywords: Non-Ionic Surfactants, Nonyl-Phenol Ethoxylate, Adsorption, Activated Carbon, Na-Montmorillonite, Limiting Adsorption Capacity

Notes: highly cited

Panday, K.K., Prasad, G. and Singh, V.N. (1985), Copper(II) removal from aqueous solution by fly ash. Water Research, 19 (7), 869-873.

Full Text: W\Wat Res19, 869.pdf

Abstract: The removal of Cu(II) by adsorption on fly ash has been found to be concentration, pH and temperature dependent. The kinetics of adsorption indicates the process to be diffusion controlled. The Langmuir constants have been calculated at different temperatures, and the adsorption has been found to be endothermic (H = 15.652 kcal mol^-1). The maximum removal is observed at pH 8.0, and variation in adsorption with pH has been explained on the basis of surface ionisation and complexation.

Keywords: Fly Ash, Cu(II), Adsorption Dynamics, Mass Transfer Coefficient, Pore Diffusion, Langmuir Isotherm, Surface Ionization, Complexation

? Hoigné, J., Bader, H., Haag, W.R. and Staehelin, J. (1985), Rate constants of reactions of ozone with organic and inorganic compounds in water. III. Inorganic compounds and radicals. Water Research, 19 (8), 993-1004.

Full Text: 1985\Wat Res19, 993.pdf

Abstract: Second-order rate constants for reactions of ozone with 40 inorganic aqueous solutes are reported. Included are compounds of sulfur (e.g. H₂S, H₂SO₃, HOCH₂SO₃H), chlorine (e.g. Cl⁻, HOCl, NH₂Cl, HClO₂, ClO₂), bromine (e.g. Br⁻, HOBr), nitrogen (e.g. NH3, NH₂OH, N₂O, HNO₂) and oxygen (e.g. H₂O₂), as well as free radicals (e.g. O²⁻, OH•). Most of these compounds exhibit an increase in rate constant with increasing pH corresponding to their degree of dissociation. Rate constants are based on ozone consumption rates measured by conventional batch-type or continuous-flow methods (10⁻³-10⁺⁶ M⁻¹ s⁻¹ range) and determinations of stoichiometric factors. Also listed are data determined by pulse-irradiation techniques using kinetic spectroscopy (1010 M⁻¹ s⁻¹ range). Additional literature data are reviewed for completeness. Results are discussed with respect to water treatment and environmental processes.

Keywords: Free Radicals (Ozonation), Inorganic Anions (Ozonation), Nitrite (Ozonation), Oxidation (Ozone), Ozone, Rate Constants (Ozone), Reaction Kinetics (Ozone), Sulfite (Ozonation), Water Treatment

Forster, C.F. (1985), Factors involved in the settlement of activated-sludge. I. Nutrients and surface polymers. Water Research, 19 (10), 1259-1264.

Full Text: W\Wat Res19, 1259.pdf

Abstract: Using data obtained from a number of full-scale plants, the settlement characteristics of activated sludge were examined in relation to the variations in the main nutrients (carbon, nitrogen, phosphorus) present in the sewage being fed to the aeration tank. The results tended to confirm previous work by showing that there were certain combinations of nutrients that were more likely to produce poor settlement. The molecular weights of the surface polymers extracted from activated sludge by heat were determined by a gel-filtration unit with an exclusion limit of 100,000. The distributions found by this technique were similar to those reported previously; a fraction at 100,000, a major fraction at < 100,000 and one or more minor fractions. The actual weight of the major fraction was found to increase as the settlement of the sludge deteriorated. It is suggested that this could be due to steric effects allowing greater amounts of interstitial water to be bound in the sludge. Molecular weight distributions were also obtained with a gel system whose exclusion limit was four million. These showed the presence of several high molecular weight (> 100,000) species with the highest exceeding 2×10⁶.

Keywords: Nutrients, Activated Sludge Settlement, Extracellular Polymers, Molecular Weights

Forster, C.F. (1976), Factors involved in the settlement of activated sludge II. The binding of polyvalent metals. Water Research, 19 (10), 1265-1271.

Full Text: W\Wat Res10, 1265.pdf

Abstract: Extra cellular polymers (ECP) were extracted from a series of activated sludges which were obtained from a number of full-time plants. The sludges had settlement properties characterized by SSVI values (measured at 3.5 g 1^-1) ranging from 63 to 260. The metal binding properties of these polymers were examined by two methods; gel filtration and equilibrium analysis. This enabled three parameters to be quantified for each of the ECPs; the conditional stability constants for the metal/polymer sites, the number of binding sites per molecule of polymer and the complexation capacities of the ECPs. In addition, the equilibrium analysis method enabled an assessment to be made as to the number of types of binding site existing for any metal/polymer series. The gel filtration results show that the affinity series (based on stability constants) varied randomly as the SSVI varied and that the number of binding sites did not show any particular pattern in relation to settlement. The equilibrium analysis results show that whilst copper, zinc and chromium exhibit a similar behaviour at all SSVI values, the way in which nickel behaves depends on the settlement properties of the sludge.

Keywords: Activated Sludge, Metal-Binding, Equilibrium Analysis, Conditional Stability Constants, Extra Cellular Polymer

Alibhai, K.R.K., Mehrotra, I. and Forster, C.F. (1985), Heavy metal binding to digested sludge. Water Research, 19 (12), 1483-1488.

Full Text: W\Wat Res19, 1483.pdf

Abstract: The interactions of heavy metals with anaerobically digested sludges and with digested sludge which had been washed with EDTA have been examined by equilibrating the sludge solids with solutions containing zinc acetate, lead acetate, ferrous sulphate and chromic chloride. This equilibration has been studied at 20 and 35°C. Langmuir and Freundlich isotherms were used to describe the metal binding behaviour of the solids. The linear part of the isotherm was obtained by regression analysis and conditional adsorption constants were calculated from the slope of these lines. These calculations suggested that, under the conditions used in this work, the mechanism of attachment was predominantly one involving metal/surface ligand interactions. Attachment series, based on the various constants, are reported and lead the authors to question the suitability of such series for describing the binding of metals relative to one another.

Keywords: Digested Sludge, Heavy Metals, Adsorption, Isotherms, Sorption Constants, Binding Series

Gosset, T., Trancart, J.L. and Thévenot, D.R. (1986), Batch metal removal by peat: Kinetics and thermodynamics. Water Research, 20 (1), 21-26.

Full Text: W\Wat Res20, 21.pdf

Abstract: Peat moss, a natural inexpensive material, is able to play an important rôle in treatment processes of metal-bearing industrial effluents since it adsorbs, complexes or exchanges various metal cations. This paper presents kinetics and thermodynamics of batch metal removal reactions by 50 g l^-1 (dry wt) eutrophic or oligotrophic peat particles using Cu²⁺, Cd²⁺, Zn²⁺ and Ni²⁺ concentrations ranging from 0.01 to 100 mM.

Metal cation removal reactions are moderately rapid in 10 mM metal unbuffered solutions: the forward kinetic constant ranges between 0.005 and 0.17 M^-1s^-1, and equilibrium is reached within about 1 h. Under these conditions of pH (2.2–4.2) and concentrations, apparent binding equilibrium constants were found to range between 2 and 3150 M^-1 depending upon the peat origin and the metal cation.

In 0–6.5 pH-buffered metal cation solutions, the four cations binding reactions behaved differently demonstrating that metal binding equilibrium constant decrease in the order Ni²⁺ > Cu²⁺ > Cd²⁺ = Zn²⁺. When pH is higher than 6.7, more than 90% of a 10 mM metal cation solution is removed by 50 g 1^-1 peat particles and metal binding capacities equal 200 mmol kg^-1 dry wt, whatever the metal nature and the peat origin. Except for nickel cation which is very strongly bound to peat, all metal cations are completely released when pH is fixed below 1.5.

Keywords: Peat, Heavy Metals, Ion Exchange, Complexation, Kinetics, Thermodynamics

McKay, G., Bino, M.J. and Altememi, A. (1986), External mass transfer during the adsorption of various pollutants onto activated carbon. Water Research, 20 (4), 435-442.

Full Text: W\Wat Res20, 435.pdf

Abstract: A wide range of experimental studies are reported for the adsorption of phenol and p-chlorophenol onto activated carbon––Type Filtrasorb 400––in an agitated batch adsorber. A model has been used to determine the external mass transfer coefficient for the systems and the effect of several experimental variables have been investigated: these include agitation, initial pollutant concentration, carbon mass, carbon particle size and solution temperature. The mass transfer coefficient has been correlated in terms of the dimensionless Sh/Sc^0.33 against each variable. The Sherwood number, Sh = k_fR/D_mol, relates the external mass transfer coefficient k_f to particle radius, R, and molecular diffusivity, D_mol. The Schmidt number, Sc, is the ratio of kinematic viscosity, v, to molecular diffusivity. A few results are also reported for the adsorption of sodium dodecyl sulphate and mercuric ions onto activated carbon.

Keywords: Adsorption, Activated Carbon, Phenol, p-Chlorophenol, Mercury, Sodium Dodecyl Sulphate, Mass Transfer

? Matthews, R.W. (1986), Photo-oxidation of organic material in aqueous suspensions of titanium dioxide. Water Research, 20 (5), 569-578.

Full Text: 1986\Wat Res20, 569.pdf

Abstract: Twenty-one organic compounds, known to be possible contaminants of water, have been treated with u.v.-illuminated titanium dioxide powder in aqueous suspension. In each case the organic material was converted to carbon dioxide. The rate of carbon dioxide formation did not vary greatly from one compound to another; even nitrobenzene was converted at 40% of the maximum rate observed with 2,4 dichlorophenol. Chlorobenzene, benzoic acid and 4-chlorophenol were selected for more detailed studies of the effect of solute concentration, pH and products other than CO₂. Results were compared using illumination by a 100 W medium pressure mercury lamp, an 0.25 m² parabolic trough solar collector and by solar illumination of a flat bed. The CO₂ production rate from 300 ml of 10⁻³ M 4-chlorophenol in contact with 0.15 g TiO₂ solar illuminated with the 0.25 m² collector was 20 μM min−1 which corresponds to the oxidizing radicals generated in water by a 60Co gamma ray dose rate of not less than 8.3 krad min⁻¹. The possible use of solar-illuminated TiO₂ for the disinfection of water is suggested.