Personal Research Database

Full Text: W\Wat Sci Tec35, 205.pdf

Abstract: The adsorption isotherm of cadmium on activated carbon was measured in a batch adsorber. Effects of temperature and solution pH on the adsorption isotherm were investigated by determining the adsorption isotherm at temperatures of 10, 25, and 40°C and at initial pH values from 2 to 8. Langmuir isotherm better fitted the experimental data since the average percent deviation was lower than with the Freundlich isotherm. It was noticed that the amount of Cd²⁺ adsorbed was reduced about 3 times by increasing the temperature from 10 to 40°C. it was found that Cd²⁺ was not adsorbed on activated carbon at pH of 2 or lower and that Cd²⁺ was precipitated out as Cd(OH)₂ at pH values above 9. Maximum adsorption capacity was observed at pH of 8 and the adsorption capacity was decreased about 12 times by reducing the initial pH from 8 to 3. According to the cadmium speciation diagram the predominant species below pH of 8 is Cd²⁺. Thus, cadmium was adsorbed on the activated carbon surface as Cd²⁺. It was concluded that the adsorption capacity is a strong function of pH and temperature.

Keywords: Adsorption, Cadmium, Isotherm, pH Effect, Temperature Effect

Hand, D.W., Crittenden, J.C., Hokanson, D.R. and Bulloch, J.L. (1997), Predicting the performance of fixed-bed granular activated carbon adsorbers. Water Science and Technology, 35 (7), 235-241.

Full Text: W\Wat Sci Tec35, 235.pdf

Abstract: Granular Activated Carbon (GAG) adsorption is an effective treatment technology for the removal of Synthetic Organic Chemicals (SOCs) from drinking water supplies. This treatment process can be expensive if not properly designed. Application of mathematical models is an attractive method to evaluate the impact of process variables on process design and performance. In this study, A. mathematical modeling methodology incorporating the pore and surface diffusion model (PSDM) is proposed for known mixtures in fixed-bed adsorbers. Thermodynamic correlations for estimation of equilibrium parameters and empirical correlations for estimation of mass transfer parameters are presented. The PSDM was successfully compared to a 6-component mixture for empty bed contact times (EBCTs) of 2.4, 4.9, and 9.56 minutes. (C) 1997 IAWQ. Published by Elsevier Science Ltd.

Keywords: Mixtures, Adsorption, Granular Activated Carbon, Adsorbers, Computer Software, Water Supply, Water Treatment

Hwa, T.J. and Jeyaseelan, S. (1997), Conditioning of oily sludges with municipal solid wastes incinerator fly ash. Water Science and Technology, 35 (8), 231-238.

Full Text: W\Wat Sci Tec35, 231.pdf

Abstract: Conditioning of sludges improves dewatering characteristics and reduces the quantity of sludge to be handled. Anaerobic digested sludge collected from a sewage treatment plant contained 1.8% to 8% oil. The increase of specific resistance and capillary suction time (CST) with increasing oil content observed in these samples indicates the interference of oil in dewatering. It has been found that addition of municipal solid wastes incinerator fly ash decreases the specific resistances and capillary suction times of oily sludges rapidly up to 3% dosage. Beyond 3% fly ash, the decrease is less significant and the solids content in the sludge cake increases. This optimum dosage remains the same for sludges with varying oil contents from 1.8% to 12%. The total suspended solids of filtrate decreases with fly ash dosage but the toxic concentrations of heavy metals increases considerably. However at the optimum dosage of 3%, concentrations of heavy metals are within the limits for discharging into the sewers. The correlations of CST with the dewatering characteristics such as specific resistance, filter yield and corrected filter yield are established. These correlations can be used to obtain a quick prediction on dewaterability. (C) 1997 IAWQ. Published by Elsevier Science Ltd.

Keywords: Sludge Dewatering, Oily Sludges, Sludge Conditioning, Capillary Suction Time, Specific Resistance To Filtration, Dewaterability, Municipal Solids Waste Incinerator Fly Ash, Particle-Size

Butler, D. and Parkinson, J. (1997), Towards sustainable urban drainage. Water Science and Technology, 35 (9), 53-63.

Full Text: W\Wat Sci Tec35, 53.pdf

Abstract: The issue of sustainable development is now high on the global agenda, but there is still a considerable degree of uncertainty in its definition, let alone implementation. The aim of this paper is to reappraise the provision of urban drainage services in the light of this current debate. The approach advocated is not to strive far the unattainable goal of completely sustainable drainage, rather to actively promote ‘less unsustainable’ systems. To do this requires both an understanding of the long-term and widespread impacts of continuing current practices and an understanding of the implications of making changes. Sustainable urban drainage should: maintain a good public health barrier, avoid local or distant pollution of the environment, minimise the utilisation of natural resources (e.g. water, energy, materials), and be operable in the long-term and adaptable to future requirements. Three strategies are proposed that can be carried out immediately, incrementally and effectively and these are to reduce potable water ‘use’, to reduce and then eliminate the mixing of industrial wastewater with domestic waste, and to reduce and then eliminate the mixing of stormwater and domestic wastewater. A number of techniques are described which may allow adoption of these strategies, many of them small-scale, source control technologies. An incremental approach containing both high-tech and low-tech answers to appropriate problems is the most likely to be implemented but each case must be decided on its merits. (C) 1997 IAWQ. Published by Elsevier Science Ltd.

Charlton, J. (1997), Application of waste stabilisation ponds in Bhutan-Lessons within a sustainable development context. Water Science and Technology, 35 (9), 199-208.

Full Text: W\Wat Sci Tec35, 199.pdf

Abstract: The Danish International Development Assistance agency has funded a project in Bhutan which includes a water supply component in six urban centres, a sewerage component in the two largest cities plus associated institutional development. The project includes the implementation of an extensive water-home sewerage system and associated wastewater treatment. The treatment process adopted was waste stabilisation pond technology due to the low associated construction, operations and maintenance costs and low requirements for technical skills hence contributing to financial and O&M sustainability of the project, as well as meeting the water quality requirements for the receiving waters. Since essentially all available land is utilised in the country, the locations of the treatment plants are adjacent to rivers which are fast flowing, leading to a risk of severe erosion conditions during the monsoon season. In order to protect the treatment plant structure, river training was necessary. The high elevation of the country also has consequences for the design and operation of the plants. The wastewater treatment process includes a train of anaerobic, secondary facultative and maturation ponds, lined with a high density polyethylene liner. This paper describes the project as implemented, focusing on the wastewater treatment plants and the hurdles required to be overcome to ensure sustainable operation of the waste stabilisation pond treatment plants, in particular overall design of the system, the re-design required due to the lass of land occasioned by the intense monsoon rains in the south of the country prior to construction of river training works, the training required for the local staff from the operations and maintenance authorities and the financial aspects of the project The project is discussed within a broader framework of Danish development aid in the country which covers the health, environment and the public health infrastructure sectors. Lessons learnt from the project are discussed. (C) 1997 IAWQ. Published by Elsevier Science Ltd.

Bornhardt, C., Drewes, J.E. and Jekel, M. (1997), Removal of organic halogens (AOX) from municipal wastewater by powdered activated carbon (PAC)/activated sludge (AS) treatment. Water Science and Technology, 35 (10), 147-153.

Full Text: W\Wat Sci Tec35, 147.pdf

Abstract: The effectiveness of different treatments with powdered activated carbons (PAC) to reduce the AOX-levels in municipal wastewater was investigated in a bench-scale activated sludge (AS) treatment plant. The PAC was added either directly to the aerated basin (simultaneous PAC-treatment), or to a partial stream of clarified effluent, which was treated with PAC in an agitated tank and recirculated to the aerated basin (subsequent PAC-treatment with recirculation). The standard advanced biological treatment reduced the AOX-content by 24%. In the pilot-plant, three types of powdered activated carbons were tested for a simultaneous treatment. The treatment with 100 mg/l PICA PCO Super produced an additional reduction of AOX by 20%, whereas a dosage of 50 mg/l NORIT W-20 showed no enhancement effect, and W-35 led to an additional AOX-removal of about 9%. Also, an improved removal of DOG, NH₄-N and PO₄-P was observed. In all cases, the PAC addition caused a significantly improved settling of the AS, reducing the sludge-volume-index, and increasing the content of volatile solids of the PAC-sludge. In general, no evidence of a synergistic effect of the PAC addition to activated sludge, nor bioregeneration of the activated carbon, could be observed. This suggests, that the observed effects probably are caused only by simple adsorption.

Keywords: Activated Sludge, Adsorbable Organic Halogens (AOX), Advanced Wastewater Treatment, Dissolved Organic Carbon (DOG), Municipal Wastewater, Pact-Process, Powdered Activated Carbon (PAC), Wastewater Treatment Plant

Wiedenmann, A., Braun, M. and Botzenhart, K. (1997), Evaluation of the disinfection potential of low chlorine concentrations in tap water using immobilised Enterococcus faecium in a continuous flow device. Water Science and Technology, 35 (11-12), 77-80.

Full Text: W\Wat Sci Tec35, 77.pdf

Abstract: A simple continuous now device in which bacteria were immobilised on membrane filters and flushed with tap water with free chlorine residuals of 0.05, 0.1, 0.2 and 0.4mg/L at pH 7.7 and 10°C, has been used for disinfection experiments with faecal streptococci. A 99.99% reduction of Enterococcus faecium was observed between 3.4-5.2min (0.05mg/L), between 2.8-4.1min (0.1mg/L), between 1.7-3.1min (0.2mg/L) and between 0.8-2.1min (0.4mg/L). CT-products covered a range of 0.17 (0.05mg/L, lower limit) up to 0.85mg/L/min (0.4mg/L, upper limit). The test system is suggested as a more reliable alternative to batch experiments when the disinfection potential of low chlorine concentrations acting for several minutes has to be evaluated. The system cannot be used to demonstrate exact reduction kinetics but it allows the calculation of CT values and the evaluation of the disinfection potential of chlorinated water at any point of a distribution system where initial chlorine concentrations may have already remarkably declined. (C) 1997 IAWQ. Published by Elsevier Science Ltd.

Keywords: Drinking Water, Disinfection, Chlorine, Faecal Streptococci, CT-Values, Distribution System

Meier, H., Koob, C., Ludwig, W., Amann, R., Frahm, E., Hoffmann, S., Obst, U. and Schleifer, K.H. (1997), Detection of enterococci with rRNA targeted DNA probes and their use for hygienic drinking water control. Water Science and Technology, 35 (11-12), 437-444.

Full Text: W\Wat Sci Tec35, 437.pdf

Abstract: Enterococci are useful indicators of faecal contamination with their high abundance in faeces and long survival in the environment and the possibility of indicating the source of contamination by species identification has lead to discussion of whether enterococci would be more reliable faecal indicators than E. coli. In an attempt to facilitate rapid and accurate identification of enterococci, 16S rRNA targeted oligonucleotide probes were designed by computer-aided analysis of more than 4,000 rRNA sequences. Probes were labelled non-isotopically with digoxigenin and fluorescent dyes. Conditions for specific hybridisation were optimised for dot blot hybridisation and whole cell hybridisation for all probes. With a combination of two probes, all hygienically important enterococci could be detected and 24 biochemically identified environmental isolates also hybridised with one of these probes. A quantitative detection method with a high sensitivity was developed based on filtration of water samples through polycarbonate filters, a short incubation on agar and microcolony filter hybridisation with fluorescently labelled probes followed by epifluorescence microscopy. Within 8-20h sampling a specific identification of enterococcal microcolonies was possible. With this method 15/32 well- and tap-water sources from the Mainz area were identified as being of substandard quality. The proposed method detects faecal contamination significantly earlier than conventional methods and could be helpful in the hygienic monitoring of drinking water. (C) 1997 IAWQ. Published by Elsevier Science Ltd.

Keywords: Enterococci, Drinking Water, Hygienic Monitoring, Hybridisation, DNA Probes, rRNA, Microscopy, Oligonucleotide Probes, Genus Enterococcus, Escherichia-Coli, Microbial-Cells, Identification, RNA, Differentiation, Lactococci, Bacteria

Lambert, S.D., Graham, N.J.D., Sollars, C.J. and Fowler, G.D. (1997), Evaluation of inorganic adsorbents for the removal of problematic textile dyes and pesticides. Water Science and Technology, 36 (2-3), 173-180.

Full Text: W\Wat Sci Tec36, 173.pdf

Abstract: This paper evaluates three inorganic adsorbents (activated bauxite, fullers earth and a synthetic clay), relative to activated carbon, for the removal of several representative contaminants of major concern and frequent occurrence in UK textile industry effluents; reactive dyes, pentachlorophenol and Propetamphos. The results indicate that, for the removal of reactive dyes, the synthetic clay was the most effective adsorbent over the pH range from pH 5.5 to pH 8.5 and temperature range from 20 to 40°C, although comparable dye removals were exhibited by activated carbon under neutral and alkaline conditions. Under acidic conditions activated bauxite was as effective as activated carbon. Fullers; Earth was largely ineffective. With regard to the removal of pesticides activated carbon was highly effective, whereas the three inorganic adsorbents showed negligible removals.

Keywords: Dissolved Organic-Matter, Potable Water-Supplies, Adsorption, Activated Bauxite, Activated Carbon, Adsorption, Fullers Earth, Macrosorb, Pentachlorophenol, Propetamphos, Reactive Dyes, Textile Effluents

Ramakrishna, K.R. and Viraraghavan, T. (1997), Dye removal using low cost adsorbents. Water Science and Technology, 36 (2-3), 189-196.

Full Text: W\Wat Sci Tec36, 189.pdf

Abstract: Dyestuff production units and dyeing units have always had a pressing need for techniques that allow economical pretreatment for color in the effluent. The effectiveness of adsorption for dye removal from wastewaters has made it an ideal alternative to other expensive treatment options. The current paper deals with an investigation on four low-cost adsorbents locally available in Saskatchewan, Canada for dye removal. Feat, steel plant slag, bentonite clay and fly ash were utilized for this study and their performance evaluated against that of granular activated carbon. Batch kinetic and isotherm studies, and column studies were undertaken, and the data evaluated for compliance with the Langmuir, Freundlich and BET isotherm models. Synthetic dye wastewaters prepared from commercial grade acid, basic and disperse dyes were used in this study and the results showed high removals of acid dyes by fly ash and slag while peat and bentonite exhibited high basic dye removals. For the acid and basic dyes, the removals were comparable with that of granular activated carbon, while for the disperse dyes, the performance was much better than that of granular activated carbon. The results obtained point towards viable adsorbents which are both effective as well as economically attractive for color removal from wastewaters.

Keywords: Peat, Adsorption, Ions, Adsorption, Bentonite, Dyes, Fly Ash, Peat, Slag

Notes: highly cited

? McArthur, J.M., Ravenscroft, P., Safiulla, S. and Thirlwall, M.F. (2001), Arsenic in groundwater: Testing pollution mechanisms for sedimentary aquifers in Bangladesh. Water Science and Technology, 37 (1), 109-117.

Full Text: 2001\Wat Sci Tec37, 109.pdf

Abstract: In the deltaic plain of the Ganges-Meghna-Brahmaputra Rivers, arsenic concentrations in groundwater commonly exceed regulatory limits (>50 mug L(-1)) because FeOOH is microbially reduced and releases its sorbed load of arsenic to groundwater. Neither pyrite oxidation nor competitive exchange with fertilizer phosphate contribute to arsenic pollution. The most intense reduction and so severest pollution is driven by microbial degradation of buried deposits of peat. Concentrations of ammonium up to 23 mg L(-1) come from microbial fermentation of buried peat and organic waste in latrines. Concentrations of phosphorus of up to 5 mg L(-)1 come from the release of sorbed phosphorus when FeOOH is reductively dissolved and from degradation of peat and organic waste from latrines. Calcium and barium in groundwater come from dissolution of detrital land possibly pedogenic) carbonate, while magnesium is supplied by both carbonate dissolution and weathering of mica. The (87)Sr/(86)Sr values of dissolved strontium define a two-component mixing trend between monsoonal rainfall (0.711 +/- 0.001) and detrital carbonate (<0.735).

Keywords: Ganges Delta, West-Bengal, Lacustrine Sediments, Sulfate Reduction, Himalayan Rivers, United-States, Water, Carbon, Mineralization, Geochemistry

? Dong, Q.H., Springeal, D., Schoeters, J., Nuyts, G., Mergeay, M. and Diels, L. (1998), Horizontal transfer of bacterial heavy metal resistance genes and its applications in activated sludge systems. Water Science and Technology, 37 (4-5), 465-468.

Full Text: 1998\Wat Sci Tec37, 465.pdf

Abstract: The bacterial nickel (Ni) resistance determinant ncc-nre of Alcaligenes 31A strain cloned to an IncQ broad-host-range plasmid pKT240 gave rise to pMOL222. The plasmid was subsequently mobilized into various Eubacteria and found to confer an increased Ni resistance on these recipients. An increase of Ni resistance was also observed after the transfer of pMOL222 into activated sludge bacteria by plate mating. The dissemination of pMOL222 into an activated sludge pilot stabilized the system during a heavy metal shock loading with 0.25 mM Ni. (C) 1998 IAWQ. Published by Elsevier Science Ltd.

Keywords: Activated Sludge; Gene Transfer; Heavy Metal Resistance, Plasmid

Richardson, M. (1998), Pesticides: Friend or foe? Water Science and Technology, 37 (8), 19-25.

Full Text: W\Wat Sci Tec37, 19.pdf

Abstract: Pesticides, where used correctly, can save up to 40% in crop losses; however, when pesticides are mal-, mis-or over-used the environmental and public health consequences can be very considerable. The United Nations has issued a list of chemicals that are banned or severely restricted in use; many of the chemicals on this list are pesticides. Whilst the use of highly persistent pesticides such as DDT has proved very effective in the eradication of diseases such as malaria, the adverse effects to the natural environment have been devastating-whole populations of birds have been eliminated. Within the former Soviet Union, the use of highly persistent pesticides was widespread; this has resulted in contamination of both crops, with pesticide residues well in excess of internationally acceptable maximum residue limits, and water resources to such high level that remediation through natural processes will take decades, or by xenobiotic or physicochemical precesses will be extremely costly. This is an extraordinary situation as the former Soviet Union had one of the most stringent of environmental regulation-the GOST regulations; unfortunately these were not pragmatic and rarely applied. When in the Ukraine in 1994, I heard that farmers where paid for every application made; the result was crops, soil, water and the environment were highly contaminated, and in some cases the land became barren. Currently, the situation in some countries is that no pesticides are being applied because under the new market conditions farmers cannot afford to purchase pesticides. In Armenia in July 1995, one could not purchase fruit which was not diseased. The effects of mis-use of pesticides are known to cause very serious adverse effects to human health: in some countries children are exhibiting excessive cancer incidences; crops found to be highly contaminated with up to five different pesticides are being condemned, often being burnt in the fields. As these crops in all probability contained now banned and highly persistent pesticides, mere burning at low temperatures is producing even more toxic dioxins, furans, etc. This leads to both air and soil contamination. One answer would be for the farmer to be obliged to pay for high-temperature incineration in a high-tech incinerator in a developed country, which, subject to prior informed consent, could cost US $ 5000/tonne. However, the application of modem pesticides in accordance with manufacturers’ specifications can incur none of these problems; this presentation will outline how pesticides can be used judiciously. (C) 1998 IAWQ. Published by Elsevier Science Ltd.

Martin, J.C., Hoggart, C. and Matisa, A. (1998), Improvement priorities for sewage treatment in Latvian small and medium sized Towns. Water Science and Technology, 37 (8), 137-144.

Full Text: W\Wat Sci Tec37, 137.pdf

Abstract: This paper describes the development of a strategy to identify the priorities for investment in sewage treatment in the rural areas in Latvia. The strategy is developed from the baseline conditions ascertained for the present quality of the many receiving waters (rivers, lakes, ground water and the Baltic Sea) and from the condition of the 800 Plus sewerage systems which serve all of the small and medium sized towns in the country. Technical solutions are developed consistent with Latvian policy goals and the priorities established for improvement to the environment and public health. An investmeni strategy has been prepared to optimise the use of the available funds, to achieve the best value for money. It has been agreed in consultation with interested parties at national, regional and local levels, to produce a plan with wide acceptance. The strategy is known in Latvia as ‘800 Plus’. (C) 1998 IAWQ. Published by Elsevier Science Ltd.

Adin, A. and Asano, T. (1998), The role of physical-chemical treatment in wastewater reclamation and reuse. Water Science and Technology, 37 (10), 79-90.

Full Text: W\Wat Sci Tec37, 79.pdf

Abstract: Amid the heightened public health concerns for emerging microorganisms such as Cryptosporidium and enteropathogenic E. coli in the water environment, there have been many instances where optimization of chemical coagulation-flocculation processes and filtration of wastewater was not achieved in practice, resulting in waste of coagulant chemicals and breach of the multiple barriers to pathogen removal and inactivation; thus, unnecessarily endangering public health. In addition, lack of information on the optimization of these processes has hampered the establishment of alternative and more cost-effective wastewater reclamation methods for tertiary and advanced wastewater treatment. Thus, the purpose of this paper is to evaluate the basic factors affecting the optimization of chemical coagulation-flocculation and filtration processes in municipal wastewater reclamation and reuse, based on the theoretical developments and practical applications. Reference is also made to the wastewater treatment processes and operations that can produce reclaimed water with an extremely small probability of enteric virus contamination. (C) 1998 Published by Elsevier Science Ltd. All rights reserved

Yuasa, A. (1998), Drinking water production by coagulation-microfiltration and adsorption-ultrafiltration. Water Science and Technology,