Environmental Technology

Poggi‐Varaldo, Hector M.; Oleszkiewicz, Jan A.

doi: 10.1080/09593339209385169pmid: N/A

Abstract The feasibility of anaerobic co‐composting of waste activated sludge (WSS) and simulated organic fraction of typical North‐American municipal solid waste (NA‐MSW), rich in lignocellulosics, at high total solids (TS) content, was examined. Sixteen semicontinuous reactors were run, at 4 levels of TS (25, 30, 35 and 40%), 2 levels of retention time (15 and 21 days), 2 temperature regimes (mesophilic at 39°C and thermophilic at 53°C), and 2 ratios of MSW‐to‐WSS (1: 1 and 2: 1 on total weight basis). Reactors operated at 35% TS and 21 days gave the best organic matter removal efficiencies (up to 44% and 53% on volatile solids basis, for mesophilic and thermophilic regimes respectively) and highest biogas productivities (up to 6 L kg‐1 reactor content day‐1). The methane concentration in biogas was between 55 and 60%. Successful thermophilic reactors generated 15 to 30% more biogas than the corresponding mesophilic digesters. Instability and failure of some thermophilic reactors at 15 days retention time were observed. Addition of WSS (ratio 1: 1, richest in sludge) had a beneficial effect on the process.

Baudu, M.; Le Cloirec, P.; Martin, G.

doi: 10.1080/09593339209385170pmid: N/A

Abstract A procedure allowing an efficient regeneration by Joule effect, of activated carbons (granular or fibrous) used for the purification of hydrocarbon polluted air is proposed. This process was developped on pilot units feed. Optimal operation conditions (electrical power, temperature, air flow rate) were determined. Further, suggestions were made for the recovery of the desorbed solvents and potential applications of the procedure.

FreirIa‐Gádara, M.J.; Lorenzo‐Perreira, R.A.; Alvarez‐Devesa, A.; Bermejo, F.

doi: 10.1080/09593339209385171pmid: N/A

Abstract Some of the most frequent drinking water contaminants are halogenated hydrocarbons formed, in part, by the chlorination of water. This study involves the gas‐chromatographic analysis of water samples from the water supply of different cities in ‘Galicia (Spain): La Coruna, Ferrol, Lugo, Orense, Pontevedra and Vigo. The compounds investigated were: bromochloromethane, bromodichloroznethane, chlorobenzene, chloroform, dibromochloromethane, 1,2‐dichloroethane, dichloromethane, tetrachloroethylene, carbon tetrachloride and trichloroethylene. A total of 400 samples were analyzed. The results obtained showed that the range of concentrations is between 160.9–1.3 μg.l‐1 for bromochloromethane, 79.5–2.0 μg.1‐1 for chloroform, 53–1.5 μg.l‐1 for dichloromethane, 58.7–1.5 μg.1‐1 for tetrachloroethylene, 39.5–1.5 μg.1‐1 for carbon tetrachloride, 44.6–2 μg.1‐1 for bromodichloromethane, 22–2 μg.1‐1 for 1,2 dichloroethane and 11.6–1.0 μg.1‐1 for trichloroethylene. Dibromochloromethane and chlorobenzene were not detected.

Fukunaga, Isao; Takamizawa, Kazuhiro; Inoue, Zensuke; Hasebe, Toshhiko; Konae, Miyoji; Hatano, Kiyoshi; Mori, Shoichi

doi: 10.1080/09593339209385172pmid: N/A

Abstract Field observations of water and organisms were performed in the stabilization ponds at a solid disposal site between 1983 and 1987 to plan measures against wastewater pollution at Sites II and III in the North Section of the Osaka North Port Sea‐Based Solid Waste Disposal Site. The number of phytoplankton cells varied 103 to 105 (cells)mL‐1 and phytoplankton grew rapidly in spring and autumn. Principal dominant species were Skeletonema eostatum, Chlorella sp. and Chlamydomonas spp. Zooplankton ranged 10 to 105 individuals (10L)‐1 and were more numerous in the spring to summer. Brachionus plicatilis was dominant. CODMn of the stabilization ponds had a high correlation coefficient with p‐CODMn namely, phytoplankton cells and showed a high value during the growth period of phytoplankton in spring and autumn. These observation results showed that suppression or elimination of phytoplankton would be suitable to lower CODMn of effluent at disposal sites.

Graham, N.J.D.; Buckley, D.; Croll, B.

doi: 10.1080/09593339209385173pmid: N/A

Abstract An extensive investigation has been made of alternative disinfection regimes for the control of trihalomethane (THM) formation in surface water treatment in the Anglian region of the U.K A laboratory experimental protocol has been applied to raw water samples, involving pre‐and post‐disinfection stages, in order to measure THM formation. Ozone, as well as chlorine dioxide and potassium permanganate, have been evaluated as alternative pre‐disinfectants in direct comparison with breakpoint and sub‐breakpoint pre‐chlorination. For ozone, and chlorine dioxide, the significance of the applied dose has been examined.

Sfriso, A.; Pavoni, B.; Marcomini, A.; Raccanelli, S.; Orio, A.A.

doi: 10.1080/09593339209385174pmid: N/A

Abstract Suspended particulate matter (SPM) deposition has been quantified by means of traps placed on the sediment surface in three areas of the Venice lagoon differentiating for the biogeochemical properties. The average amounts of SPM collected in areas A, B, C were 41, 65, and 140 kg m‐2 year‐1, respectively, and in the ranges 22–533, 17–535 and 46–947 g m‐2 day‐1. Suspended matter deposition was uneven throughout the year with remarkable seasonal variations. Total nitrogen and phosphorus bound to SPM were in the ranges: 18.4–104.7 and 2.2–11.5 mmol m‐2 day‐1, respectively. Nutrient deposition onto surface sediments has been compared with the nutrient fluxes from sediment to overlying waters previously measured by benthic chambers and with laboratory experiments by sediment cores.

O'Brien, P.F.; Cooper, T.P.; Jeffrey, D.W.

doi: 10.1080/09593339209385175pmid: N/A

Abstract A method is described for measuring decay rates of carbonate stones over a relatively short time scale (months). The development of this method from flat topped microcatchment units where runoff was collected and analysed is described. The improved unit employs ion exchange resins to collect ions of interest while allowing the bulk of the runoff to flow to waste. The resins can later be eluted in the laboratory to produce figures for stone loss. Initial results for four urban sites around Europe are presented.

Klekner, V.; Kosaric, N.

doi: 10.1080/09593339209385176pmid: N/A

Abstract Strains of Chlorella sp., Scenedesmus obliquus and Spirulina maxima were tested for degradation of some phenolic compounds listed by U.S. EPA as priority pollutants. Toxins were dissolved in a medium (pH 7–7.2) without carbon source (except for testing Spirulina, in which case sodium bicarbonate was part of the medium at pH 9–9.2) and algae prepared by batch cultivation were added. Phenol was found to be degraded easily by all tested algae at a concentration about 1000 mg 1‐1. 2,4‐dimethylphenol was found to be converted by Chlorella (even at a concentration of about 1000 mg1‐1) to an isomer of dimethylbenzenediol that was in some cases accumulated in the medium. Depending upon biomass and toxin concentration the rate of degradation changed and an optimum of toxin concentration which induces degradation might exist. Complete degradation could be reached with biomass concentrations higher than 4 g 1‐1. 2,4‐dinitrophenol at a concentration of about 190 mg 1‐1 was degraded by Scenedesmus quickly after an adaptation period of 5 days. 2‐chlorophenol at a concentration about 200 mg 1‐1 was degraded and partly dechlorinated by Chlorella. Biodegradation of 2,4‐dichlorophenol was not proven but the condition under which algae can survive a higher concentration of toxin could be found. All algae tested have a mechanism for degradation of phenolic compounds.

Klekner, V.; Kosaric, N.

doi: 10.1080/09593339209385177pmid: N/A

Abstract Phenol in mixture with more toxic derivatives did not stimulate the degradation of 2,4‐dimethylphenol and 2‐chlorophenol by cells of Chlorella but improved the removal of 2,4‐dichlorophenol. However, these derivatives clearly inhibited biodvegradation of phenol itself.