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Auteurs : Joung-Dae Kim, Joon-Seok Park, Byung-Hoon In, Daekeun Kimd, Wan Namkoong

This study is aimed to evaluate the performance of pilot-scale in-vessel composting for food wastes treatment. The composting plant was installed with 324m3 of the composting bay volume and 14,000 kg/day of the composting material flow rate. The evaluations studied included the operational indices, the compost maturity indices, and the quality of the final compost. Blowers of this system were useful in maintaining aerobic condition (over 6% oxygen concentration in off-gas) through the entire compost bay. The levels of indices evaluated remained constant in the final part of composting. The final compost was satisfactory for its agricultural application. It was revealed in this study that bulk density bore a linear relation to moisture content during composting, and the final compost without bulking agent showed negative correlation between heavy metal and organic matters content.

© 2007 Elsevier B.V. All rights reserved.

Article consultable en ligne sur www.elsevier.com/locate/jhazmat

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Auteurs : U. Sonesson, A. Bjo¨rklund, M. Carlsson, M. Dalemo

The management system for solid and liquid organic waste affects the environment and surrounding technical systems in several ways. In order to decrease the environmental impact and resource use, biological waste treatment and alternative solutions for sewage treatment are often advocated. These alternatives include increased agricultural use of waste residuals. To analyse whether such proposed systems indicate improvements for the environment and its sustainability, systems analysis is a useful method. The changes in environmental impact and resource use is not only a result of changes in waste treatment methods, but also largely a result of changes in surrounding systems (energy and agriculture) caused by changes in waste management practices. In order to perform a systems analysis, a substance-flow simulation model, the organic waste research model (ORWARE), has been used. The results are evaluated by using methodology from life cycle assessment (LCA). An economic analysis was also performed on three of the studied scenarios. The management system for solid organic waste and sewage in the municipality of Uppsala, Sweden, was studied. Three scenarios for different treatments of solid waste were analysed: incineration with heat recovery, composting, and anaerobic digestion. These three scenarios included conventional sewage treatment. A fourth scenario reviewed was anaerobic digestion of solid waste, using urine-separating toilets and separate handling of the urine fraction. The results are only validfor the case study and under the assumptions made. In this case study anaerobic digestion result in the lowest environmental impact of all the solid waste management systems, but is costly. Economically, incineration with heat recovery is the cheapest way to treat solid waste. Composting gives environmental advantages compared to incineration methods, without significantly increased costs. Urine separation, which may be implemented together with any solid waste treatment, has great advantages, particularly in its low impact on the environment. However, there is a large increase in acidification. © 2000 Elsevier Science B.V.

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Auteurs : Ramaraj Boopathy, Timothy Beary, Paul J.Templet

A laboratory in situ composting study was conducted as a possible alternative method for the current practise of open air burning of post-harvest sugarcane residue by sugarcane farmers. In situ composting of the sugarcane residue by the indigenious bacteria and fungi was accelerated using molasses as an initial substrate. A one-time application of molasses boosted the soil microbial

Auteurs : Romeela Mohee, Revin Panray Beeharry

Life cycle analysis has been used to compare the environmental performance of di€erent sugarcane bioenergy systems. Environmental performance indicators such as resource consumption, chemical stressors and ecological health are used to analyse the trade-o€ between options. The reference fuel chain is based on current practices in Mauritius whereby bagasse in excess of sugar factory requirements is used to generate electricity for the grid. An alternative option uses the excess bagasse and factory ®lter cake to produce compost which when applied to the sugarcane plantations increases cane yield by up to 30% but at the expense of surplus electricity production. A third option combines improvements in steam management with composting of bagasse/®lter cake. Results obtained from the comparative analysis show that it is possible to improve both the production of raw sugar (by 30%) and surplus electricity (by 190%) while reducing environmental stress as measured by the prede®ned eco-eciency indicators.

# 1999 Elsevier Science Ltd. All rights reserved.

Article consultable en ligne sur www.elsevier.com/locate/biombioe

Auteurs : M.A. Sanchez-Monederoa, C. Mondini, M. de Nobili, L. Leita, A. Roig

The effect of land application of biosolids on an agricultural soil was studied in a 2-month incubation experiment. The soil microbial biomass and the availability of heavy metals in the soil was monitored after the application of four different composting mixtures of sewage sludge and cotton waste, at different stages of composting. Land application caused an increase of both size and activity of soil microbial biomass that was related to the stabilization degree of the composting mixture. Sewage sludge stabilization through composting reduced the perturbance of the soil microbial biomass. At the end of the experiment, the size and the activity of the soil microbial biomass following the addition of untreated sewage sludge were twice those developed with mature compost. For the mature compost, the soil microbial biomass recovered its original equilibrium status (defined as the specific respiration activity, qCO2) after 18 days of incubation, whereas the soil amended with less stabilized materials did not recover equilibrium even after the two-month incubation period. The stabilization degree of the added materials did not affect the availability of Zn, Ni, Pb, Cu, Cr and Cd in the soil in the low heavy metal content of the sewage sludge studied. Stabilization of organic wastes before soil application is advisable for the lower perturbation of soil equilibria status and the more efficient C mineralization.

# 2003 Elsevier Ltd. All rights reserved.

Article consultable en ligne sur www.elsevier.com/locate/wasman

Auteurs : M del Carmen Vargas-Garcı, F. Francisca Suarez-Estrella, M Jose Lopez, Joaquın Moreno

Four different raw materials (olive-oil mill, pruning waste, rice straw and almond shell waste) used as additives were mixed with pepper plant wastes for composting purposes. Three bacterial strains isolated from prior composting processes and identified as Bacillus shackletonni, Streptomyces thermovulgaris and Ureibacillus thermosphaericus were added to every windrow and their effect on humic-like substances evolution was studied. In all the cases, an increase in the humification indices (humic to fulvic acids ratio, humification ratio and humification index) was obtained. On the other hand, inoculation significantly affected the humification indices, and differences due to both raw materials and microbial inoculants could be observed. When inoculated in almond shell and rice straw heaps respectively, B. shackletonni and U. thermosphaericus induced higher humification levels than those obtained for other raw material/inoculant combinations. Thus, the improvement of composting processes by means of inoculation seems to depend on properties of raw materials and microorganisms applied.

# 2006 Elsevier Ltd. All rights reserved.

Article consultable en ligne sur www.elsevier.com/locate/procbio

Auteur : Gerald Scott

The utilisation of waste polymers by mechanical recycling and incineration have ecological limitations. Consequently, degradable polymers are gaining acceptance in biological recycling in areas of agricultural technology and packaging where the waste product is located in a microbially active environment. The ecological bene®ts of the synthetic polymers, particularly the polyole®ns, are compared with hydro-biodegradable polymers made from renewable resources with emphasis on energy utilisation, environmental pollution and land utilisation. It is concluded that polymers that degrade by peroxidation followed by bioassimilation of the oxi-dation products (oxo-biodegradable polymers) are in general more environmentally acceptable (`green’) than the the biologically produced hydro-biodegradable polymers.

# 2000 Elsevier Science Ltd. All rights reserved.

Article consultable en ligne sur le site de Elsevier

Auteurs : P. Alvarenga, P. Palma, A.P. Gonçalves, R.M. Fernandes, A.C. Cunha-Queda, E. Duarte, G. Vallini

The use of organic waste and compost as a source of organic matter and nutrients is a common practice to improve soil physico-chemical properties, meanwhile reducing the need for inorganic fertilisers. Official guidelines to assess sewage sludge and compost quality are mostly based on total metal content of these residues. Measurement of the total concentration of metals may be useful as a general index of contamination, but provides inadequate or little information about their bioavailability, mobility or toxicity when the organic residue is applied to the soil. However, ecotoxicity tests provide an integrated measure of bioavailability and detrimental effects of contaminants in the ecosystem. In the present study, three different types of biodegradable organic residues (BORs) have been considered: sewage sludge from municipal wastewater treatment (SS), compost from the organic fraction of unsorted municipal solid waste (MSWC), and garden waste compost (GWC). The BORs were subjected to chemical characterisation and total metal quantification (Cd, Cr, Cu, Ni, Pb and Zn), in order to verify their suitability for land application. Water leachability was determined through the DIN 38414-S4 method, while the modified BCR sequential extraction procedure was used for metal speciation. Ecotoxicity of the BORs was studied by direct and indirect bioassays. Direct toxicity bioassays were: plant growth tests with cress (Lepidium sativum L.) and barley (Hordeum vulgare L.), and earthworm (Eisenia fetida) mortality. On the other hand, indirect exposure bioassays, with leachate from the residues, took into account: luminescent bacteria (Vibrio fischeri), seed germination (L. sativum and H. vulgare) and Daphnia magna immobilization. As far as total metal concentration is concerned, with particular reference to Zn, SS resulted neither suitable for the use in agriculture nor compatible to be disposed of as an inert material into landfill, according to the Directive 1999/31/EC. Zinc in SS was mainly present in exchangeable form (28.5%), appearing as highly bioavailable. As a consequence, SS exhibited either high ecotoxicity effects with the indirect exposure bioassays or significant mortality with the earthworm bioassay. Total content of metals in MSWC allowed its classification as “stabilised biowaste”, according to 2nd draft [DG Env.A.2. Working document of Biological treatment of biowaste — 2nd draft. Directorate- General Environment, Brussels, 12th February; 2001. accessed in:http://europa.eu.int/comm/environment/waste/facts_en.htm, at 10/09/2002] while leachate, on the basis of the concentration of these contaminants, could be classified as “inert waste”. This residue showed significant ecotoxicity effects with direct exposure bioassays as well as with the luminescent bacteria bioassay. However, it resulted less toxic than SS. Finally, GWC could be classified as a Class 2 compost, with no detectable toxic effects on the organisms used in the bioassays, except for the luminescent bacteria. In this case, an EC50 of 73.0% was observed. Considering the results, the use of a battery of toxicity test in conjunction with chemical analysis should be suggested, in order to correctly assess possible environmental risks deriving from disposal or land application of biodegradable organic residues.

© 2006 Elsevier Ltd. All rights reserved.

Article consultable en ligne sur www.elsevier.com/locate/envint

Auteurs : Joung-Dae Kim, Joon-Seok Park, Byung-Hoon In, Daekeun Kim, Wan Namkoong

This study is aimed to evaluate the performance of pilot-scale in-vessel composting for food wastes treatment. The  composting plant was installed with 324m3 of the composting bay volume and 14,000 kg/day of the composting material flow rate. The evaluations studied included the operational indices, the compost maturity indices, and the quality of the final compost. Blowers of this system were useful in maintaining aerobic condition (over 6% oxygen concentration in off-gas) through the entire compost bay. The levels of indices evaluated remained constant in the final part of composting. The final compost was satisfactory for its agricultural application. It was revealed in this study that bulk density bore a linear relation to moisture content during composting, and the final compost without bulking agent showed negative correlation between heavy metal and organic matters content.

© 2007 Elsevier B.V. All rights reserved.

Article consultable en ligne sur www.elsevier.com/locate/jhazmat

Auteurs : U. Sonesson, A. Bjo¨rklund, M. Carlsson, M. Dalemo

The management system for solid and liquid organic waste affects the environment and  surrounding technical systems in several ways. In order to decrease the environmental impact and resource use, biological waste treatment and alternative solutions for sewage treatment are often advocated. These alternatives include increased agricultural use of waste residuals. To analyse whether such proposed systems indicate improvements for the environment and its sustainability, systems analysis is a useful method. The changes in environmental impact and resource use is not only a result of changes in waste treatment methods, but also largely a result of changes in surrounding systems (energy and agriculture) caused by changes in waste management practices. In order to perform a systems analysis, a substance-flow simulation model, the organic waste research model (ORWARE), has been used. The results are evaluated by using methodology from life cycle assessment (LCA). An economic analysis was also performed on three of the studied scenarios. The management system for solid organic waste and sewage in the municipality of Uppsala, Sweden, was studied. Three scenarios for different treatments of solid waste were analysed: incineration with heat recovery, composting, and anaerobic digestion. These three scenarios included conventional sewage treatment. A fourth scenario reviewed was anaerobic digestion of solid waste, using urine-separating toilets and separate handling of the urine fraction. The results are only valid for the case study and under the assumptions made. In this case study anaerobic digestion result in the lowest environmental impact of all the solid waste management systems, but is costly. Economically, incineration with heat recovery is the cheapest way to treat solid waste.
Composting gives environmental advantages compared to incineration methods, without significantly increased costs. Urine separation, which may be implemented together with any solid waste treatment, has great advantages, particularly in its low impact on the environment. However, there is a large increase in acidification.

© 2000 Elsevier Science B.V. All rights reserved.

Article en ligne sur www.elsevier.com/locate/resconrec