Anaerobic Digestion Sludge Composting - Assessment of the Star-up process

The aim of this work was to follow the start-up of the composting process of sludge from the anaerobic digestion of municipal solid waste and to assess the quality of the final product. The temperature profile and dry matter content was registered over 10 weeks. The composting process was monitored by standard physical and chemical parameters and the quality of the final compost was assessed by phytotoxicity and stability assays. The low average temperature values registered during composting suggest over aeration. In addition, all the standard physical and chemical parameters analysed showed slight variations over composting, suggesting that the anaerobic digestion sludge was already a stable raw material. The final compost was not phytotoxic and was stable, but contained some inert materials. Overall, the final compost had quality compatible to be used as soil amendment. Nevertheless, the operational conditions optimization should be carried out to improve its qualityinfo:eu-repo/semantics/publishedVersio

Assisted phytostabilization of soils affected by mining activities using Lolium perenne L.

We studied the application of Lolium per-enne L. and of different organic residues in the assisted phytostabilization of mine-contaminated soils (Aljustrel Mine Area, Iberian Pyrite Belt). Although the applica-tion of the organic residues led to immobilization of Cu, Pb, and Zn in the soil, decreas-ing their effective available fraction, their concentrations in the above-ground plant material did not change. The accumulation factors (AF) obtained were AF(Cu) and AF(Pb) <<1, and AF(Zn) <1, allowing its election as a possible candidate for phytos-tabilization purposes. However, Pb and Cu concentrations in ryegrass shoots were con-sidered toxic, which suggests that there is a risk of contamination of the human food chain. Multivariate statistical analysis em-phasized sewage sludge as the organic resi-due with the greatest capacity to correct soil acidity, and to improve soil characteristics, followed by the compost obtained from municipal solid waste residues. However, an impaired growth was obtained when using the highest application rate (100 Mg ha-1) of both residues. All garden waste compost rates were unable to correct general soil constraints to plant growth

Utilização de Lolium Perenne L. na fitoestabilização controlada de solos degradados por actividades mineiras

Foi estudada a utilização de Lolium perenne L. e de diferentes resíduos orgânicos (RO) na fitoestabilização controlada de solos degradados por atividades mineiras (Mina de Aljustrel, Faixa Piritosa Ibérica). Apesar da aplicação dos RO ter permitido a imobilização de Cu, Pb e Zn no solo, baixando a fracção efetivamente disponível, os teores foliares destes elementos não diminuíram significativamente. Os factores de acumulação (FA) obtidos, FA(Cu) e FA(Pb) <<1 e FA(Zn) <1, permitem considerar esta espécie adequada para a fitoestabilização deste tipo de solos. Os teores foliares de Pb e Cu atingiram níveis considerados tóxicos, indicando risco de entrada destes metais na cadeia alimentar humana. Métodos estatísticos multivariados evidenciaram a lama residual urbana como o RO com maior capacidade para corrigir a acidez do solo e para melhorar as características deste, seguida do composto de resíduos sólidos urbanos. Porém,observou-se um crescimento reduzido por aplicação do nível mais elevado (100 Mg ha-1) destes RO. Todos os níveis do composto de resíduos verdes foram insuficientes para corrigir as principais restrições do solo ao crescimento vegetal

Dinamica do azoto durante a compostagem de materiais biologicos putresciveis

In this study, several composting assays were performed with different types of organic wastes (municipal solid wastes, manures, green wastes from municipal markets and algae biomass) mixed with diverse bulking agents. The assays were conducted in two different plants: Pilot plant-scale of Horto de Quimica Agricola - in aerated pile with forced-pressure ventilation and feedback temperature control. Industrial plant-scale for municipal solid wastes treatment of Setubal - inside a closed hall, in aerated piles, turned weekly and with moisture control. During the composting assays physical, physico-chemical, chemical and microbiological parameters were followed. The enzymatic activities of phosphatases, proteases, lipases (C10), N-acetyl-#beta#-glucosaminidase, #beta#-glucosidase, total cellulases and polyphenol oxidases were also determined. The phyto toxicity was evaluated through the germination index. Results showed that enzymatic activities are related to the physico-chemical and chemical changes through the whole process and the microbiological populations. Along the composting process the organic nitrogen was mineralized. Nitrogen content decreased mostly through ammonia volatilization which was more significant during the thermophilic phase and at high values of ph. Nitrogen losses can be recovered through asymbiotic nitrogen fixation, for which the activity of cellulolytic microorganisms and enzymatic activities of cellulases seems to be very importantAvailable from Fundacao para a Ciencia e a Tecnologia, Servico de Informacao e Documentacao, Av. D. Carlos I, 126, 1249-074 Lisboa, Portugal / FCT - Fundação para o Ciência e a TecnologiaSIGLEPTPortuga

Estudo da evolução de actividades enzimáticas durante a compostagem de resíduos provenientes de mercados horto-frutícolas

We studied the evolution of some enzymatic activities related to the C, N and P cycles during the composting of vegetable waste from the Lisbon municipal market. The evolution of several physical, physico-chemical, chemical, biological and microbiological parameters were also evaluated in order to relate them to the enzymatic activities studied

Influence of the composition of the initial mixtures on the chemical composition, physicochemical properties and humic-like substances content of composts

The influence of the proportion of C- and N-rich raw materials (initial C/N ratio) and bulking agent on the chemical functional groups composition, humic-like substances (HS-like) content and physicochemical properties of composts was assessed. To achieve these goals, seven initial mixtures (BA1-6 and C1) of dog food (N-rich raw material) were composted with wheat flour (C-rich raw material). Composts were analyzed in terms of chemical functional groups, physicochemical, maturity and stability parameters. The C-rich raw material favored the formation of oxidized organic matter (OM) during the composting process, as suggested by the variation of the ratios of the peaks intensity of FT-IR spectra, corresponding to a decrease of the polysaccharides and an increase of aromatic and carboxyl-containing compounds. However, although with high proportion of C-rich raw material, mixtures with low initial C/N seems to have favored the accumulation of partially oxidized OM, which may have contributed to high electrical conductivity values in the final composts. Therefore, although favoring the partial transformation of OM into stabilized HS-like, initial mixtures with high proportion of C-rich raw material but with low initial C/N led to unstable composts. On the other hand, as long as a high percentage of bulking agent was used to promote the structure of biomass and consequently improve of the aeration conditions, low initial C/N was not a limiting factor of OM oxidation into extractable stabilized humic-like acids

Organic olive growing in Northeastern Portugal: Present state and future prospects

The olive tree is of great socio-economic and ecological importance in theMediterranean region. In several countries, namely in Portugal, olive production is asignificant land use, and so, the olive agro-ecosystem is an important reservoir forbiodiversity. During the last years we are assisting to a growing interest for organic olivegrove cultivation, to fulfil the requirements of consumers who are more and moreinterested in ecologically clean products due to health and environmental reasons as wellas the increasing concern for safe and quality food. In Portugal organic olive surface hassteadily increased in the last few years and from only 3 781 ha in 1994, it grew to 19 341ha in 2006. Almost all this surface (about 99.3%) was distributed by the districts of theinterior along the Spanish border (Trás-os-Montes, Beira Interior and Alentejo) whereclimatic conditions are suitable for the crop and pest and disease pressure is relativelylow. Moreover traditional farming practised in these regions approximates organicfarming methods, which eases conversion. The financial support provided by theEuropean Union under the agri-environmental measures for organic production throughthe Common Agricultural Policy, which largely have stimulated farmers' interest towardsorganic agriculture, have also expanded the development of scientific and technicalresearch regarding this type of crop management. In this chapter, results from organicolive research carried on during the last ten years in the northeast of Portugal will be discussed. Emphasis will be given on activities having as objective the enhancement ofsoil fertility through the application of composting of plant and animal materials, as wellas those focusing on arthropod pest management. Progresses attained and areas whichneed to be explored will be analyzed. © 2009 Nova Science Publishers, Inc. All rights reserved.info:eu-repo/semantics/publishedVersio

Reclamation of a mine contaminated soil using biologically reactive organic matrices

Organic residues such as sewage sludge, biowastes and composts are increasingly used in land rehabilitation because they can improve the physical, chemical and biochemical properties of soil, and reduce the need for inorganic fertilization. Furthermore, their use contributes to an integrated approach to waste management by promoting recycling of nutrients and minimizing final disposal, especially of organic residues that, due to their composition, can pose problems to agricultural soils. In the present study, three different types of organic residues were considered as amendments to be used in the reclamation of a metal-contaminated mine soil from the Aljustrel mining area (a pyrite mine located in the SW Portugal in the Iberian Pyrite Belt), with high Cu, Pb and Zn total contents: sewage sludge from a municipal wastewater treatment plant (SS), compost from the organic fraction of unsorted municipal solid waste (MSWC), and garden waste compost (GWC), applied at 100 and 200 Mg ha—1 . The soil and mixtures of soil and amendments were adjusted to 70% of the maximum water-holding capacity determined for each type of sample and incubated in a controlled-temperature room at 20 ± 1 °C. Sub-samples were taken prior to wetting (time zero), and after 7, 14, 21 and 28 days of incubation, and analysed for pH, electrical conductivity, organic matter content, effectively bioavailable Cu, Zn and Pb (extracted with 0.01 mol L— 1 calcium chloride) and potentially bioavailable metals (extracted with 0.5 mol L—1 ammonium acetate, 0.5 mol L —1 acetic acid and 0.01 mol L— 1 EDTA, pH 4.7). In general, organic residues corrected soil acidity, and increased the total organic matter content of the soil. The SS and the MSWC amendments were roughly equivalent in their ability to correct soil acidity whereas the GWC had the smallest liming capacity and only with 200 Mg ha—1 GWC did the soil pH reach acceptable values. As expected, all the tested organic residues, at both application rates, were effective in reducing the effectively bioavailable metals in the soil. The Zn bioavailability was the most affected by the addition of organic residues, whereas Pb bioavailability was small even in the unamended soil and was the least affected by treatments. Potentially bioavailable metals increased with SS and MSWC application and the opposite was true following amendment with GWC

Anaerobic digestion sludge compsoting - assessment of the star-up process

The aim of this work was to follow the start-up of the composting process of sludge from the anaerobic digestion of municipal solid waste and to assess the quality of the final product. The temperature profile and dry matter content was registered over 10 weeks. The composting process was monitored by standard physical and chemical parameters and the quality of the final compost was assessed by phytotoxicity and stability assays. The low average temperature values registered during composting suggest over aeration. In addition, all the standard physical and chemical parameters analysed showed slight variations over composting, suggesting that the anaerobic digestion sludge was already a stable raw material. The final compost was not phytotoxic and was stable, but contained some inert materials. Overall, the final compost had quality compatible to be used as soil amendment. Nevertheless, the operational conditions optimization should be carried out to improve its quality.info:eu-repo/semantics/publishedVersio

Effect of organic residues and liming materials on metal extraction from a mining-contaminated soil

Incubation tests were used to assess the effectiveness of three different organic residues and three different liming materials, alone or in combination, in the remediation of a mine contaminated soil. The organic residues tested were sewage sludge from a municipal wastewater treatment plant (SS), compost from the organic fraction of unsorted municipal solid waste (MSWC), and garden waste compost (GWC), applied at 100 and 200 Mg ha- 1. The liming materials tested were agriculture limestone (6.4 Mg ha- 1), calcium oxide (3.7 Mg ha- 1), and sugar beet sludge (12.2 Mg ha- 1) from the sugar manufacturing process. The soil and mixtures of soil and amendments were adjusted to 70% of the maximum water holding capacity and incubated for 28 days in a controlled-temperature room at 20\ub0C \ub1 1\ub0C. At the end of the incubation, samples were analyzed for pH, electrical conductivity, organic matter content, CaCl2-extractable, and' NH4Ac/HAc+ EDTA-extractable metal fractions (Cu, Zn, and Pb). Correlations among the variables and/or similarities among the treatments were identified by principal component analysis and hierarchical cluster analysis. The amendments tested decreased the CaCl2-extractable Cu and Zn fractions, considered as mobile metal fractions, to below analytical detectable limits, providing organic matter to the soil with levels between 1% and 2% at the end of the experiment, significantly different relatively to the original soil. pH and electrical conductivity reached high values when using 200 Mg ha- 1 SS or 200 Mg ha- 1 MSWC, with any of the liming materials tested, making these application rates excessive for this particular situation. Furthermore, the treatments using MSWC increased the NH4Ac/HAc+ EDTA-extractable Cu, Pb, and Zn fractions, considered as mobilizable metal fractions, as did the 200 Mg ha- 1 SS for Pb and Zn. Considering the overall results, the compost made from garden waste decreased metal solubility in the soil and increased soil pH and organic matter content, without the addition of large amounts of soluble salts, and without increasing the mobilizable metal content. Of the organic materials tested, this was the only one that can be considered adequate for remediation of the contaminated soil under study, at the application rates tested