Empirical analysis of solid management waste costs: Some evidence from Galicia, Spain

This paper analyses the factors that determine solid waste service costs. The empirical analysis is based on information derived from a survey conducted in a sample of Galician municipalities. The results reveal economies of scale in municipalities of fewer than 50,000 inhabitants, such that cooperation between these municipalities could lead to cost savings. It also appears that private delivery is not cheaper than public delivery. Finally, designating a larger proportion of the total waste volume to recycling does not imply greater costs.

Kuntien vastuulla olevan jätehuollon palvelurakenteen kehittäminen Etelä-Karjalan Jätehuolto Oy:n strategian mukaisesti

Työn tavoitteena on määritellä Etelä-Karjalan Jätehuolto Oy:n toiminta-alueella asumisessa syntyvän jätehuollon palvelutaso muuttunutta jätelainsäädäntöä sekä yhtiön hoidettavaksi siirrettäviä palvelutehtäviä vastaavaksi. Tavoitteena on myös valmistella kunnalliset jätehuoltomääräykset, joilla muutokset pannaan täytäntöön jätehuollon kuljetuksen, keräyksen ja käsittelyn sekä hyötykäyttöön toimittamisen osalta. Tavoitteena on laatia esitys palveluun perustuvasta taksamallista koko toiminta-alueelle. Työn alkuosassa tutustutaan jätelainsäädännön kehittymiseen EU:ssa ja Suomessa sekä valmistelussa oleviin muutoksiin, joilla on vaikutusta jätehuollon suunnittelun ja toteuttamisen kannalta. Tutkitaan miten jätehuoltopalvelut omistajakunnissa on toteutettu ja mitä muutoksia jätelain 10 § ja 13 §:n muutos edellyttää nykyiseen järjestelmään. Työn tuloksena valmistuu maakuntaan asumisen jätehuollon vähimmäispalvelutasoesitys sekä ehdotukset sen kehittämisestä ja kustannusten keräämisestä aiheuttamisperiaatteen mukaisesti alueen yhtenäisillä jätetaksoilla. Jätehuoltomääräysehdotukseen sisällytetään jätehuoltoa koskevat tekniset ja laadulliset vaatimukset sekä keinot, joilla kunnan vastuulla olevia jätteitä saadaan ohjattua hyötykäyttöön.

Química orgânica experimental: integração de teoria, experimento e análise

A new approach for teaching in basic experimental organic chemistry is presented. Experimental work goes on parallel to theoretical lectures leading to an immediate application of theoretical concepts transmitted therein. One day/week is dedicated exclusively to the organic laboratory. Reactions are proposed as problems to be solved; the student has to deduce the structure of the product on the basis of his observations, the analytical data and his mechanistical knowledge. 70 different experiments, divided in 7 thematical chapters, are presented. All experiments require the analysis and discussion of 1H and 13C NMR, IR and UV spectra. Additional questions about each reaction have to be answered by the student in his written report. Laboratory safety is garanteed by the exclusion or substitution of hazardous and toxic reagents. Microscale preparations are adopted in most cases to lower the cost of materials and the amount of waste. Recycling of many reaction products as starting materials in other experiments reduces the need for commercial reagents and allows the execution of longer reaction sequences. Only unexpensive standard laboratory equipment and simple glassware are required. All experiments include instructions for the save treatment or disposal of chemical waste.

Relato de uma experiência: recuperação e cadastramento de resíduos dos laboratórios de graduação do Instituto de Química da Universidade Federal do Rio Grande do Sul

An experience aiming to promote a residue interchange and recovery between the teaching laboratories of the Chemistry Institute of this University is described. At the present, several residues interchange have already appeared as advantageous. To make the work easier, a software has been developed in order to keep a record of all the residues generated by the teaching laboratories. Standard labels have been developed for the residues in order to organize them. The software and the label design are described.

Reaction Kinetics and Viscosity Modelling in the Fusion Syntheses of Ca- and Ca/Mg-resinates

Rosin is a natural product from pine forests and it is used as a raw material in resinate syntheses. Resinates are polyvalent metal salts of rosin acids and especially Ca- and Ca/Mg- resinates find wide application in the printing ink industry. In this thesis, analytical methods were applied to increase general knowledge of resinate chemistry and the reaction kinetics was studied in order to model the non linear solution viscosity increase during resinate syntheses by the fusion method. Solution viscosity in toluene is an important quality factor for resinates to be used in printing inks. The concept of critical resinate concentration, c crit, was introduced to define an abrupt change in viscosity dependence on resinate concentration in the solution. The concept was then used to explain the non-inear solution viscosity increase during resinate syntheses. A semi empirical model with two estimated parameters was derived for the viscosity increase on the basis of apparent reaction kinetics. The model was used to control the viscosity and to predict the total reaction time of the resinate process. The kinetic data from the complex reaction media was obtained by acid value titration and by FTIR spectroscopic analyses using a conventional calibration method to measure the resinate concentration and the concentration of free rosin acids. A multivariate calibration method was successfully applied to make partial least square (PLS) models for monitoring acid value and solution viscosity in both mid-infrared (MIR) and near infrared (NIR) regions during the syntheses. The calibration models can be used for on line resinate process monitoring. In kinetic studies, two main reaction steps were observed during the syntheses. First a fast irreversible resination reaction occurs at 235 °C and then a slow thermal decarboxylation of rosin acids starts to take place at 265 °C. Rosin oil is formed during the decarboxylation reaction step causing significant mass loss as the rosin oil evaporates from the system while the viscosity increases to the target level. The mass balance of the syntheses was determined based on the resinate concentration increase during the decarboxylation reaction step. A mechanistic study of the decarboxylation reaction was based on the observation that resinate molecules are partly solvated by rosin acids during the syntheses. Different decarboxylation mechanisms were proposed for the free and solvating rosin acids. The deduced kinetic model supported the analytical data of the syntheses in a wide resinate concentration region, over a wide range of viscosity values and at different reaction temperatures. In addition, the application of the kinetic model to the modified resinate syntheses gave a good fit. A novel synthesis method with the addition of decarboxylated rosin (i.e. rosin oil) to the reaction mixture was introduced. The conversion of rosin acid to resinate was increased to the level necessary to obtain the target viscosity for the product at 235 °C. Due to a lower reaction temperature than in traditional fusion synthesis at 265 °C, thermal decarboxylation is avoided. As a consequence, the mass yield of the resinate syntheses can be increased from ca. 70% to almost 100% by recycling the added rosin oil.

Wood pellet markets in Russia

Bioenergy came to Russia through wood pellets. On account of prevalence of oil and gas in the Russian economy «bioenergy» has come with a great delay. Certainly, there were many woodworking enterprises and even municipal boiler-houses using wood waste and fire wood for energy reception, but this activity was not purposeful. More likely it was connected with necessity of waste recycling and with the organization of heat supply in the remote areas of the country. However, in 2001 was founded the first pellet plant in Russia. The purpose of this work was to analyze wood pellets market in Russia, investigate current situation on the home and export market, evaluates supply and demand development, opportunities for wood pellets manufactures in Russia, the main manufactures in Russian market; cost and prices for wood pellets in Russia. Also the work was intended to give better understanding of the main problems of wood pellets industry in Russia. Besides, this work had updated information about Russian customs and logistic systems.

Recuperação de sílica-gel utilizando processos oxidativos avançados: uma alternativa simples e de baixo custo

Silica gel is widely used as adsorbent for isolating and purifying natural compounds. Intensive use and high cost make this process expensive and generate solid residues contaminated with many different organic compounds. In the present work a simple method for recycling silica was investigated, by using Advanced Oxidative Processes. Silica gel was treated with H2O2/solar light and compared with a sample treated by conventional methods (high temperature and oxidation with KMnO4). High temperature treatment changes the structure of the silica and, consequently, the separation efficiency. Oxidation by using KMnO4 requires multiple steps and produces residues, including manganese and oxalic acid. The method using H2O2/solar light to recuperate silica gel does not modify its separation efficiency and is less expensive than the traditional methods. Additionally, HPLC and GC-MS analysis indicate that H2O2/solar light eliminates all residues of the silica gel.

Reciclagem química de zeólitas comerciais desativadas

Pyro and hydrometallurgical processes were applied to the treatment of spent commercial zeolites (a molecular sieve and a ZSM-5 sample). Both catalysts were employed in pilot plant units. They were kept in their original shape, they were not regenerated and were not subjected neither to mechanical stress nor to overheating zones during their time on-stream. Two recycling processes were tested: (i) direct solubilization of samples in mixtures of HF + H2O2 (60 ºC, 1 h). Although silicon was solubilized, insoluble matter was found in both samples, particularly in the molecular sieve, due to its high amounts of alkaline and alkaline-earth metals; (ii) fusion with KHSO4 (5 h, 600 ºC) with KHSO4/zeolite mass ratio 6:1. After fusion the solid was solubilized in water (100 ºC), leaving silicon as SiO2 residue. In both processes, solubilized metals were isolated by conventional selective precipitation techniques. Analysis of final products by common analytical methods shows that metals present in the original catalysts were recovered with very high yields except when the molecular sieve was treated with HF + H2O2. This reactant mixture proved to be suitable for processing zeolites with a low alkaline and alkaline-earth metal content whereas fusion with KHSO4 appeared to be adequate for all types of zeolites.

Chaotic dynamics of electric-field domains in periodically driven superlattices

Self-sustained time-dependent current oscillations under dc voltage bias have been observed in recent experiments on n-doped semiconductor superlattices with sequential resonant tunneling. The current oscillations are caused by the motion and recycling of the domain wall separating low- and high-electric-field regions of the superlattice, as the analysis of a discrete drift model shows and experimental evidence supports. Numerical simulation shows that different nonlinear dynamical regimes of the domain wall appear when an external microwave signal is superimposed on the dc bias and its driving frequency and driving amplitude vary. On the frequency-amplitude parameter plane, there are regions of entrainment and quasiperiodicity forming Arnold tongues. Chaos is demonstrated to appear at the boundaries of the tongues and in the regions where they overlap. Coexistence of up to four electric-field domains randomly nucleated in space is detected under ac+dc driving.

Chaos in resonant-tunneling superlattices

Spatiotemporal chaos is predicted to occur in n-doped semiconductor superlattices with sequential resonant tunneling as their main charge transport mechanism. Under dc voltage bias, undamped time-dependent oscillations of the current (due to the motion and recycling of electric field domain walls) have been observed in recent experiments. Chaos is the result of forcing this natural oscillation by means of an appropriate external microwave signal.

A tecnologia da reciclagem de polímeros

Solid municipal waste contains a large volume of polymers and its final disposal is a serious environmental problem. Consequently, the recycling of the principal polymers present in the solid waste is an alternative. In this review we describe the mechanical and chemical recycling of polymers and the energy recovery from plastic wastes. Polymer recycling involves not only the development of processing technologies, but also the solution of many chemical and analytical problems. The technological, economical and social aspects of polymer recycling are also considered.

Synthesis and NMR characterization of aliphatic-aromatic copolyesters by reaction of poly(ethylene terephthalate) post-consumer and poly(ethylene adipate)

An aliphatic-aromatic copolyester of poly(ethylene terephthalate), PET, and poly(ethylene adipate), PEA, PET-co-PEA, was synthesized by the high temperature melt reaction of post-consumer PET and PEA. As observed by NMR spectroscopy, the reaction yielded random copolyesters in a few minutes through ester-interchange reactions, even without added catalyst. The copolyesters obtained in the presence of a catalyst presented higher intrinsic viscosity than that obtained without the addition of catalyst, due to simultaneous polycondensation and ester-interchange reactions. The structure of the aliphatic-aromatic copolyesters obtained in different PET/PEA ratio is random as observed by NMR analysis.

Methods for assessing the sustainability of integrated municipal waste management and

The general striving to bring down the number of municipal landfills and to increase the reuse and recycling of waste-derived materials across the EU supports the debates concerning the feasibility and rationality of waste management systems. Substantial decrease in the volume and mass of landfill-disposed waste flows can be achieved by directing suitable waste fractions to energy recovery. Global fossil energy supplies are becoming more and more valuable and expensive energy sources for the mankind, and efforts to save fossil fuels have been made. Waste-derived fuels offer one potential partial solution to two different problems. First, waste that cannot be feasibly re-used or recycled is utilized in the energy conversion process according to EU’s Waste Hierarchy. Second, fossil fuels can be saved for other purposes than energy, mainly as transport fuels. This thesis presents the principles of assessing the most sustainable system solution for an integrated municipal waste management and energy system. The assessment process includes: · formation of a SISMan (Simple Integrated System Management) model of an integrated system including mass, energy and financial flows, and · formation of a MEFLO (Mass, Energy, Financial, Legislational, Other decisionsupport data) decision matrix according to the selected decision criteria, including essential and optional decision criteria. The methods are described and theoretical examples of the utilization of the methods are presented in the thesis. The assessment process involves the selection of different system alternatives (process alternatives for treatment of different waste fractions) and comparison between the alternatives. The first of the two novelty values of the utilization of the presented methods is the perspective selected for the formation of the SISMan model. Normally waste management and energy systems are operated separately according to the targets and principles set for each system. In the thesis the waste management and energy supply systems are considered as one larger integrated system with one primary target of serving the customers, i.e. citizens, as efficiently as possible in the spirit of sustainable development, including the following requirements: · reasonable overall costs, including waste management costs and energy costs; · minimum environmental burdens caused by the integrated waste management and energy system, taking into account the requirement above; and · social acceptance of the selected waste treatment and energy production methods. The integrated waste management and energy system is described by forming a SISMan model including three different flows of the system: energy, mass and financial flows. By defining the three types of flows for an integrated system, the selected factor results needed in the decision-making process of the selection of waste management treatment processes for different waste fractions can be calculated. The model and its results form a transparent description of the integrated system under discussion. The MEFLO decision matrix has been formed from the results of the SISMan model, combined with additional data, including e.g. environmental restrictions and regional aspects. System alternatives which do not meet the requirements set by legislation can be deleted from the comparisons before any closer numerical considerations. The second novelty value of this thesis is the three-level ranking method for combining the factor results of the MEFLO decision matrix. As a result of the MEFLO decision matrix, a transparent ranking of different system alternatives, including selection of treatment processes for different waste fractions, is achieved. SISMan and MEFLO are methods meant to be utilized in municipal decision-making processes concerning waste management and energy supply as simple, transparent and easyto- understand tools. The methods can be utilized in the assessment of existing systems, and particularly in the planning processes of future regional integrated systems. The principles of SISMan and MEFLO can be utilized also in other environments, where synergies of integrating two (or more) systems can be obtained. The SISMan flow model and the MEFLO decision matrix can be formed with or without any applicable commercial or free-of-charge tool/software. SISMan and MEFLO are not bound to any libraries or data-bases including process information, such as different emission data libraries utilized in life cycle assessments.

Study and modeling of the desintegration kinetics of coated paper

The disintegration of recovered paper is the first operation in the preparation of recycled pulp. It is known that the defibering process follows a first order kinetics from which it is possible to obtain the disintegration kinetic constant (KD) by means of different ways. The disintegration constant can be obtained from the Somerville index results (%lsv and from the dissipated energy per volume unit (Ss). The %slv is related to the quantity of non-defibrated paper, as a measure of the non-disintegrated fiber residual (percentage of flakes), which is expressed in disintegration time units. In this work, disintegration kinetics from recycled coated paper has been evaluated, working at 20 revise rotor speed and for different fiber consistency (6, 8, 10, 12 and 14%). The results showed that the values of experimental disintegration kinetic constant, Ko, through the analysis of Somerville index, as function of time. Increased, the disintegration time was drastically reduced. The calculation of the disintegration kinetic constant (modelled Ko), extracted from the Rayleigh’s dissipation function, showed a good correlation with the experimental values using the evolution of the Somerville index or with the dissipated energy

Polímeros biodegradáveis - uma solução parcial para diminuir a quantidade dos resíduos plásticos

The large use of plastics has generated a waste deposit problem. Today plastic wastes represent 20% in volume of the total waste in the municipal landfills. To solve the disposal problem of plastics methods have been employed such as incineration, recycling, landfill disposal, biodegradation and the use of biodegradable polymers. Incineration of plastic wastes provokes pollution due to the production of poisonous gases. Recycling is important to reduce final costs of plastic materials, but is not enough in face of the amount of discarded plastic. In landfills plastic wastes remain undegraded for a long time, causing space and pollution problems. Biodegradation is a feasible method to treat some plastics, but intensive research is necessary to find conditions for the action of microorganisms. All of these methods are important and the practical application of each one depends on the type and amount of the plastic wastes and the environmental conditions. Therefore, a great deal of research has focused on developing biodegradable plastics and its application because it is an important way for minimizing the effect of the large volume of plastic waste discarded in the world.