Kinetic studies of urban solid residues and leachate from sanitary landfill

Urban solid residues are constituted of food remaining, grass leaves, fruit peelings, paper, cardboard, rubber, plastic, etc. The organic fraction formed represents about 50% during the decomposition yields biogas and leachate, which are sources of pollution. Residue samples were collected from the landfill in different and cells from several ages and the corresponding leachate, both after treatments, were submitted to thermal analysis. Kinetic parameters were determined using Flynn–Wall–Ozawa method. The linear relation between the two kinetic parameters (ln A and E) was verified for organic residue urban’s samples, but not for leachate’s sample. The occurred difference can be attributed to the constituents present in leachate.     

A novel process for anaerobic composting of municipal solid waste

A novel process has been developed and evaluated in a pilotscale program for conversion of the biodegradable fraction of municipal solid waste (MSW) to methane via anaerobic composting. The sequential batch anaerobic composting (SEBAC) process employs leachate management to provide organisms, moisture, and nutrients required for rapid conversion of MSW and removal of inhibitory fermentation products during start-up. The biodegradable organic materials are converted to methane and carbon dioxide in 21–42 d, rather than the years required in landfills.     

Characterization of volatile and semivolatile compounds in waste landfill leachates using stir bar sorptive extraction–GC/MS

Stir bar sorptive extraction in combination with thermal desorption coupled online to capillary gas chromatography–mass spectrometry was applied to investigate volatile and semivolatile fractions in two waste leachate samples: old and fresh ones. The present study helps to improve our knowledge of waste leachate organic composition. The aim is to then make use of this knowledge afterwards in order to generate more reliable and specific treatment processes for waste leachates and thus to respect the environmental statute law regarding their rejection. The volatile and semivolatile compounds appeared to be mainly anthropogenic in origin. Moreover, lactic acid and cyclic octaatomic sulfur could potentially be used as microbiological activity indicators, since they occur during organic matter degradation processes within waste leachates. Figure TDU-CGC-MS analytical equipment     

Kinetics study of norbixin’s first stage thermal decomposition,using dynamic method

Cis-norbixin isomer obtained by hydrolysis of cis-bixin and isolated by solvent extraction from annatto seeds. The thermal decomposition data of the cis-norbixin samples were analyzed by thermogravimetric analysis at different heating rates in the 25–900°C temperature range. DSC curves showed that thermal decomposition reactions for cis-norbixin occurred in the solid phase. The kinetic parameters, such as activation energy and pre-exponential factor were determined using integral and approximate methods: Coats–Redfern, Madhusudanan, Horowitz–Metzger and Van Krevelen. F1 mechanism describes well the first stage of the thermal decomposition.     

Kinetic of thermal decomposition of residues from different kinds of composting

Non-isothermal kinetic parameters regarding to the thermal decomposition of the ligninocellulosic fraction present in compost from urban solid residues (USR) obtained through stack covered (SC) with composted material, comes from the usine in composing of Araraquara city, Săo Paulo state, Brazil, and from stack containing academic restaurant organic solid residues (SAR). The samples were periodically revolved round 132 days of composting. Results from TG, DTG and DSC curves obtained on inert atmosphere indicated that the lignocellulosic fraction present, despite the slow degradation during the composting process, is thermally less stable than other substances originated during that process. The lignocellulosic fraction decomposition, between 200 and 400°C, were kinetically evaluated through non-isothermal methods of analysis. By using the Flynn-Wall and Ozawa isoconversional method, the medium activation energy, Ea, and pre-exponential factor, lgA, were 283.0±14.6, 257.6±1.3 kJ mol^-1 and 25.4±0.8, 23.2±0.2 min^-1, to the SC and SAR, respectively, at 95% confidence level. From E _a and lgA values and DSC curves, Malek procedure could be applied, suggesting that the SB (Sesták-Berggren) kinetic model is suitable for the first thermal decomposition step. This revised version was published online in August 2006 with corrections to the Cover Date.     

Thermal study of unaltered and altered dolomitic rock samples from ancient monuments

In this study, the decomposition behaviour of unaltered and altered dolomitic rock samples used in Cultural Heritage buildings was studied by simultaneous TG–DTA experiments at different atmospheres, X-ray diffraction in a high-temperature chamber, and evolved gas analysis. The components of dolomite rock samples and hydrated calcium oxalate formed during the alteration processes of the rocks were characterized, and the decomposition mechanisms of these components were determined. The TG–DTA experiments carried out at CO₂ atmosphere were used to determine the carbonate compounds in the rock samples. The TG–DTA study characterized the presence of organic compounds formed during the biological degradation of the rock samples, possibly responsible of the hydrated calcium oxalate formation.     

Synthesis and thermal decomposition of ditetrazol-5-ylamine

Ditetrazol-5-ylamine (DTA) was synthesized from cyanuric chloride in four steps. The thermal decomposition of DTA in the solid state was studied by thermogravimetry, volumetry, mass spectrometry, IR spectroscopy, and calorimetry. Under isothermal conditions at 200–242 °C, thermal decomposition obeys the first order autocatalytic kinetics. The kinetic and activation parameters of DTA decomposition were determined. The composition of gaseous reaction products and the structure of condensed residue were studied. The thermal effect of thermal DTA decomposition is 281.4 kJ mol⁻¹. The nitrogen content in a mixture of gaseous products formed by the reaction in a temperature interval of 200–242 °C exceeds 97 vol.%. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1660–1664, July, 2005.     

Adsorption and DSC study of mineral–carbon sorbents obtained from coal tar pitch–polymer compositions

The purpose of this study was to determine the possibility of producing hydrophobic mesoporous mineral–carbon sorbents from aluminum hydroxide and compositions of coal tar pitch–polymers on carbonization at 600 °C in a nitrogen atmosphere. Blends of the products of co-precipitation of aluminum hydroxide in the carbonaceous substances medium were subjected to carbonization process. The extent of porous structure development was evaluated using low temperature nitrogen adsorption, adsorption of benzene vapors, and adsorption of iodine from aqueous solution. The highest value of BET surface area of about 370 m²/g was achieved for the carbonization product obtained from co-precipitated raw components with 10 wt% compositions coal tar pitch–polymer. These materials demonstrated high capacity to reduce organic pollutions from sewage. Pitch–polymer composition containing poly(ethylene terephthalate) or phenol–formaldehyde resin was studied by the means of DSC method in order to determine the high-temperature transformations taking place under the conditions of carbonization. DSC method enables to determine i.a. the decomposition temperatures of carbonizates produced from pitch–polymer compositions and the evaluation of their sorption abilities. The additive of poly(ethylene terephthalate) and phenol–formaldehyde resin caused the increase of thermal resistance of the pitch expressed by higher decomposition temperatures.     

Calorimetric studies of solid wastes,sewage sludge,wastewaters and their effects on soil biodegradation processes

Calorimetric studies of solid wastes, sewage sludge, wastewaters and their environmental effects focus on three main research areas. The first research area involves determination of selected thermal and physical parameters characterizing the above substances, such as specific heat, thermal conductivity and others. The second area covers processes of total or gradual destruction of the examined substances at a fixed composition of the gaseous phase. The methods applied in this case enable to determine the heat of combustion or the calorific value of the analyzed material, as well as changes in the rate of heat production, measured by differential scanning calorimetry (DSC). The third area of calorimetric studies covers microbial calorimetry as a method for non-destructive monitoring of organic matter biodegradation in order to measure the kinetic and thermodynamic parameters of the investigated processes, i.e., wastewater treatment, composting and decomposition of organic soil matter, as well as to determine the stability of wastes. This paper describes, based on available literature data, the major directions of investigations, using different calorimetric methods, of solid wastes, sewage sludge and wastewaters and additionally their effects on soil microbial processes. The paper also presents the selected calorimetric studies and analyses the biodegradation kinetics of organic wastewaters and glucose decomposition in the presence of phosphogypsum in different soils.     

Analysis of decomposition processes of ausferrite in copper–nickel austempered ductile iron

Analysis of thermal decomposition processes of the ausferrite obtained during simulation of austempering heat treatment was performed on austempered ductile iron (ADI). The analysis method consisting in investigation of inverse phase transformations was applied. The material with specified phase composition and well-defined thermophysical properties, both resulting from the conducted heat treatment cycle, was heated under controlled conditions and the thermal effects—enthalpy change and volume change were recorded by means of differential scanning calorimetry (DSC) and differential dilatometry. The process of ausferrite decomposition in the range of 100–800 °C was discussed; the identification scheme and temperature sequence of phase transformations accompanying the ausferrite decomposition were established. The elaborated decomposition scheme allows selection of the ADI heat treatment and its optimization by means of the non-isothermal thermal analysis methods.     

Influence of encapsulation on the mechanism of thermal decomposition of hexacyanotransition metal complexes

It has been established that, in contrast to the pure substances, the thermal decomposition of hexacyanotransition metal complexes, encapsulated in the large cavities of faujasite, occurs by a hydrolytic mechanism. The composition of the gaseous products of the thermal decomposition depend on the characteristics of the localization of the cations in the inclusion compounds. L. V. Pisarzhevskii Institute of Physical Chemistry, National Academy of Sciences of Ukraine, 31 Prospekt Nauki, Kiev 252039, Ukraine. Translated from Teoreticheskaya i éksperimental'naya Khimiya, Vol. 35, No. 2, pp. 107–112, March–April, 1999.     

Retardation of monomolecular reactions in the solid phase

The rate constants of initial monomolecular stages of thermal decomposition in the solid phase were measured for 22 organic compounds. The ratio of rate constants of decomposition in the melt and solid state, characterizing the reaction retardation in the crystal lattice, was determined. The retardation effect was compared to the physical properties of the crystal. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1261–1264, July, 1999.     

Non-traditional pathways of extraterrestrial formation of organic compounds

The mechanisms of solid-phase reactions that have been experimentally and theoretically studied during recent decades and can be directly related to the formation of organic substances in space and their delivery to Earth and to the problems of prebiotic evolution are considered. Among these mechanisms are molecular tunneling (hypothesis of the cold prehistory of life), polycondensation of solid monomers by shock waves (problem of the delivery of organic substances to Earth by meteorites), thermal and thermal-wave explosions. and oscillations of temperature and radical concentrations in small cold particles under radiation exposure, mechanochemical explosions and autowave propagation of chemical reactions due to the positive feedback between fragile destruction of solids and reactions at freshly formed surfaces. Written on the basis of the report at the International Conference “Chemical Physics at the Threshold of XXI Century,” April 16–19, 1996, Moscow. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 409–417, March, 1997.     

Thermal decomposition study of sewage sludge and of organicwaste used in the sorption of metals

The conventional treatments of effluents containing heavy metals produce significant quantities of byproducts with recalcitrant characteristics, making necessary looking after alternative techniques in order to avoid the production of new contaminated residues. Sorption process of chromium and zinc in vertical columns loaded with sewage sludge and organic solid waste has been studied in this work. The data from the TG curves of the two sorbents presented significant differences when they were submitted to the metal uptake, being noticed the displacement of the thermal events towards lower temperatures for both types of sorbents studied. As it was expected, for both sorbents, an increase in the mass of samples has been observed at the completion of the thermal tests upon metal uptake. Therefore, these facts demonstrate that during the biosorption process a physico-chemical interaction took place between sorbents and metals, as it was evidenced by the more than 100 K increase in the decomposition temperatures as well as the variation of the ΔH values of the samples.     

Treatment of Sanitary Landfill Leachates in a Lab-Scale Gradual Concentric Chamber (GCC) Reactor

Sanitary landfill leachates are a major environmental problem in South American countries where sanitary landfills are still constructed and appropriate designs for the treatment of these leachates remain problematic. The performance of a lab-scale Gradual Concentric Chamber (GCC) reactor for leachates treatment is presented in this study. Two types of sanitary landfill residuals were evaluated, one directly collected from the garbage trucks (JGL), with high organic strength (84 g COD/l) and the second one, a 6-month-generated leachate (YL) collected from the lagoon of the sanitary landfill in Quito, Ecuador, with an organic strength of 66 g COD/l. Different operational parameters, such as organic loading rate (OLR), temperature, recycling and aeration, were tested. The GCC reactor was found to be a robust technology to treat these high-strength streams with organic matter removal efficiencies higher than 65%. The best performance of the reactors (COD removal efficiencies of 75–80%) was obtained at a Hydraulic Retention Time (HRT) of around 20 h and at 35 °C, with an applied OLR up to 70 and 100 g COD/l per day. Overall, the GCC reactor concept appears worth to be further developed for the treatment of leachates in low-income countries.     

Relation Between Thermal Decomposition of Medicinal Herbs and their Non-Metals Concentration

The studies on the concentration of total nitrogen, phosphorus, sulphur, chlorine, iodine and boron as well as on the thermal decomposition of commercial raw plant materials used in medicine were performed. The 50 independent samples of herbs originating from 25 medicinal plant species collected in 1986–92 were analysed. The content of non-metallic elements was determined spectrophotometrically after previous mineralization of plant sample. The thermal decomposition was performed using the derivatograph with the application of 100 mg samples and heating rate of 5°C min⁻¹. In order to obtain more clear classification of the analysed plant materials principal component analysis (PCA) was applied. Interpretation of PCA results for two databases (non-metals and thermoanalytical data sets) allows to state, that samples of herbs from the same plant species in majority of cases are characterized by similar elemental composition and similar course of their thermal decomposition. In this way the differences in general chemical composition of medicinal plants raw materials can be determined. This revised version was published online in August 2006 with corrections to the Cover Date.     

Bioremediation strategies of palm oil mill effluent and landfill leachate using microalgae cultivation: An approach contributing towards environmental sustainability

Palm oil mill effluent (POME) is defined as the wastewater that contains high concentrations of organics, nutrients and oil and grease generated from the production process of palm oil. Therefore, proper discharge and management of POME is important to avoid deleterious impact on the environment. In fact, solid waste generation is a precursor for its disposal issues as most of the solid waste generated in developing nations is dumped into landfills. This has led to the threat posed by the generation of landfill leachate (LL). LL is a complex dark coloured liquid consisting of organic matter, inorganic substances, trace elements and xenobiotics. Hence, it is essential to effectively treat the landfill leachate before discharging it to avoid contamination of soil, surface & groundwater bodies. Conventional treatment methods comprises of physical, biological and chemical treatment, however, microalgal-based treatment could also be incorporated. Furthermore, with the benefits offered by microalgae in valorisation, the application of microalgae in POME and leachate treatment as well as biofuel production, is considerably viable. This paper provides an acumen of the microalgae-based treatment of POME and LL, integrated with biofuel production in a systematic and critical manner. The pollutants assimilation from wastewater and CO₂ biosequestration are discussed for environmental protection. Cultivation systems for wastewater treatment with simultaneous biomass production and its valorisation, are summarised. The study aims to provide insight to industrial stakeholders on economically viable and environmentally sustainable treatment of wastewaters using microalgae, and eventually contributing to the circular bioeconomy and environmental sustainability.     

Flavonoids and silicon in certain plant pollen

The flavonoid composition of certain plant pollens is studied. Pollen from representatives of various families differs in the quantitative and qualitative composition of the flavonoid complex. A specially developed method is used to estimate the content of three Si species that differ in the strength of bonding to organic substances in the pollen samples. The coexistence in plant pollen of the bioflavonoids and Si increases the pharmacological value of this natural product. Translated from Khimiya Prirodnykh Soedinenii. No. 5, pp. 592–597, September–October, 1999.     

Thermal characteristics of bitumen pyrolysis

The pyrolysis behavior of bitumen was investigated using a thermogravimetric analyzer–mass spectrometer system (TG–MS) and a differential scanning calorimeter (DSC) as well as a pyrolysis-gas chromatograph/mass spectrometer system (Py-GC/MS). TG results showed that there were three stages of weight loss during pyrolysis—less than 110, 110–380, and 380–600 °C. Using distributed activation energy model, the average activation energy of the thermal decomposition of bitumen was calculated at 79 kJ mol⁻¹. The evolved gas from the pyrolysis showed that organic species, such as alkane and alkene fragments had a peak maximum temperature of 130 and 480 °C, respectively. Benzene, toluene, and styrene released at 100 and 420 °C. Most of the inorganic compounds, such as H₂, H₂S, COS, and SO₂, released at about 380 °C while the CO₂ had the maximum temperature peaks at 400 and 540 °C, respectively. FTIR spectra were taken of the residues of the different stages, and the results showed that the C–H bond intensity decreased dramatically at 380 °C. Py-GC/MS confirmed the composition of the evolved gas. The DSC revealed the endothermic nature of the bitumen pyrolysis.     

Influence of The Elemental Composition of Medicinal Fruits on The Results of Their Thermal Analysis

Studies on the thermal decomposition and on the elemental composition of commercial raw plant materials used in medicine were performed. 16independent samples of fruits originating from 12 medicinal plant species collected in1988–92 were analysed. The thermal decomposition was performed using the derivatograph. The content of non-metallic (N, P, S, Cl, I and B) and metallic (Ca, Mg, Fe, Mn, Cu and Zn)elements was determined by spectrophotometric techniques after previous mineralization of sample. In order to obtain more clear classification of the analysed plant materials principal component analysis was applied. The interpretation of PCA results for three databases (thermoanalytical, non-metals and metals data sets) allows to state, that samples of fruits from the same plant species in the majority of cases are characterized by similar elemental composition and similar course of their thermal decomposition. In this way the differences in general chemical composition of medicinal plants raw materials can be determined. This revised version was published online in August 2006 with corrections to the Cover Date.