A b s t r a c t. The paper shows the results of a study on the effect of starch binder on the mechanical, physical and burning properties of charcoal briquettes. Two types of binders were repeatedly used to make briquettes of native wheat starch and modified wheat starch, at 8% of the whole. Briquetting was performed in a roller press unit, and pillow-shaped briquettes were made. The moisture of the mixed material ranged from 28 to 32%. The product, whether the former or the latter, was characterized by very good mechanical properties and satisfactory physical properties. Moreover, the type of starch binder had no effect on toughness, calorific heating value, volatiles, fixed carbon content and ash content. However, the combustion test showed quite different burning properties. As briquettes should have short firing up time and lower smokiness, as well as high maximum temperature and long burning time, we have concluded that briquettes with native wheat starch as a binder are more appropriate for burning in the grill.K e y w o r d s: charcoal briquette, starch binder, burning INTRODUCTIONCharcoal fuel has many attractive features: it contains almost no sulfur or mercury and is low in nitrogen and ash, in addition, it is easy to store and handle (Antal and Grønli, 2003). Further technical and economic aspects of fine coal and charcoal briquettes have been evaluated because of the binder and briquetting parameters. Briquetting pressure and dwell time have a weak impact, while binder type and curing conditions exert the greatest influence on briquettes quality (Borowski and Hycnar, 2013;Taulbee et al., 2009). What is more, mechanical properties increase with time of curing at room temperature of carbonized-coal briquettes (Blesa et al., 2003).Binders such as molasses, starch, tar, etc. are added to produce fuel briquettes, and the addition of starch binder, as well as gum Arabic binder improves the caloric value of biofuel briquettes (Zakari et al., 2013). Physical properties such as density, compressive strength and impact resistance index of briquettes also show significant improvement because of binders (Sen et al., 2016). Further additives are inorganic fillers which delay the heat release of the burning briquette, and ignition enhancers, which promote greater combustibility. Charcoal briquettes are promoted as substitutes for natural coal, petroleum coke or lignite. Still, the advantages of charcoal fuel depend on important factors: low sulphur content, high carbon to ash ratio, relatively few and nonreactive inorganic impurities, specific pore structure with large surface area, good reduction ability, almost smokeless emissions (Emrich, 1985). The disadvantages of charcoal fuel are clearly seen when compared to liquefied petroleum gas (LPG) fuel. The charcoal grilling footprint of CO 2 is almost three times larger than for LPG combustion. In addition, LPG is radically more efficient than charcoal in its production, and considerably more efficient in cooking. However, the use of LPG requires a heavier and more...

Biosolids comprise organic matter and plant nutrients, but are also a source of heavy metals hazardous to soils, plants and humans. The aim of this work was to evaluate accumulation, movement in the soil profile and availability to maize plants of heavy metals in two oxisols amended with biosolids for five years. The experiment was carried out in Jaboticabal, SP, Brazil, under field conditions, using a split-plot design. Biosolids were added to the soils at four different rates, 0.0 (control with mineral fertilization), 2.5; 5.0 and 10.0 t ha -1 , dry weight basis, annualy for three years. In the fourth and fifth years, the 2.5 t ha METAIS PESADOS EM LATOSSOLOS TRATADOS COM BIOSSÓLIDO E CULTIVADOS COM MILHO EM EXPERIMENTO DE LONGA DURAÇÃORESUMO: O biossólido contém em sua composição matéria orgânica e nutrientes das plantas, mas também metais pesados danosos para solos, plantas e a saúde humana. O objetivo deste trabalho foi avaliar o acúmulo de metais pesados e sua mobilidade no perfil do solo, assim como a disponibilidade para plantas de milho cultivadas em Latossolo Vermelho distrófico (LVd) e Latossolo Vermelho eutroférrico (LVef) tratados com doses crescentes de biossólido durante cinco anos. O experimento foi conduzido em Jaboticabal, SP, Brasil, em condições de campo, utilizando-se delineamento de parcelas subdivididas com cinco repetições. Foram testadas quatro doses de biossólido: 0,0; 2,5; 5,0 e 10,0 t ha -1 (base seca) nos três primeiros anos. A partir do quarto ano a dose 2,5 foi substituída por 20,0 t ha -1. No quinto ano de experimentação amostras de solo foram obtidas nas profundidades 0-20 e 20-40 cm e analisadas para totais e extraíveis (Mehlich 1) de Cu, Mn, Ni, Pb e Zn. O biossólido aumentou os teores de Ni e Zn no LVef e Ni, Pb, Zn e Cu no LVd, mas os valores não ultrapassaram os níveis críticos legais. Os elementos geralmente acumularam-se na profundidade 0-20 cm em ambos os solos. Os teores de Pb e Ni nos grãos ficaram abaixo do limite de detecção da metodologia empregada. As concentrações de metais pesados na planta geralmente não foram afetados pela adição de biossólido. O extrator Mehlich 1 não foi eficiente para avaliar a disponibilidade de Ni, Mn e Pb para planta de milho. Palavras-chave: Mehlich 1, lodo de esgoto, milho, fitodisponibilidade

The global fluxes of carbon in the ecosystem of Earth, with particular attention drawn to the cycle of CO2 were characterised. The sequestration of carbon dioxide in the biomass of plants, especially the ones which can be cultivated as catch crops is described. It was shown that the cultivation of catch crops may play an important role in the mitigation of CO2 emissions.

Organic and non-organic pollution present in the drilling waste may negatively impact flora and fauna. The tests conducted on earthworms may serve as indicators for the assessment of pollution bioavailability, i.a. heavy metals, polycyclic aromatic hydrocarbons, due to the relatively stable ratios between the concentration of certain pollutants in earthworms and soil. Moreover, earthworms are capable of metal bioaccumulation in tissues; therefore, they can be utilized as an ecological indicator of soil pollution. The studies on bioaccumulation of heavy metals from soils with the addition of drilling wastes in tissues of earthworms were conducted. The reduction percentage (R) of each scenario was calculated for the total concentration of all heavy metals. As data showed, all heavy metal content was reduced from its initial concentration.

Popularization of intercrops in agriculture, resulting in an increased sequestration of carbon dioxide may bring additional benefits, becoming a source of biomass constituting a feedstock for biogas production. The residue formed in the course of biogas production, i.e. digestate, is also an alternative or a valuable supplement for mineral fertilizers necessary to maintain the proper condition of the agricultural soil. Therefore, the application of substrates from the intecrop biomass enables to improve the quality of soil, without sacrificing the main crop, by preventing the leaching of nutrients; it also reduces the risk of plant diseases, has a significant influence on diversification of energy sources, and contributes to solving the issue of excessive greenhouse gases emission. The aim of the work was to investigate the biogas and methanogenic potential of white mustard (Sinapis alba) and estimate the biogas efficiency of its biomass (the above-ground part) per hectare of arable land. The studies were conducted on the plants cultivated on experimental plots located in Emilianów and Wierzbica (Lubelskie Voivoideship). The cultivation of plants was conducted simultaneously, as stubble crop. The studies indicated a significant quantitative and qualitative differentiation of plant biomass collected from particular plots. The C:N ratio, which constitutes the basic factors governing the correct course of methane fermentation, in the case of the shoot biomass of the considered plants, ranged from 13.5:1 to 19.9:1, depending on the location. The biomass efficiency of mustard biomass ranged from 0.6 t d.m. ha -1 to 0.8 t d.m. ha -1 , whereas its biogas potential amounted to 350-440 m 3 t -1 d.m. Therefore, one hectare of intercrop mustard yields 264-280 m 3 of biogas and the produced digestate can be recirculated to the soil, increasing the amount of biogenic substances and enriching it with humic substances.