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Sorption and desorption of heavy metals (Cd, Cu, Pb, and Zn) was evaluated in biochars derived from sugarcane bagasse (SB), eucalyptus forest residues (CE), castor meal (CM), green coconut pericarp (PC), and water hyacinth (WH) as candidate materials for the treatment of contaminated waters and soils. Solid-liquid distribution coefficients depended strongly on the initial metal concentration, with K d,max values mostly within the range 10(3)-10(4) L kg(-1). For all biochars, up to 95 % removal of all the target metals from water was achieved. The WH biochar showed the highest K d,max values for all the metals, especially Cd and Zn, followed by CE (for Cd and Pb) and PC (for Cd, Pb, and Zn). Sorption data were fitted satisfactorily with Freundlich and linear models (in the latter case, for the low concentration range). The sorption appeared to be controlled by cationic exchange, together with specific surface complexation at low metal concentrations. The low desorption yields, generally less than 5 %, confirmed that the sorption process was largely irreversible and that the biochars could potentially be used in decontamination applications.

News coagulants for water and sewage treatment are synthesized trough the chemical transformation of tannin extracts. Tanfloc® is a cationic polymeric coagulant produced from tannin extract of Acacia mearnsii. In this paper we are supporting the use of cationic polymeric coagulant for treatment of polluted water instead of aluminum or iron salts to support the sustainable water supply systems according with the principles of the green chemistry.

Resumo -O objetivo deste trabalho foi avaliar o efeito da aplicação de doses crescentes de xisto retortado (XR) sobre características biológicas indicadoras da qualidade do solo. Foram realizados experimentos, em Argissolo Vermelho distrófico arênico, em condições de laboratório e de campo. Em laboratório, os tratamentos consistiram da aplicação ao solo de sete diferentes doses de XR (0, 300, 450, 600, 750, 1.500 e 3.000 kg ha -1 ). Em campo, os tratamentos foram compostos por quatro diferentes doses de XR (0, 750, 1.500, 3.000 kg ha -1 ) combinadas à adubação mineral recomendada, avaliados em dois cultivos de feijão (Phaseolus vulgaris L.), no sistema plantio direto. Avaliaram-se: a evolução de CO 2 , o carbono da biomassa microbiana (CBM), a atividade enzimática do solo e o teste de ecotoxicidade. A aplicação de doses crescentes de XR melhorou a atividade microbiológica do solo, por reduzir a emissão de CO 2 sem causar variação no CBM e sem provocar impactos negativos sobre a atividade enzimática do solo. Os resultados obtidos com as enzimas em condições de campo, após duas aplicações de XR, aliados aos de CBM, do quociente metabólico (qCO 2 ) e do teste ecotoxicológico, em condições de laboratório, indicam que o uso do XR não provoca a degradação biológica do solo.Termos para indexação: biomassa microbiana, ecotoxicidade, enzimas do solo, mineralização do carbono, qualidade do solo. Microbial and enzymatic activities in the soil after application of retorted oil shaleAbstract -The objective of this study was to assess the effect of increasing doses of retorted oil shale (ROS) application on the biological property indicators of soil quality. Experiments were carried out, under field and laboratory conditions, on a Hapludalf soil. In the laboratory, the treatments consisted of the application of seven different ROS rates (0, 300, 450, 600, 750, 1,500 and 3,000 kg ha -1 ) to the soil. In the field, the treatments were composed by four different ROS rates (0, 750, 1,500 and 3,000 kg ha -1 ) combined with the recommended mineral fertilizer rate, evaluated in two croppings of common bean (Phaseolus vulgaris L.), under no-till system. CO 2 evolution, microbial biomass carbon (MBC), soil enzyme activity and the ecotoxicity test were evaluated. Application of increasing ROS rates improved the soil microbial activity by decreasing CO 2 emission and causing no variations in MBC nor negative impacts on the soil enzymatic activity. The results obtained with the enzymes under field conditions, after two ROS applications, allied to MBC results, and to the metabolic quocient (qCO 2 ) and to the ecotoxicity test, under laboratory conditions, show that the use of ROS cause no soil biological degradation.

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