Studies on fermentative systems applied to cassava processing wastewaters usually indicate favorable scenarios for biohydrogen (BioH 2) production, considering the appreciable levels of carbohydrates found on such wastewaters. To assess the suitability of cassava flour wastewater (CFWW), a high-strength effluent from cassava flour industries, for BioH 2 production, a continuous multiple tube reactor (CMTR) was applied in bench-scale assays. The CMTR is an innovative bioreactor configuration that promotes continuous biomass discharge and prevents the accumulation of solids in the long-term. Continuous experiments were conducted using raw and heat-treated CFWW, with and without nutrient supplementation. Although the carbohydrate conversion exceeded 90%, little to no hydrogen production was observed regardless of the feeding conditions. The poor performance of the CMTR could be associated with the presence of organic acids but is likely attributed primarily to bacteriocins Nisin A and Nisin Z in the CFWW, as an evidence of the presence of lactic acid bacteria. The type of cassava wastewater may severely affect hydrogen production; therefore, prior characterization of the CFWW influent is essential to determine its suitability for acidogenic systems.

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Maize (Zea mays L.) production accounts for the largest share of crop land area in the United States and is the largest consumer of nitrogen (N) fertilizers. Routine application of N fertilizer in excess of crop demand has led to well-documented environmental problems and social costs. Current N rate recommendation tools are highly generalized over space and time and therefore do not allow for precision N management through adaptive and site-specifi c approaches. Adapt-N is a computational tool that combines soil, crop, and management information with nearreal-time weather data to estimate optimum N application rates for maize. We evaluated this precision nutrient management tool during four growing seasons (2011 through 2014) with 113 on-farm strip trials in Iowa and New York. Each trial included yield results from replicated fi eld-scale plots involving two sidedress N rate treatments: Adapt-N-estimated and grower-selected (conventional). Adapt-N rates were on average 53 and 31 kg ha -1 lower than Grower rates for New York and Iowa, respectively (-34% overall), with no statistically signifi cant diff erence in yields. On average, Adapt-N rates increased grower profi ts by $65 ha -1 and reduced simulated environmental N losses by 28 kg ha -1 (38%). Profi ts from Adapt-N rates were noticeably higher under wet early-season conditions when higher N rate recommendations than the Grower rates prevented yield losses from N defi ciencies. In conclusion, Adapt-N recommendations resulted in both increased grower profi ts and decreased environmental N losses by accounting for variable site and weather conditions.

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BACKGROUND Metallurgic wastewaters are acidic effluents containing large amounts of nitrate and heavy metals. Citric acid is one of the acids used by this industry and forms stable complexes with metal ions. The aim of this study was to elucidate the chemical aspects driving inhibitory or stimulatory effects of heavy metals on denitrifying processes, based on speciation analysis and monitoring key denitrification intermediates (nitrite and N2O). RESULTS Denitrifying sludge incubations were conducted with iron, chromium and nickel, in single and multi‐metal assays, using citrate and ethanol as electron donors. Ferric‐citrate complex, [Fe‐cit](aq), was readily consumed, while complexes of divalent metals, [Fe‐cit]‐ and [Ni‐cit2]4‐, remained very stable affecting denitrification. Nitrate reduction was affected by Ni2+, while nitrite and N2O accumulation was observed with NiCO3 and Ni(OH)2 oversaturation. [Cr‐cit2]4‐ resulted in overall denitrification inhibition, while species of [Cr‐cit]2‐ caused denitrification stimulation. CONCLUSION Fe and Cr inhibited the overall denitrification process, while Ni caused accumulation of intermediates. Synergistic inhibition imposed by multi‐metal systems revealed lower inhibitory effects compared with those observed by the sum of individual effects of metals. This study elucidates chemical aspects determining the effects of heavy metals on denitrification, which is relevant to develop efficient biological processes for metallurgic effluents. © 2017 Society of Chemical Industry

ABSTRACT:The objective of this research was to evaluate the performance of the aquatic macrophyte Eichhornia crassipes applied in situ in a slaughter house treatment system, located in the west of the Paraná state, Brazil, regarding the nutrients removal and organic matter. Moreover, it aimed to obtain data from the production, management and composting practices of the biomass generated in the system. During 11 months of macrophytes development, physic and chemical parameters were monitored and plant density was controlled by periodical removal of excess biomass, which was weekly monitored and it is expressed in kg of aquatic plant per m 2 covered area. The degradation of the macrophytes removed from the treatment system was evaluated at the pilot scale in eight composting piles of 0.60 m 3 that underwent four different treatments and two repetitions: T1 -water hyacinth (Eichhornia crassipes); T2 -water hyacinth and swine excrement (7:1), T3 -water hyacinth, swine excrement and earth (7:1:0,67), and T4 -water hyacinth, swine excrement and cellulosic gut (7:1:0,67), for a period of 90 days. The results indicated maximum removal efficiencies of 77.2% for COD; 77.8% for BOD, 87.9% for total nitrogen, 47.5% for ammonia nitrogen and 38.9% for total phosphorus for a five-day retention time. For biomass stabilization by composting, considering the C:N ratio as an indicator of compost maturity, it was observed that treatment T4 resulted in the shortest stabilization period (60 days). No difference was verified in the biostabilization rates at 5% level by the F test.KEYWORDS: agroindustrial effluent, nutrient removal, water hyacinth, composting, C:N ratio. REMOÇÃO DE MATÉRIA ORGÂNICA E NUTRIENTES DE EFLUENTE DE ABATEDOURO E FRIGORIFICO UTILIZANDO Eichhornia crassipes E AVALIAÇÃO DA COMPOSTAGEMDA BIOMASSA GERADA RESUMO: O presente trabalho teve por objetivo avaliar o desempenho da macrófita aquática Eichhornia crassipes, aplicada in situ em sistema de tratamento de abatedouro e frigorífico, localizado no Oeste do Paraná, com relação à remoção de nutrientes e matéria orgânica, bem como obter dados da produção, de práticas de manejo e de compostagem da biomassa gerada no sistema. Durante 11 meses de desenvolvimento das macrófitas na lagoa, realizou-se o monitoramento de parâmetros físico--químicos e controlou-se a densidade das plantas, retirando-se periodicamente a biomassa em excesso por meio do acompanhamento semanal da densidade de plantas, expressa em kg de aguapé por m 2 de área líquida coberta. Avaliou-se, em escala-piloto, a degradação das macrófitas retiradas do sistema de tratamento, montando-se oito leiras de compostagem com aproximadamente 0,60 m 3 , com quatro tratamentos distintos e duas repetições, sendo: T1-aguapé (Eichhornia crassipes); T2 -aguapé e dejeto suíno; T3 -aguapé, dejeto suíno e terra, e T4 -aguapé, dejeto suíno e tripa celulósica, por período de 90 dias. Os resultados obtidos demonstraram as eficiências máximas de remoções: DQO de 77,2%; DBO de 77,8%; nitrogênio total de 87,9%; nitrogênio amoni...

The Brazil's Biodiesel Production and Use Program introduces biodiesel in the Brazilian energy matrix, bringing along the perspective of a growth of the glycerin offer, co-product generated in the proportion of 10 kg for each 100 L of biodiesel. The aim of this study was to evaluate the addition of crude glycerin in the anaerobic digestion of cassava starch industry effluent (cassava wastewater), in a horizontal semi-continuous flow reactor of one phase in laboratory scale. It was used a reactor with a 8.77 L of useful volume, a medium support for corrugated conduit of polyvinyl chloride (PVC), temperature of 261 ºC, fed with cassava wastewater and glycerin, with hydraulic detention times of 4 and 5 days and increasing volumetric organic load of 3.05; 9.32; 14.83 and 13.59 g COD L -1 d -1 , obtained with the addition of glycerin at 0; 2; 3 and 2% (v/v), respectively. The average removal efficiencies of TS and TVS were decreasing from the addition of glycerin to the cassava wastewater, averaging 81.19 to 55.58% for TS and 90.21 to 61.45% for TVS. The addition of glycerin at 2% increased the biogas production compared to the control treatment, reaching 1.979 L L -1 d -1 . The biogas production as a function of the consumed COD was higher for the control treatment than for the treatments with addition of glycerin, which indicates lower conversion of organic matter into biogas.KEYWORDS: cassava wastewater, biodiesel, biogas, glycerol. CODIGESTÃO ANAERÓBIA DE GLICERINA BRUTA E EFLUENTE DE FECULARIARESUMO: O Programa Nacional de Produção e Uso do Biodiesel introduziu o biodiesel na matriz energética brasileira, trazendo a perspectiva de aumento da oferta de glicerina, coproduto gerado na proporção de 10 kg para cada 100 L de biodiesel. O objetivo principal deste trabalho foi avaliar a adição de glicerina bruta na digestão anaeróbia de efluente de indústria de fécula de mandioca (manipueira), em reator de fluxo semicontínuo horizontal de uma fase, em escala de laboratório. Foi utilizado um reator com volume útil de 8,77 L, meio suporte em eletroduto corrugado de policloreto de vinila (PVC), temperatura de 261 ºC, alimentado com manipueira e glicerina, aplicando-se tempos de detenção hidráulica de 4 e 5, dias e cargas orgânicas volumétricas crescentes de 3,05; 9,32; 14,83 e 13,59 g COD L -1 d -1 , obtidas com a adição de glicerina aos níveis de 0; 2; 3 e 2% (v/v), respectivamente. As eficiências de remoção média de ST e STV foram decrescendo a partir da adição de glicerina à manipueira, com médias de 81,19 a 55,58 % para ST e 90,21 a 61,45% para STV. A adição de glicerina em 2% aumentou a produção de biogás em relação ao tratamentocontrole, chegando a 1,979 L L -1 d -1 . A produção de biogás em função da DQO consumida foi maior para o tratamento-controle que, para os tratamentos com adição de glicerina, indica menor conversão da matéria orgânica em biogás.

Attempting to associate waste treatment to the production of clean and renewable energy, this research sought to evaluate the biological production of hydrogen using wastewater from the cassava starch treatment industry, generated during the processes of extraction and purification of starch. This experiment was carried out in a continuous anaerobic reactor with a working volume of 3L, with bamboo stems as the support medium. The system was operated at a temperature of 36°C, an initial pH of 6.0 and under variations of organic load. The highest rate of hydrogen production, of 1.1 L.d-1.L-1, was obtained with application of an organic loading rate of 35 g.L-1.d-1, in terms of total sugar content and hydraulic retention time of 3h, with a prevalence of butyric and acetic acids as final products of the fermentation process. Low C/N ratios contributed to the excessive growth of the biomass, causing a reduction of up to 35% in hydrogen production, low percentages of H2 and high concentrations of CO2in the biogas.