Fenologia e produção de cultivares de amoreira-preta em sistema agroecológico.

A amoreira-preta é uma espécie de exploração recente no Brasil. Nos últimos ano, s tem sido dada especial atenção ao cultivo orgânico ou agroecológico dessa espécie. O objetivo deste trabalho foi verificar o comportamento fenológico e produtivo das cultivares de amora-preta ‘Tupy’, ‘Guarani’, ‘Caingangue’, ‘Cherokee’ e ‘Brazos’, e das seleções denominadas ‘seleção 97’ e ‘seleção 787’ na região de Pelotas, Rio Grande do Sul(RS), em sistema agroecológico. O trabalho foi realizado na Estação Experimental de Cascata (EEC), Embrapa Clima Temperado. As plantas foram dispostas no pomar, em blocos varietais aleatórios, com 10 plantas por genótipo, perfazendo quatro linhas com duas cultivares por linha. Foram observadas as datas de início da floração e fim da floração, início e final de colheita, massa (gramas) e número de frutos por planta, teor de sólidos solúveis totais (ºBrix), produção média por planta (g pl-1) e produtividade estimada por hectare (kg ha-1). Para análise das características dos frutos, a média de cada ano de avaliação (três) foi considerada como uma repetição. Na região de Pelotas-RS, é viável o cultivo agroecológico de amoreira-preta. Não há diferenças de produção, produtividade, número de frutos e teores de sólidos solúveis totais entre os genótipos estudados

A pH-based control of ammonia in biogas during anaerobic digestion of artificial pig manure and maize silage

The purposes of this study were to prove that ammonia can be present in biogas from anaerobic digestion and to control this ammonia by reducing the reactor pH. Ammonia containing biogas was produced for a period of more than 100 days, with a maximum of 332 ppm. Especially during periods of high free ammonia concentrations in the reactor was ammonia present in biogas. The free ammonia was effectively reduced to less than the inhibition level by pH-based control and the ammonia in biogas concentration was reduced to 9 ppm. Simultaneously the CH4-yield was severely reduced. A pH-based control of ammonia in biogas with a satisfactory biogas production was thus so far proven not to be achievable. In the carrying out this study it was shown that high ammonia concentrations lead to a range of problems: process inhibition, decreased COD removal efficiency, reduced biogas production, malodour and a poor biogas quality that requires treatment

Prediction of trace compounds in biogas from anaerobic digestion using the MATLAB Neural Network Toolbox

The outlook to apply the highly energetic biogas from anaerobic digestion into fuel cells will result in a significantly higher electrical efficiency and can contribute to an increase of renewable energy production. The practical bottleneck is the fuel cell poisoning caused by several gaseous trace compounds like hydrogen sulfide and ammonia. Hence artificial neural networks were developed to predict these trace compounds. The experiments concluded that ammonia in biogas can indeed be present up to 93 ppm. Hydrogen sulfide and ammonia concentrations in biogas were modelled successfully using the MATLAB Neural Network Toolbox. A script was developed which made it easy to search for the best neural network models' input/output-parameters, settings and architectures. The models were predicting the trace compounds, even under dynamical conditions. The resulted determination coefficients (R2) were for hydrogen sulfide 0.91 and ammonia 0.83. Several model predictive control tool strategies were introduced which showed the potential to foresee, control, reduce or even avoid the presence of the trace compounds