No abstract

The stillage, which is a liquid residue from the distillation of the sugarcane ethanolic fermentation, contains organic matter and can be a big source of pollution when it is discarded in the wrong way. Its application as fertilizer has been extended, which is reason to cause concerns regarding the environment. The aim of this work was to evaluate and quantify the biodegradation of stillage in sandy and clay soils, besides verifying the efficiency of the Embiotic Line ® inoculum as an accelerator of the biodegradation. Bartha and Pramer respirometric technique was used to determine the production of CO 2 during the 50 days of the biodegradation process, and the quantification of the initial and final microorganisms was also conducted. Results were analyzed using the Friedman statistical test. Clay soils were significantly better on stillage decomposition when compared to sandy soils (p=0.0153). Clay soils presented greater efficiency in stillage biodegradation, with higher field capacity, better water, organic matter and microbial retention. Regarding the use of the embiotic line, the experiment has shown this product does not interfere positively in the stillage biodegradation for both soils, possibly needing adjustments in its composition.

Alcohol production in industry is carried out almost exclusively by means of batch or continuous fermentation processes. In both cases, cells are found spread throughout the fermenting substrate and have to go through a centrifugation cycle in order to be recovered. Investment in equipment is very high and performance is often lower than expected. According to available information, ethanol fermentation performance could be better in conditions where the cells are immobilized in continuous processes. In this experiment, it was possible to affirm, based on statistical data that fermentation with immobilized cells improves alcohol yields. Using a free cell batch fermentation process, Zymomonas mobilis reached 59.95% of the theoretical yield. Immobilized cells reached 68.53% using a batch and 74.49% using a continuous fermentation process. Under the same conditions, Saccharomyces cerevisiae reached respectively 70.03, 77.10 and 78.47% of the theoretical yield. Higher yields were achieved for both microorganisms using mixed culture fermentation, compared to pure cultures. Under the same conditions for both pure cultures, mixed cultures reached respectively 70.86, 79.07 and 80.86% of the theoretical yield. Findings suggest that association and immobilization cultures of S. cerevisiae and Z. mobilis result in better yields for batch as well as continuous fermentation processes.

a b s t r ac tLandfill leachate is formed by organic and inorganic toxic compounds. It has high salt concentration and pathogenic organisms that can cause environmental harm. Hydrotalcite, activated carbon and Moringa oleifera seeds have been used for the adsorption of contaminants and the purification of water. In the present study, landfill leachate was submitted to physicochemical and microbiological analysis before and after treatment with these adsorbents. The characterization of the leachate revealed a small number of heterotrophic bacteria and fungi. Total coliforms and Escherichia coli reached mean values of 17,900 and 890 NMP/100 mL, respectively. The physicochemical analysis indicated high conductivity, color, turbidity, chemical oxygen demand (COD), biochemical oxygen demand in 5 d, ammonia, boron, sodium and chlorides. Treatment with hydrotalcite produced the best results regarding the improvement in these variables, but led to an increase in pH. Reused hydrotalcite (Hr) provided reasonable results, but with less efficiency than hydrotalcite. Moreover, Hr failed to remove boron and aluminum and magnesium levels increased. In addition, 4% activated carbon (AC4%) obtained better results regarding color and COD, but failed to remove boron and ammonia efficiently and 1% activated carbon achieved similar results to AC4%, but with lower degrees of removal. M. oleífera seed and extract achieved unsatisfactory results. All adsorbents, except M. oleifera extract, decreased the amount of heterotrophic bacteria approximately 10-fold. Total coliforms and E. coli did not resist the treatments. None of the adsorbents removed sodium, chloride or the toxicity of the leachate.