Uptake of Zn, Cr and Cd by water hyacinths

Studies were conducted in a greenhouse to determine the phytotoxic effect and uptake capacity of Zn, Cr and Cd by the water hyacinth Eichhornia crassipes. Results show that among the three elements tested, Cd was the most phytotoxic, showing up some necrosis in the plant when the concentration was greater than 2.5 ppm. In the case of Cr and Zn, the phytotoxicity produced the appearance of chlorosis in the aerial part of the plant. For the tested rates of Cr (maximum 9 ppm) no reduction of productivity was found, whereas in the case of Zn the concentration of 9 ppm in solution caused a 30% reduction in the weight. As for the heavy metal absorption, it was proved that after 24 days of growth, the heavy metals were totally depleted from the nutritive solution suggesting complete absorption of these metals by the plants. © 1993

Organic and inorganic nutrients removal from pig slurry by water hyacinth

Studies were conducted to determine the capacity of water hyacinth (Eichhornia crassipes [Mart] solms) for uptake of organic and inorganic nutrients from pig slurry because the water hyacinth is considered the species with the highest biomass production capacity, and due to its high nutrient content and heavy metals absorption, it was used for the tertiary depuration of pig slurry. Results showed that a wastewater treatment system using water hyacinth was capable of reducing COD by 100% (60% of reduction to the water hyacinth) when the effluent had up to 1000 mg/1 COD. Significant relationships were observed between the depuration rate and climatic factors (temperature, solar radiation, humidity, etc.). For the months of maximum production of biomass, from June to September, which coincided with the optimum climate, the extent of removal of COD above mentioned was obtained in 8 to 10 days, whereas in the remaining months it required much more time. Inorganic nitrogen (NH4-N and NO3-N) was removed by the water hyacinth the ammonium nitrogen (NH4-N) of the wastewater was reduced by 88% from June t o September, but i n t h e other months ammonium only decreased by 75%, however, only 60% of the nitrate nitrogen was removed. Copyright © 1995 Taylor & Francis Group, LLC. All rights reserved

Methane generation from water hyacinth biomass

One of the most pressing problems of our industrialized society is the uncertainty of maintaining an adequated supply of energy. As fossil fuels continue to decline in availability, the search for alternative sources of energy intensifies. One alternative is the production of methane gas by the fermentation of various types, of biomass. Research has been conducted for the cultivation of the fresh-water macrophyte, the water hyacinth (Eichhornia crassipes), as a potential biomass source able to be converted into methane and as a nutritive feed. The results were the anaerobic filter digester had a maximum production of 130 liters methane/Kg volatile solids added with a hidraulic retention time of 10 days and the biogas contains 64% methane. The contact process had a maximum production of 162 I CH/Kg v.s. added with a hidraulic retention time of 15 days and the biogas contains 65% methane. The mixed flow reactor had a maximum production of 146 L CH/Kg v.s. added with hidraulic retention time of 25 days and the biogas contains 65% methane. The maximum depuration obtained for these digesters were 49% with a hidraulic retention time of 10 days for the anaerobic filter digester. The contact proce s and mixed flow eactors had 65% for 15 and 25 days of hidraulic retention time, repectively. Finally, the acids volatile concentration for these digesters were for the anaerobic filter digester 71 mg acetic/l with a retention time of 10 days. For the contact process 65 mg acetic/l with retention time of 15 days and for the mixed flow reactor 58 mg acetic/l with retention time of 25 days. © 1992, Taylor & Francis Group, LLC. All rights reserved

Effect of different dietary strategies on gas emissions and productive performance in post- weaned piglets

The objective of this study was to assess the effects of different dietary strategies in post-weaned piglets on gas emissions and animal performance. Eighty piglets were allotted in ten environmentally-controlled chambers. Piglets were fed with five different isoenergetic diets: control, low protein (LP), inclusion of sugar beet pulp (SBP), addition of benzoic acid (BA) and a combination of LP, SBP and BA (LP+SBP+BA). The gases analyzed were ammonia (NH3), methane (CH4), nitrous oxide (N2O) and carbon dioxide (CO2). For NH3, the most effective treatment was LP, with a reduction of 61%. The LP+SBP+BA reduced NH3 emission by 51%, the inclusion of SBP by 43% and the least effective technique was BA, which decreased by 9.5%, compared to control. The CH4 emission was reduced by 30% for LP, but was increased by 23% for SBP and 24.6% for LP+SBP+BA. Benzoic acid did not differ from control group. The N2O emission did not show statistically differences, and CO2 and carbon dioxide equivalent (CO2eq) emission increased with LP+SBP+BA (14 and 15% respectively), but were not affected by other diets. No effect of dietary treatment was observed on the growth performances compared with control group (p >0.05). We can conclude that the best technique to reduce NH3 emission was LP. Inclusion of SBP decreases NH3 emission, but can increase greenhouse gas emissions. It would be interesting to evaluate the effect of higher percentages of BA because the promising results. Combining techniques is not a good strategy to obtain an additive effect in gas emissions reduction.The objective of this study was to assess the effects of different dietary strategies in post-weaned piglets on gas emissions and animal performance. A total of 80 piglets were allotted in ten environmentally-controlled chambers located in Quebec, Canada. Piglets were fed with five different isoenergetic diets: control, low protein diet (LP), inclusion of sugar beet pulp (SBP), addition of benzoic acid (BA) and a combination of LP, SBP and BA. The gases analyzed were ammonia (NH3), methane (CH4), nitrous oxide (N2O) and carbon dioxide (CO2).For ammonia, the most effective treatment was LP, with a reduction of 61%. The LP+SBP+BA reduced ammonia emissions by 51%, the inclusion of SBP by 43% and the least effective technique was BA, which decreased by 9.5%. Methane emissions were reduced by 30% for LP, but were increased by 23% for SBP and 24.6% for LP+SBP+BA. Acidifying components did not make a statistically significant difference. Nitrous oxide emissions did not have statistically differences and CO2 and CO2eq emissions increased with LP+SBP+BA (14 and 15% respectively), but were not affected by other diets. No effect of dietary treatment was observed on the performances of the piglets (p >0.05). We can conclude that the best technique to reduce ammonia emissions is LP. Inclusion of SBP decreases ammonia emissions, but can increase greenhouse gas emissions. It would be interesting to evaluate the effect of higher percentages of BA because the promising results. Combining techniques is not a good strategy because it does not have an additive effect in gas reduction

Water hyacinth biomass production in Madrid

Studies were conducted to determine the production of biomass of the water hyacinth in Madrid. The production of biomass at ambient temperature during the warm months (from May to October) was 215 t wet wt ha-1 · year-1 equivalent 10.7 t dry wt · ha-1 · year-1 In the greenhouse, the production of biomass was 791 t wt ha-1 · year-1 equivalent 39.5 t dry ha-1 · year-1 During August the increase in weight was 361 kg · m -2 at ambient temperatures and in the greenhouse the greatest production was in September with 677 kg · m-2. To evaluate the nutritive value of the water hyacinth the biomass was fractionated to obtain a liquid fraction with 23.78% protein and a solid fraction with 5.61% protein. For animal food, it is necessary to use both fractions, solid and liquid. The protein content is 21.14% (dry weight), which is higher or at least equal to normally used green fodder. © 1992

Preliminary result of the application from composted sewage sludge as fertilizer and its implication in the migration of nitrate through the unsatured zone

The results of field experiments over use of the composted sewage sludge compared with mineral fertilizer in corn crops are presented. Also, the nitrate leaching through the unsaturated zone and its arrival to groundwater is studied. The amount of nitrate adds from the composted sewage sludge is, lesser than the traditionally fertilizers. This can substitute the traditionally fertilizers, because reduced the possibility of contamination and equaled the yiel

Heterotypic inhibition of foot-and-mouth disease virus infection by combinations of RNA transcripts corresponding to the 5' and 3' regions

Strategies to inhibit RNA virus multiplication based on the use of interfering nucleic acids have to consider the high genetic polymorphism exhibited by this group of viruses. Here, we report high levels of heterotypic inhibition of foot-and-mouth disease virus (FMDV) infective particle formation in cotransfection experiments of susceptible cell lines with infections viral RNA and combinations of viral transcripts. The interfering molecules used include the following regions on type C FMDV RNA (i) sequences from the 5' region, spanning the proximal part of the internal ribosome entry site element and the two functional initiator AUGs; and (ii) the 3' terminal region including the 3' end of 3D gene and the complete 3' non-coding region. Combination of 5' antisense RNA molecules with either sense or antisense RNA molecules from the 3' region resulted in inhibition of up to 90% of the infectivity of homologous type C FMDV RNA. The inhibition was dose-dependent and specific, as no reduction was observed in the plaque- forming units recovered from RNA of swine vesicular disease virus, a related picornavirus. Interestingly, high levels of intertypic inhibition, about 60% or higher, were observed when viral RNAs of serotypes O and A were analysed. These levels of inhibition are consistent with the levels of nucleotide homology exhibited by the viruses analysed in the target sequences. Inhibition of virus yield was also observed in FMDV-infected cells transiently expressing the interfering RNAs. Thus, transcripts of the FMDV RNA corresponding to the 5' and 3' regions specifically inhibit FMDV particle formation in a serotype-independent manner

Mineralización del nitrógeno procedente de residuos orgánicos

The main objective of this work was to determine the total mineral nitrogen in three soils with three organic residues pig slurry, urban waste and sewage sludge, after 42 weeks in laboratory incubation. When the residue was pig slurry the results showed that the cumulative N mineralized (NH4+NO3)-N lor soil A was 600 mg (NH4+NO3) -N/kg; 313 and 408 mg (NH4+NO3)-N /kg for soil B and sand respectively. The cumulative N mineralized (NH4+NO3)-N /kg for sewage sludge was 253 mg (NH4+NO3)-N /kg in soil A, 366 mg (NH4+NO3) -N /kg in soil B and 258 mg(NH4+NO3) -N /kg in sand. Finally, in urban waste, nitrogen was immobilizated in the three studied soils