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L Travieso

Publications and source records attributed to L Travieso.

9 recordsLinked to original sources
PubMed2006

An evaluation of variables affecting the stability and performance of down-flow anaerobic fixed bed reactors treating piggery wastewater.

The influence of the most important variables on the stability and performance of down-flow anaerobic fixed bed reactors treating piggery wastewater after primary sedimentation was evaluated at HRT in the range of 1-6 d and influent substrate concentration in the range of 2 to 12 g TCOD l(-1). The effect of HRT was more pronounced compared to that of influent strength. An increase in the HRT increased the process stability and process performance at different influent strengths. TCOD, SCOD, BOD5 TSS, organic nitrogen (N) and Orthophosphate (P) removals increased with the HRT, independently of the initial substrate concentration (S0). The increase in S0 brought about an increase in the attached biomass concentration (X) at the end of the experiment. Two empirical models based on the individual effect of HRT, X and S0 were evaluated and found to be adequate to describe the influence of these variables on the process performance. The first model took all the above-mentioned variables into consideration while the second model was simplified and based on the use of HRT as the only independent variable. The results obtained by using both models were found to be similar. This demonstrated that independently of the characteristics of the operation, the behaviour and performance of the reactors were comparable. The methane yield coefficient was found to be 0.3371 methane g(-1) TCOD removed.

Anaerobiosis↗
PubMed2006

Production of biomass (algae-bacteria) by using a mixture of settled swine and sewage as substrate.

This paper presents the use of a mixture of settled swine and sewage as substrate for biomass production, mainly constituted by microalgae Chlorella vulgaris and aerobic bacteria, growing outdoor at different dilution rates in a continuous mode. The experiments were carried out in 16-litre volume laboratory ponds operating at hydraulic retention times (HRT) in a range of 4-14 days equivalent to dilution rates (D) in a range of 0.250-0.071 d(-1). Total chemical oxygen demand (TCOD), soluble chemical oxygen demand (SCOD), total biochemical oxygen demand (TBOD(5)), total suspended solids (TSS), volatile suspended solids (VSS), total Chlorophyll (S C), total Kjeldahl nitrogen (TKN), ammonia nitrogen, total phosphorous, orthophosphate and pH were monitored. An empirical relationship between the dilution rate (D) and the removal efficiencies of TCOD, SCOD, TBOD(5), TKN and total phosphorous was found. The occurrence of an inhibition process for TCOD, TBOD(5), TKN and total phosphorous removals was observed. The Andrews kinetic model was successfully applied to these experimental data, while the Monod model was more suitable for studying the variation of the SCOD removal rate with the effluent SCOD concentration. The maximum microalgal biomass productivity was found to be in the range of 93-98 mg VSS(A)/L d (37.2-39.2 g/m(2)d) at dilution rates in the range of 0.167-0.250 d(-1), where VSS(A) is the concentration of microalgae expressed in VSS. In the case of the bacteria, the productivity increased linearly with the dilution rate being maximum at a D value of 0.25 d(-1). It was concluded that the mixture of pre-treated swine and sewage used as substrate, contributed to the obtention of a high biomass (microalgae-bacteria) production, providing a simple technology feasible to be applied in developing countries.

Animals↗
PubMed2005

Effect of organic loading rate on the stability, operational parameters and performance of a secondary upflow anaerobic sludge bed reactor treating piggery waste.

A study of anaerobic digestion of piggery wastewater was carried out in a laboratory-scale sludge bed reactor as a secondary treatment. The effect of organic volumetric loading rates (BV) in the range of 1.0-8.1 g TCOD/ld on the process performance was evaluated. The best results were obtained at BV equal to or lower than 4 g TCOD/ld. At higher BV values, the removal efficiency of the process decreased suddenly. A linear relationship was found between the effluent SCOD and the TVFA/alkalinity ratio (P). A relationship was found among the different operational variables (BV , removal efficiency, effluent soluble COD, soluble COD removal rate (R), retention factor (phi), specific microbial growth rate (mu), methane production rate per volume of reactor and per volume of waste treated--QM and qM, respectively) and the corresponding regression equations were obtained. An increase of BV determined a decrease of removal efficiency, phi and qM and an increase of effluent soluble COD, mu, R and QM. The value of the maximum specific microbial growth rate (muM) determined through the equation that correlated BV and mu was found to be 0.19 d(-1). This value was of the same magnitude as those reported in other works of anaerobic digestion of piggery waste.

Anaerobiosis↗
PubMed2004

Evaluation of a laboratory and full-scale microalgae pond for tertiary treatment of piggery wastes.

Piggery wastes tertiary treatment in laboratory and full-scale microalgal ponds was evaluated. COD, BOD, inorganic nitrogen and orthophosphate removals of up to 57%, 69%, 79% and 74%, respectively, were obtained. The effect of the hydraulic retention time (HRT) on removal efficiencies followed an exponential relationship. COD, BOD and orthophosphate removal rate decreased with increased effluent concentration while the inorganic nitrogen removal rate increased with an increasing effluent substrate concentration at inorganic nitrogen concentration values lower than 0.07 g l(-1). Values of maximum substrate removal rate, half rate constant, cell yield coefficient, endogenous constant and maximum specific growth rate were 7.1 +/- 0.5 d(-1), 0.21 +/- 0.02 g l(-1), 0.26 +/- 0.01 g VSS g(-1) COD, 0.012 +/- 0.001 d(-1)and 1.9 +/- 0.9 d(-1), respectively. At full-scale, effluent COD, BOD, MPN, inorganic nitrogen and orthophosphate decreased while pH and Chlorophyll a increased with the operation time. It was found that the use of the final effluent as drinking water did not affect pigs growth.

Animals↗
PubMed2003

Population dynamic of algae and bacteria in an oxidation channel.

A study on algae and bacteria population changes, as a function of time, was carried out in a pilot scale oxidation channel bioreactor using a carrousel system. Total Coliforms, Pseudomonas aeruginosa, and Streptococcus faecalis, the most common bacteria found in sewage, Scenedesmus obliquus and Chlorella vulgaris were the microalgae considered in this work. Physicochemical parameters such as COD, BOD, Chlorophyll a, nitrogen, and phosphorous compounds were studied and determined during the experiments. It was demonstrated that the level of wastewater contamination could be predicted based on the bacterial and algae composition. The relationships between the algae and bacteria population, and the variation of these microorganism populations as a measurement of the level of purification were established. The oxidation channel was able to remove a considerable amount of organic matter and pathogenic microorganisms in a relatively short time. The nitrification process could not be measured. The increase in the relative concentration of microalgae contributed toward improving the global efficiency of the system as well as reducing the pathogenic bacteria population.

Bacteria↗
PubMed1994

Growth of Phormidium sp. in aerobic secondary piggery waste-water.

The potential of a cyanobacterium Phormidium sp., for the tertiary treatment of piggery waste-water chemical oxygen demand > or = 3000 mg.l-1, using an aerobically stabilized secondary effluent, was studied. Batch cultures were carried out in 2-l glass reactors and in a 30-l glass-fibre carousel reactor. The nutrient removal efficiency as well as biomass production were compared in synthetic mineral medium and in different concentrations of aerobically stabilized piggery effluent. The best performance of Phormidium sp. occurred in diluted stabilized secondary effluent (1:1). Removal efficiencies were 100% for P-PO4(-3), 50% for N-NH4+ and 35% for N-NO3- in small-volume cultures; and 31% for P-PO4(-3), 100% for N-NH4+ and 70% for N-NO3- in an open carousel reactor. Biomass production on the aerobically stabilized effluent was six times higher in the 2-l reactors and 1.7 times higher in the carousel reactor when compared to the synthetic medium.

Aerobiosis↗