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344 results on '"Lema, J.M."'

33. Combined system for biological removal of nitrogen and carbon from a fish cannery wastewater

Author

Mosquera-Corral, A., Campos J.L., Sanchez, M., Mendez, R., and Lema, J.M.

Subjects
Fisheries -- Research, Fisheries -- Health aspects, Water -- Contamination, Engineering and manufacturing industries, Environmental issues
Abstract

A combined system composed of three sequentially arranged reactors, anaerobic-anoxic-aerobic reactors, was used to treat the wastewater generated in the tuna cookers of a fish canning factory. These wastewaters are characterized by high chemical oxygen demand (COD) and nitrogen concentrations. The anaerobic process was performed in an upflow anaerobic sludge blanket reactor operated in two steps. During Step I different influent COD concentrations were applied and organic loading rates (OLRs) up to 4 g COD/(L*d) were achieved. During Step II hydraulic retention time (HRT) was varied from 0.5 to 0.8 days while COD concentration in the influent was constant at 6 g COD/L. The OLRs treated were up to 15 g COD/(L*d). When HRTs longer than 0.8 days were used, COD removal percentages of 60% were obtained and these values decreased to 40% for a HRT of 0.5 days. The denitrification process carried out in an upflow anoxic filter was clearly influenced by the amount of carbon source supplied. When available carbon was present, the necessary COD/N ratio for complete denitrification was around 4 and denitrification percentages of 80% were obtained. The nitrification process was successful and was almost unaffected by the presence of organic carbon (0.2-0.8 g TOC/L), with ammonia removal percentages of 100%. Three recycling ratios (R/F) between the denitrification and nitrification reactors were applied at 1, 2, and 2.5. The overall balance of the combined system indicated that COD and N removal percentages of 90% and up to 60%, respectively, were achieved when the R/F ratio was between 2 and 2.5.

Published
2003

45. Multi-fed upflow anaerobic filter: development and features

Author

Punal, A., Mendez, R., and Lema, J.M.

Subjects
Sewage disposal -- Equipment and supplies, Sewage disposal plants -- Equipment and supplies, Engineering and manufacturing industries, Environmental issues
Abstract

To overcome two of the main problems intrinsic to upflow anaerobic filters, clogging and poor efficiency in the upper zone, a new feeding strategy consisting of distributing the influent flow through several entrances along the system was studied. Two identical upflow anaerobic filters, a single-fed reactor (SFR) and a multi-fed reactor (MFR), were used with synthetic substrate of ~10-kg chemical oxygen demand (COD)[m.sup.3] at an organic loading rate of up to 32-kg COD/[m.sub.3]. day. After more than 1 year of operation, the MFR strategy proved to be more efficient than the SFR, in terms of COD removal as well as with regard to stability against hydraulic and organic overloads. The MFR developed a more homogeneous bacteria consortium throughout the filter, therefore the specific methanogenic and nonmethanogenic activities are very similar in the bottom and the upper part of the filter. The MFR does not need a recycling flow to increase mixing. Moreover, the working volume of the MFR was higher than 85%, while only 65% of SFR remained active after 410 days.

Published
1998

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