Brewery and liquid manure wastewaters as potential feedstocks for microbial fuel cells: a performance study.

This work aims at the comparison of the electrical and chemical performance of microbial fuel cells (MFCs) fed with several types of brewery and manure industrial wastewaters. Experiments were conducted in a single-cell MFC with the cathode exposed to air operated in batch and fed-batch modes. In fed-batch mode, after 4 days of operation, a standard MFC was refilled with crude wastewater to regenerate the biofilm and recreate initial feeding conditions. Brewery wastewater (CV1) mixed with pig-farm liquid manure (PU sample) gave the highest voltage (199.8 mV) and power density (340 mW/m3) outputs than non-mixed brewery waste water. Also, coulombic efficiency is much larger in the mixture (11%) than in the others (2-3%). However, in terms of chemical oxygen demand removal, the performance showed to be poorer (53%) for the mixed sample than in the pure brewery sample (93%). Fed-batch operation showed to be a good alternate for quasi-continuous operation, with equivalent electrical and chemical yields as compared with normal batchwise operation.

Environmental and physiological factors affecting lead and cadmium levels in deciduous teeth.

Shed deciduous teeth lead and cadmium content of children from Cartagena (Spain) was assessed. Parents were provided with an interview containing different questions concerning family socioeconomic status, child's health history, zone of residence, or home antiquity. Besides, physiological variables were considered, i.e., sex of donor, presence of caries, type of tooth donated, tooth weight, age of shedding, and position within the mouth. Tooth lead and cadmium data showed a positively skewed distribution and were log-normalized for further analyses. No statistically significant differences could be observed for lead and cadmium values according to the sex of donor. Both heavy metals decreased in content from incisors to molars and with age of shedding. The one-way analysis of variance (ANOVA) displayed both environmental and physiological risk factors contributing to high tooth lead and cadmium values. When a multifactor ANOVA was carried out, the associations between home antiquity, nail biting habit, and jaw with tooth lead levels, as well as those between zone of residence and tooth cadmium levels were found to persist. However, the only common factor for both heavy metals in the multiple analyses was the type of tooth.

Electroanalytical determination of cadmium and lead in deciduous teeth after microwave oven digestion.

A method using differential pulse anodic stripping voltammetry after microwave oven digestion was developed for the simultaneous determination of Cd(II) and Pb(II) in the deciduous teeth of children. Each tooth was weighed; deposited in a 120 mL capped Teflon vessel with 5 mL 65% nitric acid, Suprapur analytical grade; and digested in a 2-step microwave oven for 15 min. The detection limits for Cd(II) and Pb(II) in the final solution were 0.078 and 0.323 microg/L, and the quantitation limits 0.394 and 1.613 microg/L, respectively, with a linearity range of 2 microg/L for Cd(II) and 23.3 microg/L for Pb(II). The sensitivity was 2.51 nA/microg-L and 1.37 nA/microg-L, for Cd(II) and Pb(II). The main advantages of this technique are a complete and satisfactory dissolution of the tooth material with the proposed microwave oven digestion procedure, without sample pretreatments, such as drying, ashing, or powdering. The voltammetric procedure proved to be well designed because of significant goodness of fit to a linear model, and the accuracy of the method was established as compared with standard reference material. The methodology has enabled us to study Cd(II) and Pb(II) in 371 deciduous teeth from school children in Cartagena, Spain.