Anaerobic digestion of residual municipal solid waste using biological-mechanical pre-treatment: the plant of Varennes Jarcy.

Residual municipal solid waste can be treated by anaerobic digestion after a sorting process in order to remove the unwanted materials. After a mechanical sorting the quality of the final compost can hardly cope with requirements for agriculture use. In this way, a more efficient sorting process using a specific equipment that provides a combined biological and mechanical effect, has been implemented on the plant of Varennes Jarcy prior to anaerobic digestion. This paper presents the main results obtained on this plant. The reduction of biodegradable organics in particle lower than 10 mm allows a very efficient separation by screening. An additional ballistic sorting removes the remaining glass. The composition of the resulting sorted waste was close to a source-sorted organic fraction. The sorted waste exhibit methane yields comparable with raw biodegradable organics, showing that the pre-treatment had little impact on anaerobic digestion performance.

Determinant impact of waste collection and composition on anaerobic digestion performance: industrial results.

The performance of the anaerobic digestion process depends deeply on the quality of the waste to be treated. This has been already demonstrated at the lab-scale. The objective of this study is to confirm this result at the industrial scale, with very long representative period and with the same process, the Valorga process. According to the waste quality and the collection type and even with the same conditions of fermentation, the biogas yield can vary by a factor of 1.5 when it is expressed (under normal conditions of pressure and temperature) in m3 biogas/t fresh waste, and by a factor of 2 when it is expressed in m3 CH4/t volatile solids. So, the biogas performance does not characterise a process since it is deeply governed by waste composition. This biogas productivity becomes a pertinent parameter only with consistent and relevant hypothesis and/or analytical results on the waste composition which depends on the collection procedure, the site characteristics and the season.

Reduction in phosalone residue levels during industrial dehydration of apples.

Dehydrated fruits and vegetables, which may well be used in baby foods, must be of excellent bacteriological quality with an absence of contamination. In order to define the effects of the industrial dehydration process, according to the 'Hatmacker' drying method, on an organophosphorus pesticide, we have studied phosalone in Golden Delicious apples as an example. The technological process undertaken leads to a reduction in phosalone levels on the apples of more than 80%, whatever the initial dose between 0 and 4.29 micrograms/kg. Washing brings about a reduction of 30-50%, probably by the dissolution of the phosalone in the water. The cooking and especially the filtration of the puréed apple mechanically eliminates, without notable deterioration, 40-70% of the phosalone. However, drying, which takes place at the end of the process, does not lead to significant variations in phosalone levels. Consequently, the reduction in phosalone residue levels in dehydrated apple products manufactured by this process provides the consumer with a greater degree of security with respect to this contaminant. In addition, we have presented several possibilities to add to the quality of dehydrated products.

Discrimination between five oral frusemide preparations using renal chloride excretion and frusemide recovery.

The bioavailabilities of five preparations of frusemide (an aqueous solution, Diurin, Frusid, Lasix and Selemide tablets) were studied in healthy subjects, using Latin square designs and administering doses at weekly intervals. Relative to the solution, Lasix had reduced chloride excretion (0.88) and frusemide recovery (0.80) while Diurin and Frusid had reduced frusemide recoveries (0.90 and 0.92 respectively) There were no other significant differences. Potassium excretion tended to fall as the trials progressed.