7. THẢO LUẬNDuring the experimental processes in both Asian areas, certain problems appeared due to weather conditions, quantity and composition of raw material, as well as the lack of previous experience in composting process. Collaboration between EU and Asian researchers resulted to an exchange of knowledge and experience on various SWM issues and on composting in particular. During the experimental phases, two were the main issues to be addressed; the quantity and composition of the raw material, as well as their retention time. The first issue was solved by adding green waste and by avoid using soil, which was traditionally added during composting. Leaves and used tissue paper were added in the input material in order to prevent plastic lining of the sanitary napkins from sticking on to the blades of the shredder and to improve the composting process by attaining the appropriate C/N values. All three experiments showed that sanitary napkins should be shredded prior to composting and that the use of rotating drums with either Tricho or no added microorganisms was the most efficient solution. Retention time was suggested to be increased, since it was determined on the field (both at the test sites, as well as on other facilities especially in Metro Manilla) to be initially very limited. This ‘hurriness’ to prematurely terminate the composting process –out of good will and often enthusiasm of course, but to the wrong result- is been practised widely in Asian areas as on-site visits showed. During and between the experiments, a number of neighbourhood composting facilities in Metro Manila were visited and examined by the research group, consisting of both Asian and EU experts. At these facilities, source separated organic MSW was mixed mostly with saw dust and introduced into elevated rotating drums for composting. However, a low-product quality was observed (rather ‘enriched saw dust’ instead of compost), which was attributed to low residence time, as the operators were in a hurry to take out the compost in order to produce more. Unfortunately, in this way, most of the material did not go through the final screen and was dumped.
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