Study of lead, mercury, cadmium and arsenic contents in rubbish manures obtained from phetchaburi municipality, Changwat Phetchaburi
1993
Taweesit Isaradej
Analysis of lead, mercury, cadmium and arsenic contents in rubbish manure of Phetchaburi Municipality was conducted, using composting agents in the experiment which lasted 3 months, from November 1992 to February 1993. There were 5 treatments each of which was made in 3 replicates. Treatment A was for non-sorted rubbish left to decompose naturally, Treatment B for sorted rubbish spread over with composting agents, Treatment C for sorted rubbish mixed with composting agents, Treatment D for non-sorted rubbish spread over with composting agents. Samples was collected 4 times, first on the starting day of composting, then collected once a month, 15 samples at a time. It was found that average contents of lead, mercury and cadmium in the rubbish manure were 51.817, 0.362 and 0.899 mg/kg, respectively, which were even lower than the standard limit on rubbish manure in West Germany (150, 3.2 and 2.5 mg/kg, respectively) while the average arsenic content was 3.824 mg/kg, which was lower than those average contents found in the soil all over the world (8.7 mg/kg). The heavy metal contents in all the composting techniques were not significantly different. So any technique may be chosen for large-scale manure production, depending on the nature and components of the rubbish, investment cost and output. However, there should be public relations campaings to gain people's cooperation in separating rubbish before disposal with a view to more efficient management of rubbish.
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