Construction technique of disposable bin from sludge cake and its environmental risk.
OBJECTIVE
Now, a lot of researchers have tried to make recycled rigid materials from the sludge cake produced in paper mill industries for the purpose of decreasing its volume. In this study, the researchers tried to make economically a disposable bin and to examine whether it is toxic or not to the outside environment.


METHODS
To make a disposable bin, the researchers used the sludge cake, a plastic basket, as a fixed mold, white cloth or newspaper, as a removable supporter for wrapping around the mold, and latex or plaster, as a binder. The strength of the samples was measured by tensile-stress testing. The water absorption was evaluated by Cobb test. As toxicological tests, leaching test and seed germination test were selected.


RESULTS
It was possible to form the disposal bin from the cleaned sludge cake. They seemed safe to carry garbage in the industry judging from the results of tensile-stress testing. Some of them showed less water absorptiveness (higher water resistance) in the results of Cobb test. The results of leaching test showed small values of three heavy metals, lead, nickel and copper, in the leachate. The seed germination test suggested no adverse effects of the bins in the clay and sand on the tomato growth.


CONCLUSIONS
The results of these tests suggest that the bins have good strength, sufficient water resistance and no toxicological effect on the environment. This new recycled bin has the possibility to solve the environmental and health problems at disposing the sludge cake.
Department of Sanitary Engineering, Faculty of Public Health, Mahidol University, Bangkok, Thailand.
Udomsak
U
Kongmuang
Duangta
D
Kiykaew
Ikuharu
I
Morioka
D060389:Construction Industry; D003252:Construction Materials / Q000592:standards; D004209:Disposable Equipment / Q000592:standards; D004781:Environmental Exposure; D006801:Humans; D019216:Metals, Heavy; D010209:Paper; D059027:Recycling / Q000379:methods*; D018570:Risk Assessment; D012722:Sewage / Q000032:analysis; D013785:Thailand; D014874:Water Pollutants, Chemical / Q000032:analysis
D019216:Metals, Heavy; D012722:Sewage; D014874:Water Pollutants, Chemical