Toxicity assessment of the extract of compost as a final product from Bio-Toilet

Bio-Toilet is the name of a dry closet or composting toilet using sawdust as an artificial soil matrix for bioconversion of human excrement into compost. Since feces and urine contain several chemicals such as pharmaceutical residues and endocrine disruptors and they may still remain in compost afte...

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Bibliographic Details
Published in:	Water science and technology Vol. 54; no. 11-12; pp. 421 - 428
Main Authors:	Kakimolo, T, Imai, Y, Funamizu, N, Takakuwa, T, Kunimoto, M
Format:	Journal Article
Language:	English
Published:	England IWA Publishing 01-01-2006
Subjects:	Agricultural land Assaying Bioaccumulation Bioconversion Biological effects Composting Composts Endocrine disruptors Equipment Design Faeces Feces Feces - chemistry Groundwater Groundwater pollution Humans Hydrogen-Ion Concentration Inorganic Chemicals - isolation & purification Inorganic Chemicals - toxicity Inorganic matter Japan Low level Molecular weight Organic Chemicals - isolation & purification Organic Chemicals - toxicity Organic matter Sawdust Sodium Sodium - analysis Sodium chloride Soil Soil - analysis Soil pollution Soils Toilet Facilities Toilets Toxicity Ultrafiltration Urine Viability Water - analysis Water pollution Weight Japan
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Summary:	Bio-Toilet is the name of a dry closet or composting toilet using sawdust as an artificial soil matrix for bioconversion of human excrement into compost. Since feces and urine contain several chemicals such as pharmaceutical residues and endocrine disruptors and they may still remain in compost after biological reaction in the Bio-Toilet, it is required to examine the possibility of soil and/or groundwater pollution by applying compost to a soil system in farmland. In this study, toxicity of Bio-Toilet compost was evaluated by measuring the viability of human neuroblast (NB-1). The bio-assay was applied to the water extract of compost from the Bio-Toilets which are in practical use in Japan. The assay results showed that (1) the extract of feces showed no toxicity, and the extracts of unused sawdust had no or low level toxicity and (2) the extracts of composts had heavier toxicity than unused sawdust. These results implied that some chemicals that have toxicity were generated by biological reactions or accumulated in toilet system. The bioassay results with fractionated organic matter by its molecular weight showed that the small molecular weight fraction had stronger toxicity than other fractions. The effect of inorganic matter on toxicity was examined by comparing the dose-response relationship of the extracts of compost with positive control with 1M of sodium chloride solution. The comparison showed that sodium concentration in the extract was too low to develop the toxicity and the effect of inorganic matter could be neglected in this study.
Bibliography:	ObjectType-Article-2 SourceType-Scholarly Journals-1 ObjectType-Feature-1 content type line 23 ObjectType-Conference-1 ObjectType-Feature-3 ObjectType-Article-1 ObjectType-Feature-2
ISBN:	184339586X 9781843395867
ISSN:	0273-1223 1996-9732
DOI:	10.2166/wst.2006.922