title: Potential use of sludge cake from paper mill wastewater treatment as degradable flower pot.
abstract: OBJECTIVE
  Sludge cake produced in paper mill industries is disposed into a landfill and may cause the environmental and health problems. Now many researchers have tried to recycle rigid materials from it for the purpose of decreasing its volume. The aims of this study were to clarify three hypotheses: (1) whether a flower pot would be economically made from sludge cake, (2) whether it would be safe for environment, and (3) when vegetables would grow enough in it, whether they would be safe for human consumption.
  
  
  METHODS
  Sludge cake was mixed with soil (soil texture: heavy clay). The circular plaster mold was used as a fixed mold. As the toxicological testing, leaching test and seed germination test were used. Heavy metal concentrations in vegetables grown in the flower pot were measured.
  
  
  RESULTS
  The flower pot was sufficiently formed by drying in natural open air. The results of leaching test showed three heavy metals, lead, nickel and copper, were lower than the standard in Thailand. The seed germination test suggested no negative effects of the flower pot on the germination of Chinese kale. Lead concentrations in the Chinese kale were higher than the recommended maximum level in leafy vegetables.
  
  
  CONCLUSIONS
  The new flower pot can be made from sludge cake with soil. It has the possibility to have no negative effect on the environment. Although the vegetables grown in this flower pot are not suitable to eat, this flower pot has the possibility to solve the environmental and health problems.
authors.affiliation: Faculty of Public Health, Bangkokthonburi University, Bangkok, Thailand.
authors.forename: Udomsak
authors.initials: U
authors.lastname: Kongmuang
authors.affiliation: Faculty of Dentistry, Mahidol University, Bangkok, Thailand.
authors.forename: Hathaitip
authors.initials: H
authors.lastname: Sritanaudomchai
authors.affiliation: Graduate School of Health and Nursing Science, Wakayama Medical University, Mikazura 580, Wakayama, 641-0011, Japan. moriokai@wakayama-med.ac.jp.
authors.forename: Ikuharu
authors.initials: I
authors.lastname: Morioka
mesh_terms: D004785:Environmental Pollutants / Q000032:analysis; D035264:Flowers; D007220:Industrial Waste / Q000032:analysis*; D019216:Metals, Heavy / Q000032:analysis; D010209:Paper; D059027:Recycling; D012722:Sewage / Q000032:analysis*; D013785:Thailand; D014675:Vegetables / Q000737:chemistry* / Q000254:growth & development*
chemical_list: D004785:Environmental Pollutants; D007220:Industrial Waste; D019216:Metals, Heavy; D012722:Sewage
keywords: Edible use; Flower pot; Lead; Paper mill; Sludge cake