Suchergebnisse

ABSTRACTYokohama city has developed facilities to dry and granulate digested sludge, and has been producing and selling sludge fertilizer since 1977. Concurrently, investigations have been carried out on the continuous use of sludge fertilizer with respect to its nutrient value and the influence of heavy metals.Four types of fertilizer and eight types of crop were used in the test. The nutrient values and other aspects were compared statistically for assessment.It was found that (a) sludge fertilizer had the same nutrient value as organic fertilizer, (b) there was minimal transfer of heavy metals from sludge to crops, and (c) sludge fertilizer could be used continuously over a long period.