Abstract
Field experiments were conducted to investigate the restoration effects of biological environment in reduced sludge under the use of alkaline material. The sewage-derived sludge that accumulated on seafloor was collected and used in the experiments. To restore the biological environment, an alkaline material that mainly comprised of SiO2, Al2O3, CaO was used. The restoration effects were investigated through analyses of soil properties in cases of with/without the alkaline material. It was found that the biological environment of reduced sludge was restored by the use of the alkaline material; namely, macrobenthos are able to inhabit in the sludge within the alkaline material. The results also ensured that dissolution of the alkaline material removed electrons and protons that accumulated during the biodegration of organic matter in sludge. Therefore, COD and hydrogen sulfide declined, leading to the enhancement of biological environment restoration.
