Abstract
In wastewater treatment systems, a pre-coagulation process increases the amount of sludge. Therefore, we examined carbonization as a material recovery method from sewage sludge.
We postulated that there would be differences between the char derived from pre-coagulated sludge and that from the sludge generated in typical wastewater treatment processes. This study investigated the effects of sludge pre-coagulated with ferric chloride on the carbonization process. We used pre-coagulated sludge and mixed sludge in a carbonization experiment and investigated the solid yield, surface area, and adsorptive capacity for hydrogen sulfide.
We found that the solid yield was higher for pre-coagulated sludge than for mixed sludge, because of the increase in iron resulting from use of the coagulating agent and the inorganic content. The surface area of the char from pre-coagulated sludge was greater than that from mixed sludge when the carbonization temperature was 700°C, because iron compounds affected the organic content. Moreover, char from pre-coagulated sludge had a greater adsorptive capacity for hydrogen sulfide than that from mixed sludge.
