Paper Sludge Carbon as an Adsorbent for Fukushima Radiocontaminated Paddy Soil

Radiocontaminated soil in a paddy field in the Iitate village in Fukushima was treated with an industrial paper sludge carbon (PSC) prior to growing rice in May 2011. The results showed that the sum of the activity concentrations of 134Cs and 137Cs in the polished rice harvested in October 2011 was 30 Bq·kg−1, a level much lower than the Japanese governmental safeguard value of 100 Bq·kg−1. Upon contacting with the contaminated soil, the contents of calcium, magnesium, copper, potassium, and barium in the PSC were decreased. Among the PSCs impregnated with various chlorides and sulfates of the previously mentioned minerals, potassium chloride, copper sulfate, magnesium sulfate, and potassium sulfate yielded higher decontamination degrees compared to the original PSC. The results imply that radioactive cesium in the soil exchanges cations with these minerals.