The document summarizes research on applications of paper sludge in different fields. It discusses using paper sludge in agricultural fields to improve soil conditions, as a hydraulic barrier material in landfills, and in hydrophobic concrete. Studies found that applying paper sludge to agricultural land provided benefits like soil conditioning from organic matter, increased soil pH and addition of plant nutrients. Research also showed some types of paper sludge have properties suitable for use as low permeability barriers in landfill covers. Additionally, transforming waste paper sludge ash into a super hydrophobic powder was found to improve the water resistance of concrete.