Water Treatment Sludge as Coagulant and Adsorbent: A Recent Review

The use of metal coagulants in water treatment generates huge amounts of sludge. Effective management to mitigate the challenges associated with the increasing amount of WTS remains a significant concern. This paper provides an overview of the beneficial reuses of water treatment sludge (WTS) as coagulant and adsorbent. Recent advancements in coagulant and adsorbent synthesizing techniques are discussed. Recovered coagulant (RC) and adsorbent have been successfully removed several pollutants in both water and wastewater, reducing the need for new coagulant production and disposal of sludge. Coagulant and adsorbent from sludge have potential to be utilized in both water and wastewater treatment processes and, hence promoting sustainability. Sulfuric acid is commonly used to recover contaminated coagulant. Calcination, activation, or impregnation have been studied in adsorbent production. Recovered coagulant/adsorbent could be as effective as or even better than fresh coagulants/adsorbent.