Ferric coagulant recovered from coagulation sludge and its recycle in chemically enhanced primary treatment

摘要

An investigation was conducted to study the feasibility of ferric coagulant recovery from chemicalnsludge and its recycle in chemically enhanced primary treatment (CEPT) to make the processnmore cost-effective, as well as reduce sludge volume. The optimum conditions and efficiencynof the acidification for ferric coagulant recovery from coagulation sludge were investigated.nExperimental results showed that the recovered coagulants can be used in CEPT and thenpollutants removal efficiency is similar to that of fresh coagulant, and for some aspects the effectnof recovered coagulants is better than that of fresh ones, such as turbidity removal. Althoughnsome substances will be enriched during recycle, they have little effect on treated wastewaternquality. Acidification condition also had significant influence on reduction of sludge volume.nThe efficiency of coagulant recovery had a linear relationship with sludge reduction. Experimentsnverify that it would be a sustainable and cost-effective way to recover ferric coagulant fromncoagulation sludge in water treatment and chemical wastewater treatment, and then recyclenit to CEPT, as well as reduce sludge volume.