Sludge is the solid, semisolid, or slurry residual material that is produced as a by-product of wastewater treatment processes. This residue is commonly classified as primary and secondary sludge.

Treatment and disposal of sewage sludge are major factors in the operation of all wastewater treatment plants. Two basic goals of treating sludge before final disposal are to reduce its volume and to stabilize the organic materials. OMEX offer a range of aluminium and ferrous salts to improve the coagulation of fine suspended solids in wastewater treatment plants. The Alumex range offers specialised combinations of inorganic aluminium salt-based coagulants to improve sludge settlement and to coagulate suspended solids.