The Use of Okra as a Coagulant and Coagulant Aids in the Removal of Heavy Metals of Solid Waste Leachates

Abstract

Coagulation-Flocculation processes play an important role in the treatment of waterand wastewater. Aluminum sulfate (alum) and polyelectrolyte (polymer) are thecommon chemical coagulants which are used in this process. The produced leachate inwaste disposal places is considered to be one of the highly contaminated resourcesfrom the physical, chemical, and biological point of view.In Sulaimaniah, Tanjaro was found to be one of those solid waste landfill areas.Okra is used for the treatment of raw leachate samples that obtained directly fromSulaimaniah – Iraq solid waste sanitary landfill area. Fresh solid waste samples of theleachates were taken and tested for their heavy metals concentrations contents. It wasfound that the leachate contains a high amount of heavy metals of cadmium,chromium, copper, nickel, and zinc. By using conventional coagulants of alum,polymer and natural indigenous okra (as a primary coagulant or in combination withthe other two primary coagulants) and by the jar testing, the best concentrations and pHvalues of the coagulants were determined. Analyzing the results, it was found that theoptimal pH values were 6.65, 9.00 and 7.00 for alum, polymer and okra, respectively.In addition, the best dose of alum was1400 mg/L in which a removal of heavy metalsyielded 45-80 %, while the best dose of polymer was 500 mg/L in which a removal of70-95% was achieved. For okra, the best dose was 500 mg/L in which a removal ofheavy metals yielded 20-100%. It was found that okra has an efficient coagulationpower with respect to alum and polymer in removing heavy metals elements in solidwaste leachates.

Keywords

• coagulation
• natural coagulants
• solid waste leachate
• okra
• heavy metals