Removal of humic acid and toxic organic compounds by iron precipitation

Removal of humic acid is necessary to ensure efficient removal of many toxic organic compounds such as PCBs and chlorinated pesticides. Precipitation either as ferrous or ferric hydroxide is far more effective for removing humic acid than activated carbon adsorption and lime-soda softening processes. Many recalcitrant compounds, such as HET acid, are also removed by chemisorption on newly-formed ferric hydroxide flocs. An integrated waste treatment process consisting of iron precipitation, biodegradation, and carbon adsorption was developed for complete and efficient treatment of chemical waste landfill leachates and other highly contaminated industrial wastewaters.