Abstract
Phytoremediation being a low cost treatment system has been attempted to mitigate effluent from a specific pharmaceutical
industry manufacturing sodium oxalate. The effluent being too high in organic content (COD≈91264 mg/l) is chemically
treated first with calcium oxide (CaO), so that organics in the wastewater contributing high COD forms salts and
precipitates out. The optimum dosing of calcium oxide is found to be 2g/100 ml of the raw sample. COD reduction through
chemical treatment is found to be approximately 19.35%. The chemically treated effluent having COD value 73,600 mg/l is
subjected to anaerobic biological treatment and the COD value comes down to 12800 mg/l after 29 days. The fact that the
plant species simply die, if they come in touch with this raw wastewater sample signifying excessive toxic effect of the
ingredients of the wastewater to the plant, necessitates dilution of the anaerobically treated effluent 40 and 80 times by
mixing municipal wastewater with it in the ratio 1:39 and 1:79 respectively, These dilutions are selected after some trial
experiments ensuring sustenance of the aquatic macrophytes (Pistia stratiotes) meant for phytoremediation study, which
has been conducted for 10 days. The plant sustains and grows in the test samples (both dilutions). The quantities of
biomass at the beginning are 29.26g and 31.31g in 40 times and 80 times diluted test samples respectively and after 10
days the biomass have increased to 60.62g and 58.10 g respectively in the two dilutions. So it is examined that even in 40
times dilution (COD≈600 mg/l), the plant can survive and helps removal of organics (81.61%) after 10 days of
phytoremediation, after which the plant starts decaying gradually. Hence this experiment cannot be continued beyond 10
days. The COD value still remains close to 100 mg/l, which needs further polishing before disposal.