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| Solidification and Stabilization of Petrochemical Flocculation Effluent (Sludge) after Treatment with Activated Carbon |
Amgbara, Tamunokuro O. , Ayotamuno, Miebaka J., Uche, Chikadibia K.A.
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Abstract:
Petrochemical flocculation effluent (sludge), pose serious environmental and health risks in its use, storage, transportation and disposal. A brief exposure to this effluent has been associated with adverse effects such as: birth defects, nervous disorders, cancer and even fatalities. The objective of this study is solidification and stabilization of Petrochemical flocculation effluent after treatment with activated carbon. Characterization of petrochemical flocculation effluent shows concentrations of toxic substances as follows: Arsenic (0.005 mg/l), Barium (7mg/l), Cadmium (0.023mg/l), Chromium (0.162 mg/l), Lead (0.18 mg/l) Mercury (0.98 mg/l), Selenium (0.12 mg/l, Silver (0.04 mg/l) and Zinc (2.9 mg/l). The sludge was mixed with activated carbon and allowed to stand for sixty minutes as a treatment procedure. Characterization of the treated sludge was carried out and the concentrations of the toxic substances were ascertained and then used as a baseline for further treatment. The treated sludge was solidified and stabilized by mixing with Portland cement in the ratio of 1:4 (that is 20 percent of cement to 80 percent of pre-treated sludge). Characterization was carried out on the samples after 7, 14 and 28 days curing time, respectively. pH as a characteristic feature of toxicity of a substance was also determined at the various intervals of characterization. The solidified and stabilized treated sludge showed concentrations of: Arsenic (0.03mg/l), Barium (4mg/l), Cadmium (0.017mg/l), Lead (0.06mg/l), Mercury (0.30 mg/l), Selenium (0.09mg/l), Silver (0.02 mg/l) and Zinc (1.5 mg/l). The reduction in the concentration of the toxic substances was determined as the ratio of the final concentration to the initial concentration presented in percentage values as follows: Arsenic (< 66.67%), Barium (45.25%), Cadmium (62.94%), Chromium (7.86%), Lead (96.67%), Mercury (30%), Selenium (88.89%), Silver (< 95%) and Zinc (76.67%). These met the permissible limits of the Department of Petroleum Resources standards 2002 [which is the regulatory standard for Petroleum or hydrocarbon related waste in Nigeria] and the International Statutory requirements for remediation of toxic substances with exception of mercury.
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