Summer 2004, Volume 1 - Number2 (5 صفحه - از 103 تا 107)
In this research, physical, chemical and biological treatability of Tehran solid waste leachate was studied.Results indicate that the amount of COD for the fresh raw leachate of Tehran is equal to 66,608 mg/l. Theleachate is transferred to an equalization tank for storage and pH control process. After neutralization, leachate isintroduced to an up flow and down flow anaerobic reactor. The effluent of anaerobic reactor is conducted to asequencing batch reactor. Sequence batch reactor (SBR) effluent was pumped in to sand and activated carbonfilters, after chemical coagulation and clarification. Results showed that anaerobic reactor with detention time of3 days had a 35% COD removal and increasing the detention time to 4.5 days would improve the COD removal to 45%. Nutrient adjustment with phosphorus and nitrogen increased the initial 23% efficiency of sequence batchreactor to 44%. The effluent COD of SBR reactor was 21,309 mg/l. Recycling of aerobic reactor effluent withincoming feed to anaerobic reactor reduced the anaerobic reactor influent COD to 20,000 mg/l and this caused53% and 57% COD removal in the anaerobic and aerobic effluent, respectively. The total systems CODperformance increased to 80% and SBR effluent COD eventually reduced to 4,000 mg/l. Coagulation,flocculation and sedimentation processes were practiced to make the 4,000 mg/l effluent COD comply with environmental standards of Iran. The optimum coagulant found to be ferric chloride with the dosage of 50 mg/lat pH of 12, which reduced 10% of COD to an amount of 3,676 mg/l. The effluent was stored in a tank and thenpumped in to pressure sand filter and afterwards to activated carbon filter. The COD removal was three and 90%for sand and activated carbon filters, respectively. The total process reduced the remaining COD to 36 mg/l,which is in compliance with environmental standards of Iran.
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