Biological nutrient removal from pre-treated landfill leachate in a sequencing batch reactor.
Biological treatment of landfill leachate usually results in low nutrient removals because of high chemical oxygen demand (COD), high ammonium-N content and the presence of toxic compounds such as heavy metals. Landfill leachate with high COD content was pre-treated by coagulation-flocculation with lime followed by air stripping of ammonia at pH=12. Nutrient removal from pre-treated leachate was carried out using a lab-scale sequencing batch reactor (SBR). Three different operations consisting of different numbers of steps were tested and their performances were compared. These operations were the three-step anaerobic (An)/anoxic (Ax)/oxic (Ox); the four-step (An/Ox/Ax/Ox), and the five-step (An/Ax/Ox/Ax/Ox) operations with total residence time of seven hours each. Experiments were carried out using three consecutive operations with a total cycle time of 21 h at a constant sludge age of 10 days. The lowest effluent nutrient levels were realized by using the five-step operation which resulted in effluent COD, NH4-N and PO4-P contents of 1,400, 107 and 65 mg l(-1), respectively, at the end of 21 h. Addition of domestic wastewater (1/1, v/v) and powdered activated carbon (PAC, 1 g l(-1)) to the pre-treated leachate improved nutrient removals in the five-step SBR operation, resulting in 75% COD, 44% NH4-N and 44% PO4-P removals after 21 hours of operation.
Uygur
Ahmet
A
Department of Environmental Engineering, Dokuz Eylul University, Buca, Izmir, Turkey.
Kargi
Fikret
F
D001421:Bacteria, Anaerobic; D019149:Bioreactors; D005427:Flocculation; D009584:Nitrogen / Q000302:isolation & purification* / Q000378:metabolism*; D010100:Oxygen; D010758:Phosphorus / Q000302:isolation & purification* / Q000378:metabolism*; D012037:Refuse Disposal; D012995:Solubility; D014873:Water Pollutants / Q000302:isolation & purification* / Q000378:metabolism*
D014873:Water Pollutants; D010758:Phosphorus; D009584:Nitrogen; D010100:Oxygen