Wastewater treatment plants designed for the combined treatment of domestic wastewater and landfill leachate provides opportunities for the lower costs to the landfill, economic opportunities for municipalities, and resource recovery opportunities from the leachate. This work examines the combined treatment of domestic wastewater with landfill leachate at a 50/50 ratio (v/v) in 1-L sequencing batch reactors (SBRs) inoculated with activate sludge. The SBR influent had high levels of ammonia (500 ppm-N), heavy metals (2100 ppb total metals) and COD (2000 ppm), but low BOD5 (100 ppm). While BOD removal was significant (&gt; 80%), COD removal was limited (~ 20%). Heavy metals accumulated in the activated sludge (7400 ppb total metals), and at steady-state operation, became a source in the effluent, in particular Zn (3000 ppb), Cu (1000 ppb), Pb (300 ppb) and Ni (200 ppb). After amicrobial adaptation period), the SBRs successfully lowered ammonia concentrations to &lt; 5 ppm-N, albeit with slower kinetics than in the control SBR treating only domestic wastewater. Nitrite accumulated in the SBR (&lt; 400 ppm-N), indicating severe inhibition of nitrite oxidizing bacteria (NOB) by the leachate. Shortcut denitrification was achieved through methanol addition, reducing nitrite levels to &lt; 5 ppm-N. A series of batch reactor experiments were conducted to determine how various pretreatment processes could help improve the leachate treatment efficiency. Powdered activated carbon (PAC) addition successfully lowered COD by 80% and removed color from the effluent. However, PAC-treated leachate still severely inhibited NOB. NaOH pretreatment resulted in significant metal precipitation and NH3 volatilization, which resulted in the complete oxidation of ammonia to nitrate. Pretreatment with FeCl3 coagulation/flocculation resulted in a 20% decrease in COD and a significant decrease in heavy metals. Similar to NaOH pretreatment, FeCl3 pretreatment resulted in the complete oxidation of ammonia to nitrate.

Simultaneous treatment of landfill leachate and domestic wastewater: Evaluation of pretreatment methods

251st National Meeting (2016)

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