Abstract
A pilot-scale two-stage process including an anaerobic pretreatment (up-flow anaerobic sludge blanket, UASB) unit and a pre-denitrification activated sludge process was studied for treating leachates from a municipal landfill (waste aged 4 to 5 years, area 2.5 ha) and from a windrow composting area (1 ha). A single-stage pilot process was used for nitrification studies. The leachate characteristics were as follows: COD 740 to 2400 mg l–1 (chemical oxygen demand), BOD7 (biochemical oxygen demand) approximately 1000 mg l–1, Ntot 40 to 120 mg l–1 and the temperature was between 2 and 21°C. The results show that 45 to 50% COD removal could be achieved in the UASB reactor even at temperatures below 10°C. The activated sludge process was operated with a 1.1 to 2.2 d hydraulic retention time and at between 8 and 21°C. The removal efficiencies were 80 to 90% for COD, over 98% for BOD7, over 90% for NH4-N and over 70% for Ntot. The dependence of denitrification efficiency on leachate biodegradable COD fraction and COD to N ratio was evaluated. Overall treatment efficiencies were good and applicable for design purposes. The total costs were estimated for a full scale pre-denitrification process at FIM 10 to 20 m−3 and FIM 50 to 90 (kg N removed)−1 (3.5 to 7 D m m–3 and 17 to 30 D m [kg N removed]–1) for a landfill representing circumstances in Southern Finland with an annual average flow of 50 m3 d–1.
Published Version
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call