A thesis submitted in partial fulfillment of the requirements for the degree of Master of Engineering, School of Environment, Resources and Development

Thesis (M.Eng.) - Asian Institute of Technology, 2006

This study investigates the nitrogen removal performance of a two stage Upflow Floating Filter system (in series with recycle from aerobic stage to anoxic stage) for digested piggery waste based on nitritation-denitritation processes. The system was operated continuously for 120 days, without external carbon source for denitritation and without backwashing. As such, treatment of digested Piggery waste becomes possible with a maximum overall removal efficiency of 77% for Total Kjeldahl Nitrogen (TKN), 74% for ammonia nitrogen (NH3-N), and 60% for Total Nitrogen (TN), when running with influent concentration of 1346mg/L COD, 257mg/L TKN and 180mg/L NH3-N, with a total hydraulic retention time (HRT) l lh, dissolved oxygen (DO) concentration 1.0-1.5mg/L in aerobic stage, and recycle rate 1:1 from aerobic stage to anoxic stage. Fluorescence in situ hybridization (FISH) and Polymerase Chain Reaction (PCR) were performed to study the microbial community in anaerobic reactor. FISH analysis shown that the dominant microbial in anaerobic reactor were methanogens (Archae) - 16%, other microorganisms included bacteria: a- ,B- and y-proteobacteria which comprised 13, 5 and 14% of total bacteria, respectively. PCR analysis for the microbial community of the anaerobic reactor has shown that DGGE fingerprints of total bacterial 16S rDNA have significantly changed after one month (6th to 37th day) of operation. Between 68th day and 86th day samples suggests an insignificant shift or a relatively stable structure of the microbial community after 2-2.5 months of the UA3FF system operation