Melvin Maaliw Galera

Two-step pilot-scale biofilter system for the abatement of food waste composting emission

A pilot-scale two-step biofilter system was evaluated in treating food waste composting emission for 220 days. Wood chips were packed at the bottom section while mixture of rock wool and earthworm compost (6% w/v) was packed at the top section. Inlet ammonia concentration was found to be dominant and intermittent. The overall ammonia removal of over 98% was achieved, 70% of which was removed in the wood chip section. The highest ammonia elimination capacity was determined to be 39.43 g-NH3/m3/h at 99.5% removal efficiency. From biodegradation kinetic analysis, the maximum removal rate, V m, of the wood chip section was determined to be 200 g-NH3/m3/h and the saturation constant, K s, 180 mg/m3. For the rock wool-earthworm cast mixture section, the V m was 87 g-NH3/m3/h and K s was 87 mg/m3. Complete removal of hydrogen sulfide and most trace compounds were achieved by the biofilter. Highest hydrogen sulfide elimination rate was 0.22 g-H2S/m3/h. The biofilter was optimized from 24 to 16 s EBRT with resulting low average pressure drops of 16 and 29 mm H2O/m, respectively.

Performance Evaluation of Pilot Scale Sulfur-Oxidizing Denitrification for Treatment of Metal Plating Wastewater

A full-scale and two pilot-scale upflow sulfur-oxidizing denitrification (SOD) columns were evaluated using metal plating wastewater as feed. The sludge was autotrophically enriched, and inoculated in the SOD columns attached to the effluent line of three metal plating wastewater treatment facilities. The effects of activated carbon and aeration were also studied, and found effective for the removal of suspended solids and ammonia, respectively. The results showed that the constituents, such as the total nitrogen, nitrates, nitrites, ammonia, chemical oxygen demand (COD), and heavy metals, were effectively removed. The pH was observed to be maintained at 7–8 due to the alkalinity supplied by the sulfur–calcium carbonate (SC) pellet. The denitrification efficiency and start-up period were observed to be affected by the influent quality. Chromium, iron, nickel, copper, and zinc—the major heavy metal components of the influent—were effectively reduced at certain concentrations. Other metal ions were also detected and reduced to undetectable concentrations, but no trends in the comparison with denitrification were observed. From the results it can be concluded that SOD is effective for the removal of nitrogen, particularly nitrates, without a drastic pH change, and can effectively remove minute concentrations of heavy metals and COD in metal plating wastewaters.

Removal of odorous compounds emitted from a food-waste composting facility in Korea using a pilot-scale scrubber.

ABSTRACT Monitoring and control of odorous compound emissions have been enforced by the Korean government since 2005. One of the point sources for these emissions was from food waste composting facilities. In this study, a pilot-scale scrubber installed in a composting facility was evaluated for its performance in the removal of malodorous compounds. The exhaust stream contained ammonia and methylamine as the major odorants detected by the threshold odor test and various instrumental techniques (GC-FID, FPD, MS and HPLC/UV). For the scrubber operation, the column was randomly packed with polypropylene Hi-Rex 200, while aqueous sulfuric acid was selected as the scrubbing solution. To achieve 95% removal, the scrubber must be operated by using H2SO4 solution with pH at < 6.5, liquid to gas ratio > 4.5, gas loading rate < 1750 m3/m3-hr and contact time < 0.94 s. The scrubber performance was further evaluated by determining the mass transfer coefficients and then monitoring for 355 days of operation. The pilot-scale scrubber maintained > 95% ammonia and methylamine removal efficiencies despite the fluctuations in the inlet (from composting facility exhaust stream) concentration. The optimum operating conditions and scrubber performance indicators determined in this study provides a basis for the design of a plant-scale scrubber for treatment of composting facility gas emissions.