Biological treatment of ammonia gas at high loading

Abstract

The exhaust gas from compost processing plants contains a large amount of ammonia. To treat ammonia gas at high loads, bench-scale experiments were carried out. First, nitrifying bacteria were enriched from soil and immobilized on porous ceramics. The ceramics were packed in an acrylic cylinder (diameter, 100 mm; packed height, 190 mm) and ammonia gas was introduced to the top of the cylinder. The concentration and flow rate of ammonia gas were gradually increased and finally 85 ppm was introduced at a space velocity of 800 h(-1) (empty bed residence time (EBRT), 4.5 sec). The ammonia load was 1.0 kg N/m3 day(-1). The exhaust contained 1.5-2 ppm of ammonia. Then the packed ceramics were transferred to another acrylic cylinder (diameter, 50 mm; packed height, 800 mm). A high concentration of ammonia gas (1,000 ppm) was introduced at a space velocity of 96 h(-1) (ammonia loading, 1.44 kg N/m3 day(-1); EBRT, 37.5 sec). The exhaust contained 2 ppm of ammonia (removal rate, 99.8%). The packed bed was washed with water intermittently or continuously, and the wastewater from the cylinder contained a large amount of ammonium and nitrate ions of at a 1:1 ratio. Stoichiometric analysis showed that half of the introduced ammonia was oxidized to nitrate, and the rest was converted to ammonium ion. Thus, ammonia gas was effectively treated at a high load by biofiltration with nitrifying bacteria.

The Roles of Porous Coral Sands in Initial Enrichment of Ammonia-Oxidizing Bacteria

“…The coral sands are abundant in the coastal marine environment where periphytic AOB are found. However, using porous coral sands in the enrichment of media for AOB could be problematic because the regular calcium source in the enrichment and isolation media of AOB is soluble CaCl 2 or insoluble CaCO 3 powder, and soluble CaCl 2 is used more often than insoluble CaCO 3 powder [8,9,16,19,20]. Prior studies indicated that AOB were isolated and purified easily when they were grown in the state of dispersion, so the selection of a liquid medium containing only soluble salts was more likely to occur [8].…”

“…Natural or artificial porous materials, such as ceramics, can be used as substrates for the growth of nitrifying bacteria, improving significantly their efficiency of converting ammonium-nitrogen (NH 4 + -N) to nitrite-nitrogen (NO 2 − -N) and NO 2 − -N to nitrate-nitrogen (NO 3 − -N). However, few studies have used porous materials in the initial enrichment of nitrifying bacteria [9,10]. In this study, porous coral sands containing mainly calcium carbonate (CaCO 3 ) and other chemical compounds were used to replace CaCO 3 powder, one of the commonly used calcium sources in initial enrichment media of AOB [2].…”

Responses of community structure of amoA -encoding archaea and ammonia-oxidizing bacteria in ammonia biofilter with rockwool mixtures to the gradual increases in ammonium and nitrate

“…The products of nitrification, together with the residual ammonium (NH 4 + ), therefore tend to be accumulated in the packing materials and drain water (Kanagawa et al . ; Chen et al . ; Yasuda et al .…”

“…Nitrification plays an important role in the biofiltration systems as a critical step in NH 3 removal, and NH 3 absorption is accelerated in the resultant acidity (Joshi et al 2000). The products of nitrification, together with the residual ammonium (NH 4 + ), therefore tend to be accumulated in the packing materials and drain water (Kanagawa et al 2004;Chen et al 2005;Yasuda et al 2009).…”

Gaseous Emissions from Wastewater Facilities

“…The column operating under variable conditions similar to the waste gas emission from the microelectronics fabrication processes achieved a total hydrocarbon (THC) removal efficiency in excess of 85% and a mineralization capacity of over 50%. Kanagawa et al (2004) conducted bench-scale biofiltration experiments to treat ammonia gas at high loads as a possible treatment of the exhaust gas from compost processing plants. Stoichiometric analysis showed that half of the ammonia was oxidized to nitrate, and the rest was converted to ammonium ion.…”