Kiyonori Haga

Patterns and quantities of NH3, N2O and CH4 emissions during swine manure composting without forced aeration: effect of compost pile scale

To evaluate the NH(3), N(2)O, and CH(4) emissions from composting of livestock waste without forced aeration in turned piles, and to investigate the possible relationship between the scale of the compost pile and gas emission rates, we conducted swine manure composting experiments in parallel on small- and large-scale compost piles. Continuous measurements of gas emissions during composting were carried out using a chamber system, and detailed gas emission patterns were obtained. The total amount of each gas emission was computed from the amount of ventilation and gas concentration. NH(3) emission was observed in the early period of composting when the material was at a high temperature. Sharp peaks in CH(4) emission occurred immediately after swine manure was piled up, although a high emissions level continued after the first turning only in the large-scale pile. N(2)O emissions started around the middle stage of the composting period when NH(3) emissions and the temperature of the compost material began to decline. The emission rates of each gas in the small and large piles were 112.8 and 127.4 g NH(3)-N/kg T-N, 37.2 and 46.5 g N(2)O-N/kg T-N, and 1.0 and 1.9 g CH(4)/kg OM, respectively. It was found that changing the piling scale of the compost material was a major factor in gas emission rates.

Removal of nitrogen and phosphorus from swine wastewater by the activated sludge units with the intermittent aeration process

Abstract Nitrogen and phosphorus removal in fill-and-draw type activated sludge units with an intermittent aeration process (IAP) was evaluated with typical wastewater from swine housing (total N/BOD5 ratios were 0.18, 0.31 and 0.45), in comparison with a non-limited aeration process (a conventional process, NLAP), under 0.50 kg m−3 d−1 BOD loading for each unit in bench scale. Operational conditions for the units were the same except for the aeration program; in the NLAP, a conventional consecutive aeration for 21 h was adopted, whereas in the IAP, aeration was intermittent and aeration and non-aeration periods were alternated at intervals of 1.0 h (IAP-1.0) or 3.5 h (IAP-3.5). When the units were high in MLSS concentrations, high removal efficiencies (89.0–99.5%) for BOD and TOC were attained with both IAP and NLAP in all runs. While, large differences in the removal of nitrogen and phosphorus between IAP and NLAP were observed; at influent N/BOD5 of 0.18, removal efficiencies for total nitrogen in IAP-1.0 and NLAP were 96.9 and 58.6%, and for total phosphorus were 80.8 and 47.8%, respectively. However, those removal efficiencies decreased with the increase in the N/BOD5 ratio of wastewater charged. Removal efficiencies for total nitrogen in IAP-1.0 was 72.2%, even at influent N/BOD5 of 0.45. Thus, high removal efficiencies for organic substances, nitrogen and phosphorus in swine wastewater were simultaneously obtained by IAPs. By adopting an adequate aeration program for individual swine wastewater treatment, this system will provide a promising means for nitrogen and phosphorus control without pH control, divided change of wastewater or addition of methanol.

Isolation of Thermophilic Ammonium-tolerant Bacterium and Its Application to Reduce Ammonia Emission during Composting of Animal Wastes

A thermophilic bacterium, strain TAT105, was isolated from compost made of animal wastes. TAT105 had high tolerance to ammonium nitrogen up to 1200 mM, and highly assimilated nitrogen during the growth on swine feces. The strain was classified into Bacillus, close to Bacillus pallidus. To evaluate the effect of adding TAT105 to ammonia (NH3) emission during the composting process of animal wastes, laboratory scale composting was done. NH3 emission tended to be lower and nitrogen loss was smaller in the TAT105-added material than in the control material to which TAT105 was not added. Thermophilic ammonium-tolerant bacteria in the TAT105-added material increased to about 8×109 CFU/g of dry matter on the average during the tests, and most of them were judged to be TAT105 from morphological colony discrimination. These results suggested the possibility of reducing NH3 emission from composting of animal wastes by adding TAT105.

Enhancement of the thermophilic stage in cattle waste composting by addition of tofu residue

The microbial degradation and temperature rise during the composting of a cattle waste and rice straw mixture blended with tofu (soybean curd) residue was investigated using an insulated and unheated in-vessel composter (effective volume, 12 1) and a static pile with passive aeration. The addition of 11% (dry weight basis) of tofu residue shortened the time required for temperature to reach the thermophilic phase and increased the duration of the temperatures above 55 degrees C significantly, but the maximum temperature was not affected by the additive level. As shown by the change in BOD, most of the easily biodegradable matter in the tofu residue was consumed during 12 days of composting. The same results were observed in the temperature profile of the static pile with passive aeration. Tofu residue addition yielded a higher maximum temperature and a nearly two times longer duration of temperatures above 55 degrees C in almost all locations of the pile. The use of tofu residue as a co-composting material would promote thermophilic degradation throughout the entire composting mass.