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241.
Effects of biofilter media depth and moisture content on removal of gases from a swine barn 总被引:1,自引:0,他引:1
Tongshuai Liu Zhiping Zhu Bin Shang Fubin Yin Wanqin Zhang 《Journal of the Air & Waste Management Association (1995)》2017,67(12):1288-1297
Media depth (MD) and moisture content (MC) are two important factors that greatly influence biofilter performance. The purpose of this study was to investigate the combined effect of MC and MD on removing ammonia (NH3), hydrogen sulfide (H2S), and nitrous oxide (N2O) from swine barns. Biofiltration performance of different MDs and MCs in combination based on a mixed medium of wood chips and compost was monitored. A 3 × 3 factorial design was adopted, which included three levels of the two factors (MC: 45%, 55%, and 67% [wet basis]; MD: 0.17, 0.33, and 0.50 m). Results indicated that high MC and MD could improve NH3 removal efficiency, but increase outlet N2O concentration. When MC was 67%, the average NH3 removal efficiency of three MDs (0.17, 0.33, and, 0.50 m) ranged from 77.4% to 78.7%; the range of average H2S removal efficiency dropped from 68.1–90.0% (1–34 days of the test period) to 36.8–63.7% (35–58 days of the test period); and the average outlet N2O concentration increased by 25.5–60.1%. When MC was 55%, the average removal efficiency of NH3, H2S, and N2O for treatment with 0.33 m MD was 72.8 ± 5.9%, 70.9 ± 13.3%, and –18.9 ± 8.1%, respectively; and the average removal efficiency of NH3, H2S, and N2O for treatment with 0.50 m MD was 77.7 ± 4.2%, 65.8 ± 13.7%, and –24.5 ±12.1%, respectively. When MC was 45%, the highest average NH3 reduction efficiency among three MDs was 60.7% for 0.5 m MD, and the average N2O removal efficiency for three MDs ranged from –18.8% to –12.7%. In addition, the pressure drop of 0.33 m MD was significantly lower than that of 0.50 m MD (p < 0.05). To obtain high mitigation of NH3 and H2S and avoid elevated emission of N2O and large pressure drop, 0.33 m MD at 55% MC is recommended.
Implications: The performances of biofilters with three different media depths (0.17, 0.33, and 0.50 m) and three different media moisture contents (45%, 55%, and 67% [wet basis]) were compared to remove gases from a swine barn. Using wood chips and compost mixture as the biofilters media, the combination of 0.33 m media depth and 55% media moisture content is recommended to obtain good reduction of NH3 and H2S, and to simultaneously prevent elevated emission of N2O and large pressure drop across the media. 相似文献
242.
243.
Ping Li Xinbin Feng Guangle Qiu Lihai Shang Guanghui Li 《Environmental geochemistry and health》2009,31(6):683-691
The total mercury (T-Hg) and methyl mercury (Me-Hg) concentrations in the hair were measured to evaluate mercury (Hg) exposure
for the residents in Da-shui-xi Village (DSX) and Xia-chang-xi Village (XCX) in the Wanshan Hg mining area, Guizhou Province,
Southwestern China. The mean concentrations in the hair of DSX residents were 5.5 ± 2.7 μg/g and 1.9 ± 0.9 μg/g for T-Hg and
Me-Hg, respectively. The concentrations in the hair of XCX residents were 3.3 ± 1.4 μg/g and 1.2 ± 0.5 μg/g for T-Hg and Me-Hg,
respectively. Hair Me-Hg concentrations were significantly correlated to T-Hg (r = 0.42, P < 0.01) in the two sites; on average, hair Me-Hg concentration accounted for 40 and 44% of T-Hg for DSX and XCX residents,
respectively. Age has no obvious correlation with hair Hg and the hair Hg levels showed a significant gender difference, with
higher T-Hg and Me-Hg concentrations in the hair from males than females. The rice collected from the two sites showed high
levels of T-Hg and Me-Hg concentration. The results indicated a certain Hg exposure for the residents in DSX and XCX in the
Wanshan Hg mining area. 相似文献
244.
245.
H. Vandenhove G. Olyslaegers N. Sanzharova O. Shubina E. Reed Z. Shang H. Velasco 《Journal of environmental radioactivity》2009
There is increasing interest in radiological assessment of discharges of naturally occurring radionuclides into the terrestrial environment. Such assessments require parameter values for the pathways considered in predictive models. An important pathway for human exposure is via ingestion of food crops and animal products. One of the key parameters in environmental assessment is therefore the soil-to-plant transfer factor to food and fodder crops. The objective of this study was to compile data, based on an extensive literature survey, concerning soil-to-plant transfer factors for uranium, thorium, radium, lead, and polonium. Transfer factor estimates were presented for major crop groups (Cereals, Leafy vegetables, Non-leafy vegetables, Root crops, Tubers, Fruits, Herbs, Pastures/grasses, Fodder), and also for some compartments within crop groups. Transfer factors were also calculated per soil group, as defined by their texture and organic matter content (Sand, Loam, Clay and Organic), and evaluation of transfer factors' dependency on specific soil characteristics was performed following regression analysis. The derived estimates were compared with estimates currently in use. 相似文献
246.
Youguo Gong Min Hu Yafang Cheng Hang Su Dingli Yue Feng Liu A. Wiedensohler Zhibin Wang H. Kalesse Shang Liu Zhijun Wu Kaitao Xiao Puchun Mi Yuanhang Zhang 《Atmospheric environment (Oxford, England : 1994)》2010,44(27):3278-3285
The coagulation sink and its role in new particle formation are investigated based on data obtained during the PRIDE-PRD2004 campaign at Xinken of Pearl River Delta, China. Analysis of size distributions and mode contributions of the coagulation sink show that the observed higher load of accumulation mode particles impose a significant effect on the coagulation sink and result in higher coagulation sinks at Xinken despite of the lower total particle number compared with other areas. Hence it is concluded that the higher coagulation sink may depress the occurrence frequency of new particle formation events. The strategies targeting at controlling accumulation mode particles may have influences on the frequency of new particle formation events at this area. The factors affecting the coagulation sink are evaluated. The relatively lower ambient relative humidities may weaken the coagulation sink and facilitate the occurrence of new particle formation events during noontime, while the surmise of nucleation and growth involving organic matter may imply an actually higher coagulation sink than expected. These factors have a significant influence on the ultimate fate of the newly formed nuclei and new particle formation. A comparison of event and non-event days indicates that the coagulation sink is not the only decisive factor affecting new particle formation, other factors including the precursor vapors and photochemical activity are none the less important either. Competition of coagulation sink and high source rate leads to the occurrence of new particle formation events at Xinken. 相似文献
247.
1,1-二氯乙烯降解菌的分离鉴定及降解特性 总被引:2,自引:1,他引:1
从好氧活性污泥中分离得到一株能以1,1-二氯乙烯(1,1-DCE)作为惟一碳源和能源生长的革兰氏阴性菌株D-B,经鉴定属于产碱杆菌属(Alcaligenessp.)。当维持菌株D-B浓度一定时,1,1-DCE的去除率随着1,1-DCE浓度的增大先增加后降低,且降解过程主要发生在加入1,1-DCE后的3~5 h内。当1,1-DCE的初始浓度为300μg/L时去除率达到最大值85.32%。菌株D-B对1,1-DCE的降解符合Monod方程,饱和常数Ks=21.96 mg/L,1,1-DCE的最大比基质降解速率Vmax=50.76 mg/(L.h)。 相似文献
248.
Shang G Shen G Wang T Chen Q 《Journal of the Air & Waste Management Association (1995)》2012,62(8):873-879
The characteristics and mechanisms of hydrogen sulfide (H2S) adsorption on a biochar through pyrolysis at various temperatures (100 to 500 degrees C) were investigated. The biochar used in the current study was derived from the camphor tree (Cinnamomum camphora). The samples were ground and sieved to produceparticle sizes of 0.4 mm to 1.25 mm, 0.3 mm to 0.4 mm, and <0.3 mm. The H2S breakthrough capacity was measured using a laboratory-designed test. The surface properties of the biochar were characterized using pH and Fourier-transform infrared spectroscopy (FTIR) analysis. The results obtained demonstrate that all camphor-derived biochars were effective in H2S sorption. Certain threshold ranges ofthepyrolysis temperature and surfacepH were observed, which, when exceeded, have dramatic effects on the H2S adsorption capacity. The sorption capacity ranged from 1.2 mg/g to 121.4 mg/g. The biochar with 0.3 mm to 0.4 mm particle size possesses a maximum sorption capacity at 400 degrees C. The pH and FTIR analysis results showed that carboxylic and hydroxide radical groups were responsible for H2S sorption. These observations will be helpful in designing biochar as engineered sorbents for the removal of H2S. 相似文献
249.
改性蛭石结合鸟粪石沉淀法回收垃圾渗滤液中氨氮的实验研究 总被引:2,自引:0,他引:2
研究了使用氯化镁改性蛭石,利用磷酸铵镁沉淀的原理,在垃圾渗滤液中按比例加入PO43-,处理垃圾渗滤液中氨氮的同时,在蛭石上生成磷酸铵镁沉淀,以便于磷酸铵镁沉淀的回收利用。结果表明,筛取蛭石粒径为60~80目,配制浓度20%的氯化镁溶液浸泡改性蛭石20 min,取25 g改性蛭石,100 mL垃圾渗滤液调节pH为9,按n(NH4+)∶n(PO34-)=1∶1.2的比例加入PO43-离子,垃圾渗滤液中氨氮去除率为85.06%,实验并对磷酸铵镁沉淀进行了结构成分分析,为垃圾渗滤液中氨氮的处理及磷酸铵镁沉淀的回收提供了一种新的方法。 相似文献
250.
The Horqin sandy rangeland of northern China is a seriously desertified region with a fragile ecology. The sandy alluvial and aeolian sediments have a coarse texture and loose structure and are therefore vulnerable to damage caused by grazing animals and wind erosion. We investigated whether grazing exclusion could enhance ecosystem carbon (C) and nitrogen (N) storage and thereby improve overall soil quality. We compared soil properties, C and N storage in biomass (aboveground and below-ground), and the total and light fraction soil organic matter between adjacent areas with continuous grazing and a 12-year grazing exclosure. The soil silt?+?clay content, organic C, total Kjeldahl N, available N and K, and cation-exchange capacity were significantly (P?0.05) greater in the exclosure. We found that to a depth of 100?cm, the exclosure plots had greater light fraction C storage (by 267.2?g?m(-2)?=?73.3?%), light fraction N storage (by 16.6?g?m(-2)?=?105.7?%), total soil C storage (by 1174.4?g?m(-2)?=?43.9?%), and total N storage (by 91.1?g?m(-2)?=?31.3?%). Biomass C and N storage were also 205.0 and 8.0?g?m(-2) greater (154.8 and 181.8?%, respectively). The increase was greatest in the light fraction organic matter and biomass and decreased with increasing depth in the soil. The results suggest that light fraction C and N respond more rapidly than total soil C and N to grazing exclusion and that vegetation recovers faster than soil. Our results confirmed that the degraded sandy rangeland is recovering and sequestering C after the removal of grazing pressure. 相似文献