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451.
几种污水处理厂氨气排放因子测试方法比较 总被引:2,自引:0,他引:2
选用4种方法测试污水处理厂的沉砂池、初沉池、曝气池、二沉池工艺段的氨气浓度、污水指标和氨气排放因子,结果表明:氨气排放浓度与污水中氨氮浓度及总氮浓度有较好的线性关系,氨气很大程度上来自水中氨氮或总氮的转化;其中挥发速率模型法现场实测获得的氨气排放因子最高,为0.919 g/m3。 相似文献
452.
453.
高氨垃圾渗滤液的吹脱条件控制研究 总被引:4,自引:0,他引:4
采用吹脱塔处理含有高浓度氨氮的垃圾渗滤液,研究了操作参数的控制对吹脱效率的影响.结果表明,当pH≤11.0时,气水比决定了高径比对吹脱效率的影响,气水比较低时,高径比越小,吹脱效率越高;气水比较高时,高径比越大,吹脱效率越高;当pH过高时,高径比对吹脱效率没有影响.初始pH和温度相互影响,pH越低时,温度对吹脱效率的影响越显著;温度越低时,初始pH对吹脱效率的影响越显著.当pH≥10.4时,出水pH和残余氨氮浓度呈指数关系,可以作为反应吹脱运行状况的指示参数或控制参数.合理控制pH和气水比并实时监控出水pH是获得稳定、经济的吹脱效果的关键. 相似文献
454.
455.
Goal, Scope and Background Marine cage aquaculture produces a large amount of waste that is released directly into the environment. To effectively manage
the mariculture environment, it is important to determine the carrying capacity of an aquaculture area. In many Asian countries
trash fish is dominantly used in marine cage aquaculture, which contains more water than pellet feed. The traditional nutrient
loading analysis is for pellet feed not for trash fish feed. So, a more critical analysis is necessary in trash fish feed
culturing areas.
Methods Corresponding to FCR (feed conversion rate), dry feed conversion rate (DFCR) was used to analyze the nutrient loadings from
marine cage aquaculture where trash fish is used. Based on the hydrodynamic model and the mass transport model in Xiangshan
Harbor, the relationship between the water quality and the waste discharged from cage aquaculture has been determined. The
environmental carrying capacity of the aquaculture sea area was calculated by applying the models noted above.
Results Nitrogen and phosphorus are the water quality parameters considered in this study. The simulated results show that the maximum
nitrogen and phosphorus concentrations were 0.216 mg/L and 0.039 mg/L, respectively. In most of the sea area, the nutrient
concentrations were higher than the water quality standard. The calculated environmental carrying capacity of nitrogen and
phosphorus in Xiangshan Harbor were 1,107.37 t/yr and 134.35 t/yr, respectively. The waste generated from cage culturing in
2000 has already exceeded the environmental carrying capacity.
Discussion Unconsumed feed has been identified as the most important origin of all pollutants in cage culturing systems. It suggests
the importance of increasing the feed utilization and improving the feed composition on the basis of nutrient requirement.
For the sustainable development of the aquaculture industry, it is an effective management measure to keep the stocking density
and pollution loadings below the environmental carrying capacity.
Conclusions The DFCR-based nutrient loadings analysis indicates, in trash fish feed culturing areas, that it is more critical and has
been proved to be a valuable loading calculation method. The modeling approach for Xiangshan Harbor presented in this paper
is a cost-effective method for assessing the environmental impact and determining the capacity. Carrying capacity information
can give scientific suggestions for the sustainable management of aquaculture environments.
Recommendations and Perspectives It has been proved that numerical models were convenient tools to predict the environmental carrying capacity. The development
of models coupled with dynamic and aquaculture ecology is a requirement of further research. Such models can also be useful
in monitoring the ecological impacts caused by mariculture activities.
ESS-Submission Editor: Hailong Wang (hailong.wang@ensisjv.com) 相似文献
456.
Ammonia removal from pretreated methane fermentation effluent through a soil trench system: a column experiment 总被引:1,自引:0,他引:1
In order to find the optimal running conditions and mechanisms of ammonia removal through a soil trench system that is designed for treating pretreated methane fermentation effluent, a soil column whose structure was similar to the soil trench system was prepared, and irrigated with wastewater below 30 °C. At the beginning, ammonia was mainly adsorbed by the soils, and the ammonia adsorption capacity of soils gradually saturated. After the 12th day, nitrification began in the soil column; the ammonia in the soil column decreased sharply, and the nitrite and nitrate peak appeared sequentially as the wastewater application rate decreased from 0.74 to 0.37 l h−1. When the nitrification in the soil column reached a steady-state, 98% of all the ammonia in the influent was transformed into nitrate.
By changing the running conditions such as temperature, aeration, and wastewater application rate, it was found that the ammonia removal efficiency can be improved by aeration and impeded by low temperature. In these three variables, wastewater application rate has much greater affect on the ammonia removal efficiency; a lower wastewater application rate can increase the ammonia removal efficiency substantially because of the longer travel time. 相似文献
457.
ABSTRACTNitrogen (N) application is the main agricultural management that increases nitrous oxide (N2O) concentration in the atmosphere. Freezing conditions are common phenomenon in the northern China that significantly affect soil N2O emissions through alterations in nutrients availability and microbial population. To develop a comprehensive understanding of how N fertilizer managements affect soil N2O emissions during the freezing process, a lab incubation was conducted in three typical cultivated soils (black soil, fluvo-aquic soil, or loess soil) by adding different N fertilizer sources, including ammonium chloride, sodium nitrate, or urea at different N levels (0, 80, 200, or 500 mg N/kg) at the start of freezing. The N2O emissions in the fluvo-aquic soil were significantly higher than in other soils. The application of nitrate in the fluvo-aquic soil promoted N2O emissions by five- and seven-fold higher compared to ammonium chloride and urea, whereas N2O emissions in black soil were enhanced by application of ammonium chloride. Data indicate that denitrification is the major pathway for N2O production in the fluvo-aquic soil during the freezing process, while ammonia oxidation responses accounts for elevated N2O production in black soil. No significant influence of N fertilizer levels on N2O emissions were found during soil freezing. These results suggest that agricultural practices that focus on mitigation of N2O emissions need to avoid selection of nitrate as N fertilizer source in fluvo-aquic soil prior to the freezing season. Future studies need to focus on how the expression of enzymes and/or shifts in microbial communities respond to different N fertilizers during freezing conditions. 相似文献
458.
Madhavaraj Lavanya Ho-Dong Lim Kong-Min Kim Dae-Hyuk Kim Balasubramani Ravindran Gui Hwan Han 《Frontiers of Environmental Science & Engineering》2020,14(3):53
459.
Xiaofeng Liao Shuangyan Zhu Delai Zhong Jingping Zhu Li Liao 《Waste management (New York, N.Y.)》2014,34(11):2278-2284
In order to investigate the effect of raw leachate on anaerobic digestion of food waste, co-digestions of food waste with raw leachate were carried out. A series of single-phase batch mesophilic (35 ± 1 °C) anaerobic digestions were performed at a food waste concentration of 41.8 g VS/L. The results showed that inhibition of biogas production by volatile fatty acids (VFA) occurred without raw leachate addition. A certain amount of raw leachate in the reactors effectively relieved acidic inhibition caused by VFA accumulation, and the system maintained stable with methane yield of 369–466 mL/g VS. Total ammonia nitrogen introduced into the digestion systems with initial 2000–3000 mgNH4–N/L not only replenished nitrogen for bacterial growth, but also formed a buffer system with VFA to maintain a delicate biochemical balance between the acidogenic and methanogenic microorganisms. UV spectroscopy and fluorescence excitation–emission matrix spectroscopy data showed that food waste was completely degraded.We concluded that using raw leachate for supplement water addition and pH modifier on anaerobic digestion of food waste was effective. An appropriate fraction of leachate could stimulate methanogenic activity and enhance biogas production. 相似文献
460.
为了解光合细菌的产氢机理,对沼泽红假单胞光合产氢菌CQK-01在光生物平板反应器中进行序批次培养,以470 nm LED灯提供连续光照,葡萄糖为碳源底物,研究不同初始酸碱条件下产氢光合细菌的生长特性、产氢特性以及能量转化效率.结果表明,在弱碱性条件下最适宜产氢光合细菌的生长;在反应液为酸性条件下,光合细菌具有较高的产氢量、产氢速率和能量转化效率,然而产氢纯度随着初始pH值的增大而升高;在温度30℃、光照强度1 000lx、底物浓度75 mmol/L的实验条件下,光合细菌的最佳产氢pH值为7.0,实验中最大累积产氢量为8.0 mmol,最大产氢速率为3.39 mmol g-1(cell dry weight)h-1,产氢纯度高达70%,底物能量转化效率最大为1.98%,光能转化效率最大为7.7%. 相似文献