SCR脱硝系统氨需量计算的优化

随着国家环保标准的不断提高,SCR烟气脱硝技术因其技术成熟、脱硝效率高将会得到更为广泛的应用。以上海外高桥第二发电厂脱硝工程为例,介绍了SCR脱硝技术的原理和工艺流程,并针对SCR脱硝系统氨需量的计算控制不合理的部分提出优化方案,使氨需量的计算更趋合理,SCR脱硝控制系统稳定性增强。

超低排放下SCR脱硝喷氨控制策略的探讨

针对涿州热电氮氧化物超低排放的标准,以及喷氨控制系统中存在的问题,包括被控对象的大迟延特性,CEMS自动反吹和校准对调节的影响,煤量变化对脱硝入口NOx的影响,探讨产生问题的原因,提出了以理论计算氨需量为基础的脱硝喷氨控制策略,初步取得了良好的效果。

Study on Piggery Anaerobic Fermentation Slurry Treated by Anoxic/Oxic Process

[Objective] The aim of this study was to provide a fast, stable and efficient piggery wastewater processing technology. [Method] The start-up process was studied through the experiment of piggery anaerobic fermentation slurry treated by Anoxic/Oxic （A/O） reactor. The process was divided into two stages： at the first stage, dominant micro flora were cultivated in Anoxic and Oxic reaction tanks respectively; at the second stage. Anoxic and Oxic reaction tanks were initiated jointly to gradually enhance water load and continued to cultivate and domesticate microorganisms, and finally the start-up process was completed. [ Result] The results showed that return mixture ratio and return sludge ratio was 2 and 1 respectively when the temperature reached 32 ±2 ℃. However. when aeration rate of Oxic reaction amounted to 0.5 m^3/h, the re- moval rate of COD and NH4^＋ -H were 89.87% and 89.31% respectively through practical operation within 50 days, which indicated that the start- up process through A/O reactor was successful. Conclusion This study can provide a scientific basis and reference for innocuous technique of piggery anaerobic fermentation slurry treatment.

Seasonal biochemical changes in composition of body wall tissues of sea cucumber Apostichopus japonicus

Seasonal variation in proximate, amino acid and fatty acid composition of the body wall of sea cucumber Apostichopus japonicus was evaluated. The proximate composition, except for ash content, changed significantly among seasons （P〈0.05）. Alanine, glycine, glutamic acid and asparagic acid were the most abundant amino acids. Total amino acid and essential amino acid contents both varied clearly with seasons （P〈0.05）. 16：0 and 16：1n7 were the primary saturated fatty acid （SFA） and monounsaturated fatty acid （MUFA） respectively for all months. EPA （20：5n-3）, AA （20：4n-6） and DHA （22：6n-3） were the major polyunsaturated fatty acids （PUFA）. The proportions of SFA and PUFA yielded significant seasonal variations （P〈0.001）, but MUFA did not changed significantly. The results indicated that the biochemical compositions of the body wall in A. japonieus were significantly influenced by seasons and that the body wall tissue is an excellent source of protein, MUFA and n-3 PUFA for humans.

Comparative study of the nutritional composition and toxic elements of farmed and wild Chanodichthys mongolicus

Information of the difference in quality between farmed and wild fish is central to better ensuring fish products produced in aquaculture meet regulatory and consumer requirements. Proximate composition, amino acid and fatty acid profiles, and toxic elements contents of fanned and wild Chanodichthys mongolicus were established and compared. Significantly higher crude protein content while lower moisture content in farmed fish compared to wild fish were observed （P〈0.05）. The percentages of total amino acids （TAA）, total essential amino acids （TEAA）, total non-essential amino acids （TNEAA） and total delicious amino acids （TDAA） in farmed fish were all significantly higher than those in the wild equivalent （P〈0.05）. Compared to the FAO/WHO recommended reference values, the ratios of TEAA/ TAA （39.84%o-40.33%） were comparable to 40% and TEAA / TNEAA （66.22%-67.60%） were above 60%. Fatty acid profiles in both farmed and wild C. mongolicus were dominated by monounsaturated fatty acid （MUFA）, with farmed fish contained much more MUFA content compared to wild counterpart （P〈0.05）. Notably, wild fish exhibited significantly higher levels of total polyunsaturated fatty acid （PUFA） including eicosapentaenoic acid （EPA） and docosahexaenoic acid （DHA） than fanned fish （P〈0.05）. The EPA （C20：503） and linoleic acid （C18：206） were the predominant PUFA in wild and farmed C. mongolicus, respectively. Moreover, farmed fish displayed an overall lower toxic element levels （As, Cd, Pb and Hg） in comparison with wild fish, and both were far lower than the established limit standard. In conclusion, our results suggest that the nutritional quality of fanned C. mongolicus was inferior to their wild counterpart with respect to fatty acids nutrition, and therefore further studies should focus on the improving C. mongolicus diet in order to enhance the overall nutritional composition.

Effect of germination on the nutritional quality of Pearl millet

Changes in proximate composition, trypsin inhibitor activity, phytic acid, tannins, in vitro protein digestibility and amino acids content of Pearl millet were investigated after germination for 5 days. Germination significantly increased protein content of pearl millet, with a parallel decrease in lipid and carbohydrates. Trypsin inhibitor activity and the phytic acid content showed significant decrease whereas tannin content increased after 5 days germination. In vitro protein digestibility （IVPD） was significantly decreased with germination, suggesting that tannins may be responsible for enzymes inhibition. Amino acid analysis revealed significant increase in essential amino acids and none essential amino acids.

Body composition and compensatory growth in Nile tilapia Oreochromis niloticus under different feeding intervals

We investigated the growth and body composition of Nile tilapia under five different feeding regimes. A control group was fed to satiation twice daily for 185 days; four treatment groups were fed at intervals of 2, 3, 4 or 7 days(dietary ‘restricted' period, days 0–80) and then fed to satiation(‘refeeding' period, days 80–185). Compensatory growth in weight and length of the feed-restricted groups was observed during the refeeding period. However, the growth of none of the restricted groups caught up with that of the control group over the experimental period. Feed intake upon refeeding increased with the duration of deprivation. There were no significant differences in feed efficiency between the restricted and control groups during the refeeding stage, suggesting that hyperphagia was the mechanism responsible for the increased growth rates during this period. Tilapia preferentially used n-3 polyunsaturated fatty acids and nonessential amino acids during the restricted-feeding period. Higher production was achieved by higher feed consumption. We suggest that if attainment of market size in minimum time is required, fish should be consistently fed to satiation, while taking care to avoid the possible negative consequences of overfeeding.

The Role of Formed Microorganism in Sludge on Processing of Wastewater Treatment

Several microorganisms such as bacteria, fungi, Protozoa, Rotifera, cystic amoeba and algae diagnosed in activated sludge aerobic （Rustumiya treatment plant） and anaerobic reactor. Results have shown a reduction in the turbidity rates when using activated sludge at Rustumiya plant of 76.3 to 2.653 NTU in pre-treatment and final tank respectively, also COD （chemical oxygen demand） amount reduced from 427.263 to 82 mg/L respectively, In addition, concentrations of phosphates and nitrates decreased from 12.083 to 8.426 mg/L and 3.59 to 2.43 mg/L respectively, by removing 30.2% and 32.3% respectively of the final tank. The ratio of ammonia removing was 89.6% for ammonia, reducing process from 1358 to 140 mg/L. Furthermore, sulfates concentration decreased from 30.883 to 23.337 mg/L. However, the system in the anaerobic reactor depends on non-aerated activated sludge. Results show turbidity reduced from 12.5 to 2 NTU in pre-treatment and final tank respectively, also the COD mount reduced from 191 to 130 mg/L, the percentage removal of 31.9%. In addition phosphates, nitrates and sulfates concentrations were decreased by using activated sludge from 17.15 to 8.15, 1.2 to 0.1 and 28 to 9.2 mg/L respectively. The ammonia concentration has reduced from 1.2 to 0. i mg/L where at a removal percentage of 90.9%.