Wood chips and wheat straw as alternative biofilter media for denitrification reactors treating aquaculture and other wastewaters with high nitrate concentrations

This study evaluated wood chips and wheat straw as inexpensive and readily available alternatives to more expensive plastic media for denitrification processes in treating aquaculture wastewaters or other high nitrate waters. Nine 3.8-L laboratory scale reactors (40 cm packed height × 10 cm diameter) were used to compare the performance of wood chips, wheat straw, and Kaldnes plastic media in the removal of nitrate from synthetic aquaculture wastewater. These upflow bioreactors were loaded at a constant flow rate and three influent NO₃–N concentrations of 50, 120, and 200 mg/L each for at least 4 weeks, in sequence. These experiments showed that both wood chips and wheat straw produced comparable denitrification rates to the Kaldnes plastic media. As much as 99% of nitrate was removed from the wastewater of 200 mg NO₃–N/L influent concentration. Pseudo-steady state denitrification rates for 200 mg NO₃–N/L influent concentrations averaged (1360 ± 40) g N/(m³ d) for wood chips, (1360 ± 80) g N/(m³ d) for wheat straw, and (1330 ± 70) g N/(m³ d) for Kaldnes media. These values were not the maximum potential of the reactors as nitrate profiles up through the reactors indicated that nitrate reductions in the lower half of the reactors were more than double the averages for the whole reactor. COD consumption per unit of NO₃–N removed was highest with the Kaldnes media (3.41–3.95) compared to wood chips (3.34–3.64) and wheat straw (3.26–3.46). Effluent ammonia concentrations were near zero while nitrites were around 2.0 mg NO₂–N/L for all reactor types and loading rates. During the denitrification process, alkalinity and pH increased while the oxidation–reduction potential decreased with nitrate removal.

Wood chips and wheat straw lost 16.2% and 37.7% of their masses, respectively, during the 140-day experiment. There were signs of physical degradation that included discoloration and structural transformation. The carbon to nitrogen ratio of the media also decreased. Both wood chips and wheat straw can be used as filter media for biological denitrification, but time limitations for the life of both materials must be considered.     

Fungal growth on a common wood substrate across a tropical elevation gradient: Temperature sensitivity, community composition, and potential for above-ground decomposition

Fungal breakdown of plant material rich in lignin and cellulose (i.e. lignocellulose) is of central importance to terrestrial carbon (C) cycling due to the abundance of lignocellulose above and below-ground. Fungal growth on lignocellulose is particularly influential in tropical forests, as woody debris and plant litter contain between 50% and 75% lignocellulose by weight, and can account for 20% of the C stored in these ecosystems. In this study, we evaluated factors affecting fungal growth on a common wood substrate along a wet tropical elevation gradient in the Peruvian Andes. We had three objectives: 1) to determine the temperature sensitivity of fungal growth - i.e. Q₁₀, the factor by which fungal biomass increases given a 10 °C temperature increase; 2) to assess the potential for above-ground fungal colonization and growth on lignocellulose in a wet tropical forest; and 3) to characterize the community composition of fungal wood decomposers across the elevation gradient. We found that fungal growth had a Q₁₀ of 3.93 (95% CI of 2.76-5.61), indicating that fungal biomass accumulation on the wood substrate nearly quadrupled with a 10 °C increase in temperature. The Q₁₀ for fungal growth on wood at our site is higher than Q₁₀ values reported for litter decomposition in other tropical forests. Moreover, we found that above-ground fungal growth on the wood substrate ranged between 37% and 50% of that measured in the soil, suggesting above-ground breakdown of lignocellulose represents an unexplored component of the C cycle in wet tropical forests. Fungal community composition also changed significantly along the elevation gradient, and Ascomycota were the dominant wood decomposers at all elevations. Fungal richness did not change significantly with elevation, directly contrasting with diversity patterns observed for plant and animal taxa across this gradient. Significant variation in fungal community composition across the gradient suggests that the characteristics of fungal decomposer communities are, directly or indirectly, influenced by temperature.     

木材采运环节中木材检验的控制

本论述了木材采运环节中，木材检验的过程以及检验质量的控制方法和经验，做到木材检量准确无误。     

断裂力学在木材学中的应用

本文介绍断裂力学基本概念及其在木材科学中的应用，应力强度因子的测试方法和计算方法以及国内外木材断裂力学的研究现状。     

不同药剂预防白蚁蛀蚀木材的效果测定

室内采用河砂木块法研究了 15种药剂对白蚁的防治效果 ,48%毒死蜱、5 %锐劲特、48%毒死蜱 + 10 %安绿宝、2 5 %辛硫·灭扫利、5 %锐劲特 + 76 9%樟脑油、10 %安绿宝等 6种药剂 (或混配剂 )抗白蚁蛀蚀效果显著优于氯丹。野外试验了15种药剂 ,2 2个月后的结果表明 :48%毒死蜱单独使用或与 76 9%松节油等混配使用 ,可以保持木材近 2a仍不受白蚁蛀蚀 ;5 %锐劲特、2 5 %辛硫·灭扫利等药剂单独使用或与巴丹等混配使用 ,其效果也优于 70 %氯丹     

遂川天然林乔木树种间关联分析与测定

通过专题调查遂川县天然林的树种分布，研究得出在天然林中的乔木树种分布络局及种间关联度，为人工更新、人工林近自然经营提供理论指导与决策支持。     

杨木及其刨花板炭化制取木酢液的比较研究

[目的]探求回收利用废旧刨花板的方法。[方法]采用电加热炭化炉对杨木刨花板及杨木加热炭化,比较杨木刨花板和杨木在炭化热解过程中产物收率以及物理化学性质。[结果]由于受原料形态及刨花板中脲醛树脂胶的影响,杨木刨花板酢液的收率低于杨木酢液,pH高于杨木酢液。GC/MS成分分析结果表明,杨木刨花板酢液中存在较多含氮成分。[结论]杨木刨花板酢液中含有丰富的含氮物质,在农林生产中可以作为氮肥促进植物生长。     

Coarse woody debris in late-successional Picea abies forests in northern Europe: Variability in quantities and models of decay class dynamics

Coarse woody debris pools and their decay class dynamics were studied in three areas of unmanaged boreal forest in northern Finland, and in the Murmansk and Arkhangelsk provinces in northwestern Russia. The study areas had varying climatic and edaphic conditions, and disturbance histories. Living and dead trees (diameter at 1.3 m height ≥10 cm) were measured in five late-successional Picea abies-dominated stands in each of the three areas. Wood density and time since death were determined from randomly sampled dead P. abies, and their decay class dynamics were modeled using stage-based matrix models.     

工程质量综合评价方法

针对工程质量评价的问题进行了探讨，并应用模糊数学的理论的提出了工程质量的综合评价方法。     

PLC在木材防腐设备机组中的应用

本文讨论了ＰＬＣ在满细胞法和频压法中的应用情况，说明了ＰＬＣ与快开门安全联锁的关系，阐述了推广ＰＬＣ控制的木材防腐设备机组的意义。