多孔填料特性对生物膜形成影响

多孔填料是曝气生物滤池(BAF)的重要构成部分,是影响BAF污水处理效果的关键.目前填料种类繁多,但其表面理化特性对生物膜形成的影响规律并不清楚,如何比选最佳生物填料一直是BAF工程应用的难题.通过研究BAF常用的几种多孔生物填料本身的物化特性,考察其物化特性与填料上生物膜的生物附着量及酶活性之间的相关性.结果表明,海绵填料虽然易吸附污泥,但是易堵塞,整体生物膜活性不高;立体空心填料虽然表面吸附的生物量较低,但是比表面积大,表面附着生长的生物膜活性较强;陶粒因具有良好的亲水性和较高的表面粗糙度,且Zeta电位最正,易于微生物附着生长,污泥附着性能最强,且生物膜活性最好.通过冗余分析(RDA)分析可知,影响填料表面生物量的主要因素是Zeta电位;影响填料表面污泥活性的主要因素是空隙率.通过6组反应器对NH~+_4-N的去除负荷可知,陶粒对NH~+_4-N的去除负荷最大,为68 g·(m~3·d)~(-1),火山岩次之,为67 g·(m~3·d)~(-1).综合上述因素比选出,陶粒最适合作为BAF的填料.     

Integrated assessment of biochemical responses in Mediterranean crab (Carcinus maenas) collected from Monastir Bay, Tunisia

The biochemical response of Mediteranean Crab (Carcinus maenas) collected at five stations of Monastir Bay and from Kuriat station as control was studied using a set of complementary biomarkers. The catalase, glutathione S-transferase, lactate dehydrogenase, acetycholinesterase activities; and metallothionein and malonediladehyde levels in gills were evaluated. Results revealed differences among sites in relation to each specific biomarker. Hence, a suite of biomarkers can be used to discriminate sampling sites according to types of pollution, reflecting differing conditions of anthropogenic impact. Based on Integrated Biomarker Response, the highest values and critical biochemical alteration were observed at Khniss and Ksibat in response to urban and industrial discharges and the lowest IBR value was found at reference site. The current study has shown clearly that a biomarker-based index is usefulness tool in the monitoring Tunisian coast using C. maenas as sentinel specie. Further studies in progress to investigate the seasonal variations of IBR levels and its relationship to pollutants concentrations in the sediment, gills and digestive gland of Carcinus maenas from Monastir Bay.     

Influence of lactic acid on the two-phase anaerobic digestion of kitchen wastes

To evaluate the influence of lactic acid on the methanogenesis, anaerobic digestion of kitchen wastes was firstly conducted in a two-phase anaerobic digestion process, and performance of two digesters fed with lactic acid and glucose was subsequently compared. The results showed that the lactic acid was the main fermentation products of hydrolysis-acidification stage in the two-phase anaerobic digestion process for kitchen wastes. The lactic acid concentration constituted approximately 50% of the chemical oxygen demand （COD） concentration in the hydrolysis-acidification liquid. The maximum organic loading rate was lower in the digester fed with lactic acid than that fed with glucose. Volatile fatty acids （VFAs） and COD removal were deteriorated in the methanogenic reactor fed with lactic acid compared to that fed with glucose. The specific methanogenic activity （SMA） declined to 0.343 g COD/（gVSS-d） when the COD loading were designated as 18.8 g/（L-d） in the digester fed with lactic acid. The propionic acid accumulation occurred due to the high concentration of lactic acid fed. It could be concluded that avoiding the presence of the lactic acid is necessary in the hydrolysis-acidification process for the improvement of the two-phase anaerobic digestion process of kitchen wastes.     

不同阴离子在生物质发酵产氢中的作用研究

为揭示不同阴离子在生物质发酵产氢中的作用规律,以混合菌群发酵产氢为研究对象,采用正交试验设计的方法考察了6种不同的阴离子及添加尿素对发酵产氢过程的影响.通过对不同阴离子浓度及相互关系对发酵产氢的影响的综合比较,获得以下结论:促进混合菌群发酵产氢的阴离子组成为:SO42-1.5 g·L-1,Cl-0 g·L-1,NO3-0 g·L-1,Mo7O246-0.1 g·L-1,C2O42- 1g·L-1,C6H5O73- 5g·L-1,(H2N)2CO 0 g·L-1;以PDB(马铃薯水解液)为基质发酵原料,H2最高含量和平均含量分别比对照组提高了21.4%和24.1%;平均产氢速率由对照组的36.79 mL·L-1·h-1提高到96.25 mL·L-1·h-1;氢气产率由对照组的0.76 mol·mol-1提高到1.17 mol·mol-1.研究同时证明,尿素对H2的产生具有显著的抑制作用,Mo7O246-则可促进混合微生物对原料的利用和转化;阴离子C2O42-和C6H5O73-的交互作用显著,说明两者同时使用可改善发酵产氢.从理论上对上述结果进行了分析探讨.     

Effect of high-strength ammonia nitrogen acclimation on sludge activity in sequencing batch reactor

The effect of high-strength ammonia nitrogen acclimation on sludge activity in sequencing batch reactor (SBR) was investigated. Two batch experiments, RUN1 and RUN2, were conducted with the influent ammonia nitrogen concentrations 60 and 500 mg/L, respectively. The sludges inoculated from RUN1 and RUN2 were used to treat a series of influent with ammonia nitrogen concentrations of 59, 232, 368, 604 and 1152 mg/L. It is found that the activated sludge acclimated to higher ammonia nitrogen concentrations revealed higher COD and NH4 +-N removal efficiencies, and slower DHA decrease. The results confirmed that the activities of the bacteria in activated sludge in SBR were inhibited by high-strength ammonia nitrogen, whereas the activated sludge acclimated to high-strength ammonia nitrogen showed substantial resistance to inhibition by influents containing high levels of ammonia nitrogen.     

耕作措施对华北夏玉米田土壤温度和酶活性的影响

为探讨长期耕作措施下华北平原夏玉米生长季土壤温度与酶活性的变化规律,本研究对四种耕作处理（免耕秸秆还田NTS,旋耕秸秆还田RTS,翻耕秸秆还田CTS和翻耕秸秆不还田CT）下土壤层次的温度和酶活性进行了测定和分析。结果表明：同一土壤层次的各耕作处理均从6：00．18：00呈现正弦波的变化特征;免耕、旋耕等保护性耕作处理在玉米的生育期内温度变化平稳,日均差均小于翻耕秸秆还田和翻耕秸秆不还田;免耕秸秆还田处理土壤酶活性最高,脲酶活性在夏玉米的3个生育期（播种期、大喇叭口期和收获期）分别高于翻耕秸秆不还田处理28．98％,35．62％和24．9％,碱性磷酸酶分别高32．7％,11．94％和10．39％,脱氢酶分别高27．53％,20．39％和30．53％,旋耕和翻耕秸秆还田处理3种酶的活性也明显高于翻耕秸秆不还田处理;旋耕与翻耕秸秆还田处理脲酶和碱性磷酸酶的差异不显著,脱氢酶的差异达到了5％的差异显著水平;通过研究表明在华北平原采用少免耕为主的保护性耕作措施,可以提高土壤酶活性,降低成本,提高经济效益。     

Effect of illumination on the hydrogen-production capability of anaerobic activated sludge

To investigate the influence of illumination on the fermentative hydrogen production system, the hydrogen production efficiencies of two kinds of anaerobic activated sludge (floc and granule) from an anaerobic baffled reactor were detected under visible light, dark and light-dark, respectively. The 10 mL floc sludge or granular sludge was respectively inoculated to 100 mL diluted molasses (chemical oxygen demand of 8000 mg·L^-1) in a 250 mL serum bottle, and cultured for 24 h at 37°C under different illumination conditions. The results showed that the floc was more sensitive to illumination than the granule. A hydrogen yield of 19.8 mL was obtained in the dark with a specific hydrogen production rate of 3.52 mol·kg^-1MLVSS·d^-1 (floc), which was the highest among the three illumination conditions. Under dark condition, the hydrogen yield of floc sludge reached the highest with the specific hydrogen production rate of 3.52 mol·kg^-1MLVSS·d^-1, and under light-dark, light, the specific hydrogen production rate was 3.11 and 2.21 mol·kg^-1MLVSS·d^-1, respectively. The results demonstrated that the illumination may affect the dehydrogenase activity of sludge as well as the activity of hydrogen-producing acetogens and then impact hydrogen production capacity.     

食物垃圾开放式乳酸发酵的实验研究

利用食物垃圾发酵生产乳酸,是实现其资源化的有效途径之一.底物不灭菌的开放式发酵,是一种简单、有效的利用食物垃圾生产乳酸的方式.通过对发酵过程中ρ(乳酸),ρ(总糖),ρ(可溶性糖)以及细菌数量变化的研究,对开放式发酵的机理进行了分析.结果表明:食物垃圾适于作为乳酸发酵的底物,在不投加任何营养物质的条件下,能促进乳酸菌的大量增殖.采用开放式发酵,可从食物垃圾产生36.29 g/L的乳酸,远高于封闭式发酵(底物灭菌).垃圾中土著菌群在开放式发酵中起到了分解复杂多糖和为乳酸菌提供可发酵性底物的作用,从而提高ρ(乳酸).      

Ecotoxicological effect of zinc oxide nanoparticles on soil microorganisms

The widespread production and use of zinc oxide nanoparticles (ZnO-NPs) in recent years have posed potential threat to the ecosystem. This study aimed to investigate the ecotoxicological effect of ZnO-NPs on soil microorganisms using laboratory microcosm test. Respiration, ammonification, dehydrogenase (DH) activity, and fluorescent diacetate hydrolase (FDAH) activity were used as ecotoxicological parameters. The results showed that in the neutral soil treated with 1 mg ZnO-NPs per g soil (fresh, neutral), ammonification was significantly inhibited during the study period of three months, but the inhibition rate decreased over increasing time. Inhibition in respiration was observed in the first month of the test. In various ZnO-NPs treatments (1 mg, 5 mg, and 10 mg ZnO-NPs per g soil), DH activity and FDAH activity were inhibited during the study period of one month. For both enzyme activities, there were positive dose–response relationships between the concentration of ZnO-NPs and the inhibition rates, but the curves changed over time due to changes of ZnO-NPs toxicity. Soil type affected the toxicity of ZnO-NPs in soil. The toxicity was highest in the acid soil, followed by the neutral soil. The toxicity was relatively low in the alkaline soil. The toxicity was not accounted for by the Zn²⁺ released from the ZnO-NPs. Direct interaction of ZnO-NPs with biologic targets might be one of the reasons. The adverse effect of ZnO-NPs on soil microorganisms in neutral and acid soils is worthy of attention.     

Dehydrogenase activity as an indicator of different microbial responses to pesticide-treated soils

A laboratory study was conducted to assess the impacts of diazinon, linuron or a fungicidal preparation of mancozeb supplemented with dimethomorph on dehydrogenase activity (DHA) in loamy sand (LS) and sandy loam (SL) soils with different features. The pesticides were applied at the maximum predicted environmental concentrations (PEC) under field conditions and at 5 or 100 times the PEC. More distinct effects were observed in LS than SL soils at all sampling times. For PEC, a significant decrease in DHA was found in LS soil treated with diazinon or the fungicidal preparation on day 1 and during the incubation period, respectively. However, DHA did not decrease in SL soil treated with the pesticides at this dosage. For the higher concentrations, decreased DHA was ascertained in LS soil treated with diazinon and the fungicidal preparation at all sampling times, whereas for linuron this effect was evident on days 14 and 28. By contrast, only 100-fold PEC significantly decreased DHA in SL soil amended with diazinon or linuron, compared with the fungicidal preparation that decreased DHA at five-fold PEC. Our results indicate that DHA was particularly sensitive to the fungicidal preparation in both soils, whereas linuron was less harmful than diazinon.