Aerobic granulation of pure bacterial strain Bacillus thuringiensis

The objective of this study is to cultivate aerobic granules by pure bacterial strain, Bacillus thuringiensis, in a sequencing batch reactor. Stable granules sized 2.0–2.2 mm were formed in the reactor after a five-week cultivation. These granules exhibited excellent settling attributes, and degraded phenol at rates of 1.49 and 1.19 g phenol/(g VSS?d) at 250 and 1500 mg/L of phenol concentration, respectively. Confocal laser scanning microscopic test results show that Bacillus thuringiensis was distributed over the initial small aggregates, and the outer edge of the granule was away from the core regime in the following stage.     

Removal of heavy metals using waste eggshell

The removal capacity of toxic heavy metals by the reused eggshell was studied.As a pretreatment process for the preparation of reused material from waste eggshell,calcination was performed in the furnace at 800℃for 2 h after crushing the dried waste eggshell.Calcination behavior,qualitative and quantitative elemental information,mineral type and surface characteristics before and after calcination of eggshell were examined by thermal gravimetric analysis(TGA),X-ray fluorescence (XRF),X-ray diffraction(XRD) and scanning electron microscopy(SEM),respectively.After calcination,the major inorganic composition was identified as Ca(lime, 99.63%)and K,P and Sr were identified as minor components.When calcined eggshell was applied in the treatment of synthetic wastewater containing heavy metals,a complete removal of Cd as well as above 99% removal of Cr was observed after 10 min. Although the natural eggshell had some removal capacity of Cd and Cr,a complete removal was not accomplished even after 60 min due to quite slower removal rate.However,in contrast to Cd and Cr,an efficient removal of Pb was observed with the natural eggshell rather than the calcined eggshell.From the application of the calcined eggshell in the treatment of real electroplating wastewater, the calcined eggshell showed a promising removal capacity of heavy metal ions as well as had a good neutralization capacity in the treatment of strong acidic wastewater.     

中国北方干旱-半干旱地区草地NH_3通量原位观测研究

NH3挥发是导致农业和畜牧业施肥中N素流失的主要途径之一。基于这一认识,人们推测NH3的释放也可能在干旱-半干旱地区天然草地氮素流失中起着重要作用。然而这方面的观测研究却十分有限。我国北方天然草地面积约150万平方千米,而且在干旱-半干旱过渡地区的草地中存在N相对于C不足的现象。认识NH3挥发在其中所起的作用对防治草地退化、保护干旱区生态环境安全具有重要意义。本文利用Thermo-Fisher公司生产的Model17iNOx-NH3分析仪和动态箱法对黄土高原西北部边缘和宁夏中东部地区,也即农牧过渡带地区在8～9月份的地-气NH3交换通量进行了观测研究,发现其通量昼夜变化存在多种类型,平均通量在-2～2g NH3/(m2.h)之间;在空间变化上,NH3的地-气交换在毛乌素沙地西侧表现为对大气NH3的净吸收,经黄土高原边缘和宁夏中东部的过渡,到宁夏南部的固原地区变化为草地NH3的净释放。这种草地NH3释放通量自北向南增加的现象主要是由于降水对土壤的湿润作用所致。干旱的环境条件使得水分超过了土壤pH和温度等众多影响因素而成为NH3挥发的主要限制因素。据此可以推测NH3挥发作用在我国北方自然草地N素流失中的作用可能较小,不可能是导致农牧交错地区土壤N素相对不足的原因。     

土壤CO2浓度与地表CO2通量的季节变化及其相互关系

采用气相色谱法对贵州喀斯特地区不同土地利用方式土壤剖面CO2浓度与地表CO2通量的季节变化特征进行为期一年的观测.结果表明:土壤CO2浓度和地表CO2通量具有明显的季节变化规律,均表现为:从春季到夏季浓度和通量逐渐增加,而从秋季到冬季浓度和通量又逐渐降低,这与该区域的温度和降雨量变化趋势一致.不同土地利用方式土壤CO2...     

改性生物炭对水体中抗生素的去除研究进展

随着社会经济的不断发展,抗生素造成的水体环境污染问题已不容忽视.利用生物炭去除水体中的抗生素是解决这一问题的有效手段之一.然而,原始生物炭对水体中抗生素等有机污染物的去除存在一定局限性,因此对生物炭进行改性以提升其吸附能力尤为必要.生物炭的吸附性能受生物质类型、碳化条件和改性方法等因素影响较大,导致目前虽然开展了许多相关研究,但结论不一,尤其是在不同改性生物炭对不同抗生素吸附机理的解释方面还不是很清楚,因此有必要对现有研究进行系统地归纳和总结.本文首先对用于抗生素吸附的改性生物炭制备方法及理化性质表征方法进行了介绍,综述了改性生物炭对不同种类抗生素(磺胺类、喹诺酮类、四环素类、大环内酯类、氯霉素类)的吸附效果、吸附机理及其影响因素(如溶液pH值、热解温度、改性材料等),对比分析了生物炭改性前后吸附效果的差异,对目前改性生物炭用于去除水体中抗生素存在的问题进行了分析和总结,在此基础上,对今后该领域的研究和发展方向进行了展望,以期为将来开展相关的研究工作提供一定的参考.     

三江平原保护区社区居民对湿地生态系统服务功能的贡献意愿

为了解社区对维持保护区湿地生态系统服务功能的贡献意愿,研究选取三江平原5个湿地自然保护区及其社区,依据条件价值评估法设计双边界二分式问卷,进行实地走访调查,从居民社会经济背景等方面探讨影响贡献意愿的因素、居民支付意愿（WTP）和劳动意愿（WTW）的差异。结果表明：1）居民对湿地生态系统服务的劳动意愿（73.57%）高于支付意愿（55.65%）,居民的抗议支付率随WTP和WTW投标值增加呈上升趋势,人均WTP为387.25±7.08元/a,WTW为31.40±0.39 h/月;2）月收入水平较高及对支付金钱有较高接受程度的受访居民,其WTP相对较高;加入环保类协会、对付出劳动的接受程度较高、受教育程度较高及男性的受访居民,则有较高的WTW;3）49.46%的居民愿意同时贡献金钱与劳动,远高于其他贡献意愿类型。建议在保护区的资源保护与管理实践中鼓励社区参与,充分发挥社区居民乐于提供志愿服务时间的贡献意愿。     

Regenerable adsorbent for removing ammonia evolved from anaerobic reaction of animal urine

The waste gas evolved from biodegradation of animal urine contains ammonia causing environmental concerns. A new and effective method for removing ammonia from such waste gas using reactive adsorption is presented. In the process, activated carbon impregnated with H2SO4（H2SO4/C） is employed. Ammonia in the waste gas reacts with H2SO4 on the adsorbent instantaneously and completely to form （NIL）2SO4. The H2SO4/C adsorbent is high in NH3 adsorption capacity and regenerable. The NH3 removal capacity of this regenerable adsorbent is more than 30 times that of the adsorbents used normally in the industry. The spent H2SO4/C is regenerated by flowing low-pressure steam through the adsorbent bed to remove the （NH4）2SO4 from the adsorbent. The regeneration by-product is concentrated （NH4）2SO4 solution, which is a perfect liquid fertilizer for local use. Re-soaking the activated carbon with H2SO4 solution rejuvenates the activity of the adsorbent. Thus the H2SOJC can be reused repeatedly. In the mechanism of this reactive adsorption process, trace of H20 in the waste gas is a required, which lends itself to treating ammonia gas saturated with moisture from biodegradation of animal urine.     

Phytoremediation of Atrazine by Poplar Trees: Toxicity,Uptake, and Transformation

Toxicity, uptake, and transformation of atrazine [2-chloro-4-(ethylamino)-6-(isopropylamino)-s-triazine] by three species of poplar tree were assessed. Poplar cuttings were grown in sealed flasks with hydrophonic solutions and exposed to various concentrations of atrazine for a period of two weeks. Toxicity effects were evaluated by monitoring transpiration and measuring poplar cutting mass. Exposure to higher atrazine concentrations resulted in decrease of biomass and transpiration accompanied by leaf chlorosis and abscission. However, poplar cuttings exposed to lower concentrations of atrazine grew well and transpired at a constant rate during experiment periods. Poplar cuttings could take up, hydrolyze, and dealkylate atrazine to less toxic metabolites. Metabolism of atrazine occurred in roots, stems, and leaves and became more complete with increased residence time in tissue. These results suggest that phytoremediation is a viable approach to removing atrazine from contaminated water and should be considered for other contaminants.     

Sorption of acidic organic solute onto kaolinitic soils from methanol-water mixtures

The fate of the acidic organic solute from the soil-water-solvent system is not well-understood. In this study, the effect of the acidic functional group of organic solute in the sorption from cosolvent system was evaluated. The sorption of naphthalene (NAP) and 1-naphthoic acid (1-NAPA) by three kaolinitic soils and two model sorbents (kaolinite and humic acid) were measured as functions of the methanol volume fractions (f (c) ≤ 0.4) and ionic compositions (CaCl(2) and KCl). The solubility of 1-NAPA was also measured in various ionic compositions. The sorption data were interpreted using the cosolvency-induced sorption model. The K (m) values (= the linear sorption coefficient) of NAP with kaolinitic soil for both ionic compositions was log linearly decreased with f (c). However, the K (m) values of 1-NAPA with both ionic compositions remained relatively constant over the f (c) range. For the model sorbent, the K (m) values of 1-NAPA with kaolinite for the KCl system and with humic acid for both ionic compositions decreased with f (c), while the sorption of 1-NAPA with kaolinite for the CaCl(2) system was increased with f (c). From the solubility data of 1-NAPA with f (c), no significant difference was observed with the different ionic compositions, indicating an insignificant change in the aqueous activity of the liquid phase. In conclusion, the enhanced 1-NAPA sorption, greater than that predicted from the cosolvency-induced model, was due to an untraceable interaction between the carboxylate and hydrophilic soil domain in the methanol-water system. Therefore, in order to accurately predict the environmental fate of acidic pesticides and organic solutes, an effort to quantitatively incorporate the enhanced hydrophilic sorption into the current cosolvency-induced sorption model is required.