不同因素对人工湿地基质脱氮除磷效果的影响

在人工配制的污水中投入一定量的基质,不同条件下振荡培养,评价沸石、炉渣和陶瓷滤料3种基质在不同因素影响下对氨氮(NH4+-N)和总磷(TP)的吸附能力。结果表明,不同吸附时间时,沸石对NH4+-N的吸附效果最好,陶瓷滤料对TP的吸附效果最好;进水浓度对沸石吸附NH4+-N的影响较大,其吸附量随进水浓度的增大而增大,进水浓度对炉渣和陶瓷滤料吸附NH4+-N及炉渣吸附TP影响不大;3种基质对NH4+-N和TP的吸附量均是随吸附剂量的增加而降低,要达到较好的去污效果,应根据实验结果考虑基质投入量;pH值对沸石吸附NH4+-N影响显著,pH值6～7范围内吸附效果最好,pH值8～12的碱性条件有利于基质对TP的吸附。     

复合生物阴极型微生物燃料电池处理废水及同步产电性能

为研究生物阴极在MFC（微生物燃料电池）中的应用,分别以粒径为2~4 mm的颗粒活性炭和粒径为2~4、4~8、8~12 mm的颗粒石墨为阴极基质材料,构建升流复合生物阴极型单室MFC,研究阴极基质材料的种类和粒径对MFC的产电性能和净水效能的影响.结果表明:当阳极基质材料为2~4 mm粒径的颗粒活性炭时,燃料电池中利用玻璃纤维取代离子交换膜,阴极基质材料为选用4~8 mm粒径颗粒石墨的反应柱产电量最大,为534 mV（外电阻为1 000 Ω）,最大功率密度达到631.6 mW/m3,库伦效率为3.82%;阴极的pH越低越有利于阴极的产电反应;不同阴极基质材料的MFC对COD_Cr去除率均在80%左右,TN、NH₄+-N及TP的去除率最高可分别达到79%、93%和34%.研究显示,阴极基质材料的种类和粒径对MFC的产电性影响较大,但对其净水效能的影响不大.      

不同粒径羟基磷灰石对污染土壤铜镉磷有效性和酶活性的影响

为研究不同粒径羟基磷灰石对重金属污染土壤的修复效果,采用向污染土壤添加常规磷灰石（150 μm）、微米（3 μm）和纳米（40 nm）羟基磷灰石的田间原位试验方法,考察其钝化修复5 a后对土壤铜镉磷有效性和酶活性的影响.结果表明:3种粒径羟基磷灰石均提高了土壤pH,降低了土壤交换性酸和交换性铝的含量,且微米羟基磷灰石处理效果最好.常规磷灰石、微米和纳米羟基磷灰石处理分别使w（离子交换态铜）降低了62.6%、74.3%和70.4%,w（离子交换态镉）降低了15.7%、25.3%和26.7%.3种材料均增加了土壤w（TP）,其中4.61%~17.4%和73.4%~89.8%分别转化为树脂磷和稳定态磷.微米羟基磷灰石处理分别使土壤脲酶活性和微生物量碳含量提高了4.66和0.66倍.研究显示,微米羟基磷灰石更有利于铜和镉由活性态向非活性态转化,增加土壤磷的有效性,提高土壤微生物活性,在我国南方重金属污染红壤区具有较好的应用潜力.      

低浓度含磷水体除磷填料的选择研究

通过对不同填料进行初筛,选择红瓦、环保砖和水泥砖作为研究对象,对低浓度含磷水体进行磷吸附能力试验研究.结果表明,Langmuir 和Freundlich方程均能合理地描述低浓度含磷水体中各填料的等温吸附特性,Langmuir方程中3种填料对磷的理论饱和吸附量由大到小依次为：红瓦（38.13 mg·kg^-1）>环保砖（25.79 mg·kg^-1）>水泥砖（8.85 mg·kg^-1）,Freundlich方程中反应吸附能力的K值由大到小的规律同Langmuir方程的饱和吸附量一致.一级动力学方程、Elovich方程和双常数速率方程均能很好地描述填料对磷素的吸附动力学特征,从可决系数来看,Elovich型方程的拟合效果最好.从磷释放及其安全性分析,3种填料没有向水体释放磷,释放的重金属元素非常低,不会对水体造成二次污染.各填料出水均偏碱性,因此,选择湿地植物时必须具有较强的耐碱性.综合考察得出,红瓦和环保砖可作为处理低浓度含磷水体的除磷填料.     

进水底物浓度对蔗糖废水产酸合成PHA影响研究

混合菌群合成生物可降解塑料(PHA)成为目前研究的热点,三段式PHA合成工艺(水解产酸、产PHA菌富集、PHA合成)被广泛应用.在三段式工艺中,产PHA菌的富集非常关键,只有稳定产生PHA菌才能保障PHA合成的产量.针对产PHA菌富集系统容易出现污泥膨胀的问题,本研究考察了进水底物浓度对产PHA菌富集效率及运行稳定性的影响.在560mg·L-1、1 120 mg·L-1、1 680 mg·L-1这3组不同进水底物浓度的对比实验中,证实了COD 1 120 mg·L-1条件下富集反应器能够在较短污泥龄下稳定富集具有较高污泥浓度的高效产PHA菌,且不会发生污泥膨胀.在94 d的富集期后其批次实验最大PHA含量、PHA转化率(COD/COD)及PHA比合成速率能分别达到50%、0.714 5及0.191 2 mg·(mg·h)-1.研究还同时证实细胞内糖原水平高低与其PHA合成能力密切相关,可采用其作为富集效果的重要检测指标之一.     

SRT影响MBR有机污染物去除速率研究

通过考察污泥停留时间(SRT)对膜生物反应器(MBR)和粉末活性炭膜生物反应器(PAc-MBR)降解有机物速率的影响,探讨了污泥活性与胞外聚合物(EPS)的关系.结果表明:MBR和.PAC-MBR中COD降解速率随SRT延长均呈先上升后下降的趋势,分别在39～48d和48d时达到最快,对应速率常数为2.586和3.856,PAC-MBR中COD降解速率普遍高于MBR,说明投加PAC使污泥活性提高,SRT对污泥活性影响较大;MBR和PAC-MBR中胞外聚合物质量浓度与COD降解速率常数K1变化趋势一致,且胞外聚合物质量浓度与K1呈良好正相关关系,说明系统的胞外聚合物质量浓度可以作为衡量污泥活性的指标.     

Heavy metal availability and impact on activity of soil microorganisms along a Cu/Zn contamination gradient

All the regulations that define a maximum concentration of metals in the receiving soil are based on total soil metal concentration. However, the potential toxicity of a heavy metal in the soil depends on its speciation and availability. We studied the effects of heavy metal speciation and availability on soil microorganism activities along a Cu/Zn contamination gradient. Microbial biomass and enzyme activity of soil contaminated with both Cu and Zn were investigated. The results showed that microbial biomass was negatively affected by the elevated metal levels. The microbial biomass-C （Cmic）/organic C （Corg） ratio was closely correlated to heavy metal stress. There were negative correlations between soil microbial biomass, phosphatase activity and NH4NO3 extractable heavy metals. The soil microorganism activity could be predicted using empirical models with the availability of Cu and Zn. We observed that 72% of the variation in phosphatase activity could be explained by the NH4NO3-extractable and total heavy metal concentration. By considering different monitoring approaches and different viewpoints, this set of methods applied in this study seemed sensitive to site differences and contributed to a better understanding of the effects of heavy metals on the size and activity of microorganisms in soils. The data presented demonstrate the relationship between heavy metals availability and heavy metal toxicity to soil microorganism along a contamination gradient.     

Variation of soil fertility and carbon sequestration by planting Hevea brasiliensis in Hainan Island, China

The development of rubber industry depends on the sustainable management of rubber plantation. To evaluate the environmental effects of planting Hevea brasiliensis on a subsystem of tropical forest ecosystem, the variation of soil fertility and carbon sequestration under rubber plantation within 30-year life period were investigated in Hainan Island. Results showed that （1） with the increase of stand age of rubber plantation, soil fertility decreased all along. From 1954 to 1995, soil organic matter, total N, available K and available P decreased by 48.2%, 54.1%, 56.7% and 64.1%, respectively. （2） If the complete return of litters was considered without additional fertilizer application to the soil of the rubber plantations, the consumption periods for P, N, K, Mg were only 825 years, 329 years, 94 years and 65 years, respectively~ To improve soil fertility is essential for rubber plantation development. （3） The C sequestration of rubber trees per hectare accounts for 272.08 t within 30-year life period and 57.91% of them was fixed in litters. In comparison with C sequestration by rain forest （234.305 t/hm^2） and by secondary rain forest （150.203 t/hm^2）, rubber forest has more potentials for C fixation. On the base of above results, the following measures would benefit the maintenance of soil fertility and the development of rubber industry, including applying fertilizer to maintain the balance of soil nutrients, intercropping leguminous plant to improve soil fertility, reducing the collection of litters, optimizing soil properties to improve element P availability such as applying CaCO3. The information gathered from the study can be used as baseline data for the sustainable management of rubber plantation elsewhere.     

Water quality characteristics along the course of the Huangpu River （China）

Huangpu River is about 114.5 km from upriver Dianfeng to downriver Wusong,near the estuary of the Yangtze River.It plays a key role in supplying water for production,life,shipment and irrigation.With the industrial development,the pollution of the Huangpu River has become serious recently.The biological oxygen demand (BOD),total nitrogen (TN),total phosphorus (TP),oil,phenol and suspended solids (SS) were lower in the upstream sites than in the downstream sites,indicating pollutants being input along its course. Water quality was the worst in the Yangpu site,near the center of Shanghai City.Dissolved oxygen (DO) content was less than 2 mg/L in the site of Yangpu in July.Among relations between thirteen characteristics,relations between BOD,DO,TN,TP,NH_4~ -N, NO_3~--N and the count of total bacteria or Escherichia coli were significant and interdependent.Inner relationships between these main characteristics in the Huangpu River were studied.High nutrient concentration led to growth of microorganisms,including E.coli. Degradation of organic matters and respiration of bacteria made oxygen concentration decreased in the water body,and DO was a key factor for nitrification-denitrification process of nitrogen.In the Yangpu site,DO was decreased to less than 3.0 mg/L with BOD higher than 7.5 mg/L in May and July.Low DO concentration will decrease nitrification rate.Nitrification need at higher DO value than other organic substrate oxidation.Consequently,river water contains low NO_3~--N values with high amounts of TN and NH_4~ -N there.This will block the self-purification of surface water,by decreasing the rate of nitrification-denitrification transformation process in the water body.     

垂直流人工湿地系统基质优化级配研究

选取生物陶粒、无烟煤、沸石、钢渣和蛭石为基质,按不同的级配方式填充成基质柱,进行垂直流人工湿地模拟柱净化污水实验.研究表明,粒径分层级配基质对COD的去除率均高于单一粒径基质,其中分层生物陶粒对COD的平均去除率高达72.91%.分层沸石对总氮的净化能力较单一粒径基质有所提高,平均去除率高达91.23%.填充了生物陶粒、沸石和无烟煤的模拟柱对有机物和氮的净化效果和单一基质没有显著性差异(p0.05).填充钢渣和无烟煤的模拟柱出水pH值均在正常范围内,但是除从上到下依次填充无烟煤、蛭石和钢渣的基质柱外,其它填充钢渣和无烟煤的模拟柱对磷素的净化能力都低于单一基质.种植植物对净化效果没有明显影响.在垂直流人工湿地中,针对水质特点选择高效的级配基质,如分层生物陶粒、分层沸石、分层无烟煤以及生物陶粒、沸石和无烟煤组合,在高水力负荷条件下可获得更好的处理效果.