人工湿地不同基质和粒径对污水净化效果的比较

为研究人工湿地基质类型和粒径对水质净化效率的影响,选择了1~2、2~4、4~8 mm的沸石,2~4、4~8、8~16mm的砾石和2~4、3~5、6~8 mm的无烟煤基质,在无植物人工实验柱中开展单一基质的水质净化实验.结果表明,相同类型不同粒径的基质对COD、TN、TP的去除效果不同.4~8 mm沸石和砾石、6~8 mm无烟煤对COD的去除率最高,分别为53.74%、60.76%、62.93%;人工实验柱中氮素的去除以反硝化作用为主,粒径对TN去除效果的影响表现为小粒径更优;砾石和无烟煤的TP去除率也表现为小粒径更高,但沸石的TP去除率随着粒径的增大而增大.基质类型对COD、TP、TN的去除效果也存在差异.无烟煤对COD、TP、TN均有较好的去除效果,平均去除率在60%以上;沸石对TN的去除效果最好,TP去除率不高;砾石对COD有较高的去除率,对TP的去除效果一般.     

石灰石和黄铁矿-石灰石人工湿地净化河水的研究

利用石灰石和黄铁矿-石灰石水平潜流人工湿地处理受到污染的河水,了解它们对河水中污染物,尤其是对氮和磷的去除效果,并分析这些矿物的作用,考察了水力停留时间变化对2种人工湿地污染物净化效果的影响.结果表明,污染物去除效果的最佳停留时间出现在3 d左右,COD、TN和TP的平均去除率分别达到51%、70%和95%.在相同进水水质和水力负荷运行条件下,石灰石和黄铁矿-石灰石这2种人工湿地对COD的平均去除率分别为53.93%和51.66%,对NH4+-N的平均去除率分别为82.13%和77.43%,对TN的平均去除率分别为66%和72.06%,对TP的平均去除率分别为50.9%和97.35%.2种人工湿地对COD的去除效果差距不大,黄铁矿-石灰石人工湿地的脱氮除磷效果优于石灰石湿地,对磷有较好的去除效果,不受温度影响且净化效果稳定,适宜长期稳定运行.     

人工湿地技术的除污效果分析研究

人工湿地技术对城市污水的除污作用十分强大,因此对人工湿地技术的除污效果进行详细分析。酸模和美人蕉湿地体系的TN平均的去除率均在60%以上,在TN去除率方面,酸模要比美人蕉明显;随着时间的增长,酸模对NH+4-N的去除效果,要优于美人蕉对NH+4-N的去除效果;美人蕉对TP平均去除率大概是87%,酸模对TP平均去除率大概是77%,对于TP的去除,美人蕉要优于酸模;酸模对COD平均去除率大概为60%,美人蕉对COD平均去除率大概为54%,可见,两种植物湿地针对COD的去除效果一般。     

高水力负荷对人工湿地处理精养虾塘排水效果的影响

通过水平潜流人工湿地处理精养虾塘排水的中试试验,探讨了在不同高水力负荷条件下[1.10～5.34 m3.(m2.d)-1]人工湿地对有机物、氮磷以及悬浮物的去除效果,以期为其设计运行提供参考.结果表明,水力负荷与COD、TN、TP、SS的去除率呈负相关;COD、TN、SS去除速率随水力负荷的升高,先升后降,最高分别达到69、1.8和117.6 g.(m2.d)-1;TP的去除速率随水力负荷的升高变化并不明显.人工湿地在水力负荷2.52～3.24 m3.(m2.d)-1范围内运行时,污染物去除总量最高处理效果最佳.     

碳氧调控下人工湿地净化效果的协同与拮抗研究

从人工湿地脱氮效果的重要限制因子——溶解氧和碳源着手,构建了一种人工湿地碳氧联合调控脱氮系统,研究了曝气、碳源投加、碳氧联合调控下人工湿地的净化效果.结果表明,曝气促进了TSS、COD、TN、NH4+-N、TP的去除,但夏季时会导致NO3--N的积累;碳源投加提高了TN、NO3--N的去除,但冬季时会导致COD去除率的下降.碳氧联合调控下人工湿地对TN、NO3--N的去除表现出协同作用,对NH4+-N、COD的去除表现出独立作用,而对TP、TSS的去除表现出一定的拮抗作用.另外,对于以氨氮为主的“低碳高氮”污水,人工湿地碳氧联合调控系统脱氮效率达87.3%,可见该强化系统适用于“低碳高氮”污水的处理.     

多级垂直流人工湿地对北方农村生活污水的处理分析

文章采用多级垂直流人工湿地处理北方农村生活污水,考察了稳定运行期水力负荷、植物收割以及季节对COD、NH~+_4-N、TN和TP的去除影响。结果表明:COD、TN和TP去除随水力负荷增加呈递减趋势,在0.15 m~3/(m~2·d)时去除最佳,出水浓度分别为18～30、9～25和0.4～0.5 mg/L。NH~+_4-N去除随水力负荷增加呈先增后减趋势,在0.25 m~3/(m~2·d)时去除率最佳,出水浓度为0～6 mg/L。在水力负荷为0.15 m~3/(m~2·d)时,植物收割后COD、NH~+_4-N、TN和TP的去除均有所降低。不同季节时,夏季湿地处理效果最佳,冬季最差。同时对比实验表明,夏季水力负荷为0.15 m~3/(m~2·d)时,多级垂直流人工湿地对COD、NH~+_4-N、TN和TP的去除效果优于单级水平流人工湿地,其出水达到城镇污水处理厂污染物排放一级A标准。     

河源城南污水处理厂尾水深度处理效果的研究

河源市城南污水处理厂利用垂直流人工湿地对该厂A2-O工艺处理的尾水进行深度处理,研究了人工湿地对尾水中TN、NH4+-N、TP、COD、BOD5的去除效果。结果表明:人工湿地对污水处理厂尾水具有较好的深度处理效果,垂直流人工湿地处理系统对尾水中TN、NH4+-N、TP、COD和BOD5平均去除率分别达到97.4%、97.8%、95.06%、91.87%和95.87%以上,其出水水质基本达GB 18918—2002《城镇污水处理厂污染物排放标准》一级A标准,地表水Ⅲ类标准。     

人工湿地组合工艺削减山地城市地表径流污染

采用前置生态塘-表流人工湿地-卵石过滤带组合工艺处理山地城市地表径流,研究了各单元在COD、TN、TP和NH4+-N方面的去除效果,以及径流中COD浓度和氮素形态对污染物去除的影响。结果表明,针对COD、TN、TP和NH4+-N,生态塘可以达到82%、53%、45%和32%的去除,表流人工湿地可以达到82%、83%、80%和61%的去除。COD由60 mg/L升至500 mg/L时,整个组合工艺的TP去除率由61%升至82%后下降至64%,TN去除率由50%提高至82%,NH4+-N去除率由67%降至41%。氮素组成对TN和COD的去除影响较大,NH4+-N∶NO3--N由3∶1变为1∶3时,COD去除率从73%提高到85%,TN去除率从53%提高到86%,NH4+-N去除率变化不大,为45%~51%。该组合工艺能够有效去除和削减城市地表径流中的COD、TN和TP的污染。     

微污染饮用水源水潜流人工湿地预处理的效能研究

以济南玉清湖水库为例,采用水平潜流人工湿地系统对沉砂后的微污染黄河水进行了预处理试验,考察了湿地系统对污染物的去除效率及其变化趋势.同时,根据实验数据,构建了潜流人工湿地系统COD、TN、TP的一级动力学模拟方程.结果表明,水平潜流人工湿地系统对COD、TP、TN和NH4+-N的平均去除率分别为49.89%、50.44%、53.41%和48.45%;人工湿地对污染物的处理是物理、化学和生物及其协同作用的过程.人工湿地沿程及不同高度污染物浓度变化试验结果表明,人工湿地系统对污染物的降解沿人工湿地水流方向逐渐降低,污染物主要在人工湿地床体前部被去除,潜流人工湿地床体上部对污染物的去除效果更好.     

复合人工湿地系统净化城市富营养水体的应用研究

采用复合人工湿地系统对紫阳湖富营养水体进行净化工程性研究,在水力负荷为1 m3(/m2·d)的条件下,研究了上层表面流人工湿地单元、下层水平潜流人工湿地单元对紫阳湖水体中高锰酸盐指数、TN、TP等水质指标的去除效果。结果表明:下层水平潜流人工湿地单元对高锰酸盐指数、TN、TP的去除率分别为24.5%、23.1%、23.3%,上层表面流人工湿地单元对高锰酸盐指数、TN、TP的去除率分别为23.5%、13.3%、14.2%,上层人工湿地单元对氮、磷的去除效果比上层人工湿地单元高50%和40%,对高锰酸盐指数的去除效果两者差不多。另外,复合人工湿地对紫阳湖水净化效果较好,对高锰酸盐指数、TN、TP的平均去除率达到42%、33.2%和34.2%,出水浓度分别为9.60、2.01和0.23 mg/L,出水稳定可以为后续水体生态修复措施创造有利条件。     

Degradation of metabolites accumulated of benzo[a]pyrene by coupling Penicillium Chrysogenum with KMnO4

Several main metabolites of benzo[a]pyrene （BaP） formed by Penicillium chrysogenum, Benzo[a]pyrene-1,6-quinone （BP 1,6- quinone）, trans-7,8-dihydroxy-7,8-dihydrobenzo[a]pyrene （BP 7,8-diol）, 3-hydroxybenzo[a]pyrene （3-OHBP）, were identified by high-performance liquid chromatography （HPLC）. The three metabolites were liable to be accumulated and were hardly further metabolized because of their toxicity to microorganisms. However, their further degradation was essential for the complete degradation of BaP. To enhance their degradation, two methods, degradation by coupling Penicillium chrysogenum with KMnO4 and degradation only by Penicillium chrysogenum, were compared; Meanwhile, the parameters of degradation in the superior method were optimized. The results showed that （1） the method of coupling Penicillium chrysogenum with KMnO4 was better and was the first method to be used in the degradation of BaP and its metabolites; （2） the metabolite, BP 1,6-quinone was the most liable to be accumulated in pure cultures; （3） the effect of degradation was the best when the concentration of KMnO4 in the cultures was 0.01% （w/v）, concentration of the three compounds was 5 mg/L and pH was 6.2. Based on the experimental results, a novel concept with regard to the bioremediation of BaP-contaminated environment was discussed, considering the influence on environmental toxicity of the accumulated metabolites.     

Impact of atrazine and nitrogen fertilizers on the sorption of chlorotoluron in soil and model sorbents

Sorption of chlorotoluron in ammonium sulfate, urea and atrazine multi-solutes system was investigated by batch experiments. The results showed application of nitrogen fertilizers to the soil could affect the behavior of chlorotoluron. At the same concentration of N, sorption of chlorotoluron decreased as the concentration of atrazine increased on the day 0 and 6 in soil, respectively. The sorption of chlorotoluron increased from 0 to 6 d when soils were preincubated with deionized water, ammonium sulfate and urea solution for 6 d. That indicated incubation time was one of the most important factors for the sorption of chlorotoluron in nitrogen fertilizers treatments. The individual sorption isotherms of chlorotoluron in rubbery polymer and silica were strictly linear in single solute system, but there were competition sorption between pesticides or between pesticides and nitrogen fertilizers. That indicated the sorption taken place by concurrent solid-phase dissolution mechanism and sorption on the interface of water-organic matter or water-mineral matter.     

Toxicity assessing for chlorpyrifos-contaminated soil with three different earthworm test methods

Earthworm toxicity tests are useful tools for terrestrial risk assessment but require a hierarchy of test designs that differ in effect levels (behavior, sublethal, lethal). In this study, the toxicity of chlorpyrifos contaminated soil on earthworms was assessed. In addition to the acute and chronic tests, an avoidance response test was applied. Earthworms were exposed to sublethal and lethal concentration of chlorpyrifos, and evaluated for acute toxicity, growth, fecundity and avoidance response after a certain exposure period. The test methods covered all important ecological relevant endpoints (acute, chronic, behavioral). Concentration of 78.91 mg/kg, chlorpyrifos caused significant toxic effects in all test methods, but at lower test concentrations, only significant chronic toxic effects could be observed. In the present study, chlorpyrifos had adverse effect on growth and fecundity in earthworm exposed to 5 mg/kg chlorpyrifos after eight weeks. The avoidance response test, however, showed significant repellent effects concentration of 40 mg/kg chlorpyrifos. For chlorpyrifos, concentration affecting avoidance response was far greater than growth and fecundity, it seemed likely that earthworms were not able to escape from pesticide-contaminated soil into the clean soil in field and hence were exposed continuously to elevated concentrations of pesticides.     

Leaching of styrene and other aromatic compounds in drinking water from PS bottles

Bottled water may not be safer, or healthier, than tap water. The present studies have proved that styrene and some other aromatic compounds leach continuously from polystyrene （PS） bottles used locally for packaging. Water sapmles in contact with PS were extracted by a preconcentration technique called as ＂purge and trap＂ and analysed by gas chromatograph-mass spectrometer （GC/MS）. Eleven aromatic compounds were identified in these studies. Maximum concentration of styrene in PS bottles was 29.5 μg/L. Apart from styrene, ethyl benzene, toluene and benzene were also quantified but their concentrations were much less than WHO guide line values. All other compounds were in traces. Quality of plastic and storage time were the major factor in leaching of styrene. Concentration of styrene was increased to 69.53 μg/L after one-year storage. In Styrofoam and PS cups studies, hot water was found to be contaminated with styrene and other aromatic compounds. It was observed that temperature played a major role in the leaching of styrene monomer from Styrofoam cups. Paper cups were found to be safe for hot drinks.     

Sludge concentration dynamic distribution and its impact on the performance of UNITANK

UNITANK is a biological wastewater treatment process that combines the advantages of traditional activated sludge process and sequencing batch reactor, which is divided into Tank A, B and C. In this study, the sludge distribution and its impact on performance of UNITANK were carried out in Liede Wastewater Plant （WWTP） of Guangzhou, China. Results showed that there was a strong affiliation between Tank A and B of the system in sludge concentration distribution. The initial sludge concentration in Tank A could present the sludge distribution of the whole system. The sludge distribution was mainly influenced by hydraulic condition. Unsteady sludge distribution had an impact on variations of substrates in reactors, especially in decisive reactor, and this could lead to failure of system. Settler could partially remove substrates such as COD and NO3-N, but there was adventure of sludge deterioration. The rational initial sludge concentration in Tank A should be 4000-6000 mg/L MLSS.     

Treated wastewater irrigation effect on soil, crop and environment： Wastewater recycling in the loess area of China

A study was carried out at the Loess Plateau in Dongzhi,China,to test the feasibility of using secondary treatment sewage effluent and to determine whether the water quality would then meet the recommended irrigation norm.Seven crops,including celery,wheat, maize,millet,apples,rapeseed and yellow beans,were tested in the study.Physical and chemical properties of the soil,crop yield and quality and leachate at different soil depths were measured.In most cases,the quality of the crops that made use of treated sewage was not distinctively different from those that did not use treated sewage.However,yields for the former were much higher than they were for the latter.Leachates at different soil depths were analyzed and the results did not show alarming levels of constituents.For a period of approximately 14 months,the treated sewage irrigation had no significant effect on the loess soil and no cases of illness resulting from contact with the treated sewage were reported.With treated sewage irrigation,a slight increase in the organic content of the soil was observed.     

Spatial variability of organochlorine pesticides （DDTs and HCHs） in surface soils from the alluvial region of Beijing, China

The spatial variability in the concentrations of 1,2,3,4,5,6-hexachlorocyclohexane (HCH) and 1,1,1-trichloro-2,2-bis-(p-chlorophenyl) ethane (DDT) in surface soils was studied on the basis of the analysis of 131 soil samples collected from the surface layer (0-20 cm depth) of the alluvial region of Beijing, China. The concentrations of total HCHs (including α-, β-, γ-, and δ-isomers) and total DDTs (i ncluding p,p'-DDT, p,p'-DDD, p,p'-DDE, and o,p'-DDT) in the surface soils tested were in the range from nondetectable to 31.72 μg/kg dry soil, with a mean value of 0.91, and from nondetectable to 5910.83 μg/kg dry soil, with a mean value of 32.13,respectively. It was observed that concentrations of HCHs in all soil samples and concentrations of DDTs in 112 soil samples were much lower than the first grade (50 μg/kg) permitted in "Environment quality standard for soils in China (GB15618-1995)". This suggests that the pollution due to organochlorine pesticides was generally not significant in the farmland soils in the Beijing alluvial region. In this study, the spatial distribution and trend of HCHs and DDTs were analyzed using Geostatistical Analyst and GS (513).Spatial distribution indicated how these pesticides had been applied in the past. Trend analysis showed that the concentrations of HCHs,DDTs, and their related metabolites followed an obvious distribution trend in the surface soils from the alluvial region of Beijing.     

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.     

Bioaccumulation of heavy metals in fishes from Taihu Lake, China

The Cr,Zn,Cu,Cd,Pb contents were determined in Cyprinus carpio Linnaeus,Carassius auratus Linnaeus,Hypophthalmichthys molitrix and Aristichthys nobilis,which were caught from Meiliang Bay,Taihu Lake,a large,shallow and eutrophic lake of China.The results showed that:(1)the Cr,Cu,Pb,Cd contents in the edible parts of the four fish species were much lower than Chinese Food Health Criterion(1994),but the Zn contents were higher than the Criterion;(2)Cd contents were the highest in the liver of fish,Pb contents were almost the same in all organs of fish,Cr contents mainly enriched in the skin and gonads,Zn contents were the highest in the gonad(♀),and Cu contents were the highest in the liver;(3)the total metal accumulation was the greatest in the liver and the lowest in the muscle.The total metal accumulation was the highest in C.auratus L.This investigation indicated that fish products in Taihu Lake were still safe for human consumption,but the amount consumed should be controlled under the Chinese Food Health Criterion to avoid excessive intake of Zn.     

Biological control experiment of excess propagation of Cyclops for drinking water security

Cyclops of zooplankton propagated excessively in eutrophic water body and could not be effectively inactivated by the conventional disinfections process like chlorination due to its stronger resistance to oxidation. In this study, an ecological project was put forward for the excess propagation control of Cyclops by stocking the filter-feeding fishes such as silver carp and bighead carp under the condition of no extraneous nutrient feeding. The results of experiments with different stocking biomass showed that the propagation of Cyclops could be controlled effectively, and the water quality was improved simultaneously by impacting on nutriment level and plankton community structure at proper stocking density of 30 g/m^3 of water. The growth of Cyclops may not be effectually controlled with lower biomass of fish （10 g）, and the natural food chain relation may be destroyed for Cyclops dying out in water while the intense stocking of 120 g per cubic meter of water. In addition, the high predator pressure may accelerate supplemental rate of nutrients from bottom sediments to water body to add the content of total nitrogen and phosphorus in water.