高负荷地下土壤法处理有机污水的模拟实验研究

针对传统地下污水渗滤系统的主要缺陷,提出了采用人工土壤提高系统的污水承载能力,采用多层过渡结构增大颗粒有机物的接触氧化表面积,采用高渗透性夹层增加氧气供应,以提高污水地下处理系统的水力负荷,延长其使用寿命.以我国南方典型的红壤土、砂和砾石为填充材料进行了实验室模拟实验,供试污水来自中国科学院广州地球化学研究所生活小区.结果显示,在25 cm/d的水力负荷下,系统没有被堵塞的迹象,采用每天2次投配污水的方式（每次12.5 cm）,渗透系数为0.6 cm/min的土柱可以达到很好的出水效果,其COD、BOD5、SS、TN和TP去除率分别达到81.5%、84.6%、88.8%、82.6%和98%.     

高负荷地下土壤法处理有机污水的模拟实验研究

针对传统地下污水渗滤系统的主要缺陷,提出了采用人工土壤提高系统的污水承载能力,采用多层过渡结构增大颗粒有机物的接触氧化表面积,采用高渗透性夹层增加氧气供应,以提高污水地下处理系统的水力负荷,延长其使用寿命.以我国南方典型的红壤土、砂和砾石为填充材料进行了实验室模拟实验,供试污水来自中国科学院广州地球化学研究所生活小区.结果显示,在25 cm/d的水力负荷下,系统没有被堵塞的迹象,采用每天2次投配污水的方式(每次12.5 cm),渗透系数为0.6 cm/min的土柱可以达到很好的出水效果,其COD、BOD5、SS、TN和TP去除率分别达到81.5%、84.6%、88.8%、82.6%和98%.     

Eco-restoration: Simultaneous nutrient removal from soil and water in a complex residential-cropland area

An eco-restoration system to remove excess nutrients and restore the agricultural ecosystem balance was proposed and applied from August 2006 to August 2008 in a residential-cropland complex area (1.4 × 10⁵ m²) in Kunming, western China, where the self-purifying capacity of the agricultural ecosystem had been lost. The proposed eco-restoration system examined includes three main foci: farming management, bioremediation, and wastewater treatment. The results showed that the removal efficiencies of total phosphorus (TP) and total nitrogen (TN) from the complex wastewater were 83% and 88%, respectively. The Simpson’s diversity indices of macrophytes and zoobenthos indicated that the system had increased macrophyte and zoobenthic diversity as well as improved growth conditions of the plankton habitats. The results demonstrated that the proposed eco-restoration system is a promising approach for decreasing the output of nutrients from soil, improving agricultural ecosystem health, and minimizing the downstream eutrophication risk for surface waters.     

A modified UCT method for biological nutrient removal: configuration and performance

A pilot-scale prototype activated sludge system is presented, which combines both, the idea of University of Cape Town (UCT) concept and the step denitrification cascade for removal of carbon, nitrogen and phosphorus. The experimental set-up consists of an anaerobic selector and stepwise feeding in subsequent three identical pairs of anoxic and oxic tanks. Raw wastewater with influent flow rates ranging between 48 and 168 l d(-1) was fed to the unit at hydraulic residence times (HRTs) of 5-18 h and was distributed at percentages of 60/25/15%, 40/30/30% and 25/40/35% to the anaerobic selector, 2nd and 3rd anoxic tanks, respectively (influent flow distribution before the anaerobic selector). The results for the entire experimental period showed high removal efficiencies of organic matter of 89% as total chemical oxygen demand removal and 95% removal for biochemical oxygen demand, 90% removal of total Kjeldahl nitrogen and total nitrogen removal through denitrification of 73%, mean phosphorus removal of 67%, as well as excellent settleability. The highest removal efficiency and the optimum performance were recorded at an HRT of about 9h and influent flow rate of 96 l d(-1), in which 60% is distributed to the anaerobic selector, 25% to the second anoxic tank and 15% to the last anoxic tank. Consequently, the plant configuration enhanced removal efficiency, optimized performance, saved energy, formed good settling sludge and provided operational assurance.     

螺旋升流式反应器脱氮除磷系统的运行效果与污泥性能分析

对螺旋升流式反应器脱氮除磷及去除COD的运行效果进行了研究 ,该系统连续稳定运行 6个月的结果表明 ,能保证出水平均质量浓度TN小于 1 0mg/L ,TP小于 0 5 0mg/L ,COD小于 31mg/L ,对TN、TP和COD的去除率分别达 86 %、96 %和 94 %以上。并且对SUFR系统的污泥性能进行了分析 :(1 )螺旋升流特征使本反应系统中的污泥易于颗粒化 ;(2 )SUFR系统中的微生物种群具有多样性 ;(3)污泥在好氧反应器中表现出了同步硝化反硝化功能 ;(4 )污泥在缺氧反应器表现出了反硝化吸磷现象     

COD/N对潜流人工湿地脱氮效能及N2O排放的影响

人工湿地因其低能耗、易管理的优点被广泛应用于水处理和生态修复,尤其在发展中国家有其适用性。为探讨COD/N对潜流人工湿地脱氮效能及氧化亚氮（N2O）的排放影响,分别构建5组微型人工湿地CW1~CK,进水化学需氧量/总氮（COD/N）分别为20：1、10：1、7：1、4：1和0：1。结果表明,湿地出水DO浓度均低于0.5 mg·L-1,不同的COD/N下无显著差异,但pH表现为随COD/N的升高而降低。进水COD/N为10、7和4的湿地中COD去除率在80%以上,而进水COD/N=20的湿地中COD去除率不足70%。5组COD/N湿地中氨氮（NH4+-N）的平均去除率依次为（61±16.6）%、（23±14.1）%、（30±12.5）%、（28±14.5）%和（74±7.0）%,在碳源充足或无碳源的条件下有利于NH4+-N的去除。除COD/N=0外,其余湿地中出水未检测到硝态氮（NO3--N）。湿地中总氮（TN）的去除变化与NH4+-N相似。5组湿地系统中,N2O的平均释放通量和累积排放量,分别在0.83~11.84 mg·（m2·h）-1和30.65~490.80 mg·m-2之间。COD/N=4的人工湿地系统中,N2O的平均释放通量和累计排放量显著高于其他处理（p2O形态去除的氮占系统去除TN的百分比为4.87%。COD/N对潜流人工湿地的脱氮和N2O减量具有调控作用。     

Effect of artificial aeration, temperature, and structure on nutrient removal in constructed floating islands

To study the optimal performance characteristics and maximize the removal efficiency of contaminants by the constructed floating islands (CFIs), four kinds of parallel pilot-scale CFIs with different structures were set up outdoors to treat eutrophic water for approximately 6 months. The contribution of artificial aeration to nutrient removal on the basis of gas-water ratios was investigated, and the influences of the structure and temperature were evaluated simultaneously. It was noted that the nutrient removal rate of the multi-medium CFI was greater than those of others. In the four kinds of units, aeration could significantly increase the nutrient removal efficiency, and a gas-water ratio of 10 was adequate for the relatively high removal of nutrients. Using the aforementioned gas-water ratio of 10 and a hydraulic residence time (HRT) of 2 days, the mean removal efficiencies of the multi-medium CFI for NH3-N and total phosphorus were 71.7% and 63.6%, respectively-approximately twice as great as those in the non-aerated system. Furthermore, temperature was an important factor for nutrient removal in the multi-medium CFI. With the water temperature of >13 degrees C and the HRT of 2.5 days, the mean removal efficiencies for NH3-N and total phosphorus were 87.6% and 83.5%, respectively, whereas the removal efficiency decreased significantly when the temperature was lower than 13 degrees C.     

Algae mediate submerged macrophyte response to nutrient and dissolved inorganic carbon loading: A mesocosm study on different species

Nutrient and dissolved inorganic carbon are two important factors that influence the development and species composition of submerged macrophyte communities in shallow lake ecosystems. Yet little is known about their potential interactive effects on the submerged macrophytes and competition outcome of macrophyte–phytoplankton. We performed a mesocosm experiment to investigate the growth and photosynthetic performance of three submerged macrophytes in relation to phytoplankton/epiphyton with nutrient and bicarbonate enrichment. During the experimental period (42 d), increase in nutrient loading in water column resulted in a substantial burst of phytoplankton and epiphyton growth and increased light attenuation. When combined with nutrient loading, bicarbonate enrichment also resulted in a heavily phytoplankton- and epiphyton-dominated state, although bicarbonate enrichment per se does not cause the phytoplankton and epiphyton growth. However, increase in nutrient loading in water column had significant negative impact on individual performances (growth and photosynthesis) of the three submerged macrophytes and bicarbonate enrichment increased the effect of eutrophication on two dissected-leaf macrophytes (M. spicatum and E. nuttallii). Furthermore, our results also suggest that species-specific photosynthetic performances occurred when submerged macrophytes in an environment with high abundance of phytoplankton/epiphyton. This study highlighted that increase in nutrient loading and bicarbonate in water column is likely to interactively impact both abiotic and biotic properties of a freshwater ecosystem. The interactions of these two factors could select macrophyte species that are able to resist the shading from phytoplankton/epiphyton, making these species more dominant in natural freshwater ecosystems.     

Effect of sludge-processing mode, soil texture and soil pH on metal mobility in undisturbed soil columns under accelerated loading

The effect of sludge processing (digested dewatered, pelletized, alkaline-stabilized, composted, and incinerated), soil type and initial soil pH on trace metal mobility was examined using undisturbed soil columns. Soils tested were Hudson silt loam (Glossaquic Hapludalf) and Arkport fine sandy loam (Lamellic Hapludalf), at initial pH levels of 5 and 7. Sludges were applied during four accelerated cropping cycles (215 tons/ha cumulative application for dewatered sludge; equivalent rates for other sludges), followed by four post-application cycles. Also examined (with no sludge applications) were Hudson soil columns from a field site that received a heavy loading of sludge in 1978. Romaine (Lactuca sativa) and oats (Avena sativa) were planted in alternate cycles, with oats later replaced by red clover (Trifolium pratense). Soil columns were watered with synthetic acid rainwater, and percolates were analyzed for trace metals (ICP spectroscopy), electrical conductivity and pH. Percolate metal concentrations varied with sludge and soil treatments. Composted sludge and ash had the lowest overall metal mobilities. Dewatered and pelletized sludge had notable leaching of Ni, Cd and Zn in Arkport soils, especially at low pH. Alkaline-stabilized sludge had the widest range of percolate metals (relatively insensitive to soils) including Cu, Ni, B and Mo. Old site column percolate concentrations showed good agreement with previous field data. Little leaching of P was observed in all cases. Cumulative percolate metal losses for all treatments were low relative to total applied metals. Leachate and soil pH were substantially depressed in dewatered and pelletized sludge soil columns and increased for alkaline-stabilized and ash treatments.     

The role of rhizofiltration and allelopathy on the removal of cyanobacteria in a continuous flow system

Environmental Science and Pollution Research - A continuous flow filtration system was designed to identify and quantify the removal mechanisms of Cyanobacteria (Microcystis aeruginosa) by...     

Influence of ozone stress on growth processes, yields and grain quality characteristics among soybean cultivars

Field studies were conducted at USDA Beltsville Agricultural Research Center, Beltsville, Maryland, in 1984 and 1985 using open-top chambers to acquire information on the responses of 12 soybean (Glycine max L. Merr.) cultivars to O3 stress and to examine the interactions between maturity groups and O3 stress. Cultivars representing Groups III, IV, and V were exposed for approximately 3 months to charcoal-filtered air (CF) and nonfiltered air plus 40 nl litre(-1) O3 (NF + O3). Ozone was added 6 h d(-1), 5 d week(-1) for 13 weeks. The CF effectively reduced the accumulative oxidant exposure (AOX) to less than 1.0 microl litre(-1) h and the NF + O3 treatment approximately doubled the ambient AOX (16.7 microl litre(-1) h) to about 30 microl litre(-1) h. The AOX estimates the total O3 exposure above 30 nl litre(-1) during an entire growing season. Plant growth rates and relative growth rates were reduced by 17.0 and 14.4%, respectively, when averaged over cultivars. Based on growth rates, the Group III cultivars were the most affected by O3 stress. Averaged over cultivars, leaf expansion rates, leaf conductance, and transpiration rates were lower in the NF + O3 treatment compared to the CF control; however, wide variation was found with the stomatal results from field observations. Combined over years and cultivars, grain yield was reduced by an average of 12.5% by O3 stress with 3 of 12 cultivars showing significant reductions. Grain protein content was increased by 0.7% by O3 stress, but cultivar differences were equal to the differences caused by the O3 treatments. Grain oil content was unchanged by the O3 treatments. Group IV cultivars showed the greatest decrease in grain yield due to O3 stress. Multiple regression analyses were calculated using the difference between the CF and NF + O3 treatment as a measure of O3 stress. Significant positive relationships were found among net assimilation rates, plant growth rates, relative growth rates, and leaf expansion rates, which suggest that growth analysis characteristics would be useful in addition to yield in air pollution tolerance improvement studies with soybeans.     

A study on the characteristics of silt loading on paved roads in the Seoul metropolitan area using a mobile monitoring system

This study is considered the first attempt to apply a mobile monitoring system to estimating silt loading on paved roads in a megacity such as the Seoul metropolitan area. Using a mobile monitoring system developed in 2005, we estimated silt loadings on representative paved roads in the Seoul metropolitan area, including the city of Incheon, over a period of 3 yr. The temporal and spatial characteristics of silt loading were investigated for the carefully selected roads that may reflect the characteristics of the cities of Seoul and Incheon. In this study, changes in the average silt loading values were investigated in terms of land use, the temporal resolution of data acquisition (i.e., seasonal, daily, three-hour scale), the road width or number of lanes, and rainfall, which may affect the characteristics of the average silt loading significantly. It was found that the advantages of using the mobile monitoring system are its ability to obtain a large quantity of silt loading data in a short period of time and over a wide area and its ability to create a silt loading map showing the relative magnitude of silt loading in relation to a specific location, which makes it possible to easily locate hot spots.     

A study on the characteristics of silt loading on paved roads in the Seoul metropolitan area using a mobile monitoring system

This study is considered the first attempt to apply a mobile monitoring system to estimating silt loading on paved roads in a mega-city such as the Seoul metropolitan area. Using a mobile monitoring system developed in 2005, we estimated silt loadings on representative paved roads in the Seoul metropolitan area, including the city of Incheon, over a period of 3 yr. The temporal and spatial characteristics of silt loading were investigated for the carefully selected roads that may reflect the characteristics of the cities of Seoul and Incheon. In this study, changes in the average silt loading values were investigated in terms of land use, the temporal resolution of data acquisition (i.e., seasonal, daily, three-hour scale), the road width or number of lanes, and rainfall, which may affect the characteristics of the average silt loading significantly. It was found that the advantages of using the mobile monitoring system are its ability to obtain a large quantity of silt loading data in a short period of time and over a wide area and its ability to create a silt loading map showing the relative magnitude of silt loading in relation to a specific location, which makes it possible to easily locate hot spots.

Implications: This study may be considered the first practical application of a mobile monitoring system to obtain the silt loading data on paved roads in a mega-city such as Seoul. It was found that the advantages of using the mobile monitoring system are its ability to obtain a large quantity of silt loading data in a short period of time and over a wide area and its ability to create a silt loading map showing the relative magnitude of silt loading in relation to a specific location, which makes it possible to easily locate hot spots to be cleaned cost-effectively by city officials.     

Impacts of organic carbon availability and recipient bacteria characteristics on the potential for TOL plasmid genetic bioaugmentation in soil slurries

The effectiveness of genetic bioaugmentation relies on efficient plasmid transfer between donor and recipient cells as well as the plasmid’s phenotype in the recipient cell. In the present study, the effects of varying organic carbon substrates, initial recipient-to-donor cell density ratios, and mixtures of known recipient bacterial strains on the conjugation and function of a TOL plasmid were tested in sterile soil slurry batch reactors. The presence of soil organic carbon was sufficient in ensuring TOL plasmid transconjugant occurrence (up to 2.1 ± 0.5%) for most recipient strains in soil slurry batch mating experiments. The addition of glucose had limited effects on transconjugant occurrence; however, glucose amendment increased the specific toluene degradation rates of some Enterobacteriaceae transconjugants in soil slurry. Initial cell density ratios and mixtures of recipient strains had smaller impacts on plasmid conjugation and resulting phenotype functionality. These observations suggest that genetic bioaugmentation may be improved by minimal altering of environmental conditions.     

Recent insights into greywater treatment: a comprehensive review on characteristics,treatment technologies,and pollutant removal mechanisms

Environmental Science and Pollution Research - With the rapid socio-economic and industrial development, the problem of water shortage is becoming increasingly serious. Seeking alternative water...     

Adaptation of the CAS test system and synthetic sewage for biological nutrient removal. Part II: design and validation of test units

A global increase in biological nutrient removal (BNR) applications in wastewater treatment and concern for potential effects of anthropogenic substances on BNR processes resulted in the adaptation of the Continuous Activated Sludge (CAS) laboratory test system (cf. guideline OECD 303A or ISO 11733). In this paper two novel systems are compared to the standard CAS unit: the Behrotest KLD4 and a University of Cape Town system (CAS-UCT). Both are 'single sludge' systems with an anoxic/aerobic and an anaerobic/anoxic/aerobic configuration, respectively. They both can simulate the essential processes of full-scale BNR installations. The units where fed with a specially designed synthetic sewage, Syntho (cf. Part I of this study), or its precursor BSR3 medium. The performance of the two new units was benchmarked against the standard CAS system in terms of carbon/nitrogen/phosphorus (C/N/P) removal, as well as primary biodegradation of the surfactants linear alkylbenzene sulfonate (LAS) and glucose amide (GA). Both systems allow to easily achieve stable excess N- and P-removal. Experimental C/N/P removal data compared closely with simulations obtained with the IAWQ Activated Sludge Model No. 2 (ASM2), and with full scale BNR plants with a similar configuration. In both units the effluent concentrations of the surfactants tested were significantly reduced in comparison to the standard CAS system (up to 50% less). No adverse effects on BNR were noted for the test surfactants dosed at 400 microg/l together with an overall surfactant background concentration in the feed of ca. 20 mg/l. The proposed systems hold potential to complement the standard CAS system for situations where advanced sewage treatment plants with BNR need to be simulated in the laboratory with minimum effort.     

Influences of thermal decontamination on mercury removal, soil properties, and repartitioning of coexisting heavy metals

Thermal treatment is a useful tool to remove Hg from contaminated soils. However, thermal treatment may greatly alter the soil properties and cause the coexisting contaminants, especially trace metals, to transform and repartition. The metal repartitioning may increase the difficulty in the subsequent process of a treatment train approach. In this study, three Hg-contaminated soils were thermally treated to evaluate the effects of treating temperature and duration on Hg removal. Thermogravimetric analysis was performed to project the suitable heating parameters for subsequent bench-scale fixed-bed operation. Results showed that thermal decontamination at temperature >400 °C successfully lowered the Hg content to <20 mg kg⁻¹. The organic carbon content decreased by 0.06-0.11% and the change in soil particle size was less significant, even when the soils were thermally treated to 550 °C. Soil clay minerals such as kaolinite were shown to be decomposed. Aggregates were observed on the surface of soil particles after the treatment. The heavy metals tended to transform into acid-extractable, organic-matter bound, and residual forms from the Fe/Mn oxide bound form. These results suggest that thermal treatment may markedly influence the effectiveness of subsequent decontamination methods, such as acid washing or solvent extraction.     

同步化学除磷对A2/O工艺除污染效能与活性污泥性能的影响

考察了A2/O同步化学除磷工艺中Al2（SO4）3投加量对TP、COD、NH4+-N和TN的去除率与活性污泥性能的影响。结果表明,常温（18~32℃）条件下同步化学除磷最适宜的Al2（SO4）3投加量为铝、磷摩尔比0.5：1,此条件下出水TP、COD、NH4+-N和TN浓度均能达到《城镇污水处理厂污染物排放标准》（GB 18918-2002）一级A标准。研究同时发现,Al2（SO4）3投加后,活性污泥的沉降性能和污泥活性均有所增强,其中SVI值由93.8 mL·g-1降至81.3 mL·g-1,Zeta电位由-5.5 mV降至-11.8 mV,胞外聚合物EPS含量增加了59.9%,蛋白质与多糖的比例由5.2降至2.1,比耗氧速率由4.2 mg·（g·min）-1升高到6.7 mg·（g·min）-1（以MLSS计）。微生物菌群结构分析结果表明,投药后污泥中微生物种类由投药前的8种减少为6种,硝化菌和反硝化菌比例有所降低,聚磷菌比例升高为6%。在低温（0~10℃）条件下,Al2（SO4）3投加量需有所增加,当铝、磷摩尔比为1：1时,反应器出水TP、COD、TN和NH4+-N浓度方可达到一级A标准。