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1.
Xianqiang Tang Suiliang Huang Miklas Scholz Jinzhong Li 《Water, air, and soil pollution》2009,197(1-4):61-73
Seven experimental pilot-scale subsurface vertical-flow constructed wetlands were designed to assess the effect of plants [Typha latifolia L. (cattail)], intermittent artificial aeration and the use of polyhedron hollow polypropylene balls (PHPB) as part of the wetland substrate on nutrient removal from eutrophic Jinhe River water in Tianjin, China. During the entire running period, observations indicated that plants played a negligible role in chemical oxygen demand (COD) removal but significantly enhanced ammonia–nitrogen (NH4–N), nitrate–nitrogen (NO3–N) total nitrogen (TN), soluble reactive phosphorus (SRP) and total phosphorus (TP) removal. The introduction of intermittent artificial aeration and the presence of PHPB could both improve COD, NH4–N, TN, SRP and TP removal. Furthermore, aerated wetlands containing PHPB performed best; the following improvements were noted: 10.38 g COD/m2 day, 1.34 g NH4–N/m2 day, 1.04 g TN/m2 day, 0.07 g SRP/m2 day and 0.07 g TP/m2 day removal, if compared to non-aerated wetlands without PHPB being presented. 相似文献
2.
To improve domestic wastewater treatment for total nitrogen (TN) removal, a full-scale constructed wetlands combining an artificially aerated vertical- (AVCW) and a horizontal-flow constructed wetland (HCW) was completed in July 2007. The system covered a total area of 7,610?m2. From 2 July 2007 to 7 August 2008, the treatment capacity was 2,076?m3?day?1 with an aeration quantity of 7,400?m3?day?1. The system effectively reduced the average annual output of BOD5 (52.0?%), NH4?CN (58.41?%), and TP (41.61?%), although the percentage reductions of other pollutants, including chemical oxygen demand (34.1?%), suspended solid (38.9?%), and TN (31.05?%) were lower. The purpose of the HCW was for denitrification of the effluent from the AVCW, and annual average of 34.27?% of NO3?CN was removed compared with the reading at the AVCW outlet. With hydraulic loading increased to 4,152?m3?day?1 from 9 September to 23 November 2007, the removal rate for NO3?CN from the HCW decreased substantially from 48.80 to 18.86?%. The total removal rates of NH4?CN showed significant positive correlation with DO content in the AVCW and with total TN removal rates for the combined system (P?<?0.05). The study indicated that, even with limited artificial aeration, nitrification was very effective for NH4?CN removal. 相似文献
3.
Pinpetch Boonsook Suphakam Luanmanee Tasnee Attanandana Akira Kamidouzono Tsuigiyuki Masunaga Toshiyuki Wakatsuki 《Soil Science and Plant Nutrition》2013,59(6):873-882
Abstract Multi-soil-layering (MSL) system was designed for purifying domestic wastewater and for treating polluted river water. MSL system is typically comprised of layers of soil mixture blocks alternating with permeable layers. The permeable layer has roles of preventing clogging and to increasing the efficiency of infiltration of wastewater through the soil mixture blocks. In this study, the comparative efficiency of five MSL systems as a function of five permeable layer materials (zeolite, zeolitized perlite, perlite, gravel, and charcoal) was investigated. The MSL systems were constructed in 15 × 50 × 100 cm boxes where the soil mixture blocks contained sandy clay soil, kenaf + corncob, and iron scraps at a ratio of 6 : 1 : 1 by weight, respectively, and filled up in alternation with the permeable layer. The results indicated that all the MSL systems at loading rates of 96–346 L m?2 d?1 under nonaerated conditions were able to reduce the levels of COD (342–1,231 mg L?1), BOD5 (201–802 mg L?1), and soluble reactive phosphorus (SRP) (3.5–10.1 mg P L?1) at percentages of 79.0–98.1, 80.0–99.6, and 97.1–100%, respectively. The zeolite and the charcoal-based MSL systems under a 96–346 L m?2 d?1 loading rate effectively reduced the level of TN (41.4–65.5 mg N L?1) at percentages of 79.0–92.1 and 30.7–88.9%, respectively. In terms of prevention of clogging, the charcoal-based MSL system was the most effective, followed by the gravel and zeolite-based MSL. The apparent efficiency of pollutant removal, for zeolitized perlite, perlite, and gravel-based MSL systems was low. With an on-off aeration operation, the efficiency of the MSL systems in the reduction of the levels of COD, BOD5 , and SRP (hereafter reference to as “removal”) was significantly enhanced. Overall, the zeolite-based MSL system seemed to be more effective than the other MSL systems. However, if optimum aeration could be obtained, the removal efficiency of charcoal-based MSL system might be improved. Aeration at a rate of 64,000 L m?3 d?1 for 1 week alternating with 2 weeks of nonaeration enhanced the removal of COD, BOD5 , and SRP but not that of TN. 相似文献
4.
In less populated rural areas constructed wetlands with a groundfilter made out of the local soil mixed with peat and planted
with common reed (Phragmites australis) are increasingly used to purify waste water. Particularly in the rhizosphere of the reed, nitrification and denitrification
processes take place varying locally and temporally, and the question arises to what extent this type of waste-water treatment
plant may contribute to the release of N2O. In situ N2O measurements were carried out in the two reed beds of the Friedelhausen dairy farm, Hesse, Germany, irrigated with the waste
water from a cheese dairy and 70 local inhabitants (12 m3 waste water or 6 kg BOD5 or 11 kg chemical O2 demand (CODMn) day–1). During November 1995 to March 1996, the release of N2O was measured weekly at 1 m distances using eight open chambers and molecular-sieve traps to collect and absorb the emitted
N2O. Simultanously, the N2O trapped in the soil, the soil temperature, as well as the concentrations of NH4
+-N, NO3
–-N, NO2
–-N, water-soluble C and the pH were determined at depths of 0–20, 20–40 and 40–60 cm. In the waste water from the in- and
outflow the concentrations of CODMn, BOD5, NH4
+-N, NO3
–-N, NO2
–-N, as well as the pH, were determined weekly. Highly varying amounts of N2O were emitted at all measuring dates during the winter. Even at soil temperatures of –1.5 °C in 10 cm depth of soil or 2 °C
at a depth of 50 cm, N2O was released. The highest organic matter and N transformation rates were recorded in the upper 20 cm of soil and in the
region closest to the outflow of the constructed wetland. Not until a freezing period of several weeks did the N2O emissions drop drastically. During the period of decreasing temperatures less NO3
–-N was formed in the soil, but the NH4
+-N concentrations increased. On average the constructed wetlands of Friedelhausen emitted about 15 mg N2O-N inhabitant equivalent–1 day–1 during the winter period. Nitrification-denitrification processes rather than heterotrophic denitrification are assumed to
be responsible for the N2O production.
Received: 28 October 1998 相似文献
5.
Mingchuan Zhang Peadar G. Lawlor Jianping Li Xinmin Zhan 《Water, air, and soil pollution》2012,223(5):1973-1981
In this study, the N2O emission from an intermittently aerated sequencing batch reactor (IASBR-1) treating the separated liquid fraction of anaerobically digested pig manure (SLAP) was investigated. The wastewater had chemical oxygen demand (COD) concentrations of 11,540?±?860?mg?l?1, 5-day biochemical oxygen demand (BOD5) concentrations of 2,900?±?200?mg?l?1and total nitrogen concentrations of 4,041?±?59?mg?l?1, with low COD:N ratios (2.9, on average) and BOD5:N ratios (0.72, on average). Synthetic wastewater, simulating the SLAP with similar COD and nitrogen concentrations but with higher BOD5 concentrations of up to 11,500?±?100?mg?l?1, was treated in another identical reactor (IASBR-2) to compare the effects of carbon source on nutrient removals and N2O emissions. In steady-state, soluble N2O accumulated in the non-aeration periods, with the highest N2O concentrations measured at the end of the non-aeration periods. There was a significant reduction in N2O concentrations during the aeration periods with reductions occurring immediately on commencement of aeration. The mean N2O emissions in an operational cycle were 253.6 and 205.3?mg for IASBR-1 and IASBR-2, respectively. During the non-aeration periods, only 8.3% and 8.4% of total N2O emissions occurred in IASBR-1 and IASBR-2, respectively; while during the aeration periods, 91.7% and 91.6% of N2O emissions took place in IASBR-1 and IASBR-2, respectively. The mean specific N2O generation rates were 0.010 and 0.005?mg (g VSS·min)?1 in the aeration periods, 0.024 and 0.021?mg (g VSS·min)?1 in the non-aeration periods for IASBR-1 and IABSR-2, respectively. Mean nitrogen removal via N2O emissions was 15.6% and 10.1% for IASBR-1 and IASBR-2, respectively. The IASBR-1 with low influent BOD5 concentrations emitted and generated more N2O. 相似文献
6.
Cyanobacteria are important for global nitrogen cycle and often form complex associations referred to as cyanobacterial mats
or periphyton that are common in tropical, limestone-based wetlands. The objective of this study was to monitor the nitrogen
fixation rate using the acetylene reduction assay of these cyanobacterial mats in a tropical, unfertilized, and protected
wetland. To account for temporal and spatial variation of nitrogenase activity, we were interested in seasons in a hydrological
cycle (dry, rains, and end of rains), sites with different vascular vegetation, and rates of nitrogenase activity in a 24-h
cycle. The annual average of nitrogenase activity was 22 nmol C2H4 cm−2 h−1, with a range of <6 to 35 nmol C2H4 cm−2 h−1, and the annual nitrogen fixation rate of our study site (9.0 g N m−2 year−1) is higher than similar estimates from other freshwater wetlands. There was a clear temporal pattern in nitrogenase activity
with a maximum rate occurring during the rainy season (August) and a maximum nitrogenase activity occurring between 0600 and
1200 hours. We found spatial differences in nitrogenase activity among the four sites that could be attributed to variations
in species composition within the periphyton. 相似文献
7.
Root zone microbial populations, urease activities, and purification efficiency for a constructed wetland 总被引:5,自引:0,他引:5
In order to investigate the effects of microorganisms and their urease activities in macrophytic root zones on pollutant removal, four small-scale plots (SSPs) of vertical/reverse-vertical flow wetlands were set up to determine: a) the relationship between the abundance of microorganisms in the root zones and water purification efficiency; and b) the relationship between urease activities in the root zones and pollutant removal in a constructed wetland system. Total numbers of the microbial population (bacteria, fungi, and actinomyces) along with urease activities in the macrophytic root zones were determined. In addition, the relationships between microbial populations and urease activities as well as the wastewater purification efficiencies of total phosphorus (TP), total Kjeldahl nitrogen (TKN), biochemical oxygen demand in 5 days (BOD5), and chemical oxygen demand (COD) were also analyzed. The results showed that there was a highly significant positive correlation (r = 0.9772, P < 0.01) between the number of bacteria in the root zones and BOD5 removal efficiency and a significant negative correlation (r = -0.9092, P < 0.05) between the number of fungi and the removal efficiency of TKN. Meanwhile, there was a significant positive correlation (r = 0.8830, P < 0.05) between urease activities in the root zones and the removal efficiency of TKN. Thus, during wastewater treatment in a constructed wetland system, microorganism and urease activities in the root zones were very important factors. 相似文献
8.
In this study, the effects of 1 h aeration, nitrogen gas N2(g) sparging (15 and 30 min) and increasing ferric ions (Fe+3) as FeSO4 (10, 20 and 50 mg L−1) and Fe3O4 nanoparticles (1, 2 and 4 g L−1) concentrations on three less hydrophobic and three more hydrophobic polycyclic aromatic hydrocarbons (PAHs) and toxicity
removals from a petrochemical industry in Izmir (Turkey) were investigated in a sonicator with a power of 650 W and an ultrasound
frequency of 35 kHz; 1 h aeration increased the yields in benzo[b]fluoranthene, benzo[k]fluoranthene and benzo[a]pyrene PAHs (less hydrophobic) from 62% to 67% to around 95–97% after 150 min sonication at 60°C. However, 1 h aeration did
not contribute to the yields of more hydrophobic PAHs (indeno[1,2,3-cd]pyrene, dibenz[a,h]anthracene, benzo[g,h,i]perylene). The maximum yields were obtained at acidic and alkaline pH for more and less hydrophobic PAHs, respectively, after
60 and 120 min sonication at 30°C; 30 min N2(g) sparging, 50 mg L−1 Fe+3 increased the yields of less hydropobic PAHs after 150 min sonication at 60°C. Two milligrams per liter of Fe3O4 nanoparticles increased both less (87–88%) and more (96–98%) hydrophobic PAH yields. The Daphnia magna acute toxicity test showed that the toxicity decreased significantly with an hour aeration, 30 min N2(g) sparging, 50 mg L−1 Fe+3 and 2 g L−1 Fe3O4 nanoparticles at 60°C after 120 and 150 min sonications. Vibrio fischeri was found to be more resistant to the sonicated samples than D. magna. Significant correlations were found between the physicochemical properties of sonicated PAHs and acute toxicities both organisms. 相似文献
9.
Dual isotope evaluations of NO3 - in groundwater adjacentto ditches within constructed riparian wetlands across the Kankakee watershed may assist the determination of denitrificationefficiency. Groundwater sampling indicates that NO3 --N exceeded 10 mg L-1 in constructed riparian wetlands but not innative wetlands within the riparian zones of the Kankakee basin. Anapparent local empirical threshold for nitrification occurs in groundwater near ditches with less then 1:11 depth to width dimensions within similar hydrogeology. The 15N and 18Ocomposition of groundwater nitrate varies widely in these constructed riparian wetlands. Groundwater nitrate associated with broader ditches (e.g. 1:35) most closely matches the denitrification isotope signature of native riparian wetlands in the basin. The geometry of various cut and fill landforms may need evaluation in engineering designs for constructed riparian wetlands to ensure the establishment of local natural groundwaterflow conditions for efficient nitrate attenuation. 相似文献
10.
Shaharah Mohd Idris Paul L. Jones Scott A Salzman Graeme Allinson 《Water, air, and soil pollution》2012,223(2):549-557
Two emergent macrophytes, Arundo donax and Phragmites australis, were established in experimental subsurface flow, gravel-based constructed wetlands (CWs) and challenged by untreated stormwater
collected from the hard-pan and other surfaces of a dairy processing factory in south-west Victoria, Australia. The hydraulic
loading rate was tested at two levels, sequentially, 3.75 and 7.5 cm day−1. Some of the monitored variables were removed more efficiently by the planted beds in comparison to unplanted CWs (biochemical
oxygen demand (BOD), total nitrogen (TN) and total phosphorus (TP); p < 0.007) but there was no significant difference between the A. donax and P. australis CWs in removal of BOD, suspended solids (SS) and TN (p > 0.007) at 3.75 cm day−1 or SS and TN at 7.5 cm day−1. At 3.75 cm day−1, BOD, SS, TN and TP removal in the A. donax and P. australis CWs was 71%, 61%, 78% and 75% and 65%, 60%, 73% and 41%, respectively. Nutrient removal at 7.5 cm day−1 in the A. donax and P. australis beds was 87%, 91%, 84% and 71% and 96%, 94%, 87% and 55%, respectively. As expected, the A. donax CWs produced considerably more biomass (10 ± 1.2 kg wet weight) than the P. australis CWs (2.7 ± 1.2 kg wet weight). This equates to approximately 107 and 36 tonnes ha−1 year−1 biomass (dry weight) for A. donax and P. australis, respectively (assuming 250 days of growing season and single-cut harvest). The performance similarity of the A. donax- and P. australis-planted CWs indicates that either may be used in HSSF wetlands treating dairy factory stormwater, although the planting of
A. donax provides additional opportunities for secondary income streams through utilisation of the biomass produced. 相似文献
11.
Aracelly Caselles-Osorio Patricia Villafa?e Vanessa Caballero Yelena Manzano 《Water, air, and soil pollution》2011,220(1-4):161-171
Subsurface-flow constructed wetlands technology (SSFW) has been used successfully for treating sanitary wastewater throughout North America and Europe. However, treatment wetland technologies have not been used extensively in the tropics. To advance tropical studies, a pilot-scale SSFW was constructed on the campus of the University of the Atlantic in Barranquilla, Colombia. The systems performance was monitored from January to July of 2009. The treatment system consisted of a 760-L septic tank followed by three mesocsom-scale subsurface-flow constructed wetlands in parallel arrangement. Clarified wastewater was batch loaded to each unit at a rate of 53 L/m2/day to affect a hydraulic retention time of approximately 3 days. One of the treatment units served as a non-planted control (gravel only), while the other two treatment units were planted with either Eriochloa aristata or Eleocharis mutata. The objective of this study was to evaluate the comparative efficacy of the treatment units (planted vs. unplanted), with respect to their abilities to augment treatment of septic tank effluent (sanitary wastewater). Monitored parameters included plant biomass, oxidation?Creduction potential, chemical oxygen demand (COD), temperature, dissolved oxygen, pH, ammonia?Cnitrogen (NH 4 + ?CN) nitrate?C and nitrite?Cnitrogen (NO3?CN, NO2?CN), phosphates (PO 4 ? ), and coliform bacteria. Total biomass (dry matter) was 2.84 and 0.87 Kg/m2 for E. aristata and E. mutata, respectively. Redox potential in the plant rizospheres averaged ?172 mV (±164.1) in E. aristata, 29 mV (±251.1) in E. mutata, and 32 mV (±210.5) in the unplanted control. COD removal was superior in planted vs. non-planted systems (>75% vs. 47%). Ammonia and total phosphorus removal averaged 69% and 85%, respectively, in planted systems versus 31% and 59% in the unplanted system. Removal of total and fecal coliforms averaged 96%. Results of this pilot study revealed that SSFW technology in the tropics can provide significant removal of organic matter, nutrients, and bacteria from clarified sanitary wastewater. 相似文献
12.
Jianping Luo Mei Ma Cao Liu Jinmiao Zha Zijian Wang 《Journal of Soils and Sediments》2009,9(3):180-187
Background, aim, and scope The potential of wetlands for controlling point- and nonpoint-source pollution in surface water has attracted increasing interest.
The partitioning process of organic contaminants between water, particulate organic carbon (POC) and dissolved organic carbon
(DOC), impacts their behaviors in the aquatic environments. Meantime, the partitioning process of organic contaminants is
closely related to their physicochemical properties, such as hydrophobicity (or K
ow), and their fates in wetlands may vary greatly depending on physicochemical properties. The aim of this study was to examine
fates and removals of polycyclic aromatic hydrocarbons (PAHs), organochlorine pesticides (OCPs) and nonylphenols (NPs) in
a wetland in Beijing, China, and provide useful information for ecological remediation.
Materials and methods Water samples, collected at five sites from inlet to outlet of the wetland once a month in summer 2006, were immediately filtered
within 2 days through 0.45-μm glass fiber prefilters and enriched by solid-phase extraction. The filtered particulates were
collected as the total suspended particulates (TSPs), freeze-dried, and Soxhlet-extracted. After extraction, samples were
purified following a clean-up procedure and analyzed by GC-MS.
Results TSPs could be removed efficiently with a removal rate of 97.4%, and DOC could be moderately removed with a removal rate of
44.7% from inlet to outlet. The total removals of target contaminants varied widely from null to 82.0%. A good correlation
between logK
ow and logK
oc (organic-carbon-normalized suspended-particulate partition coefficient) was observed (r
2 = 0.84 for PAHs and r
2 = 0.86 for OCPs, p < 0.01). Ratios of the POC-bound fraction of target contaminants (or DOC-bound fraction) to the freely dissolved fraction
increased with their K
ow values. The removal of the POC fraction contributed more than 50% to the total removal for the contaminants with logK
ow > 5.0. Only a small portion of the removal was attributed to the removal of the freely dissolved fraction.
Discussion Hydrophobic compounds such as PAHs and OCPs with higher K
ow values would show stronger POC or DOC preference. Their removal depended greatly on their K
ow values and the removal of total suspended particulates. On the other hand, concentrations of NPs decreased little in the
wetland, probably due to their production through degradation of their precursors and relatively low hydrophobicity.
Conclusions POC and DOC play essential roles on the fates and removals of hydrophobic organic contaminants in the wetland. The removal
of target contaminants with a high K
ow should be mainly through association with the suspended particulates which were precipitated and retained in the wetland.
The fates of the organic contaminants in the wetland greatly depended on their hydrophobicities.
Recommendations and perspectives Further work should be done to study the influence of hydraulic retention time and some other environmental factors, e.g.,
temperature, on removals and fates of organic contaminants. Behavior of NPs and their precursors in the wetland should also
be investigated more thoroughly. 相似文献
13.
Angela Bedard-Haughn Amanda L. Matson Dan J. Pennock 《Soil biology & biochemistry》2006,38(12):3398-3406
Stable 15N isotope dilution and tracer techniques were used in cultivated (C) and uncultivated (U) ephemeral wetlands in central Saskatchewan, Canada to: (1) quantify gross mineralization and nitrification rates and (2) estimate the relative proportion of N2O emissions from these wetlands that could be attributed to denitrification versus nitrification-related processes. In-field incubation experiments were repeated in early May, mid-June and late July. Mean gross mineralization and nitrification rates (10.3 and 3.1 mg kg−1 d−1, respectively) did not differ between C and U wetlands on any given date. Despite these similarities, the mean NH4+ pool size in the U wetlands (17.2 mg kg−1) was two to three times that of the C wetlands (6.7 mg kg−1) whereas the mean NO3− pool size in U wetlands (2.2 mg kg−1) was less than half that of C wetlands (5.8 mg kg−1). Mean N2O emissions from the C wetlands decreased from 112.8 to 17.0 ng N2O m2 s−1 from May to July, whereas mean U-wetland N2O emissions ranged only from 31.8 to 51.1 ng N2O m2 s−1 over the same period. This trend is correlated to water-filled pore space in C wetlands, demonstrating a soil moisture influence on emissions. Denitrification is generally considered the dominant emitter of N2O under anaerobic conditions, but in the C wetlands, only 49% of the May emissions could be directly attributed to denitrification, decreasing to 29% in July. In contrast, more than 75% of the N2O emissions from the U wetlands arose from denitrification of the soil NO3− pool throughout the season. These land use differences in emission sources and rates should be taken into consideration when planning management strategies for greenhouse gas mitigation. 相似文献
14.
[目的] 估算湖北省鄂州市净初级生产力(net primary productivity,NPP)以及固碳释氧量,探索一种适用于中小尺度上,涉及大量水体的湿地NPP估算方法,为制定相关湿地生态保护政策提供更为准确的数据支撑。[方法] 构建湿地分类模型,将鄂州市湿地划分为浅水地表湿地与深水水体湿地。对浅水地表湿地,采用基于遥感影像的光能利用率模型进行NPP估算;对深水水体湿地,引入叶绿素a与生物量指标,构建回归模型,对湿地水体NPP进行估算。汇总两者的估算结果,得到鄂州市湿地2020年度NPP总量及其空间分布和固碳释氧量。[结果] 鄂州市湿地2020年度净初级生产力总量为2.99×105 t (以C计),CO2的固定量为4.87×105 t,O2的释放量为3.59×105 t,整体上呈现南高北低的分布格局。[结论] 采用湿地分类的方法,对深水水体湿地NPP单独进行估算,弥补了基于遥感影像的模型估算方法中对湿地水体部分估算的不足,使估算结果更接近湿地真实水平,采用的模型方法可为类似涉及水体的湿地NPP估算工作提供一种新思路和方法。 相似文献
15.
Nitrous oxide emission from wetland rice soil as affected by the application of controlled-availability fertilizers and mid-season aeration 总被引:5,自引:0,他引:5
N2O emission from a wetland rice soil as affected by the application of three controlled-availability fertilizers (CAFs) and
urea was investigated through a pot experiment. N2O fluxes from the N fertilized paddy soil averaged 44.8–69.3 μg N m–2 h–1 during the rice growing season, accounting for 0.28–0.51% of the applied N. The emission primarily occurred during the mid-season
aeration (MSA) and the subsequent re-flooding period. Fluxes were highly correlated with the NO3
– and N2O concentrations in the soil water. As there were relatively large amounts of NH4
+-N present in the soil of the CAF treatments at the beginning of MSA, leading to large amounts of NO3
–-N during the MSA and the subsequent re-flooding period, the tested CAFs were not effective in reducing N2O emission from this paddy soil. The potential of applied CAFs to reduce N2O emissions from paddy soil is discussed.
Received: 25 May 1999 相似文献
16.
Hassana Ibrahim Mustapha J. J. A. van Bruggen P. N. L. Lens 《Water, air, and soil pollution》2018,229(4):137
Typha latifolia-planted vertical subsurface flow constructed wetlands (VSSF CWs) can be used to treat petroleum refinery wastewater. This study evaluated if the removal efficiency of VSSF CWs can be improved by changing the plant species or coupling horizontal subsurface flow constructed wetlands (HSSF CWs) to the VSSF CW systems. The VSSF CWs had a removal efficiency of 76% for biological oxygen demand (BOD5), 73% for chemical oxygen demand (COD), 70% for ammonium-N (NH4+-N), 68% for nitrate-N (NO3?-N), 49% for phosphate (PO43?-P), 68% for total suspended solids (TSS), and 89% for turbidity. The HSSF CWs planted with T. latifolia further reduced the contaminant load of the VSSF CW-treated effluent, giving an additional removal efficiency of 74, 65, 43, 65, 58, 50, and 75% for, respectively, BOD5, COD, NH4+-N, NO3?-N, PO43?-P, TSS, and turbidity. The combined hybrid CW showed, therefore, an improved effluent quality with overall removal efficiencies of, respectively, 94% for BOD5, 88% for COD, 84% for NH4+-N, 89% for NO3?-N, 78% for PO43?-P, 85% for TSS, and 97% for turbidity. T. latifolia strived well in the VSSF and HSSF CWs, which may have contributed to the high NH4 +-N, NO3?-N, and PO43?-P removal efficiencies. T. latifolia-planted VSSF CWs showed a higher contaminant removal efficiency compared to the unplanted VSSF CW. T. latifolia is thus a suitable plant species for treatment of secondary refinery wastewater. Also a T. latifolia-planted hybrid CW is a viable alternative for the treatment of secondary refinery wastewater under the prevailing climatic conditions in Nigeria. 相似文献
17.
《国际水土保持研究(英文)》2019,7(3):286-296
The use of constructed wetlands to treat municipal wastewater reduces energy consumption and therefore economic costs, as well as reduces environmental pollution. The purpose of this study was to compare the purification capacity of domestic wastewater using two species of plants sown in subsurface constructed wetlands with vertical flow built on a small scale that received municipal wastewater with primary treatment. The species used were Phragmites Australis and Cyperus Papyrus. For this purpose, a constant flow of 0.6 m3 day−1 was fed from the primary lagoon to each of the two wetlands built on a pilot scale with continuous flow. Each unit was filled with granite gravel in the lower part and with silicic sand in the upper part of different granulometry, the porosity of the medium was 0.34, with a retention time of 1.12 days and a hydraulic load rate of 0.2 m day−1. To analyze the purification capacity of wastewater, physical, chemical and biological parameters were monitored during three months. Samples were taken at the entrance and exit in each experimental unit. The results obtained in the experimental tests for the two species of plants, indicated that the Cyperus Papyrus presented a greater capacity of pollutants removal as biochemical oxygen demand (80.69%), chemical oxygen demand (69.87%), ammoniacal nitrogen (69.69%), total phosphorus (50%), total coliforms (98.08%) and fecal coliforms (95.61%). In the case of Phragmites Australis retains more solids. The species with greater efficiency in the treatment of municipal wastewater for this study was Cyperus Papyrus. 相似文献
18.
Constructed wetlands for the treatment of organic pollutants 总被引:2,自引:1,他引:2
Raimund Haberl Stefano Grego Günter Langergraber Robert H. Kadlec Anna-Rita Cicalini Susete Martins Dias Julio M. Novais Sylvie Aubert Andre Gerth Hartmut Thomas Anja Hebner 《Journal of Soils and Sediments》2003,3(2):109-124
Background Constructed wetlands (wetland treatment systems) are wetlands designed to improve water quality. They use the same processes
that occur in natural wetlands but have the flexibility of being constructed. As in natural wetlands vegetation, soil and
hydrology are the major components. Different soil types and plant species are used in constructed wetlands. Regarding hydrology
surface flow and subsurface flow constructed wetlands are the main types. Subsurface flow constructed wetlands are further
subdivided into horizontal or vertical flow. Many constructed wetlands deal with domestic wastewater where BOD and COD (Biochemical
and Chemical Oxygen Demand respectively) are used as a sum parameter for organic matter. However, also special organic compounds
can be removed.
Objective The objectives are to summarise the state-of-the-art on constructed wetlands for treatment of specific organic compounds,
to the present the lack of knowledge, and to derive future research needs.
Methods Case studies in combination with a literature review are used to summarise the available knowledge on removal processes for
specific organic compounds.
Results and Discussion Case studies are presented for the treatment of wastewaters contaminated with aromatic organic compounds, and sulphonated
anthraquinones, olive mill wastewater, landfill leachate, and groundwater contaminated with hydrocarbons, cyanides, chlorinated
volatile organics, and explosives. In general the removal efficiency for organic contaminants is high in all presented studies.
Conclusion Constructed wetlands are an effective and low cost way to treat water polluted with organic compounds. There is a lack of
knowledge on the detailed removal pathways for most of the contaminants. Removal rates as well as optimal plant species are
substance-specific, and also typically not available. If a constructed wetland provides different environmental conditions
and uses different plant species the treatment efficiency can be improved.
Recommendations and Outlook There is a great need to lighten the black box ‘constructed wetland’ to obtain performance data for both microbial activity
and the contribution of the plants to the overall removal process. Also genetic modified plants should be considered to enhance
the treatment performance of constructed wetlands for specific compounds. 相似文献
19.
N transformation rates in soil from a riparian wetland that receives runoff from adjacent pastoral land were investigated in a short-term (250 min), anaerobic laboratory incubation (20°C). A joint 15N tracing-isotope dilution technique was employed that used paired incubations of labelled (99 atom % 15N) NO3–-unlabelled NH4+ and unlabelled NO3–-labelled (99 atom % 15N) NH4+ at three N input levels (0.4, 4 and 24 g N g–1 soil). At each N input level NO3– and NH4+ were added in equal proportions (0.2, 2 and 12 g N g–1 soil). Soil and gas samples were analysed after 10, 70 and 250 min, and the fate of 15N and N transformation rates were determined for each time period; 0–10 min (phase 1), 10–70 min (phase 2) and 70–250 min (phase 3). N transformation rates for all processes except gross NH4+ mineralisation were very high during phase 1. Processes favoured by aerobic conditions, NO3– immobilisation (0–17% NO3– removal, 0–8.2 g N g–1 soil h–1), autotrophic nitrification (~2% NH4+ removal, 0.58–0.88 g N g–1 soil h–1) and heterotrophic nitrification (11–35 g N g–1 soil h–1) increased with increased N input while the anaerobic dissimilatory NO3– reduction to NH4+ process (1–6% NO3– removal, 0.48–0.62 g N g–1 soil h–1) decreased, presumably due to the oxidising effect of higher NO3– inputs. Denitrification (8–78% NO3– removal, 3.8–9.6 g N g–1 soil h–1) exhibited no clear trend related to N input levels. NH4+ immobilisation (39–72% NH4+ removal, 15–19 g N g–1 soil h–1) was higher than NO3– immobilisation. Gross NH4+ mineralisation (0.27–0.80 g N g–1 soil h–1) was the only process not detected in phase 1 and one of few processes measurable in phases 2 or 3. 相似文献
20.
Nitrous oxide emissions from an irrigated sandy-clay loam cropped to maize and wheat 总被引:4,自引:0,他引:4
Nitrous oxide (N2O) emissions were measured from an irrigated sandy-clay loam cropped to maize and wheat, each receiving urea at 100 kg N ha–1. During the maize season (24 August–26 October), N2O emissions ranged between –0.94 and 1.53 g N ha–1 h–1 with peaks during different irrigation cycles (four) ranging between 0.08 and 1.53 g N ha–1 h–1. N2O sink activity during the maize season was recorded on 10 of the 29 sampling occasions and ranged between 0.18 and 0.94 g
N ha–1 h–1. N2O emissions during the wheat season (22 November–20 April) varied between –0.85 and 3.27 g N ha–1 h–1, whereas peaks during different irrigation cycles (six) were in the range of 0.05–3.27 g N ha–1 h–1. N2O sink activity was recorded on 14 of the 41 samplings during the wheat season and ranged between 0.01 and 0.87 g N ha–1 h–1. Total N2O emissions were 0.16 and 0.49 kg N ha–1, whereas the total N2O sink activity was 0.04 and 0.06 kg N ha–1 during the maize and wheat seasons, respectively. N2O emissions under maize were significantly correlated with denitrification rate and soil NO3
–-N but not with soil NH4
+-N or soil temperature. Under wheat, however, N2O emissions showed a strong correlation with soil NH4
+-N, soil NO3
–-N and soil temperature but not with the denitrification rate. Under either crop, N2O emissions did not show a significant relationship with water-filled pore space or soil respiration.
Received: 11 June 1997 相似文献