Constructed treatment wetland: a study of eight plant species under saline conditions

A series of investigations was conducted to evaluate the feasibility of using constructed treatment wetlands to remove pollutants from saline wastewater. Eight emergent plants; cattail, sedge, water grass, Asia crabgrass, salt meadow cordgrass, kallar grass, vetiver grass and Amazon, were planted in experimental plots and fed with municipal wastewater that was spiked with sodium chloride (NaCl) to simulate a saline concentration of approximately 14-16 mScm-1. All macrophytes were found tolerant under the tested conditions except Amazon and vetiver grass. Nutrient assimilation of salt tolerant species was in the range of 0.006-0.061 and 0.0002-0.0024 gm-2d-1 for nitrogen and phosphorus, respectively. Treatment performances of planted units were found to be 72.4-78.9% for BOD5, 43.2-56.0% for SS, 67.4-76.5% for NH3-N and 28.9-44.9% for TP. The most satisfactory plant growth and nitrogen assimilation were found for cattail (Typha angustifolia) though the plant growth was limited, whereas Asia crabgrass (Digitaria bicornis) was superior for BOD5 removal. Both were evaluated again in a continuous flow constructed wetland system receiving saline feed processing wastewater. A high removal rate regularly occurred in long-term operating conditions. The reduction in BOD5, SS, NH3-N and TP was in the range of 44.4-67.9%, 41.4-70.4%, 18.0-65.3% and 12.2-40.5%, respectively. Asia crabgrass often provided higher removal especially for BOD5 and SS removal. Nutrient enriched wastewater promoted flourishing growth of algae and plankton in the surface flow system, which tended to reduce treatment performance.     

Evaluation of the giant reed (Arundo donax) in horizontal subsurface flow wetlands for the treatment of dairy processing factory wastewater

Two emergent macrophytes, Arundo donax and Phragmites australis, were established in experimental horizontal subsurface flow (HSSF), gravel-based constructed wetlands (CWs) and challenged by treated dairy processing factory wastewater with a median electrical conductivity of 8.9 mS cm(-1). The hydraulic loading rate was tested at 3.75 cm day(-1). In general, the plants grew well during the 7-month study period, with no obvious signs of salt stress. The major water quality parameters monitored (biological oxygen demand (BOD), suspended solids (SS) and total nitrogen (TN) but not total phosphorus) were generally improved after the effluent had passed through the CWs. There was no significance different in removal efficiencies between the planted beds and unplanted gravel beds (p?>?0.007), nor was there any significant difference in removal efficiencies between the A. donax and P. australis beds for most parameters. BOD, SS and TN removal in the A. donax and P. australis CWs was 69, 95 and 26 % and 62, 97 and 26 %, respectively. Bacterial removal was observed but only to levels that would allow reuse of the effluent for use on non-food crops under Victorian state regulations. As expected, the A. donax CWs produced considerably more biomass (37?±?7.2 kg wet weight) than the P. australis CWs (11?±?1.4 kg wet weight). This standing crop equates to approximately 179 and 68 tonnes ha(-1) year(-1) biomass (dry weight) for A. donax and P. australis, respectively (assuming a 250-day 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 wastewater, although the planting of A. donax provides additional opportunities for secondary income streams through utilisation of the biomass produced.     

不同组合垂直潜流式人工湿地对高碳或氮污水的净化效果

4种组合的垂直潜流式人工湿地在高C和高N污染物负荷条件下都可以得到很好的污染物降解效果.VDFVUF湿地组合被确定为最优的组合,它在夏末(7月和8月)和初秋(9月)可以得到较高的污染物去除率,且在8月份可以达到最大值.VDF-VUF湿地组合对于COD、TN和TP去除率的平均值在高C污染物负荷条件下分别为(96.97 ±6.32)％、(89.45 ±5.29)％和(83.12±6.03)％;在高N污染物负荷条件下分别为(93.21±7.84)％、(94.27±4.36)％和(82.36±5.52)％.各种人工湿地组合的COD和TN的去除率都受到了季节变化、湿地组合类型以及这两者的综合效应的显著影响;但是TP的去除率则不受任何因素的显著影响.     

复合人工湿地对高污染性河流营养物的去除

为了研究复合人工湿地对高污染性河流营养物的去除效果，在西安皂河人渭处建立了一座占地约13334m。包括5组不同复合人工湿地工艺的中试系统。经过1年的实验研究表明，复合型人工湿地对COD、BOD。和ss有很好的去除效果，其去除率最高分别为（82．4±7．2）％、（97．1±1．7）％和（94±2．7）％，对于脱氮除磷而言，以水力停留时间4．1d的复合湿地系列4的处理效果最佳，对TN、NH3-N和TP的年去除率达（79．4±14）％、（79．2±13．7）％和（82．3±12）％。氮的去除效果受温度季节性变化影响较大，夏季平均水温高于19℃有更好的处理效果，磷的去除效果受温度影响不大；NO2-、NO3-去除率呈现负增长，在湿地尾端出现了不同程度的积累。     

交替缺氧/好氧CAST工艺污染物去除特性

以模拟城市污水为处理对象,采用循环式活性污泥法(CAST)反应器,对交替缺氧/好氧模式下系统去除污染物的性能进行了研究。结果表明,运行期间系统内有机物的去除率稳定,出水COD小于40 mg/L,COD平均去除率为91.7%;NH4+-N、TN的平均去除率分别为83.9%、72.4%,出水TN以NO3--N为主;系统的除磷性能良好,磷酸盐的平均去除率为90.6%。此外,出水COD、TN和TP均达到《城镇污水处理厂污染物排放标准》(GB-18918-2002)的一级A要求。     

COD对生物除磷颗粒污泥稳定性影响研究

颗粒污泥稳定性是影响其应用的主要因素之一.以SBR中成熟的生物除磷颗粒污泥为研究对象,探讨进水COD浓度对系统稳定性的影响.结果表明,当进水COD浓度由300 mg/L逐渐升高到500 mg/L时,磷去除率由93%降低到88%;当进水COD浓度在400 mg/L以下时,污泥的最大比释磷速率和比吸磷速率分别为45.2 m...     

常规组合工艺-稳定塘-湿地系统处理印染废水

针对工业园区印染企业产生的印染废水和生活污水,采用独特的"常规组合工艺与‘植物稳定塘-人工湿地系统’联合工艺"对其进行集中统一处理,并考察了运行效果。数据结果表明,系统出水COD、BOD5、SS、色度、NH3-N和TP平均分别为63.2 mg/L、13.8 mg/L、5.0 mg/L、49倍、0.2 mg/L和0.4 mg/L,出水水质达到国家污水综合排放一级标准(GB8978-1996)。该工艺运行稳定,可有效去除废水中的COD、SS和色度,去除率均在90%以上。按日均处理量4×104m3计算,此工艺每年将削减COD排放近30万t。     

Dairy manure treatment, digestion and nutrient recovery as a phosphate fertilizer

A combined approach of biological treatment, solids digestion and nutrient recovery was tested on dairy manure. A sequencing batch reactor (SBR) was operated in three modes, in order to optimize nutrient (nitrogen and phosphorus) removals. The highest average removal efficiencies of 91% for NH4-N, 59% for PO4-P and 80% for total chemical oxygen demand (COD) were achieved. Staining experiments suggested the coexistence of glycogen and phosphorus accumulating organisms. Anaerobic digestion of wasted bio-solids was able to produce a PO4-P concentration of 70 mgL-1 in the supernatant. A pilot-scale experiment, designed to recover phosphorus in the supernatant as struvite (magnesium ammonium phosphate), was able to remove 82% of soluble PO4-P.     

垂直流人工花卉湿地模拟系统净化污水的效果

通过在垂直流模拟人工土柱上种植不同的花卉植物，研究了垂直流花卉人工湿地对污水COD、BOD5、TN和TP的净化效果的影响。结果表明，所选用的5种陆生花卉，甚至鲜切花卉对化粪池污水有比较好的净化效果，它们对BOD5的去除率可达到92．04％以上，对TP的去除率甚至可达到97．77％以上。而且种植花卉植物的人工湿地出水水质要好于不种植物的对照湿地系统。     

Hierarchical eco-restoration: A systematical approach to removal of COD and dissolved nutrients from an intensive agricultural area

A systematical approach based on hierarchical eco-restoration system for the simultaneous removal of COD and dissolved nutrients was proposed and applied in a complex residential-cropland area in Kunming, China from August 2006 to August 2008, where the self-purifying capacity of the agricultural ecosystem had been lost. The system includes four main parts: (1) fertilizer management and agricultural structure optimization, (2) nutrients reuse, (3) wastewater treatment, and (4) catchment restoration. The results showed that the average removal efficiencies were 90% for COD, 93% for ammonia, 94% for nitrate and 71% for total dissolved phosphorus (TDP) when the hierarchical eco-restoration agricultural system was in a relatively steady-state condition. The emergence of 14 species of macrophytes and 4 species of zoobenthos indicated that the growth conditions for the plankton were improved. The results demonstrated that this promising and environmentally benign hierarchical eco-restoration system could decrease the output of nutrients and reduce downstream eutrophication risk.     

微絮凝-直接过滤工艺在城市污水深度处理中的应用研究

微絮凝 -直接过滤工艺是一种将混凝反应、沉淀截留集中在同一滤柱内同步完成的高效水处理工艺。该工艺应用于城市污水的深度处理中 ,通过絮凝剂的加入 ,具有同步去除PO3 -4 P、SS和部分COD的功能。本文研究了该工艺对二级处理出水中PO3 -4 P、SS和COD的去除效果及其规律。研究表明 :采用聚合氯化铁 (PFC)作为絮凝剂 ,当Fe/P摩尔比为 2∶1时 ,水中PO3 -4 P的去除率达 98.8% ,浓度可降至 0 .1mg/L以下 ,同时SS、COD去除率也有明显提高。与传统的混凝、沉淀除磷工艺相比 ,该工艺具有操作简单、结构紧凑、占地面积小、污泥量少等优点 ,是一种更为经济和简单的处理单元 ,适用于现有城市污水处理厂的除磷和进一步提高水质的深度处理     

高盐工业废水人工湿地处理中植物的筛选

通过人工湿地中试实验,考察了芦苇、睡莲、水葱、狭叶香蒲和宽叶香蒲水生植物单元对经生化处理的石油和精细化工工业区的工业废水中盐含量较高、氮磷营养盐含量较低和化学需氧量(COD)含量较高的废水中污染物的去除情况,研究了在植物不同生长阶段系统中COD的去除同盐度之间的关系,探讨了盐度差异对植物生长状况的影响,为确定人工湿地适合的进水盐度,达到有效去除高含盐量工业废水中有机污染物提供依据。结果表明,芦苇、睡莲和狭叶香蒲3种植物单元内高含盐量工业废水中污染物的净化效果较水葱和宽叶香蒲单元的净化效果好:前3种植物单元内COD、生化需氧量(BOD)和总磷(TP)的去除率大约在38%、55%和62%左右,而水葱和宽叶香蒲2种植物单元内COD、BOD和TP的去除率大约在30%、36%和52%左右;系统中各个单元内总氮(TN)去除率都在85%以上。在植物的不同生长阶段,人工湿地系统中氯离子浓度与COD浓度之间的相关性存在差异:植物生长初期,系统中氯离子浓度与系统中COD浓度之间无显著相关性,而在植物生长旺期和末期,两者则成正相关关系。因此,需根据植物的生长阶段调整人工湿地的进水盐度。     

一体化生物膜技术处理滨海农村污水

对厌氧-3级好氧/缺氧生物膜工艺进行技术改进,并对改进后的"一体化生物膜技术"处理低碳氮比农村生活污水进行了实际应用。新工艺增设了回流泵(回流比2∶1),且厌氧段悬浮填料装填率由原来的15%提高到30%,3级好氧/缺氧段YDT型弹性立体填料装填率依次由原来的50%、40%、25%提高到70%、60%和40%。装置连续稳定运行12个月,平均进水量为18 m3/d,HRT为3.7 d,监测结果表明:对COD、BOD、NH3-N、TN、TP和SS平均去除率分别为75.6%、85.9%、86.7%、63.9%、69.3%和85.5%;出水COD、BOD、NH3-N、TN、TP和SS的平均浓度分别在34.9、8.9、3.4、9.9、0.9和6.9 mg/L以下。改进后出水BOD和TN的去除能力有较大提高,除TP外其他各项指标均达到了设计要求。     

反硝化除磷的影响特性试验

采用SBR反应器(厌氧/缺氧/好氧工艺),分别研究了乙酸盐及硝酸盐浓度变化对反硝化除磷的影响特性。试验结果表明,当进水COD浓度>230mg/L时,乙酸盐浓度的变化对释磷、除磷速率等影响并不显著。在硝酸盐浓度<30mg/L时,硝酸盐浓度越高,缺氧段除磷速率也就越高。在C/P>23,C/N>5条件下,SBR系统对磷、氮去除率在90%以上。     

Simultaneous nitrification and denitrification with anoxic phosphorus uptake in a membrane bioreactor system.

The performance of an innovative membrane bioreactor (MBR) process using anoxic phosphorus uptake with nitrification and denitrification for the treatment of municipal wastewater with respect to operational performance and effluent quality is addressed in this paper. The system was operated at steady-state conditions with a synthetic acetate-based wastewater at a hydraulic retention time (HRT) of 12 hours and on degritted municipal wastewater at a total system HRT of 6 hours. The MBR system was able to achieve 99% biochemical oxygen demand (BOD), chemical oxygen demand (COD), and ammonia-nitrogen (NH4(+)-N); 98% total Kjeldahl nitrogen (TKN); and 97% phosphorus removal, producing effluent BOD, COD, NH4+-N, TKN, nitrate-nitrogen, nitrite-nitrogen, and phosphate-phosphorus of <3, 14, 0.2, 0.26, 5.8, 0.21, and <0.01 mg/L, respectively, at the 6-hour HRT. The comparison of the synthetic and municipal wastewater run is presented in this paper. Steady-state mass balance on municipal wastewater was performed to reveal some key features of the modified MBR system.     

Dairy Manure Treatment,Digestion and Nutrient Recovery as a Phosphate Fertilizer

A combined approach of biological treatment, solids digestion and nutrient recovery was tested on dairy manure. A sequencing batch reactor (SBR) was operated in three modes, in order to optimize nutrient (nitrogen and phosphorus) removals. The highest average removal efficiencies of 91% for NH₄-N, 59% for PO₄-P and 80% for total chemical oxygen demand (COD) were achieved. Staining experiments suggested the coexistence of glycogen and phosphorus accumulating organisms. Anaerobic digestion of wasted bio-solids was able to produce a PO₄-P concentration of 70 mgL^?1 in the supernatant. A pilot-scale experiment, designed to recover phosphorus in the supernatant as struvite (magnesium ammonium phosphate), was able to remove 82% of soluble PO₄-P.     

Performance of a submerged membrane bioreactor system for biological nutrient removal.

A pilot submerged membrane bioreactor coupled with biological nutrient removal was used to treat the primary effluent at a municipal wastewater treatment plant. Long-term experiments were conducted by varying hydraulic retention time from 6 to 8 hours and solids retention time from 20 to 50 days, respectively. The performance was assessed by monitoring key wastewater parameters, including chemical oxygen demand (COD), nitrogen, and phosphorus concentration in individual anoxic, anaerobic, aerobic, and membrane separation zones. Results showed that the tested system can consistently achieve COD, nitrogen, and phosphorus removal efficiencies at 80 to 98%, 70 to 93%, and 89 to 98%, respectively. Effluent COD remained low as a result of efficient solid retention, even though there was great variation in influent quality. However, total nitrogen increased proportionally with influent concentration. At a 50-day solids retention time, higher COD and nitrogen oxides specific utilization rates in the anoxic zone resulted in a high production of nitrogen oxides in the subsequent aerobic zone.     

禽类屠宰加工废水处理技术

介绍了厌氧水解酸化 循环活性污泥系统在禽类屠宰加工废水中的工程应用。结果表明 ,禽类加工废水在进水SS、CODCr、BOD5分别为 75 2mg/L、16 4 7mg/L、76 4mg/L的条件下 ,经该工艺处理后 ,外排废水的SS、CODCr、BOD5分别为 5 0mg/L、6 5mg/L、10 .1mg/L。该工艺具有占地面积小 ,处理效率好 ,运行费用低等特点 ,能广泛应用于禽类屠宰加工废水的处理。     

Denitrification of nitrate wastewater using packed-bed columns.

Columnar packed-bed (PB) reactors with a specific surface area of 127 m2/m3 were investigated in this study for treating nitrate wastewater. This study demonstrated that a single-stage packed bed was able to achieve total nitrogen (TN) and chemical oxygen demand (COD) removal efficiencies higher than 83 and 75%, respectively. The highest achievable TN and COD removal rates were 47.2 g N/m2 x d and 158.0 g COD/m2 x d, respectively. The substrate removal rate in the PB column was found to follow half-order reaction kinetics, with a reaction coefficient, kappa, of 53.62 (mg/L)1/2/d. A dual-stage PB system was capable of achieving TN and COD removal efficiencies greater than 99 and 98%, respectively. Effluent TN and COD concentrations less than 6.5 mg NO3(-)-N/L and 50.0 mg COD/L, respectively, were obtained when the dual PB system was used.     

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.