Treatment of wastewater with different ratios of carbon to nitrogen using
污水处理的英文文献翻译(1)
Nutrient removal in an A2O-MBR reactor with sludgereductionABSTRACTIn the present study, an advanced sewage treatment process has been developed by incorporating excess sludge reduction and phosphorous recovery in an A2O-MBR process. The A2O-MBR reactor was operated at a flux of 77 LMH over a period of 270 days. The designed flux was increased stepwise over a period of two weeks. The reactor was operated at two different MLSS range. Thermo chemical digestion of sludge was carried out at a fixed pH (11)and temperature (75℃) for 25% COD solubilisation. The released pbospborous was recovered by precipitation process and the organics was sent back to anoxic tank. The sludge digestion did not have any impact on COD and TP removal efficiency of the reactor. During the 270 days of reactor operation, the MBR maintained relatively constant transmembrane pressure. The results based on the study indicated that the proposed process configuration has potential to reduce the excess sludge production as well as it didn't detonated the treated water quality.Keywords: A2O reactor; MBR; Nutrient removal; TMP1. IntroductionExcess sludge reduction and nutrients removal are the two important problems associated with wastewater treatment plant. MBR process has been known as a process with relatively high decay rate and less sludge production due to much longer sludge age in the reactor (Wenet al., 2004). Sludge production in MBR is reduced by 28-68%, depending on the sludge age used (Xia et al.,2008). However, minimizing the sludge production by increasing sludge age is limited due to the potential adverse effect of high MLSS concentrations on membrane (Yoon et al., 2004). This problem can be solved by introducing sludge disintegration technique in MBR (Young et al., 2007). Sludge disintegration techniques have been reported to enhance the biodegradability of excess sludge (Vlyssides and Karlis, 2004). In overall, the basis for sludge reduction processes is effective combination of the methods for sludge disintegration and biodegradation of treated sludge. Advances in sludge disintegration techniques offer a few promising options including ultrasound (Guo et al., 2008), pulse power (Choi et al.,2006), ozone (Weemaes et al., 2000), thermal (Kim et al., 2003), alkaline (Li et al., 2008) acid (Kim et al., 2003) and thermo chemical(Vlyssides and Karlis, 2004). Among the various disintegration techniques, thermo chemical was reported to be simple and cost effective (Weemaes and Verstraete, 1998). In thermal-chemical hydrolysis, alkali sodium hydroxide was found to be the most effective agent in inducing cell lysis (Rocker et al., 1999). Conventionally, the nutrient removal was carried out in an A2O process. It has advantage of achieving, nutrient removal along with organic compound oxidation in a single sludge configuration using linked reactors in series (Tchobanoglous et al., 2003). The phosphoroes removal happens by subjecting phosphorous accumulating organisms (PAO) bacteria under aerobic and anaerobic conditions (Akin and Ugurlu, 2004). These operating procedures enhance predominance PAO, which are able to uptake phosphorous in excess. During the sludge pretreatment processes the bound phosphorous was solubilised and it increases the phosphorousconcentration in the effluent stream (Nishimura, 2001).So, it is necessary to remove the solubilised phosphorus before it enters into main stream. Besides, there is a growing demand for the sustainable phosphorous resources in the industrialized world. In many developed countries, researches are currently underway to recover the phosphoroes bound in the sludge's of enhanced biological phosphorus removal system (EBPR). The released phosphorous can be recovered in usable products using calcium salts precipitation method. Keeping this fact in mind, in the present study, a new advanced wastewater treatment process is developed by integrating three processes, which are: (a) thermo chemical pretreatment in MBR for excess sludge reduction (b) A2O process for biological nutrient removal (c) P recovery through calcium salt precipitation. The experimental data obtained were then used to evaluate the performance of this integrated system.2. Methods2.1. WastewaterThe synthetic domestic wastewater was used as the experimental influent. It was basically composed of a mixed carbon source, macro nutrients (N and P), an alkalinity control (NaHCO3) and a microelement solution. The composition contained (/L) 210 mg glucose, 200 mg NH4C1, 220 mg NaHCO3, 22一34 mg KH2PO4, microelement solution (0.19 mg MnCl2 4H20, 0.0018 mg ZnCl22H2O,0.022 mg CuCl22H2O, 5.6 mg MgSO47H2O, 0.88 mg FeCl36H2O,1.3 mg CaCl2·2H2O). The synthetic wastewater was prepared three times a week with concentrations of 210±1.5 mg/L chemical oxygen demand (COD), 40±1 mg/L total nitrogen (TN) and 5.5 mg/L total phosphorus (TP).2.2. A2O-MBRThe working volume of the A2O-MBR was 83.4 L. A baffle was placed inside the reactor to divide it into anaerobic (8.4 L) anoxic (25 L) and aerobic basin (50 L). The synthetic wastewater was feed into the reactor at a flow rate of 8.4 L/h (Q) using a feed pump. A liquid level sensor, planted in aerobic basin of A2O-MBR controlled the flow of influent. The HRT of anaerobic, anoxic and aerobic basins were 1, 3 and 6 h, respectively. In order to facilitate nutrient removal, the reactor was provided with two internal recycle (1R). IRl (Q= 1)connects anoxic and anaerobic and IR 2 (Q=3) was between aerobic and anoxic. Anaerobic and anoxic basins were provided with low speed mixer to keep the mixed liquid suspended solids (MLSS) in suspension. In the aerobic zone, diffusers were used to generate air bubbles for oxidation of organics and ammonia. Dissolved oxygen (DO) concentration in the aerobic basin was maintained at 3.5 mg/1 and was monitored continuously through online DO meter. The solid liquid separation happens inaerobic basin with the help of five flat sheet membranes having a pore size of 0.23 pm. The area of each membrane was 0.1 m2. They were connected together by a common tube. A peristaltic pumpwas connected in the common tube to generate suction pressure. In the common tube provision was made to accommodate pressure gauge to measure transmembrane pressure (TMP) during suction. The suction pump was operated in sequence of timing, which consists of 10 min switch on, and 2 min switch off.2.3. Thermo chemical digestion of sludgeMixed liquor from aerobic basin of MBR was withdrawn at the ratio of 1.5% of Q/day and subjected to thermo chemical digestion. Thermo chemical digestion was carried out at a fixed pH of 11(NaOH) and temperature of 75℃for 3 h. After thermo chemical digestion the supernatant and sludge were separated. The thermo-chemicallydigested sludge was amenable to further anaerobic bio-degradation (Vlyssides and Karlis, 2004), so it was sent to theanaerobic basin of the MBR2.4. Phosphorus recoveryLime was used as a precipitant to recover the phosphorous in the supernatant. After the recovery of precipitant the content was sent back to anoxic tank as a carbon source and alkalinity supelement for denitrification.2.5. Chemical analysisCOD, MLSS, TP, TN of the raw and treated wastewater were analyzed following methods detailed in (APHA, 2003). The influent and effluent ammonia concentration was measured using an ion-selective electrode (Thereto Orion, Model: 95一12). Nitrate in the sample was analyzed using cadmium reduction method (APHA, 2003).3. Results and discussionFig. 1 presents data of MLSS and yield observed during the operational period of the reactor. One of the advantages of MBR reactor was it can be operated in high MLSS concentration. The reactor was seeded with EBPR sludge from the Kiheung, sewage treatment plant, Korea. The reactor was startup with the MLSS concentration of 5700 mg/L. It starts to increase steadily with increase in period of reactor operation and reached a value of 8100 mg/L on day 38. From then onwards, MLSS concentration was maintained in the range of 7500 mg/L by withdrawing excess sludge produced and called run I. The observed yields (Yobs) for experiments without sludge digestion (run I) and with sludge digestion were calculated and given in Fig. 1. The Yobs for run I was found to be 0.12 gMLSS/g COD. It was comparatively lower than a value of 0.4 gMLSS/g CODreported for the conventional activated sludge processes (Tchoba-noglous et al., 2003). The difference in observed yield of these two systems is attributed to their working MLSS concentration. At high MLSS concentration the yield observed was found to be low (Visva-nathan et al., 2000). As a result of that MBR generated less sludge.The presently used MLSS ranges (7.5一10.5 g/L) are selected on the basis of the recommendation by Rosenberger et al. (2002). In their study, they reported that the general trend of MLSS increase on fouling in municipal applications seems to result in no impact at medium MLSS concentrations (7一12 g/L).It is evident from the data that the COD removal efficiency of A2O system remains unaffected before and after the introduction of sludge digestion practices. A test analysis showed that the differences between the period without sludge digestion (run I) and with sludge digestion (run II and III) are not statistically significant.However, it has been reported that, in wastewater treatment processes including disintegration-induced sludge degradation, the effluent water quality is slightly detonated due to the release of nondegradable substances such as soluble microbial products (Ya-sui and Shibata, 1994; Salcai et al., 1997; Yoon et al., 2004). During the study period, COD concentration in the aerobic basin of MBR was in the range of 18-38 mg/L and corresponding organic concentration in the effluent was varied from 4 to 12 mg/L. From this data it can be concluded that the membrane separation played an important role in providing the excellent and stable effluent quality.Phosphorus is the primary nutrient responsible for algal bloom and it is necessary to reduce the concentration of phosphorus in treated wastewater to prevent the algal bloom. Fortunately its growth can be inhibited at the levels of TP well below 1 mg/L (Mer-vat and Logan, 1996).Fig. 2 depicts TP removal efficiency of the A2O-MBR system during the period of study. It is clearly evident from the figure that the TP removal efficiency of A/O system was remains unaffected after the introduction of sludge reduction. In the present study, the solubilised phosphorous was recovered in the form of calcium phosphate before it enters into main stream. So, the possibility of phosphorus increase in the effluent due to sludge reduction practices has been eliminated. The influent TP concentration was in the range of 5.5 mg/L. During thefirst four weeks of operation the TP removal efficiency of the system was not efficient as the TP concentration in the effluent exceeds over 2.5 mg/L. The lower TP removal efficiency during the initial period was due to the slow growing nature of PAO organisms and other operational factors such as anaerobic condition and internal recycling. After the initial period, the TP removal efficiency in the effluent starts to increase with increase in period of operation. TP removal in A2O process is mainly through PAO organisms. These organisms are slow growing in nature and susceptible to various physicochemical factors (Carlos et al., 2008). During the study period TP removal efficiency of the system remains unaffected and was in the range of 74-82%.。
新型自养-异养协同反硝化矿物材料脱氮效果中试
猱社科枚Journal of Green Science and Technology 第23卷第2期2021年]月新型自养一异养协同反硝化矿物材料脱氮效果中试张駅，陈方針，吕冰借1,张青1,董献段，张强1(1.安徽环境科技集团股份公司，安徽合肥230000,2.北京沬澈科技发展有限公司，北京100089)摘要：以污水厂实际污■水为处理目标，通过中试试验研究了新型硫自养一异养协同反摘化材料的特性。
结果表明：水力停留时间为1.5h,该新型材料可以为自养一异养反摘化系统提供充足的电子供体，无需外加有机凄源，即可实现进水均值总氮18mg/L到出水总■氮稳定小于8mg/L,不会出现亚硝态氮的积累，保证了稳定高效的脱氮效果。
反应结束后，体系中硫自养反摘化菌Thiobacillus、Sulfurovumonas和异养反摘化菌Simplicispira相对丰度提高，成为优势菌种。
关键词：反彌化；材料；自养一异养协同中图分类号：X52文献标识码：B文章编号：1674-9944(2021)02-0165-031引言随着“十三五”规划中对总氮排放要求的提高，国内市政生活污水处理、工业废水处理以及自然水体反硝化脱氮过程中，存在去除效率低、去除难度大、去除成本高的问题。
传统异养反硝化性能强烈依赖有机碳源，会造成出水有机物残留以及NO2--N累积等问题,其去除效率低，易造成二次污染,应对低C/N硝酸盐污水稳定性差;传统自养反硝化工艺过程酸积累严重、传质不均匀、效率低；传统反硝化过程中微生物应对季节或水质水量变化的脆弱性导致反应效率的降低因此，开发出一种低耗、高效、无二次污染的自养一异养协同反硝化材料具有重要的意义。
本次研究以安徽省滁州市南谯区污水厂实际市政污水为处理目标，通过现场中试试验并结合组分和微生物分析，研究新型自养一异养协同反硝化填料的处理效果和特性，对当前深度脱氮提标改造项目的优化运行和工艺比选设计等提供参考。
污水处理流程英文版
污水处理流程英文版Wastewater Treatment Process.Primary Treatment.The first step in wastewater treatment is primary treatment. This process removes settleable solids and floating materials from the wastewater. Primary treatment is typically accomplished through the use of sedimentation tanks, which allow the solids to settle out of the water. The settled solids are then removed from the tank and sent to a landfill or incinerated.Secondary Treatment.The second step in wastewater treatment is secondary treatment. This process removes dissolved organic matter from the wastewater. Secondary treatment is typically accomplished through the use of biological processes, such as activated sludge or trickling filters. In theseprocesses, bacteria consume the organic matter in the wastewater, converting it into carbon dioxide and water.Tertiary Treatment.The third step in wastewater treatment is tertiary treatment. This process removes nutrients, such as nitrogen and phosphorus, from the wastewater. Tertiary treatment is typically accomplished through the use of chemical processes, such as coagulation, flocculation, andfiltration. In these processes, chemicals are added to the wastewater to cause the nutrients to clump together. The clumps are then removed from the water through filtration.Disinfection.The final step in wastewater treatment is disinfection. This process destroys harmful bacteria and viruses in the wastewater. Disinfection is typically accomplished through the use of chlorine or ultraviolet light.中文回答：污水处理流程。
污水处理流程英语介绍
污水处理流程英语介绍Wastewater treatment is a critical process that aims to remove contaminants from wastewater, primarily from industrial, commercial, and domestic sources, to produce an effluent that can be safely discharged into the environment. The process typically involves several stages to ensure that the water is clean and free from harmful substances.The first stage in wastewater treatment is the preliminary treatment, which includes screening to remove large debris such as leaves, branches, and trash. This is followed by grit removal, where small stones and sand are separated from the water.The next step is the primary treatment, which is the sedimentation process. Here, suspended solids settle at the bottom of sedimentation tanks, forming sludge. This sludge is then removed and treated further, while the clarified water moves on to the secondary treatment.Secondary treatment involves biological processes that use microorganisms to break down organic matter in the wastewater. This can be done in various ways, such as activated sludge, trickling filters, or rotating biological contactors. During this stage, a significant portion of the organic material is converted into carbon dioxide, water, and new biomass.Tertiary or advanced treatment is the final stage, which may include processes like filtration, disinfection, and nutrient removal. Filtration removes fine particles, while disinfection, typically using chlorine or ultraviolet light, kills any remaining pathogens. Nutrient removal, especially phosphorus and nitrogen, is important to prevent eutrophication in water bodies.After tertiary treatment, the treated water, known as effluent, is often discharged into rivers or used for non-potable purposes such as irrigation or industrial cooling. The sludge produced during the treatment process is typically further processed to reduce its volume and treated to be used as fertilizer or disposed of in a sanitary landfill.It's important to note that the exact treatment process can vary depending on the nature of the wastewater and the local regulations. Continuous monitoring and maintenance are essential to ensure the effectiveness of the treatment plant and to protect public health and the environment.。
wastewater treatment1209 (2)
Pin Point floc
• • • • Low filamentous organisms Weak, small floc Turbid supernatant High SVI
Secondary Treatment Sequencing Batch Reactor （序列间歇反应器）
• Suspended growth system • Completely mixed mode; batch mode with discontinuous flow
Settled, Digested sludge
Wastewater Treatment
Digester gas
Digestion
Separation
Complete mix, or high-rate, anaerobic digester
Sludge Treatment and Disposal Anaerobic Digestion
Advantages • High degree of waste stabilization at high organic loading rates • Very little sludge production (< 5% of biodegradable organic matter being converted to cell material) (10% of aerobic sludge production) • Easy dewatering of the excess sludge • No aeration equipment • Methane production – very low energy input (if the methane gas is used to heat the digester) • Long preservation of adapted sludge without feeding for more than a year
污水处理流程英语介绍
污水处理流程英语介绍Wastewater treatment is a critical process that aims to remove contaminants from wastewater, primarily from household sewage and industrial effluents, to produce an effluent that can be safely returned to the environment. Here's an overview of the wastewater treatment process 英文版:Introduction to Wastewater Treatment ProcessWastewater treatment is an essential part of modern infrastructure, designed to protect the environment and human health. It involves a series of processes to removeimpurities and harmful substances from water that has been used in homes, businesses, and industries.1. Preliminary TreatmentThe first step in wastewater treatment is the preliminary treatment, which includes screening and grit removal. Large debris and grit are physically removed from the wastewater to prevent damage to the equipment and pipes downstream.2. Primary TreatmentFollowing preliminary treatment, the wastewater undergoes primary treatment, where it is allowed to settle in large tanks. This process, known as sedimentation, separates the heavier particles from the water, forming sludge that can beremoved and treated separately.3. Secondary TreatmentSecondary treatment involves the biological breakdown of organic matter in the wastewater. This is typically achieved through the use of activated sludge processes, trickling filters, or rotating biological contactors. Microorganisms consume the organic matter, converting it into carbon dioxide, water, and biomass.4. Tertiary TreatmentTertiary or advanced treatment is the final stage of the process, aimed at removing nutrients such as nitrogen and phosphorus, which can cause eutrophication in water bodies. This step may include filtration, disinfection, and the useof chemical processes to precipitate out remaining contaminants.5. Sludge TreatmentThe sludge produced during primary and secondarytreatment is not simply discarded. It undergoes further treatment to reduce its volume and stabilize it for disposalor reuse. This can involve processes such as anaerobic digestion, which produces biogas, or composting.6. DisinfectionBefore the treated water is released back into theenvironment, it is disinfected to kill any remaining pathogens. Common disinfection methods include chlorination, ultraviolet light, and ozonation.7. Discharge or ReuseFinally, the treated water, now considered effluent, is either discharged into rivers or oceans or treated furtherfor reuse in irrigation, industrial processes, or even as potable water in some cases.Wastewater treatment is a multifaceted process that requires careful management and advanced technology to ensure the protection of our water resources. As populations grow and water scarcity becomes more prevalent, the importance of efficient wastewater treatment will only increase.。
一株好氧反硝化芽孢杆菌的筛选鉴定
山东农业大学学报(自然科学版),2022,53(6):819-824VOL.53NO.62022 Journal of Shandong Agricultural University(Natural Science Edition)doi:10.3969/j.issn.1000-2324.2022.06.001一株好氧反硝化芽孢杆菌的筛选鉴定及脱氮特性研究常允康,贾莹莹,王丽华,王涵,樊惠原,居润成,徐娜*济宁医学院生物科学学院,山东日照276800摘要:为获得高效的生物脱氮细菌，从某黑臭河道水体中分离得到一株好氧反硝化细菌，通过对好氧反硝化和异养硝化两个过程中的菌体生物量、总氮、硝酸盐氮以及氨氮的浓度进行监测，研究其脱氮特性。
并且，进一步研究了碳源种类、碳氮比、温度、转速、盐度等外界因素对其好氧反硝化性能的影响。
结果表明：分离得到的好氧反硝化细菌经鉴定为芽孢杆菌属，记为Bacillus sp.N-1。
分别以硝酸钾和硫酸铵作为初始唯一氮源，截至24h，对硝酸盐氮和氨氮的去除率分别为86.14%和86.20%，去除速率分别为1.79mg/(L·h)和1.82mg/(L·h)，证明了菌株Bacillus sp.N-1在具有优异的好氧反硝化能力的同时具备较强的异养硝化能力。
另外，好氧反硝化过程的影响因素分析表明，当以丁二酸钠或者柠檬酸钠为碳源，碳氮比在15~25之间，温度在25~35℃之间，转速在200~250rpm之间，盐度在1%以内时，该菌株对硝酸盐氮的去除率均能保持在70%以上，在废水的生物脱氮处理中具备很好的应用前景。
关键词:芽孢杆菌;鉴定;生物脱氮中图法分类号:Q939.9文献标识码:A文章编号:1000-2324(2022)06-0819-06 Screening and Identification of an Aerobic Denitrification BacillusStrain and Its Nitrogen Removal CharacteristicsCHANG Yun-kang,JIA Ying-ying,WANG Li-hua,WANG Han,FAN Hui-yuan, JU Run-cheng,XU Na*School of Biological Science/Jining Medical University,Rizhao276800,ChinaAbstract:In order to obtain efficient bacteria for nitrogen removal,an aerobic denitrification bacteria was isolated from a black-odor river.The biomass and the concentrations of the total nitrogen,nitrate nitrogen and ammonia nitrogen during aerobic denitrification and heterotrophic nitrification processes were monitored to study its nitrogen removal characteristics. Moreover,the influence of external factors such as carbon source type,C/N ratio,temperature,rotate speed and salinity on the aerobic denitrification performance were further studied.The results showed that the aerobic denitrification bacteria was identified as Bacillus strain,and was recorded as Bacillus sp.N-1.With potassium nitrate and ammonium sulfate as the initial single nitrogen source,the removal efficiency of nitrate nitrogen and ammonia nitrogen was86.14%and86.20%under24 hours,respectively,and the removal rate was1.79mg/(L·h)and1.82mg/(L·h),respectively,which showed that Bacillus sp. N-1had excellent aerobic denitrification and heterotrophic nitrification performance.In addition,the analysis of factors which affecting the aerobic denitrification process showed that when sodium succinate or sodium citrate was used as carbon source,the ratio of C/N was between15and25,the temperature was between25and35℃,the rotate speed was between 200and250rpm,and the salinity was within1%,the nitrate nitrogen removal efficiency could still stay above70%,which showed good application prospect in biological denitrification treatment of wastewater.Keywords:Aerobic denitrification;identification;bioremoval of nitrogen我国生态环境部发布的《2020年中国生态环境统计年报》指出，2020年全国废水中氨氮排放量为98.4万t，总氮排放量为322.3万t。
(翻译)不同填料的曝气生物滤池对去除氨氮的研究
不同填料的曝气生物滤池对去除氨氮的研究摘要陶粒和炉渣（一种新型的滤料），均被用作曝气生物滤池（BAF）的滤料，用这两种不同填料的（陶粒和炉渣）曝气生物滤池（BAF）做了一组处理混合废水的平行试验，研究了这两种不同填料的曝气生物滤池（BAF）对氨氮的去除效果随进水的PH值和氨氮负荷率变化的特点。
结果表明，炉渣BAF对氨氮的去除率要高于陶粒BAF。
当进水氨氮的浓度在16 mg/L 到64 mg/L之间时，前者氨氮去除率达90.63%–63.46%，后者氨氮去除率达在75.62%–42.23%。
因为炉渣BAF本身可以产生碱度（碳酸钙）进而可以缓冲pH值的变化，故具有较高的氨氮去除率。
此外，对这两个BAF进行分阶段检测（五段），异氧细菌和硝化细菌的数量表明，炉渣更适合硝化细菌的附着、生长，它有利于改善炉渣BAF的硝化性能。
关键词：炉渣；曝气生物滤池；pH值；氨氮去除1.介绍曝气生物滤池（BAF）是一种混合的膜反应器，使用的填料具有很高的比表面积，适用于污水的二级和三级处理[1-3]。
曝气生物滤池（BAF）集生物过滤、生物吸附和生物氧化于一体[4]，尤其是当土地紧缺时，曝气生物滤池是首要的工艺选择。
曝气生物滤池的颗粒填料可以为生物膜的生长、繁殖提供很大的比表面积。
填料可以在深度过滤的同时去除悬浮物[5]。
滤料的特性和滤料高度对于曝气滤池的初始投资和运营成本来说占了很大的比重[6,7]。
为了使污水达到排放标准，对于曝气滤池来说无论在设计和操作过程中，选择合适的填料是很重要的。
天然材料，如沙粒、页岩和膨胀的粘土都已经被广泛的使用。
同时也使用合成材料，例如聚苯乙烯和聚乙烯材料。
在中国陶粒被广泛的用作污水处理厂的滤料，黏土是用于生产陶粒的主要原料。
黏土是一种宝贵的农业资源，从长远来看它的损失会威胁到农业的可持续发展。
因此，要找到合适的黏土的替代品是非常重要的。
炉渣是颗粒残留的一种，它是在炼钢的过程中通过水的淬火和迅速冷却产生的。
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Treatment of wastewater with different ratios of carbon to nitrogen using an enhanced nitrogen removal system of constructed wetland
Min Tao1, a, Qi-shuo Wang2, b*, Ji-Guang Li3, Juan-juan Qu1, Ya-qun Zhan1, Wei-qin Li1 and Ying-bo Luo1
1School of Environmental Science and Engineering, Hubei Key Laboratory of Mine Environmental
Pollution Control & Remediation, Hubei Polytechnic University, Huangshi 435003, China;
2Huai’an Research Center, Institute of Hydrobiology, Chinese Academy of Sciences, Huai’an
223006, China
3College of Life Sciences and Technology, Mudanjiang Teachers College, Mudanjiang,
Heilongjiang, 157012, China atmiii@163.com, bwangqishuo@ihb.ac.cn
Keywords: constructed wetland; intermittent aeration; carbon source addition; nitrogen removal Abstract. An enhanced nitrogen removal system of constructed wetland has been established, and for which kind of nitrogen containing wastewater was suitable to be treated by such enhanced system was also investigated. The results show that when co-controlled by intermittent aeration and carbon source addition, dissolved oxygen concentration and process carbon-nitrogen ratio in enhanced system were improved, meanwhile TN removal capability was enhanced. For wastewater that contains low concentration of carbon and nitrogen, or low concentration of carbon but high concentration of nitrogen, or high concentration of carbon and nitrogen, or high concentration of carbon and low concentration of nitrogen, the average removal efficiency of COD, TN, NH4+-N, NO3--N and TP in enhanced system were 68.1%, 78.2%, 70.8%, 86.7% and 71.2%, of which the purification capability was significantly better than that of the control system. The enhanced system is especially suitable for treatment of wastewater that contains low concentration of carbon and high nitrogen.
Introduction Constructed wetland is a wastewater treatment technology, which has advantages such as high efficiency, low investment and administrative cost, and has been widely used for treatment of sanitary sewage, industrial wastewater, non-point source contamination, etc [1-3]. According to statistics, there are more than 1000 and more than 5000 constructed wetlands in operation in the USA and Europe respectively [4]. In China, there are more than 400 projects of constructed wetland [3]. Presently, the constructed wetlands in operation have comparatively high removal rate of total suspended solids and organic materials, while the nitrogen removal efficiency is relatively low [5]. Therefore, how to get higher nitrogen removal efficiency in undercurrent constructed wetland becomes one of the research priorities. Due to limitation of the structure of subsurface constructed wetland itself (always in a full-water condition), the whole wetland is in an anoxic/anaerobic condition, which does not satisfy the demand of nitrification process [6, 7]. Especially when plants die, oxygen secretion from plant roots decreases, resulting in serious lack of oxygen in the wetland thus the treatment efficiency is worsening [8]. Meanwhile, the research found out that when there was a denitrification process in the far end of the wetland it appeared lack of carbon source and low rate of denitrification, which also resulted in poor effect of nitrogen removal in the wetland [9]. Presently, researchers have made use of measures strengthened oxygen to enhance the nitrification capability, oxidation and decomposition capability of organic materials [10-12]; further, denitrification process was promoted in wetland by carbon resource addition from outside [13, 14]. However, little research of nitrogen removal with both aeration and carbon source addition in the wetland was made.
Advanced Materials Research Vols. 864-867 (2014) pp 1287-1292© (2014) Trans Tech Publications, Switzerlanddoi:10.4028/www.scientific.net/AMR.864-867.1287
All rights reserved. No part of contents of this paper may be reproduced or transmitted in any form or by any means without the written permission of TTP,www.ttp.net. (ID: 123.150.219.103-06/12/13,04:33:47) In this experiment a nitrogen removal system of constructed wetland with combined adjustment and control by carbon and oxygen was set up, of which the purification capacity compared with that of normal wetland was evaluated. In addition, in this paper, for which nitrogen containing sewage is suitable for being treated with this enhanced system is discussed.