Nitrogen and Phosphorus Removal from Lake Kinneret Inputs

The Hula Valley was drained in 1957. The land use was modified from natural wetland and old shallow lake ecosystems to agricultural development. About half of the drained land area was utilized for aquaculture. Population size was enhanced and the diary was developed intensively resulting in the enhancement of domestic and husbandry sewage production that increased as well. The natural intact Hula Valley-Lake Kinneret ecosystem was heavily anthropogenically interrupted: The Hula was drained and Kinneret became a national source for domestic water supply. Some aspects of the environmental and water quality protection policy of the system are presented. The causation and operational management implications for the reduction of Nitrogen and Phosphorus migration from the Hula Valley are discussed. Drastic (81%) restriction of aquaculture accompanied by sewage totally removed achieved a reasonable improvement in pollution control which was also supported by the Hula Project. The implications of anthropogenic intervention in the process of environmental management design are presented.

Screening of Polyphosphate Accumulating Organisms and Their Phosphorus Removal Performance

[Objectives]To study the phosphorus removal performance of phosphate accumulating organisms(PAOs).[Methods]Activated sludge from domestic sewage treatment plant was used as the strain source,and phosphate accumulating organisms were screened by plate streaking method and dilution coating plate method.Six kinds of excellent phosphate accumulating organisms were obtained by metachromatic granule staining experiment,total phosphorus experiment and simulated sewage phosphorus removal experiment to assist the observation of bac-terial morphology and experiment of phosphorus removal capacity.In addition,the influencing factors of phosphorus removal capacity(nitrogen source,trace metal ions)were analyzed.[Results]In the case of simulated sewage,the phosphorus removal rate of strain b was the highest,reaching 66.25%,while the phosphorus removal rate of strain e and f was about 10%lower than that of the phosphorus uptake experiment.[Conclusions]This study is expected to provide a theoretical reference for the gradual optimization of the screening method of phosphorus re-moval bacteria in domestic sewage treatment.

Nitrogen and phosphorus removal in pilot-scale anaerobic-anoxic oxidation ditch system

To achieve high efficiency of nitrogen and phosphorus removal and to investigate the rule of simultaneous nitrification and denitrification phosphorus removal （SNDPR）, a whole course of SNDPR damage and recovery was studied in a pilot-scale, anaerobicanoxic oxidation ditch （OD）, where the volumes of anaerobic zone, anoxic zone, and ditches zone of the OD system were 7, 21, and 280 L, respectively. The reactor was fed with municipal wastewater with a flow rate of 336 L/d. The concept of simultaneous nitrification and denitrification （SND） rate （rSND） was put forward to quantify SND. The results indicate that： （1） high nitrogen and phosphorus removal efficiencies were achieved during the stable SND phase, total nitrogen （TN） and total phosphate （TP） removal rates were 80% and 85%, respectively; （2） when the system was aerated excessively, the stability of SND was damaged, and rSND dropped from 80% to 20% or less; （3） the natural logarithm of the ratio of NOx to NH4^＋ in the effluent had a linear correlation to oxidation-reduction potential （ORP）; （4） when NO3^- was less than 6 mg/L, high phosphorus removal efficiency could be achieved; （5） denitrifying phosphorus removal （DNPR） could take place in the anaerobic-anoxic OD system. The major innovation was that the SND rate was devised and quantified.

Removal of nitrogen and phosphorus in a combined A^2/O-BAF system with a short aerobic SRT

A bench-scale anaerobic/anoxic/aerobic process-biological aerated filter （A^2/O-BAF） combined system was carded out to treat wastewater with lower C/N and C/P ratios. The A^2/O process was operated in a short aerobic sludge retention time （SRT） for organic pollutants and phosphorus removal, and denitrification. The subsequent BAF process was mainly used for nitrification. The BAF effluent was partially returned to anoxic zone of the A^2/O process to provide electron acceptors for denitrification and anoxic P uptake. This unique system formed an environment for reproducing the denitdfying phosphate-accumulating organisms （DPAOs）. The ratio of DPAOs to phosphorus accumulating organisms （PAOs） could be maintained at 28% by optimizing the organic loads in the anaerobic zone and the nitrate loads into the anoxic zone in the A^2/O process. The aerobic phosphorus over-uptake and discharge of excess activated sludge was the main mechanism of phosphorus removal in the combined system. The aerobic SRT of the A^2/O process should meet the demands for the development of aerobic PAOs and the restraint on the nitrifiers growth, and the contact time in the aerobic zone of the A^2/O process should be longer than 30 min, which ensured efficient phosphorus removal in the combined system. The adequate BAF effluent return rates should be controlled with 1--4 mg/L nitrate nitrogen in the anoxic zone effluent of A^2/O process to achieve the optimal nitrogen and phosphorus removal efficiencies.

Simultaneous phosphorus and nitrogen removal in a continuous-flow two-sludge system

The ability of simultaneous biological phosphorus and nitrogen removal was investigated in a lab-scale continuous-flow two-sludge system. Alternating anaerobic and anoxic conditions were combined with contact oxidation stage for treating raw municipal wastewater. Long-term experiments showed that the contradiction of competing for the organic substrate between denitrifying bacteria and PAOs （phosphorus accumulating organisms） in traditional phosphorus and nitrogen removal system has been resolved. The system can adapt to low influent COD/TN ratio （C/N）. Furthermore the SRT （sludge retention time） of nitrifying sludge and denitrifying phosphorus removal sludge can be controlled at optimal conditions respectively. The removal efficiency of COD, TP, TN, and NH4-N was 81.78%, 92.51%, 75.75%, and 84.47% respectively. It was also found that the appropriate influent C/N should be controlled at the range of 3.8-6, while the optimal C/N to the system ranged between 4-5, and the BFR （bypass sludge flow rate） should be controlled at 0.35 around.

Simultaneous removal of nitrogen and phosphorus from swine wastewater in a sequencing batch biofilm reactor

In this study, the performance of a sequencing batch biofilm reactor(SBBR) for removal of nitrogen and phosphorus from swine wastewater was evaluated. The replacement rate of wastewater was set at 12.5% throughout the experiment. The anaerobic and aerobic times were 3 h and 7 h, respectively, and the dissolved oxygen concentration of the aerobic phase was about 3.95 mg·L-1. The SBBR process demonstrated good performance in treating swine wastewater. The percentage removal of total chemical oxygen demand(COD), ammonia nitrogen(NH4+-N), total nitrogen(TN), and total phosphorus(TP) was 98.2%, 95.7%, 95.6%, and 96.2% at effluent concentrations of COD85.6 mg·L-1, NH4+-N 35.22 mg·L-1, TN 44.64 mg·L-1, and TP 1.13 mg·L-1, respectively. Simultaneous nitrification and denitrification phenomenon was observed. Further improvement in removal efficiency of NH4+-N and TN occurred at COD/TN ratio of 11:1, with effluent concentrations at NH4+-N 18.5 mg·L-1and TN 34 mg·L-1, while no such improvement in COD and TP removal was found. Microbial electron microscopy analysis showed that the filler surface was covered with a thick biofilm, forming an anaerobic–aerobic microenvironment and facilitating the removal of nitrogen, phosphorus and organic matters. A long-term experiment(15 weeks) showed that stable removal efficiency for N and P could be achieved in the SBBR system.

Simultaneous nitrogen and phosphorus removal under low dissolved oxygen conditions

A full-scale test was operated by using low dissolved oxygen activated sludge process to enhance biological nitrogen and phosphorus removal. When the influent concentrations of CODCr, TN and TP varied in a range of 352.9 mg/L-1338.2 mg/L, 34.4 mg/L-96.3 mg/L, and 2.21 mg/L-24.0 mg/L, the average removal efficiencies were 94.9%, 86.7% and 93.0%, respectively. During the test period of two months, effluent meas of CODCr,, BOD5, NH3-N, TN and TP were below 50 mg/L, 25 mg/L, 10 mg/L and 1.0 mg/L respectively. The low dissolved oxygen activated sludge process has a simple flow sheet, fewer facilities and high N and P removal efficiency. It is very convenient to retrofit the conventional activated sludge process with the above process.

Removal of Nitrogen, Phosphorus, and Organic Pollutants From Water Using Seeding Type Immobilized Microorganisms

Objective To study the possibility of removing nitrogen, phosphorus, and organic pollutants using seeding type immobilized microorganisms. Methods Lakes P and M in Wuhan were chosen as the objects to study the removal of nitrogen, phosphorus, and organic pollutants with the seeding type immobilized microorganisms. Correlations between the quantity of heterotrophic bacteria and the total nitrogen （TN）, total phosphorus （TP）, and total organic carbon （TOC） in the two lakes were studied. The dominant bacteria were detected, inoculated to the sludge and acclimated by increasing nitrogen, phosphorus and decreasing carbon source in an intermittent, time-controlled and fixed-quantity way. The bacteria were then used to prepare the seeding type immobilized microorganisms, selecting diatomite as the adsorbent cartier. The ability and influence factors of removing nitrogen, phosphorus, and organic pollutant from water samples by the seeding type immobilized microorganisms were studied. Results The coefficients of the heterotrophic bacterial quantity correlated with TOC, TP, and TN were 0.9143, 0.8229, 0.7954 in Lake P and 0.9168, 0.7187, 0.6022 in Lake M. Ten strains of dominant heterotrophic bacteria belonging to Pseudomonas, Coccus, Aeromonas, Bacillus, and Enterobateriaceae, separately, were isolated. The appropriate conditions for the seeding type immobilized microorgansims in purifying the water sample were exposure time=24 h, pH=7.0-8.0, and quantity of the immobilized microorganisms=0.75-1g/50 mL. The removal rates of TOC, TP, and TN under the above conditions were 80.2%, 81.6%, and 86.8%, respectively. Conclusion The amount of heterotrophic bacteria in the two lakes was correlated with TOC, TP, and TN. These bacteria could be acclimatized and prepared for the immobilized microorganisms which could effectively remove nitrogen, phosphorus, and mixed organic pollutants in the water sample.

Nitrogen and Phosphorus Pollutants Removal from Rice Field Drainage with Ecological Agriculture Ditch: A Field Case

Excessive nitrogen and phosphorus in agricultural drainage can cause a series of water environmental problems such as eutrophication of water bodies and non-point source pollution.By monitoring the water purification effect of a paddy ditch wetland in Gaochun,Nanjing,Jiangsu Province,we investigated the spatial and temporal distribution patterns of N and P pollutants in paddy drains during the whole reproductive period of rice.Then,the dynamic changes of nitrogen and phosphorus in time and space during the two processes of rainfall after basal fertilization and topdressing were analyzed after comparison.At last,the effect of the ditch wetland on nutrient purification and treatment mechanism,along with changing flow and concentration in paddy drains,was clarified.The results of this study showed that the concentrations of various nitrogen and phosphorus in the ditch basically reached the peak on the second and third days after the rainfall(5.98 mg/L for TN and 0.21 mg/L for TP),which provided a response time for effective control of nitrogen and phosphorus loss.The drainage can be purified by the ecological ditch,about 89.61%,89.03%,89.61%,98.14%,and 79.05%of TN,NH4+-N,NO3−-N,NO2−-N,and TP decline.It is more effective than natural ditches for water purification with 80.59%,40%,12.07%,91.06%and 18.42%removal rates,respectively.The results of the study can provide a theoretical basis for controlling agricultural non-point source pollution and improving the water environment of rivers and lakes scientifically.

Nitrogen and phosphorus removal under intermittent aeration conditions

A practice wastewater treatment plant was operated using intermittent aeration activated sludge process to enhance biological nitrogen and phosphorus removal. When the influent concentrations of COD Cr , BOD 5, TN, TP, NH 3\|N, TKN, and SS varied in a range of 207.5—1640 mg/L, 61.8—637 mg/L, 28.5—75.6 mg/L, 4.38—20.2 mg/L, 13.6—31.9 mg/L, 28.5—75.6 mg/L, and 111—1208 mg/L, the effluent means were less than 50 mg/L, 20 mg/L, 5 mg/L, 1.0 mg/L, 5 mg/L, 10 mg/L, and 20 mg/L, respectively. Based on a long time of operating results, this process is very suitable for nutrient biological removal for treating the municipal wastewater those water characteristics are similar as that of the Songjiang Municipal Waste Water Treatment Plant(SJMWTP).

Simultaneous Nitrogen and Phosphorus Removal by Denitrifying Dephosphatation in a (AO)_2 Sequencing Batch Reactor

A 24 L working volume reactor was used for the research on simultaneous phosphorus (P) and nitrogen (N) removal by denitrifying dephosphatation in an anaerobic-oxid-anoxic-oxid sequencing batch reactor ((AO)_2SBR) system. The durations of each phase are: anaerobic 1.5 h, aerobic 2.5 h, anoxic 1.5 h, post-aerobic 0.5 h, settling 1.0 h, fill 0.5 h. The successful removal of nitrogen and phosphorus is achieved in a stable (AO)_2SBR. The effluent P concentrations is below 1 mg/L, and the COD,TN and P average removal efficiency is 88.9%, 77.5% and 88.7%, respectively. The batch experiment results show that the durations of aerobic and anoxic phase influence the P removal efficiency. Some feature points are found on the DO, ORP and pH curves to demonstrate the complete of phosphate release and phosphate uptake. These feature points can be used for the control of (AO)_2 SBR.

Optimum operation conditions of nitrogen and phosphorus removal by a biofilm-activated-sludge system

In the biofilm and activated sludge combined system, denitrifying bacteria attached on the fibrous carriers in the anoxic tank, while the sludge containing nitrifying and phosphorus removal bacteria was only recirculated between the aerobic and anaerobic tanks. Therefore, the factors affected and restricted nitrification, denitrification and phosphorus removal in a traditional A/A/O process were resolved. This paper describes the optimum operation conditions for nitrogen and phosphorus removal using this system.

Impact of external carbon source on A2/O system and its biological phosphorus and nitrogen removal efficiency before and after restoration

以啤酒废水作为外加碳源，研究了不同浓度外加碳源对A2／O系统的冲击情况，并通过调节工艺参数对系统进行修复，对比了修复前后系统的脱氮除磷效果。结果表明，投加低浓度（COD为50mg／L）外加碳源没有影响系统的正常运行，且有助于提高系统的脱氮除磷效率；用COD为150mg／L的啤酒废水对系统进行冲击时，总氮、氨氮、总磷和COD的去除率均有所下降，依次下降了31．53、16．38、7．61、10．19百分点；经过修复后，与冲击前相比较，各分析指标的去除率略有降低。用高浓度（COD为250nag／L）的啤酒废水冲击A2／O系统，冲击期间各分析指标显著下降，且产生轻微的污泥膨胀，修复后各分析指标去除率依次降低了11．75、9．56、21．20、20．79百分点。实验表明，啤酒废水可以作为外加碳源用以调节系统的C／N，且A0／o系统对浓度变化的冲击具有一定的抵抗力。

Contributions of Different Wetland Plants to Nitrogen and Phosphorus Removal in Constructed Wetlands

Constructed wetlands with Cyperus altrnlifolius,Pennisetum sinese Roxb and elephant grass as vegetation were built to study the nitrogen and phosphorous removal from domestic sewage in cold climate.It was found that these three plants could all grow slowly and stably under low temperature stress in winter,and the biomass,nitrogen and phosphorus absorption characteristics and absorbing capacity of the three plants were different.The growth rate and biomass were as follows:P.sinese Roxb>elephant grass>C.altrnlifolius,and these three plants could be used as winter wetland decontamination plants in Southwest China;the absorption characteristics of nitrogen and phosphorus in different tissues of the three plants were as follows:nitrogen content in leaf>nitrogen content in stem,phosphorus content in stem>phosphorus content in leaf;the removal of total nitrogen(TN)by three plants in the wetland was ranged form 4.3%to 7.8%,and the removal of total phosphorus(TP)was ranged from 3.3%to 5.3%.Different plants had different absorption effects on nitrogen and phosphorus.There was a significantly positive correlation between plant nitrogen and phosphorus accumulation and biomass,and nitrogen removal rate in wetland showed a significantly positive correlation with biomass.

Research Development and Application of Nitrogen and Phosphorus Removal in Sequencing Batch Biofilm Reactor

Frequent variations of the wastewater quality and quantity and other uncertain factors are the challenges faced by many wastewater treatment plants during the operation. Sequencing batch biofilm reactor（ SBBR） process provides a new idea for an effective solution to this problem. This paper introduces the basic processes and characteristics of the sequencing batch biofilm reactor（ SBBR） process,and summarizes the research status of this process in wastewater treatment. Factors affecting the nitrogen and phosphorus removal effect of the SBBR process are also analyzed.

Salt effect on MUCT system performance of nitrogen and phosphorus removal

The effect of salinity on biological nitrogen and denitrifying phosphorus removal was investigated in a Modified University of Cape Town(MUCT)system.Removal rates of COD,NH_(4)^(+)-N,NO_(3)^(-)-N,NO_(2)^(-)-N,phosphorus and the sludge characteristics at salt concentrations(0.0,3.2,6.4,11.2 and 16.0 g L^(-1))were analyzed.With the salt concentration increasing,all the COD,NH_(4)^(+)-N,TN and TP removal rates exhibited a trend of decline,and exhibited an initial reduction and subsequent increase at every stage of salt concentration.NH_(4)^(+)-N,TN and TP removal rates were 92.7%,51.5%and 67.2%in 16 g L^(-1) salt concentration,respectively.And they were outperformed the literature reported and acceptable in practical applications.When the salinity of wastewater changed from 0.0 to 16.0 g L^(-1),the biomass yield coefficients increased from 0.0794 to 0.126 g VSS/g COD.Increased salinity had a detrimental effect on phosphorus-accumulating organisms(PAOs)and denitrifying PAOs(DPAOs)(especially DPAOs).Therefore,phosphorus removal gradually depended on PAO.The simultaneous nitrification and denitrification(SND)rate and nitrogen removal rate(including nitrification rate,denitrification rate,and total nitrogen removal rate)gradually decreased with the increased salinity.

Phosphorus and Nitrogen Removal by Saturated Vertical-Flow Constructed Wetlands (SVCWs) Type Micro-Pilot Using Shale from Ivory Coast as a Substrate

This study evaluates the performance of shale from Ivory Coast used as substrate in vertical-flow constructed wetlands in removal of phosphates and nitrogen. The pilot-scale artificial wetland has been duplicated: filter planted with Panicum maximun and unplanted. They were set up outdoors, and fed with a municipal wastewater. The wetlands have been fed with three batches per week (intermittent) over a period of 3 months. During the operation period, the hydraulic residence time (HRT) 52 h was used, while wastewater temperatures varied from about ~33°C. The removal performance of the constructed wetland units was very good, since it reached on an average 98%, 89.4%, 89.4%, 84%, 80%, 84.8% and 92% for TSS, DOC, BOD5, , TKN, TP and respectively. In addition, the vegetation did not demonstrate superior performance to unplanted controls. Therefore, this study focuses on the role of shale in the phosphorus and nitrogen removal from wastewater by constructed wetland.

Discussion on nitrogen and phosphorus removal process characteristics of improved oxidation ditch

In order to enhance efficiency of the nitrogen and phosphorus removal of sewage treatment plant, Taking Wu Long kou sewage treatment plant project in Zhengzhou as an example, this article introduces the structure, the working principle, the craft character, as well as the problems existed in the practical application of the improved oxidation ditch, and raises some corresponding processing countermeasures. Looked from the running situation of Wu Long kou sewage treatment plant, the improved oxidation ditch have certain advantages in city sewage treatment, such as high organic removing efficiency, good removing effect of nitrogen and phosphorus, low investing expenses and operating cost and so on. It is a craft that is worth promoting in urban sewage treatment.

Nitrogen and Phosphorus Removal from Agricultural Wastewater Using Constructed Rhizofiltration in Durban, South Africa

Constructed rhizofiltration is a relatively new technology and has potential in agricultural wastewater treatment. It has been reported to reduce heavy metals in wastewater but no substantive work has been reported about its ability to remove nitrogen and phosphorus, particularly in agricultural wastewater. If this technology＇s worth in nutrient removal from wastewater can be proved, it can save time as well as reducing wastewater treatment cost. Influent and effluent nitrogen and phosphate concentrations in the constructed rhizofiltration were measured and it was found that there was a significant difference between the two water samples （P = 0.01）. It was also found that more nitrogen and phosphate were retained by planted region （P = 0.01） compared to unplanted （P = 0.02）, demonstrating high removal efficiency in the planted region than in the unplanted region. Eighty six percent （86%） removal efficiency of phosphorus was achieved at some points in the planted region while 71% was achieved for nitrogen. These results indicate that constructed rhizofiltration systems, if properly constructed and planted with macrophytes and maintained, can be used for nitrogen and phosphorus removal in wastewater and thus could be used as an alternative technology for agricultural wastewater treatment.

Effect of Waterscape Structures on Nitrogen and Phosphorus Removal Efficiency in Revetment Wetland System

The effect of aeration and waterscape structures reaeration system on nitrogen and phosphorus removal efficiency in revetment wetlands was studied by laboratory simulation. The results showed that the removal efficiency of TN, TP in tranquil flow waterscape was 61% and 72%; aeration and waterscape structure system promoted nitrogen and phosphorus removal efficiency in revetment wetland through increasing the DO content in the water, compared with system without artificial oxygen, the removal efficiency of TP in waterscape structures increased by 11. 6%-19. 1%, and that of TN increased by 10.5%-16. 1%; meanwhile, disturbance brought by the waterscape structure systems enhanced the adsorption of TP and flocculation effect; in addition, nitrification was confirmed as the main control step of TN removal in revetment wetland system.