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.

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 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.

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.

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).

Enhanced nitrogen removal at low temperature with mixed anoxic/oxic process

Different hydraulic retention times(HRTs)were tested in a mixed anoxic/oxic(A/O)system at 5C and 10C to investigate the effects of HRT and carrier on nitrogen removal in wastewater at low temperatures.The results showed that the addition of the fillers improved the treatment effect of each index in the system.With an optimal HRT of 7.5 h at 5C,the removal efficiencies of NHþ4-N and total nitrogen(TN)reached 91.2%and 75.6%,respectively.With an HRT of 6 h at 10C,the removal efficiencies of NHþ4-N and TN were 96.7%and 82.9%,respectively.The results of high-throughput sequencing showed that the addition of the suspended carriers in the aerobic zone could improve the treatment efficiency of nitrogen at low temperatures.The microbial analysis indicated that the addition of the suspended carriers enhanced the enrichment of nitrogen removal bacteria.Nitrospira,Nitrotoga,and Nitrosomonas were found to be the bacteria responsible for nitrification,and their relative concentrations on the biofilm at 5C and 10C accounted for 98.11%,92.79%,and 69.98%of all biological samples,respectively.

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.

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。

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.

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.

Comparative study of two biological nitrogen removal processes:A/O process and step-feeding process

Two biological nitrogen removal processes are compared in the aspect of nitrogen removal, process operation and energy saving. Results show that when the returned sludge ratio is 50% of the inflow rate, the step-feeding process achieves over 80% total nitrogen （TN） removal efficiency, but the TN removal efficiency of the A/O process is only 40%. Moreover, filamentous sludge bulking can be well restrained in the step-feeding process. Given the conditions of a returned sludge ratio of 100% and a nitrifying liquor recycle ratio of 200%, the TN removal efficiency is 78.32% in the A/O process, but the sludge volume index （SVI） value increases to 143 mL/g. In the step-feeding process, the SVI is only 94.4 mL/g when the TN removal efficiency reaches 81. 1%. The step-feeding process has distinct advantages over the A/O process in the aspects of practicability, nitrogen removal and operating stability.

Effect Research of Immobilized Algae-bacteria Removal Ammonia Nitrogen of Aquaculture Wastewater and Proposed Model

Applied Immobilized algae bacteria (ABI) to remove ammonia of freshwater aquaculture wastewater. Temperature (T),PH,light intensity (I),dissolved oxygen (DO) and filling rate five factors plays important role in the process of ammonia nitrogen removal ,related data between ammonia removal and five factors was received through multi-factor orthogonal test,and established relations model between the five factor and nitrogen removal. The results show that five-factors had significant effect on AR,and the best combinations for removing AR was temperature 30 ℃,pH=7.0,light intensity 6 000 lux,dissolved oxygen 5.0 mg/L and the fill rate 10%. According to the experimental data,equation model was proposed and coefficient of determination R2 =0.864 8,P<0.05. Samples T-test was done between the model predictions and the actual measured values.Test results showed that the significant difference of overall mean value sig. (2-tailed) was 0.978 (P>0.05),it Shows that had no significant difference between model predictions and the actual measured value,and model had a high degree of fitting.

An autotrophic nitrogen removal process:Short-cut nitrification combined with ANAMMOX for treating diluted effluent from an UASB reactor fed by landfill leachate

A combined process consisting of a short-cut nitrification （SN） reactor and an anaerobic ammonium oxidation upflow anaerobic sludge bed （ANAMMOX） reactor was developed to treat the diluted effluent from an upflow anaerobic sludge bed （UASB） reactor treating high ammonium municipal landfill leachate.The SN process was performed in an aerated upflow sludge bed （AUSB） reactor （working volume 3.05 L）,treating about 50% of the diluted raw wastewater.The ammonium removal efficiency and the ratio of NO 2 N to NOx-N in the effluent were both higher than 80%,at a maximum nitrogen loading rate of 1.47 kg/（m 3 ·day）.The ANAMMOX process was performed in an UASB reactor （working volume 8.5 L）,using the mix of SN reactor effluent and diluted raw wastewater at a ratio of 1：1.The ammonium and nitrite removal efficiency reached over 93% and 95%,respectively,after 70-day continuous operation,at a maximum total nitrogen loading rate of 0.91 kg/（m 3 ·day）,suggesting a successful operation of the combined process.The average nitrogen loading rate of the combined system was 0.56 kg/（m 3 ·day）,with an average total inorganic nitrogen removal efficiency 87%.The nitrogen in the effluent was mostly nitrate.The results provided important evidence for the possibility of applying SN-ANAMMOX after UASB reactor to treat municipal landfill leachate.

Simultaneous nitrification and denitrification in step feeding biological nitrogen removal process

The simultaneous nitrification and denitrification in step-feeding biological nitrogen removal process were investigated under different influent substrate concentrations and aeration flow rates. Biological occurrence of simultaneous nitrification and denitrification was verified in the aspect of nitrogen mass balance and alkalinity. The experimental results also showed that there was a distinct linear relationship between simultaneous nitrification and denitrification and DO concentration under the conditions of low and high aeration flow rate. In each experimental run the floc sizes of activated sludge were also measured and the results showed that simultaneous nitrification and denitrification could occur with very small size of floc.

Novel strategy of nitrogen removal from domestic wastewater using pilot Orbal oxidation ditch

A pilot-scale Orbed oxidation ditch was operated for 17 months to optimize nitrogen removal from domestic wastewater of average COD to total nitrogen ratio of 2.7, with particular concern about the roles of dissolved oxygen （DO）, mixed liquor suspended solids （MLSS） and return activated sludge （RAS） recycle ratio. Remarkable simultaneous nitrification and denitrification （SND） was observed and mean total nitrogen （TN） removal efficiency up to 72.1% was steadily achieved, at DO concentration in the out, middle and inner channel of 0.1, 0.4 and 0.7 mg/L, respectively, with an average M LSS of 5.5 g/L and RAS recycle ratio of 150%. Although the out channel took the major role in TN removal, the role of middle channel should never be ignored. The denitrification potential could be fully developed under low DO, high MLSS with adequate RAS ratio. The sludge settleability was amazingly improved under low DO operation mode, and some explanations were tried. In addition, a scries of simplified batch tests were done to determine whether novel microorganisms could make substantial contribution to the performance of nitrogen removal. The results indicated that the SND observed in this Orbal oxidation ditch was more likely a physical phenomenon.

Nitrogen removal efficiency of iron-carbon micro-electrolysis system treating high nitrate nitrogen organic pharmaceutical wastewater

The nitrate nitrogen removal efficiency of iron-carbon micro-electrolysis system was discussed in treating pharmaceutical wastewater with high nitrogen and refractory organic concentration. The results show that the granularity of fillings,pH,volume ratios of iron-carbon and gas-water,and HRT. have significant effects on the nitrogen removal efficiency of iron-carbon micro-electrolysis system. The iron-carbon micro-electrolysis system has a good removal efficiency of pharmaceutical wastewater with high nitrogen and refractory organic concentration when the influent TN,NH4+-N,NO3--N and BOD5/CODCr are 823 mg/L,30 mg/L,793 mg/L and 0.1,respectively,at the granularity of iron and carbon 0.425 mm,pH 3,iron-carbon ratio 3,gas-water ratio 5,HRT 1.5 h,and the removal rates of TN,NH4+-N and NO3--N achieve 51.5%,70% and 50.94%,respectively.

High nitrogen removal from wastewater with several new aerobic bacteria isolated from diverse ecosystems

Three new bacteria HS-03, HS-043 and HS-047 isolated from different ecosystems were found capable of aerobic denitrification. The potential application of these strains in wastewater treatment under aerobic conditions was investigated, These three bacteria all presented high nitrogen removal from wastewater that more than 98% of 10 mmol/L nitrate could be removed in 12--24 h by adding cheap external carbon source and low concentration of iron as well as molybdate. The mechanism at molecular level was analyzed. The success of this aerobic denitrification applied to wastewater treatment may serve as an alternative to enhance the practical nitrogen removal from wastewater. Main biochemical and physiological features of these strains were characterized. The 16S rDNA sequences were compared with the published data in GenBank by using BLAST. The results of phenotype and genotype proved that strain HS-03 and HS-047 belonged to Pseudomonas stutzeri and Pseudomonas pseudoalcaligenes respectively. Strain HS-043 was identified as Delftia clcidovorans of which denitrifying activity has not previously been explored.

Synergistic removal of nitrogen monoxide by non-thermal plasma and catalyst simultaneously

An experimental system of De-NO with plasma-catalyst（Cu zeolite） was established to investigate the differences between De- NO with plasma-catalyst and De-NO only with plasma, to provide the instruction for selecting appropriate catalyst and operating condition, The characteristics of De-NO with plasma and De-NO with plasma-catalyst were investigated comparatively by experiments. The experimental results show that De-NO with plasma-catalyst has high NO removal rate; Cu zeolite is an effective catalyst which can promote NO removal rate in plasma remarkably; De-NO with plasma-catalyst should be operated at low temperature and the temperature has opposite effects on the function of catalvst and plasma; water vapor and O2 can increase the NO removal rate.