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In this study, a flat sheet ceramic membrane experimental device was constructed, and the thermodynamics of membrane fouling interface was studied for oilfield produced water. The flux of ceramic membrane in three kinds of model solutions were measured with time, as well as the surface tension, contact Angle and Zeta potential of solid. The thermodynamic mechanism of membrane fouling interface combined with XDLVO theory were explored for three kinds of model solutions. The thermodynamic study of the interface of ceramic plate membrane shows that the total interaction energy between membrane and oil droplets decreases with the increase of the distance between two interfaces at initial stage of membrane fouling, and finally transforms from the mutual attraction to the mutual repulsion. The total interaction energy between reservoir and oil droplet is shown as mutual attraction, and the total interaction energy decreases with the increase of the distance between reservoir and oil droplet interface. The zeta potential of crude oil was affected by salinity to some extent. The electrostatic shielding effect of the salt ions leads to a decrease in the ζ-potential of the three solutions. They are in the order: model solution Amodel solution Bmodel solution C. This leads to a decrease in the electrostatic interaction (EL). And since the oil layer has the same composition as the oil droplets, the EL interactions in the three solutions can behave as mutual repulsion.

Cotton fiber is mainly composed of cellulose, which is rarely separated into different kinds. However, the classification and identification of waste cotton from different countries are essential for the customs service of the country. In this study, the near-infrared classification method was introduced to classify and identify cotton fibers. Waste cotton samples from six different countries were collected, and one-fifth of them were used for validation. The near-infrared calibration and prediction models were constructed using both soft independent modeling of class analogy and partial least squares methods. It was found that the optimized model has a high recognition rate, and the prediction accuracy of the model was 99% for six countries. It was demonstrated that the near-infrared model established in this study can be used for fast and accurate identification of waste cotton from different countries.

We propose a general approach for the achievement of optical sensors, where ammonia can be rapidly identified and detected through visible fluorescence changes. Here, a tetraphenylethylene derivative with carboxyl groups named TPE-2CA (4,4ʹ-(1,2-Diphenylethene-1,2-diyl) dibenzoyl acid) was applied in the sensor. The AIE (aggregation-induced emission) property of tetraphenylethylene structure provides the samples with excellent luminescent performance in aggregated state. The reaction between carboxyl groups and ammonia causes the shifts on luminescence spectra of the samples. Consequently, different ammonia concentrations can be measured by the time required for luminescent peak blue shifts of samples. Furthermore, we also succeed in growing TPE-2CA micro-spindle structured particles, which nanoparticle structure was instrumental in the miniaturisation and integration of future sensors.

Nitrous oxide (N2O), as one of the six greenhouse gases, is mainly produced in the biological nitrogen removal process of wastewater treatment plants (WWTPs). Establishing the N2O kinetic model can...

In this study, the electrolytic sequencing batch reactor (ESBR) with different current densities was constructed to investigate the nitrogen removal performance and rapid start-up of anaerobic ammonia oxidation (anammox) process. The changes of total nitrogen removal rate (TNRR), specific anammox activity (SAA) and nitrogen concentration under different current densities were analyzed, and then the effect of the optimal current density on the start-up of anammox in ESBR was explored. The results showed that ammonium nitrogen removal efficiency (92.7%), nitrite nitrogen removal efficiency (15.5%) and total nitrogen removal efficiency (28.1%) were obtained with the TNRR and SAA were 0.0118 g N L

Electro-biological particle electrode (EBPE) prepared by lithium slag was used to remove salicylic acid in a three-dimensional electrocatalytic biological coupling reactor (3D-EBCR). The physical and chemical properties of the EBPE, the removal performance of salicylic acid and the degradation mechanism were studied. Results revealed as follows: (1) the EBPE prepared by lithium slag contained effective catalytic components including Fe2O3, SnO2, ZnO, MnO, Rb2O and TiO2, with stable structure and good adsorption performance; (2) the 3D-EBCR with EBPE had strong adaptability to the current intensity in the range of 0.25-0.40 A, and the removal rates of COD and salicylic acid were maintained above 87.1% and 85.2% respectively; (3) salicylic acid was removed through the synergistic action of adsorption, electrochemical oxidation and biological action.

Nitrous oxide (N

Compared with the traditional treatment technologies, inorganic membrane technology is gradually becoming the mainstream of the treatment of oily and salty wastewater, but membrane fouling has become the bottleneck restricting the development of membrane technology. In order to solve this problem, the mechanism of membrane fouling and the control strategies of membrane fouling are introduced in this paper. The atomic layer deposition technology and the preparation of TiO2 nanowires (NWs) film by impregnation method were mainly introduced, aiming to provide a more reliable industrial research status in the field of membrane fouling control.

A novel phosphorus removal yeast BL3 was isolated from an alternating anaerobic/aerobic biofilter and identified as Diutina rugosa by 26S rDNA gene sequence analysis. Yeast BL3 could effectively remove phosphorus from synthetic wastewater containing 2–20 mg/L phosphorus under optimal environmental conditions. The highest phosphorus removal efficiency was above 70% under the conditions of DO 6.86 mg/L, C/P ratios of 60, N/P ratios of 3.3, pH 6.0–9.0, and at 25.0–35.0 °C. The phosphorus distribution in the aqueous solution and different components of yeast BL3 analysis indicated that around 55%–70% and 20%–40% of removed phosphorus were transferred into extracellular polymeric substances (EPS) and yeast cells, respectively. The plausible phosphorus transfer pathway was proposed based on the phosphorus distribution and species analysis, suggesting the important role of EPS as a phosphorus reservoir. These results indicate that yeast BL3 can efficiently remove phosphorus under aerobic conditions without alternating anaerobic/aerobic cycling, and thus has significant potential for practical application in wastewater phosphorus removal.

Pharmaceuticals and personal care products(PPCPs) were frequently detected in water bodies which were harmful to human health and environment. Three-dimensional electrocatalysis coupled biological aerated filter(3D-EBAF) was developed on the basis of biological aerated filter (BAF)，which could enhance remove rate of pharmaceuticals and personal care products(PPCPs). The effects of the current intensity and kinetic analysis on the removal of diclofenac and clofibric acid in the three-dimensional electrocatalysis coupled biological aerated filter(3D-EBAF) were investigated. Results indicated that (1)average 71.91% of diclofenac at 0.73 mA cm−2 and 58.92% of clofibric acid at 0.64 mA cm−2 could be removed in three-dimensional electrocatalysis coupled biological aerated filter(3D-EBAF), which represented increase by 42.79% and 17.52%, compared with the biological aerated filter(BAF).(2)the degradation of diclofenac and clofibric acid followed first-order kinetic plot in three-dimensional electrocatalysis coupled biological aerated filter(3D-EBAF) and the kinetic rate constant (k) reached a peak of 0.0086 and 0.0052 min−1 at 0.64 mA cm−2.(3)the contributions of removal routes, intermediate products and mechanism were explored. These results indicated that the adsorption, electrocatalytic oxidation, and biodegradation play a synergistic role in the removal of diclofenac and clofibric acid. Three-dimensional electrocatalysis coupled biological aerated filter (3D-EBAF) significantly enhanced the removal rates of pharmaceuticals and personal care products(PPCPs) compared to biological aerated filter(BAF). The application of three-dimensional electrocatalysis biological aerated filter(3D-EBAF) could achieve satisfactory results in the removal of pharmaceuticals and personal care products(PPCPs), which provided an environmentally acceptable and cost-effective technology for the treatment of pharmaceuticals and personal care products (PPCPs).

Magnesium ammonium phosphate (MAP) crystallization could be utilized for the recovery of phosphorus from wastewater. However, the effectiveness of the recovery is largely determined by the crystallization process, which is very hard to be directly observed. As a result, a specific ultrasonic device was designed to investigate the crystallization characteristics of MAP under various ultrasonic conditions. The results demonstrated that the metastable zone width (MZW) narrowed along with the rising of the ultrasonic power. Similarly, for the 6mM MAP solution, with the ultrasonic power gradually enhanced from 0W to 400W, the induction time was shortened from 340s to 38s. Meanwhile, the crystallization rate was accelerated till the power reached 350W, and then remained a constant value. It can be observed from the scanning electron microscopy (SEM), the MAP crystal became bigger in size as well as the crystal size distribution (CSD) became broad and uneven, with the increase of ultrasonic power. The results indicate that the crystallization process enhanced by power ultrasound could be used as an effective method to eliminate and recover the phosphorus from wastewater.

A laboratory-scale biological aerated filter (BAF), using volcanic scoria particles (VSP), was used for treating micro-polluted source water. The system reached a steady-state stage and performed better at removing pollutants. In steady-state stage, the effluent ammonia ( NH4+-N ) and chemical oxygen demand (COD) were consistently maintained below 0.3 and 3 mg/L, respectively. Both the NH4+-N and COD removal efficiencies decreased with shorter hydraulic retention time (HRT). The effluent NH4+-N and COD exceeded health standards at 15 min of HRT. Although performance was relatively poor for VSP-BAF at low temperature, the NH4+-N removal still achieved the drinking water quality standard. The influences of influent NH4+-N and COD concentration changes were similar to that of temperature. A better performance was observed in NH4+-N removal under higher influent NH4+-N concentrations. In contrast, the effluent COD was more than 3 mg/L when the influent COD concentrations increased to about 9 mg/L. The phylogenetic and cluster analyses indicated that the effect of HRT on bacteria community structure was higher than that of temperature, while the ammonia-oxidizing bacteria (AOB) are sensitive to temperature. The main phyla identified in total bacteria communities were Proteobacteria, Bacteroidetes, Firmicutes, and Nitrospirae. The main AOB were Nitrosomonadales and an uncultured ammonia-oxidizing bacterium. PRACTITIONER POINTS: The BAF using VSP obtained a good performance for treating micro-polluted source water. The influence of HRT on the system was more significant than that of temperature. The system is resistant to NH4+-N concentration shocks while is unable to withstand the COD increasing. The effect of HRT on bacteria community structure was significantly higher than that of temperature.

N2O (Nitrous oxide) is a strong greenhouse gas, and wastewater treatment process is one of the important artificial sources of N2O. Controlling N2O production and discharge in wastewater treatment process is beneficial to alleviate the greenhouse effect. Based on the mechanism of N2O production in biological nitrogen removal process, emission characteristics and influencing factors of N2O in three traditional biological nitrogen removal processes, A/A/O, SBR and oxidation ditch, and two new biological nitrogen removal processes, SBBR and CANON, have been reviewed. Furthermore, a control strategy for slowing the generation and release of N2O is proposed, which provides a reference for researchers in related field.

Novel particle electrodes, i.e. flotation tailings particle electrode (FPE), were prepared using flotation tailings, garden soil, and soluble starch with a mass ratio of 16:3:1, and then used in tetracycline wastewater treatment. The physicochemical properties of FPE were systematically characterized using SEM, XRD, FT-IR and XRF. Tetracycline adsorption and its adsorption mechanism onto FPE was explored for the first time. Parameters affecting FPE's degradation efficiency and energy consumption such as current density, electrolysis time, initial concentration, initial pH and aeration rate were examined. The electrocatalytic degradation of tetracycline shows that the degradation of tetracycline meets the pseudo-first-order kinetics. Moreover, the numbers of •OH produced on the surfaces of the cathode, anode and particle electrode were compared. Results showed that the adsorption-saturated FPE can be regenerated by electrochemical action to induce further absorption and form in-situ electrocatalysis. In order to find out the transformation products in water and degradation pathways of Tetracycline, UHPLC method was used to obtain the degradation pathways for Tetracycline. So, this work could provide a fabrication of high-efficiency and low-cost electrocatalytic for removal of pharmaceuticals pollutants from waste water as well as deeper insight into electrocatalytic mechanism, transformation products, and degradation pathways of Tetracycline in water.

At present, most of the source water of domestic urban water supply treatment plants is taken from micro-polluted surface water. With the further improvement of drinking water sanitation standards, the traditional “coagulation-sedimentation-filtration-disinfection” process cannot meet the requirements of the new standards. Ultrafiltration, as the core technology in the field of water treatment in the 21st century, is increasingly applied to water treatment due to its advantages of green efficiency, simple operation, small footprint, and high degree of automation. However, the use of ultrafiltration membrane alone has some problems such as substandard water quality and serious membrane pollution. Therefore, the combination of ultrafiltration and traditional water treatment technology to treat micro-polluted surface water has become the mainstream choice for treatment plants. This article mainly introduces the current research status of domestic ultrafiltration combined technology, trying to explore more reasonable and effective ways to apply ultrafiltration membranes in actual projects.

In this paper, while ceramic membrane fouling and its causes were introduced, the calculation of ceramic membrane fouling resistance, membrane fouling analysis methods and several common ceramic membrane cleaning techniques were summarized. In this process, some factors affecting the cleaning effect were also analyzed by enumerating cases, and the future development of ceramic membrane was prospected.

In order to study the rapid start-up technology of the anaerobic ammonium oxidation process, a comparison test of no magnetic field and magnetic field was performed in two identical ASBR reactors R1 and R2 respectively. The results show that both reactors can successfully start Anammox. The R2 start-up period (75d) of the applied magnetic field is shortened by 15% compared with the unloaded magnetic field R1 start-up period (90d); the R2 ammonia-nitrogen removal rate is 97% higher than that of 95% of R1. The quantitative relationship analysis between NH4+-N, NO2--N and NO3--N shows that the change of R2 ratio is closer to the theoretical value, which can better improve the activity of microbial enzymes and accelerate the enrichment of ammonia oxidizing bacteria in the reactor. It is beneficial to nitrogen removal and R2 can quickly start the anaerobic ammonium oxidation process.

In recent years, plate ceramic membrane has been applied in the field of water and wastewater treatment successfully, because of its unique advantages. As an important parameter which can characterize properties of membrane, the water flux and critical flux of plate ceramic membrane treating municipal secondary effluent of Wastewater Treatment Plant(WWTP) were studied in this paper. And the flux change characteristics under different membrane pressure were obtained. The experimental results laid foundation for further exploring of mechanism of membrane fouling and related control techniques, and provided references for expanded application of plate ceramic membrane in wastewater reuse.

In recent years, ceramic membranes have been widely used in the field of water and wastewater treatment by virtue of their advantages over conventional water treatment technologies. In this article, definition, classification and characteristics of ceramic membrane were introduced firstly. And then the application of ceramic membrane technology used in various fields of water and wastewater treatment was highlighted. Finally, several opinions on the development prospects of ceramic membrane technology were raised.

The effect of salinity on the membrane fouling characteristics was investigated in the intermittently aerated membrane bioreactor (IAMBR). Five different salinity loadings were set from 0 to 35 g·L−1(referring to NaCl), respectively. The removal of total organic carbon (TOC) and ammonia-nitrogen (NH4+-N) was gradually decreased with increasing salinity. The variation of membrane filtration resistance, particle size distribution (PSD), extracellular polymeric substances (EPS), soluble microbial products (SMP), and relative hydrophobicity (RH) analysis revealed that salinity has a significant effect on sludge characteristics in IAMBR. The results also indicated that the membrane fouling is often caused by the integration of sludge characteristics in saline wastewater.

Ceramic membrane technique was a new and efficient technology for wastewater treatment and used more and more widely in recent years. Controlling membrane fouling was the key method to ensure the efficient and stable operation of ceramic membrane. In this paper, the causes, influencing factors and control methods of ceramic membrane fouling were summarized. As one of the most effective means to control membrane fouling, several common membrane cleaning methods, such as physical cleaning, chemical cleaning, ultrasonic cleaning and combined cleaning, were introduced. And the application of ceramic membrane cleaning was presented too. Then the future directions for ceramic membrane techniquresearching was prospected.

A novel steel slag-based material (SSM) was prepared, based on the powdered steel slag and modified by hydrothermal treatment to improve its activity for phosphate removal. The phosphate removal and recovery with the SSM and the modified steel slag-based material (MSSM) as seed crystal were evaluated, and the reuse performance of the MSSM was investigated. The results showed that the hydration activity of the MSSM could be improved by hydrothermal modification, which might be attributed to the releasing of OH− and Ca2+ from MSSM after the hydrothermal treatment is in favor of the calcium phosphate crystallization. The MSSM as a seed crystal could be used repeatedly about 20 times in this experiment, and the residual phosphate concentrations were all below 0.5 mg/L with the initial concentration of 10 mg/L. The X-ray diffraction pattern of the reaction products revealed that the crystallinity of the products increased with increasing reaction time and the diffraction peaks well matched with that of...

For the sake of the shortage of phosphorus resources and the present situation of municipal sludge treatment and disposal, the necessity of recovery of phosphorus from municipal sludge is analyzed, whereas the methods of phosphorus releasing from solid phase to liquid phase in sewage sludge, such as anaerobic digestion, ozone oxidation, heat treatment, ultrasonic dissolution and alkaline hydrolysis, were discussed in this paper. And then the theories and methods of phosphorus recovering from sewage sludge were summarized, including chemical precipitation, adsorption desorption, burning heat treatment and nanofiltration. Finally, the research development and application prospects of phosphorus release recovery technology from sewage sludge were also proposed. Introduction According to statistics, phosphate has been listed as China in 2010 after the national economy, cannot meet the needs of the development of one of the 20 minerals. By the end of 2014, the amount of sludge produced by China years (by 80% water content) of about 30 million tons, annual sludge production (at 80% moisture content) will increase to 246 thousand m.Currently in the process of sewage treatment, phosphorus in the form of residual sludge in the final discharge, the phosphorus content of about 4%~9%.But the sludge treatment and disposal technology in current hardly realize recovery of phosphorus resources. Therefore, it open up a new direction for the municipal wastewater treatment plant sludge treatment and disposal by using the appropriate technology to recover phosphorus from municipal sewage sludge. This paper summarizes the research status of phosphorus recovery and utilization in sludge, and prospects the research, development and application prospect of phosphorus release and recovery technology in sludge. Release of phosphorus in sludge Stable and efficient phosphorus release method is the most important prerequisite for the recovery of residual sludge. At present, the research on phosphorus release is mainly focused on the following aspects. Anaerobic digestion.Sludge anaerobic digestion to sludge in anaerobic conditions, by facultative and anaerobic bacteria will sludge can be biodegradable organic matter decomposition into carbon dioxide, methane, and water, which is one of the common means of sludge reduction, stabilization.Bi Dongsu studied on the anaerobic digestion process of phosphorus rich excess sludge found that the phosphorus content of residual sludge 4th International Conference on Sustainable Energy and Environmental Engineering (ICSEEE 2015) © 2016. The authors Published by Atlantis Press 488 supernatant increased from 0.90mg/L to 102.90mg/L after 18d anaerobic digestion at room temperature. The method of anaerobic digestion is used to release the phosphorus in the sludge, which has the advantages of simple operation, obvious effect of phosphorus release, stable operation and low cost. At the same time, it also has a long reaction time, large reactor volume, and the shortcomings of the initial investment. Ozone oxidation method.Ozone oxidation method is by ozone cytolysis, not easy to destroy biological degradation of the cell membrane, so that the intracellular substances can quickly dissolved in the liquid phase, so not only can realize the reduction of sludge and can promote the release of phosphorus in the bacterial cell. Ozone oxidation method has the advantages of ozone oxidation ability strong, good sludge disintegration effect, plant covers an area of less; the disadvantage is that sludge disintegration depends on ability to ozone input ratio, in the large-scale application of high investment ratio will lead to a high level of energy consumption. Heat treatment method.Heat treatment method is the use of external heat source in the disintegration of sludge floc structure, the sludge in a part of cell material never dissolved into dissolved phosphorus, so that the more rapid release [2] .Kuroda [3] et al. Akio showed that the concentration of 3500mg/L activated sludge, after heating 60min at 70 °C, the total phosphorus release concentration of sludge reached 110mg/L, and the higher the temperature, the higher the rate of phosphorus release. The heat treatment method has the advantages of good phosphorus releasing effect and short reaction time, and the disadvantage is that the energy consumption is large in the heating process. Ultrasonic method.Ultrasonic lysis method is by means of ultrasonic effect in the liquid produced a series of physical and chemical reaction, change the characteristics of the liquid in the dissolved and particulate substances, destruction of cell structure in sludge, the release of the organic matter, nitrogen, phosphorus and other elements from the solid state method. The reaction condition is mild, the reaction time is short, the effect of sludge is good, but the energy consumption is large, and the strength and reaction time still need to be optimized in order to be applied in large scale. Alkali solution.The alkaline treatment of sludge by adding alkali to promote the dissolution of fiber content in the sludge, alkaline conditions can effectively inhibit the activity of activated sludge, intracellular material dissolution of the crack technology. Xiao Benyi and other [4] compared the effects of acid hydrolysis, alkali hydrolysis and pyrolysis of 3 kinds of sludge treatment methods on the nature of the sludge, found that the effect of alkali solution is best, the cracking rate of sludge reached 58.46%. Compared with other methods, the alkaline hydrolysis method has the advantages of simple equipment, easy operation and high efficiency. The PH of the sludge supernatant is alkaline, which provides a basic environment for phosphorus crystallization. But the reaction consumes a large amount of alkali, high investment . Method for recovering phosphorus from sludge At present, the main recovery methods of phosphorus rich supernatant are physical and chemical methods such as chemical precipitation method and other recovery methods. Magnesium ammonium phosphate crystallization method.In the process of residual sludge disintegration, the nitrogen element is usually accompanied with the release of nitrogen, and the nitrogen and phosphorus in the sludge can be recovered by the MAP method. Struvite is rich in nitrogen, phosphorus content, is a direct application of the farmland slow-release fertilizer; Wang et al. [6] found that map crystallization of the optimal pH was 9.0. Moerman [7] found that calcium ion interference effect in the process of formation of struvite. Generally considered to maintain Mg:PO4 =1.3:1.0 is more appropriate. According to the above conditions, the recovery of phosphorus in the residual sludge hydrolysis acidification solution can be recovered by MAP crystallization method, and the recovery rate can reach more than 80% [8]. Struvite crystallization into medicament price is high, due to the limitation of the purity, recovery of struvite economic

Denitrifying phosphorus removal process is to complete domestication and enrichment of denitrifying phosphate-accumulating organisms by using anaerobic/anoxic alternate environment instead of the traditional anaerobic/aerobic environment. Then, nitrogen and phosphorus can be removed simultaneously at the same stage. This paper mainly described the mechanism of denitrifying phosphorus removal, simply introduced the denitrifying phosphorus removal process, and discussed the influencing factors of denitrifying phosphorus removal process and the prospect of its development.

Water resources in Chinese rural areas were becoming precious because of the polluted water environment. In this paper, the status of rural areas in China has been reviewed. The typical pollutants in rural raw water bodies were different from urban raw water bodies. In rural water environment, organic matters and ammonia nitrogen concentration were high, heavy metal and other toxic pollutants were low. Enhanced coagulation, enhanced filtration, adsorption, biological oxidation and membranes were the main treating methods. The biological oxidation and membranes technology combination was prospected in future rural slightly polluted raw water treatment.

Nitrous oxide (N2O) is a kind of strong greenhouse gas, which can cause the composite pollution effect to the atmospheric environment. Wastewater biological treatment process is considered to be one of the important anthropogenic source of N2O. Therefore, the research on the generation of N2O in wastewater treatment process is of great theoretical significance and engineering application value. Based on a brief description of the mechanism of N 2O generation in wastewater treatment process, the research progress of N 2O dynamics model is deeply analyzed. And then the feasibility of building the N2O dynamic model which based on the Activated Sludge Model 3 (ASM3) is proposed and the endogenous respiration of microorganism s associated with N 2O generation is emphasized in dynamic modelling process. And on these bases, a reasonable prospect of the N 2O dynamic modelling is put forward.

Nitrous oxide (N2O) is one kind of potent greenhouse gas which can destroy ozone layer and lead to acid rain. Furthermore, nitrous oxide is quite easy to be converted into the secondary particle pollutants which can aggravate haze in certain weather conditions. Effective control of N2O emission has become imminent and the researches on N2O reduction have been get more and more attention. Related researches indicate that the process of wastewater biological denitrification is one of main artificial sources of N2O emission. And with the popularity of wastewater biological denitrification process, the emission quantity and harmness of N2O increases gradually. In this work, the mechanism of N2O generation in wastewater nitrification and denitrification process is revealed and the various influence factors to N2O emission is summarized. And then, the present reduction control techniques of N2O is analyzed in detail. On these basises, the future research directions of N2O reduction control is prospected.

In order to reveal the influence of reaction conditions on the phosphorus crystallization to recover phosphorus from wastewater with low P concentration, an alternate A/O biofiltration system for simulated domestic wastewater treatment was carried out and the effluent from anaerobic filter was considered as the reaction liquid for P crystallizatio n, as well as the influences of phosphorus by beginning phosphorus concentration, pH, Mg/P molar ratio and reaction time on the MAP crystallization and P removal were test systemlly. The results showed that the pH is the main influence factor on the crystallization time, and the higher pH value, the shorter crystallization time. Under the condition of the low P concentration, the key factor of the crystallization phosphorus removal rate is the Mg/P. Improve the Mg/P molar ratio mghit increase the phosphorus removal rate greatly.In addation, when the Mg/P molar ratio is 1:1 and the reaction time is 10 minutes, the lowest crystallization concentration is 18mg/L.