Search

In recent years, ceramic membranes have been increasingly used in membrane bioreactors (MBRs). However, membrane fouling was still the core issue restricting the large‐scale engineering application of ceramic MBRs. As a novel and alternative technology, ultrasonic could be used to control membrane fouling. This research focused on the efficiency and mechanism of ultrasonic controlling membrane fouling in ceramic MBRs. The results showed that ultrasonic reduced the sludge concentration in MBR, and the average particle size of sludge was always in a high range. The sludge activity of the system was stable at 6–9 (mg O2·(g MLSS·h)−1), indicating that ultrasonic did not destroy the activity of microorganisms in the system. The extracellular polymer substance (EPS) of the ultrasonic group was slightly higher than that of the control group, while the soluble microbial product (SMP) content was relatively stable. The ceramic membrane of the ultrasonic group has a partial retention effect on the organic components. The application of ultrasonic slowed down the decrease of the hydrophilicity of the ceramic membrane. The main pollutants on the membrane surface exist in the form of aromatic and heteroaromatic rings, alkynes, and so forth. Ultrasonic removes the amide substances from the membrane surface. Membrane fouling resistance is mainly due to membrane pore blockage, accounting for 75.53%. Practitioner Points: Enrich the research on the mechanism of ultrasonic technology in membrane fouling control.The MBR can still operate normally with ultrasonic applied.The time for the ceramic membrane to reach the fouling end point is 2.4 times that without ultrasonic.The main cause of membrane fouling was pore blocking, accounting for 75.53%. [ABSTRACT FROM AUTHOR]

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 A > model solution B > model 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. [ABSTRACT FROM AUTHOR]

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.

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.

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.

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.

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.

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.

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.

With the rapid development of society and the sustainable growth of population, people's demand for water has been increasing continually. In consequence, more and more sludge was generated from purification process in waterworks. Treating and utilizing the sludge efficiently and safely has becoming more and more important. In this paper, the composition and treatment process of sludge from municipal waterworks was introduced firstly.And then the comprehensive utilization of sludge and the problems among the utilization was focused on. New methods for sludge treatment and utilization as resources were explored at last.

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.

To meet the more strict discharging standard, some combined processes have emerged to realize denitrification and phosphorus removal of wastewater more efficiently. Among them, AAO-BAF combined process was an efficient one. The AAO-BAF system was composed of AAO reactor and BAF. The AAO process was the main unit to complete phosphorus removal and denitrification. The BAF process, external nitrification unit, was mainly used to provide enough electron acceptor for denitrifying bacteria in AAO reactor, which could enhance the efficiency of denitrification of the whole system. So the system optimizing was essential to AAO-BAF combined process. In this paper, the research progress of AAO-BAF wastewater treatment system was summarized and some system optimizing methods were raised too.

Removing efficiently and recycling of phosphorus in the wastewater, was not only an effective means to prevent and cure the eutrophication of water, but also an important way to realize the recovery of phosphorus resources. In the traditional AAO process, the discharge of phosphorus rich sludge could reach the goal of phosphorus removal. However, the treatment of phosphorus rich sludge was difficult and could not achieve the goal of phosphorus recovery. The lateral flow phosphorus removal treatment technology, building on the side of the traditional AAO system, was an efficient process to realize high efficiency phosphorus removal and phosphorus resources recovery by forming phosphate precipitation or crystallization. In this paper, by summarizing and analyzing the existing technology of lateral flow phosphorus recovery wastewater treatment based on AAO mainstream technology, the future development of this technology was also prospected.

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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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 provide insight into the N2O generation mechanism and regulate its production. This work uses Activated Sludge Model NO.3 (ASM3) as the basic framework, combines organic storage with endogenous respiration theory, and couples ammonia-oxidizing bacteria (AOB) denitrification pathway and the NH2OH/NOH model to establish a kinetic model. Meanwhile, the Sequencing Batch Reactor (SBR) process with artificial simulated urban domestic sewage was used as the carrier; MATLAB and EXCEL software were used as tools to establish a model calculation programme. The simulated values obtained by substituting the operating conditions of the SBR process into the model and the measured values of the SBR process were analysed. The correlation coefficient (R2) between the experimental values and simulated values obtained for the 5 components of COD, ammonia, nitrite, nitrate and total N2O is 0.952, 0.996, 0.902, 0.991 and 0.956, respectively, which indicates that the N2O kinetic model has great consistency, this further shows that the established model modelling mechanism is clear and accurate, and provides a new method for the N2O dynamic model. [ABSTRACT FROM AUTHOR]