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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.

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.

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.

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.

In this paper, a review on the mechanism of denitrifying phosphorus removal and the enrichment of denitrifying phosphorus-accumulating organisms in the process of nitrogen and phosphorus removal, such as A 2 /O and SBR, were presented, as well as the influence factors of enrichment were also carried out. And finally, the outlook of denitrifying phosphorus removal process for future research was suggested. Conventional biological treatment process can effectively reduce BOD5 and SS of inflow, but the removal efficiencies of nitrogen and phosphorus in wastewater are not effective, which cause that a large amount of sewage containing nitrogen and phosphorus directly discharge into water body. Therefore, the nitrogen and phosphorus pollution is the primary cause for water entrophication. Although the government put forward more and more strictly requirements for sewage discharge, it is difficult to remove nitrogen and phosphorus efficiently for the conventional nitrogen and phosphorus removal process, because of various reasons, such as carbon-nitrogen ratio in the city sewage. So it is necessary to develop more stable, economical and efficient process for nitrogen and phosphorus removal. Denitrifying phosphorus removal process is to complete domestication and enrichment of denitrifying phosphate-accumulating organisms (DNPAOs) by using anaerobic/anoxic alternate environment instead of the traditional anaerobic/aerobic environment. DNPAOs can use NO3 - as electron acceptor in denitrifying phosphorus removal system, meanwhile through their metabolism complete excess phosphorus uptake and denitrification process at the same time to achieve the dual purpose of nitrogen and phosphorus removal. Application of denitrifying phosphorus removal process for treatment of municipal wastewater can not only save aeration quantity, but also reduce the amount of residual sludge. And it also can cut down investment and operation costs. In recent years, many scholars did a number of researches on denitrifying phosphorus removal technology. Due to the varying techniques, enrichment mode and denitrifying phosphorus removal degree, the conclusion was not entirely consistent.

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.

The phosphate removal abilities and crystallization performance of quartz sand, ceramsite, blast furnace slag and steel slag were investigated. The residual phosphate concentrations in the reaction solutions were not changed by addition of the ceramsite, quartz sand and blast furnace slag. The steel slag could provide alkalinity and Ca2+ to the reaction solution due to its hydration activity, and performed a better phosphate removal performance than the other three. Under the conditions of Ca/P 2.0, pH 8.5 and 10 mg P/L, the phosphate crystallization occurred during 12 h. The quartz sand and ceramsite did not improve the phosphate crystallization, but steel slag was an effective seed crystal. The phosphate concentration decreased drastically after 12 h after addition of steel slag, and near complete removal was achieved after 48 h. The XRD analysis showed that the main crystallization products were hydroxyapatite (HAP) and the crystallinity increased with the reaction time. Phosphate was successfully recovered from low phosphate concentration wastewater using steel slag as seed material.

The influence of free chlorine on the nitrite accumulation in Biological Aerated Filter (BAF) was investigated by adding chlorine in the bioreactor in order to carry out a shortcut nitrification-denitrification. The relationship of the adding dosage and feeding modes of free chlorine and the nitrite accumulation in BAF were also considered. The results show that the nitrite accumulation could be achieved by adding chlorine. When the influent concentration of chlorine was 4mg/L, the concentration of effluent nitrite nitrogen was increased remarkably after the system had been operated for 20 days, and the nitrite accumulation rate could be kept in 60%–70%. The steady state of nitrite accumulation could be maintained with decreasing in the concentration of the influent chlorine, and could also be maintained at a certain degree with the adding mode of intermittent chlorination.

Study was made on stability and influencing factors of nitrite accumulation in Biological Aerated Filter (BAF)treating simulated municipal wastewater. The possibility of shortcut nitrification–denitrification in low ammonia wastewater treatment was discussed. The mode of natural start-up was favorable to the nitrite accumulation in BAF and the highest nitrite accumulation rate was over 80%. By adjusting pH, nitrite accumulation can take place in BAF. When the influent pH value was 6.5 to 7, the highest nitrite accumulation rate was 57%. But long-term stable nitrite accumulation cannot be obtained only through changing influent pH value. The lower concentration of DO was of advantage to the formation of the nitrite accumulation. When the concentration of DO was controlled to less than 0.5 mg/L, the nitrite accumulation rate can improved significantly to the maximum over 80%. The increasing of hydraulic loading can contribute to nitrite accumulation. When the hydraulic loading was enhanced to 10 m3/(m2•h), the average nitrite accumulation rate can be increased by 52.5 times. The increasing of influent ammonia loading cannot improve nitrite accumulation notably. When influent pH was 6.5 to 7, concentration of DO was 1.0 to1.5 and the filtration rate was 5 m/h, the nitrite accumulation of BAF reactor was of good stability. During 60 days' running, the nitrite accumulation can keep at 65% to 75% stably and obvious shortcut nitrification-denitrification was found.

A comparative study on phosphate removal between activated steel slag and blast furnace slag was investigated. The efficiency of different slags before and after activated for phosphate removal were also evaluated. The results show that the slags activated by hydrothermal treatment are more efficient than raw slags in phosphate removal. The activated slags could be reused for several times and the phosphate removal efficiency could be guaranteed by increasing there action time towards to different reused times. Compared with activated pulverized slags, the activated granular slags could be reused for a longer time for a given initial phosphate concentration. The results suggest that the activated granular slags may be effective materials for phosphate removal. The phosphate removal by activated slag was mainly through chemical precipitation.

The backwashing optimization, which included gas washing, water washing and water rinsing, was carried out in three biological aerated filters with zeolite, ceramic particle and carbonate media. The recovery of headloss and treatment efficiency in the biofilters after backwashing were also investigated for deeper understanding of the relationship of headloss and backwashing in BAF. The results showed that the COD and SS increased in effluent just after backwashing but could be recovered in 2 hours. The concentration of ammonia nitrogen in effluent almost did not change and recovered quickly. All of three BAFs have a promising backwashing performance and operational stability after backwashing. The backwashing procedure of upfollow BAF is suggested as follow: Firstly, air washing 2–3min with air flow rate of 10 L m−2 s−1, then air and water washing 3–5min with both air and water flow rate of 10 L m−2 s−1, and finally water rinsed for 9–11min with water flow rate of 10 L m−2 s−1.

The performance and nitrification properties of three BAFs, with ceramic, zeolite and carbonate media, respectively, were investigated to evaluate the feasibility of employing these materials as biological aerated filter media. All three BAFs shown a promising COD and SS removal performance, while influent pH was 6.5-8.1, air-liquid ratio was 5:1 and HRT was 1.25-2.5 h, respectively. Ammonia removal in BAFs was inhibited when organic and ammonia nitrogen loading were increased, but promoted effectively with the increase pH value. Zeolite and carbonate were more suitable for nitrification than ceramic particle when influent pH below 6.5. It is feasible to employ these media in BAF and adequate bed volume has to be supplied to satisfy the requirement of removal COD, SS and ammonia nitrogen simultaneously in a biofilter. The carbonate with a strong buffer capacity is more suitable to treat the wastewater with variable or lower pH.