Synergistic effects of combining ozonation, ceramic membrane filtration and biologically active carbon filtration for wastewater reclamation.

In this study, we proposed to apply an integrated process which is comprised of in situ ozonation, ceramic membrane filtration (CMF) and biologically active carbon (BAC) filtration to wastewater reclamation for indirect potable reuse purpose. A pilot-scale (20 m3/d) experiment had been run for ten months to validate the prospect of the process in terms of treatment performance and operational stability. Results showed that the in situ O3 + CMF + BAC process performed well in pollutant removal, with chemical oxygen demand, ammonia, nitrate nitrogen, total phosphorus and turbidity levels in the treated water being 5.1 ±â€¯0.9, 0.05 ±â€¯0.01, 10.5 ±â€¯0.8, <0.06 mg/L, and <0.10 NTU, respectively. Most detected trace organic compounds were degraded by>96%. This study demonstrated that synergistic effects existed in the in situ O3 + CMF + BAC process. Compared to pre-ozonation, in situ ozonation in the membrane tank was more effective in controlling membrane fouling (maintaining operational stability) and in degrading organic pollutants, which could be attributed to the higher residual ozone concentration in the tank. Because of the removal of particulate matter by CMF, water head loss of the BAC filter increased slowly and prolonged the backwashing interval to 30 days. BAC filtration was also effective in removing ammonia and N-nitrosodimethylamine from the ozonated water.

Acidogenic phosphorus recovery from the wastewater sludge of the membrane bioreactor systems with different iron-dosing modes.

A novel acidogenic phosphorus recovery (APR) process was developed in combination with Fe(III)-based chemical phosphorus removal and a membrane bioreactor (MBR) for enhanced wastewater treatment and effective P recovery. Two different system configurations were evaluated: Fe-dosing MBR (Fe-MBR), with the Fe-dosing into the MBR, and Fe-enhanced primary sedimentation followed by the MBR (FeP-MBR). The results show that both systems performed well for enhanced nutrient (N and P) removals and P recovery, with approximately 50% of the total P recovered from the municipal wastewater in the form of vivianite. Compared to the Fe-MBR system, FeP-MBR achieved more efficient P recovery under low food-waste loading conditions, maintained a higher ratio of biomass in activated sludge and experienced a slower rate of membrane fouling. Important functional bacteria were identified, including Prevotella and Selenomonas, which are active in hydrolysis and acidogenesis of sludge, and Aeromonas and Sulfurospirillum, which are involved in dissimilatory iron reduction.

Topochemical synthesis and photocatalytic activity of 3D hierarchical BaTiO3 microspheres constructed from crystal-axis-oriented nanosheets.

Novel BaTiO3 hierarchical porous microspheres were achieved by using H2Ti2O5·H2O (HTO) hierarchical microspheres as a precursor template via a facile solvothermal method. Interestingly, the BaTiO3 microspheres were constructed with two-dimensional (2D) nanosheets, which were composed of many order nanocrystals with crystal-axis-orientation. The special hierarchical structure, which is both macroporous and mesoporous, exhibits a large specific surface area and a high total pore volume. The photocatalytic performance of BaTiO3 hierarchical microspheres for degradation of methyl orange (MO) under UV-light irradiation was tested, its apparent rate being up to 0.10183 min-1, almost 23 times higher than that for nanoscale BaTiO3 particles. The attractive photocatalytic properties are considered to benefit from the effective features of hierarchical BaTiO3 microspheres, such as the ultrathin thickness of nanosheets and their ordered interconnected macro-mesoporous structure and intrinsic photocatalytic activity. This study offers an in situ topochemical conversion route to synthesis of other titanium-based perovskite hierarchical nanostructures, and thus opening the door for the synthesis of other titanium-based functional materials and expanding their potential application.

Comprehensive evaluation of pharmaceuticals and personal care products (PPCPs) in typical highly urbanized regions across China.

This study evaluated the occurrence of 36 PPCPs in urban river water samples collected from Beijing, Changzhou and Shenzhen. Twenty-eight compounds were detected. Compounds found with highest median concentrations included: sulfadimethoxine (164 ng/L), sulpiride (77.3 ng/L), atenolol (52.9 ng/L), and indomethacin (50.9 ng/L). Antibiotic was the predominant class detected and contributed about half of the overall PPCPs contamination level. Effluents from wastewater treatment plants (WWTPs) were demonstrated to be the predominant pathways through which PPCPs entering into aquatic environment in all investigated areas. The ratio of persistent PPCPs like sulpiride and carbamazepine was identified to be feasible in tracing their contamination sources in rivers. Concentrations of most detected PPCPs showed significant positive correlations with total nitrogen and total phosphorus. Two groups of representative PPCPs were selected as the chemical indicators for predicting the overall PPCPs contamination, based on the significant correlations between PPCPs.

[Direct removal of typical endocrine disruptors from heavily polluted river water by ozonation].

Ozone was applied to study the removal of conventional pollutants and typical endocrine disrupters (EDs), including bisphenol A (BPA), 4-n-nonylphenol(NP), 4-tert-octylphenol (OP), estrone (E1), estradiol (E2), 17alpha-estradiol (17alpha-E2), estriol (E3) and ethinylestradiol (EE2) , from heavily polluted river water. The O3 dose was designed at 28 mg x L(-1) for 30 min and 42 mg x L(-1) for 80 min. Pollutants in terms of chemical oxygen demand (COD) and ammonia nitrogen can not be removed efficiently, ranged from 3% to 7%. The colority of the black water was quickly reduced in the first 5 minutes, while the turbidities increased first and then decreased gradually. It showed that three EDs with relatively high level including BPA, OP and EE2 could be removed efficiently in thirty minutes. Concentrations of E3 increased first then decreased to be lower than the detection limit. Removal efficiencies of E1 and E2 were 41%-70% and 62%-85% respectively. Extension of ozone exposure time can not improve the efficiency of EDs removal any more.

Assimilation of 17α-ethinylestradiol by sludge and its stress on microbial communities under aerobic and anaerobic conditions.

The efficiency of 2 common types sludge, activated sludge and digesting sludge, to biodegrade ethinylestradiol (EE2) under aerobic and anaerobic conditions, and the impacts of EE2 on microbial community structure were investigated. The results showed that 75%-88% EE2 were removed under aerobic conditions and the values were 75%-84% under anaerobic conditions. The diversity of microbial species in the tested sludge decreased when exposed to EE2 and the shift of microbial community structures was dependent on both sludge types and process conditions. Predominant bacteria were identified as Proteobacteria class which was considered to have EE2 degradation capacities. Twelve strains were found, 8 of them belonged to the Class of γ-proteobacterium, 1 of ß-proteobacterium, 1 of Actinobacterium, and 2 of unclassified strains.

Thermodynamics and photochemical properties of alpha, beta, and gamma-hexabromocyclododecanes: a theoretical study.

The thermodynamics and photochemical properties of -alpha, +beta, and -gamma-hexabromocyclododecanes (HBCDs) have been investigated by density functional theory (DFT) and time-dependent DFT (TD-DFT) calculations. The optimized geometries of HBCDs are in agreement with recently published X-ray crystallographic data. The thermodynamic properties of three HBCDs indicate that alpha-HBCD is the most stable one. The TD-DFT calculations obtain the UV absorption spectra of the three HBCDs and provide a detailed assignment of the UV spectral features. Inspections of the frontier molecular orbitals reveal the n-->sigma* nature of the lowest-lying transition and predict the photodegradation and photostereoisomerization trends of HBCDs under the UV illumination with wavelengths shorter than 240 nm.

[Dynamic experiment on controlling of Microcystis aeruginosa by UV-C irradiation].

A plug-flow UV-C reactor equipped with low pressure UV lamp was utilized to study the suppression effect after UV-C irradiation under the dynamic conditions on Microcystis aeruginosa, a typical cyanobacterium in algae blooms in China. The culture fluid of Microcystis aeruginosa was exposed to UV-C irradiation when pumped through the reactor. After that, the fluid was incubated under the normal culture condition, and sampled at 2 h, 1 d, 3 d, 5 d, 7 d, 9 d for determination of cell density using the inverted system fluorescence microscope. The experiments showed that, UV-C irradiation did not cause severe cell lysis, and UV-C irradiation at dose ranged from 36 to 115 mW x s x cm(-2), and 31 to 50 mW x s x cm(-2) could suppress Microcystis aeruginosa biomass growth for the 2.6 x 10(5)-2.7 x 10(5) cells x mL(-1) and 9.0 x 10(5)-1.15 x 10(6) cells x mL(-1) fluid in 9 days, respectively.

[Effects of fractal structure on settling velocities of flocs].

Fractal structures of kaolin and humic flcos by the mass-size method based on the microbalance and free-settling method based on particle image velocimetry technique were investigated. The results showed that kaolin and humic flocs were characterized by fractal structure. The three-dimensional fractal dimensions of Fe flocs with more compact structure ranged from 2.14 to 2.28 are larger than those of alum flocs ranged from 1.75 to 1.83 by the mass-size method. The fractal dimensions of humic flocs are smaller than those of kaolin flocs. The fractal dimension has a close relationship with the settling velocity of flocs. The larger the fractal dimension, the higher the settling velocity. The fractal dimensions by the mass-size method are in good agreement with those by the free-settling method. The measured settling velocities of fractal aggregates do not follow with Stokes' law.

[Numerical simulation of TP transport after overflow of rainwater into urban lake].

Based on the three-dimensional advection-diffusion-reflection equation, a two-dimensional TP transport equation was deduced to simulate TP distribution and transport after overflow rainwater into urban lake from storm sewer system during rainstorm. The model has a good agreement with a group of monitor data at Lake Lichee in Shenzhen, China. The model was applied to compute the scenario in Lake Lichee under the design rainstorm, and analyse the fate of TP. It shows that TP flux into lake is 15.385 kg under city storm intensity of 28 mm/h, in which 62.3% of flux goes into water in lake and 28.1% TP flux settles surface sediment. It would take 3.0 days for the integrated treatment project operation to recover TP to the level before the rain.

[Water quality safety of ozonation and biologically activated carbon process in application].

Ozonation and biologically activated carbon process, one of advanced treatment technologies, has been applied in many places at home and abroad. However, some emerging water quality problems appeared in operation. Drinking water treatment plant (6 x 10(5) m3/d) with ozonation and biologically activated carbon process (O3-BAC process) was investigated systematically, including microbial safety, the excessive growth of aquatic microorganism and chemical stability of water quality. And some experiments were done in the pilot plant (10 m3/h) at the same time. O3-BAC process is reliable in microbial safety, but operation management should be enhanced. A good number of aquatic microorganisms grow immoderately during operation of O3-BAC process, which is more serious especially in place with high temperature and humidity. With prolong of runtime, the growth of aquatic microorganisms varies regularly. That is hazardous to water quality safety. When raw water is low with alkalinity, decrease of pH in O3-BAC process is obvious. That will seriously affect on chemical stability.

[Pollutant loading analyses and TP model calculation for eutrophication in Lichee Lake in Shenzhen].

Based on 9-month consecutive in situ monitoring data, this paper investigated the pollutant sources and loadings of eutrophication in Lichee Lake in Shenzhen. The external source mainly comes from overflow of storm sewer system, which will deteriorate water quality in lake. Total phosphorus concentration was measured with a maximum of 0.347 mg/L after overflow. The sediment release experiment showed that the release rate of total nitrogen during the first week was about 0.036 8 g/(m2 x d), and less release of total phosphorus from sediment into water was measured under aerobic condition. The total phosphorus modeling of each sub-lake for Lichee Lake was developed. The model had a good agreement with 2 groups of monitoring data. And calculation results showed that, it will take 2.18 days subject to 24-hour operations of the integrated treatment project per day to improve water quality in Lake to satisfy the National Standard IV of surface water.

[Treatment effect of eutrophication restoration project for Lichee Lake in Shenzhen].

Based on 9-month monitoring field data, this paper analyzes the variation of chlorophyll-a (Chl-a), total phosphorus (TP), total nitrogen (TN) and transparency (SD) in different sub-lake districts in order to study the treatment effect of eutrophication restoration project in Lichee Lake in Shenzhen. The statistical results show that, the average of TP and TN for whole lake were below 0.1 mg x L(-1) and 1.5 mg x L(-1) respectively, the average of Chl-a of north lake district and east lake district were 16.77 microg x L(-1) and 21.45 microg x L(-1) respectively, lower than that of south lake district (35.83 microg x L(-1) and west lake district (32.69 microg x L(-1)), and the average of SD for whole lake was greater than 0.5 m. During the 9-month operation of the restoration project, the average water quality satisfied the National Standard IV for surface water and the water was improved from hypereutrophic status to eutrophic status in Lake.

[Three-dimensional fluorescence fingerprint for source determination of dissolved organic matters in polluted river].

Fluorescence fingerprint technique was used to characterize dissolved organic matter (DOM) in river from different sources. The results showed that two types of DOM fluorescence signals were observed in river water: a humic-like fluorescence with three maxima at lambda(ex)/lambda(em) = 250/460 nm(A1), 220/400 nm(A2) and 325/420 nm(C); and a protein-like fluorescence with two maxima at lambda(ex)/lambda(em) = 230/360 nm(T2) and 285/357 nm(T1). The intensity of both of protein-like fluorescence distinctly increased because of the domestic wastewater drainage in the tributary stream. After the tributary converges into the main stream, the Fe3+ concentration in the main stream is 30 times as much as that of tributary stream, and the visible blue-shift of humic-like fluorescence occurred while the others didn't occur. The intensity of all types of fluorescence decreased from source to estuary resulting from different solute chemistry. However, the intensities of humic-like fluorescence C, A1 and protein-like fluorescence T2 at the longer excitation wavelength decreased significantly because of dilution from main river stream and complexation of humic-like with Fe3+, thus the peaks disappeared at the estuary while the fluorescence peaks at the shorter excitation wave-length were relatively stable on which the river solute chemistry had little effect. Therefore, the fluorophores at the shorter excitation wavelength of 220-230 nm area potential tool to determine the sources of DOM in polluted river.

[Study on the effects of organic removal by traditional purification process with three-dimensional excitation emission matrix fluorescence spectroscopy].

Fluorescence spectroscopy is widely used to elucidate the origin and structure of organic matters in water substance. Due to its high sensitivity, good selectivity and nondestructive nature, fluorescence technique is suitable to the study of chemical and physical properties of organic matters. Three-dimensional excitation emission matrix fluorescence spectroscopy (3DEEM) was applied to analyze the effects of organic removal by traditional purification process. The results show that 3DEEM is able to disclosure the changes of organic matters in the treatment processes effectively. Traditional purification process can remove some fulvic-like organic matter, but cannot remove it completely. Coagulant sedimentation basically does not have an effect of fulvic-like organic matter removal. The removal proportion of fulvic-like organic matter through filtration is 5%-15%.

[Characteristics of anaerobic sequencing batch reactor for the treatment of high-solids-content waste].

Based on the experiments of digestion of thermo-hydrolyzed sewage sludge in both mesophilic and thermophilic anaerobic sequencing batch reactors (ASBRs) with 20, 10, 7.5, 5d hydraulic retention time (HRT), operating characteristics of ASBR for treatment of high-solids-content waste were investigated. ASBR can efficiently accumulates suspended solids and keep high concentration solids, however there exists a "critical point" of ASBR, which means the maximum capability to accumulate suspended solids without negative effects on ASBR stability, and beyond which the performance deteriorates. Under steady condition, ASBR can sustains high solid retention time (SRT) and mean cell retention time (MCRT), the SRT and MCRT is 2.53 approximately 3.73 and 2.03 approximately 3.14 times of hydraulic retention time (HRT) when treating thermo-hydrolyzed sludge, respectively. Therefore, compared to traditional continuous-flow stirred tank reactor (CSTR), the efficiency of ASBR enhances about 7.13% approximately 34.68%.

[Study of sonochemical degradation of microcystins].

Sonochemical degradation of microcystins (MC) produced by microcystis in water and the influence of various ultrasonic parameters were studied. The results show that microcystins could be effectively degraded in ultrasonic fields. 150 kHz is the best ultrasound frequency for microcystins degradation, and the removal ratio of microcystins reached 70% after 20 min ultrasonic irradiation at 150 kHz and 40 W. Furthermore, ultraviolet irradiation strengthened the ultrasonic degradation of microcystins.

[Comparison on the performance of biostyr and bio-ceramic filter used for biological pretreatment of raw water].

A new biological filter called biostyr using biostyrene as media to purify raw water was compared with the widely studied bio-ceramic filter. The raw water was taken from a reservoir located in Northern China. It was shown this new biological filter could obviously improve the raw water quality. As far as the raw water investigated in this study was concerned, the removal percentage of COD(Mn), NH4+-N in the filter was 5%-20%, 80%-95%, respectively, and turbidity of the raw water decreased correspondingly, which indicated the feasibility that this filter could be applied in the field of biological pretreatment of raw water. It was also shown that under the uniform operating conditions, the performance of this new filter on the removal of contaminants, especially organics and turbidity, was slightly inferior to the bio-ceramic filter and would be more remarkably affected adversely by backwashing than bioceramic filter.

[Movement and transformation of nitrate in soil by non-uniform electrokinetics].

Movement and accumulation of nitrate in soil and groundwater has become a serious threat in many cities and agricultural areas. At the same time, application of nitrate as bacterial nitrogenous nutrient in the in-situ bioremediation of some organics-polluted sites is often required. Laboratory experiments were conducted to examine the feasibility of using non-uniform electrokinetics (NUEK) to control the movement of nitrate in unsaturated soil-water system. A natural soil taken from woodland was used as experimental soil. Three electrokinetic processes were tested in bench-scale cells at a constant potential gradient of 1.0 V/cm: unidirectional NUEK, NUEK with periodic polarity-reversal, and conventional uniform electrokinetic (UEK). The tests showed that NUEK drove NO3- through the experimental soil at a rate of 13.5-20 cm/d depending upon the concentration of NO3- and the distribution of electric field density. Compared with UEK, NUEK process more effectively concentrated and retained NO3- close to the anode. Moreover, NUEK process maintained soil characteristics and consumed much less electric energy. Reversal the polarity of NUEK weakened the concentration of NO3- to electrodes, but it stimulated the transformation of NO3- to NO2- and further lowered the electric energy consumption.

[Streaming current of waterworks sludge].

The applicability of streaming current in waterworks sludge treatment as indicator of coagulant dosage and pH control was investigated in this study. Experiments were conducted on sludge settling behaviors and dewatering processes. At the aspect of sludge settleability research showed the theoretical optimal dosage, pH was 8.9mg/L, 7.25, and the practical optimal dosage, pH was 9.0mg/L, 6.90. On the side of sludge dewaterability, the theoretical optimal dosage, pH was 25.0mg/L, 9.25, and the practical optimal dosage, pH was 26.0mg/L, 9.0. Results indicated that slightly positive streaming current coincided with the optimal dosage and pH. Thus streaming current can be used for continuous dosage feedback control as the single indicator.