Effective and mechanistic insights into shale gas wastewater reverse osmosis concentrate treatment using ozonation-biological activated carbon process.

Reverse osmosis (RO) plays a pivotal role in shale gas wastewater resource utilization. However, managing the reverse osmosis concentrate (ROC) characterized by high salinity and increased concentrations of organic matter is challenging. In this study, we aimed to elucidate the enhancement effects and mechanisms of pre-ozonation on organic matter removal efficacy in ROC using a biological activated carbon (BAC) system. Our findings revealed that during the stable operation phase, the ozonation (O3 and O3/granular activated carbon)-BAC system removes 43.6-72.2 % of dissolved organic carbon, achieving a 4-7 fold increase in efficiency compared with that in the BAC system alone. Through dynamic analysis of influent and effluent water quality, biofilm performance, and microbial community structure, succession, and function prediction, we elucidated the following primary enhancement mechanisms: 1) pre-ozonation significantly enhances the biodegradability of ROC by 4.5-6 times and diminishes the organic load on the BAC system; 2) pre-ozonation facilitates the selective enrichment of microbes capable of degrading organic compounds in the BAC system, thereby enhancing the biodegradation capacity and stability of the microbial community; and 3) pre-ozonation accelerates the regeneration rate of the granular activated carbon adsorption sites. Collectively, our findings provide valuable insights into treating ROC through pre-oxidation combined with biotreatment.

Dechlorination of 2,4-dichlorophenol by Fe/Ni nanoparticles: the pathway and the effect of pH and the Ni mass ratio.

ABSTRACTThe dechlorination of 2,4-dichlorophenol (2,4-DCP) by a nanoscale Fe/Ni material was investigated at room temperature. 2,4-DCP can be removed more quickly by an Fe/Ni material with 2% Ni. Fe/Ni exhibited excellent adsorption and reduction efficiency toward 2,4-DCP in an aqueous solution over a wide range of pH values. The removal rate of 2,4-DCP exceeded 95% in 60 min in the pH range of 3.0-9.0, and more than 75% was dechlorinated to phenol (CA). The degradation pathway of 2,4-DCP was confirmed based on analysis of the intermediate and end products. A portion of 2,4-DCP was first dechlorinated with a chlorine atom to produce 2-chlorophenol and 4-chlorophenol, and then dechlorination was performed sequentially to form CA. The other portion of 2,4-DCP was dechlorinated to remove two chlorine atoms simultaneously to generate CA. The investigations are essential to the application of iron-based remediation technology.

A sensory memory processing system with multi-wavelength synaptic-polychromatic light emission for multi-modal information recognition.

Realizing multi-modal information recognition tasks which can process external information efficiently and comprehensively is an urgent requirement in the field of artificial intelligence. However, it remains a challenge to achieve simple structure and high-performance multi-modal recognition demonstrations owing to the complex execution module and separation of memory processing based on the traditional complementary metal oxide semiconductor (CMOS) architecture. Here, we propose an efficient sensory memory processing system (SMPS), which can process sensory information and generate synapse-like and multi-wavelength light-emitting output, realizing diversified utilization of light in information processing and multi-modal information recognition. The SMPS exhibits strong robustness in information encoding/transmission and the capability of visible information display through the multi-level color responses, which can implement the multi-level pain warning process of organisms intuitively. Furthermore, different from the conventional multi-modal information processing system that requires independent and complex circuit modules, the proposed SMPS with unique optical multi-information parallel output can realize efficient multi-modal information recognition of dynamic step frequency and spatial positioning simultaneously with the accuracy of 99.5% and 98.2%, respectively. Therefore, the SMPS proposed in this work with simple component, flexible operation, strong robustness, and highly efficiency is promising for future sensory-neuromorphic photonic systems and interactive artificial intelligence.

Optimizing dewaterability of drinking water treatment sludge by ultrasound treatment: Correlations to sludge physicochemical properties.

Sludge dewatering has proven to be an effective method to reduce the volume of sludge. In this study, drinking water treatment sludge (DWTS) was treated by ultra-sonication under variable conditions comparing two sonoreactor types (bath and probe), four frequencies (25, 40, 68, 160 kHz) and four energy density levels (0.03, 1, 3, 5 W/mL). The effects of these conditions were studied using specific resistance to filtration and capillary suction time as measures of dewaterability, and floc size, the Brunauer, Emmett and Teller (BET) specific surface area and Zeta potential to determine treated sludge characteristics. The results indicated that the dewaterability of sonicated sludge improved at relatively low energy densities of 0.03 and 1.0 W/mL, while an optimum for sonication duration (within 10 min) was also identified. Higher frequencies (tested up to 160 kHz) with acoustic energy density of 0.03 W/mL also reduced the dewatering property. At higher energy densities of 3.0 and 5.0 W/mL, dewaterability of sludge deteriorated regardless of ultra-sonication time, with an increase of solubilized organic matter content and severely changed floc characteristics. The deterioration of the dewatering capacity was closely related to the considerably reduced floc sizes, dissolution of proteins and polysaccharides, and to the Zeta potential of sonicated sludge flocs. The dewaterability was not correlated with BET specific surface area. Mechanistic explanations for the observations were discussed by analyzing corrosion patterns of aluminum foil as a measure for cavitation field distribution.

Optimized removal of natural organic matter by ultrasound-assisted coagulation of recycling drinking water treatment sludge.

In previous work we have shown that recycling pre-sonicated drinking water treatment sludge (DWTS) could improve coagulated water quality. Here, the removal of naturally occurring organic matter of source water was further optimized using response surface methodology (RSM) with Box-Behnken Design (BBD). The four variables, i.e., volumetric recycling ratio of DWTS, energy density, ultra-sonication time and duty cycle in an experimental jar test of ultrasound assisted flocculation-coagulation were optimized. All the variables showed a significant effect on dissolved organic carbon (DOC) removal of source water (p < .05), of which the duty cycle had a stronger effect on the removal performance compared to the other independent variables. The predicted optimal DOC removal rate was 36.94%, and this matched well the observed performance of 36.54 ±â€¯0.56%, obtained by ultra-sonicating the sludge prior to recycling using a power input of 1.015 W/mL, an ultra-sonication time of 9 min 50 s, and a duty cycle of 80%, while the volumetric recycling ratio of DWTS was 5.8%. The natural organic matter fractions in the coagulated water samples indicated that recycling sonicated DWTS that had been washed prior to recycling in order to remove solubilized extracellular polymers could enhance removal of hydrophobic acids and 3-30 kDa fractions, but this treatment increased the presence of substances with molecular weight <3 kDa. Humic-like substances were effectively removed while tyrosine-like substances could be enriched. Sludge samples (raw DWTS, sonicated DWTS, sludge formed by recycling raw DWTS, and sludge formed by recycling sonicated DWTS without solubilized extracellular organics) were characterized by XRF, X-ray diffraction patterns and FE-SEM-EDS to reveal possible physical characteristics that could be related to the DOC removal performance.