Correlations between organic matter properties and DBP formation during chloramination

Characteristics, including fluorescence intensity and specific UV absorbance (SUVA), of 16 organic matter (OM) fractions isolated from four OM samples plus a standard were analyzed and correlated with their specific disinfection by-product (DBP) and total organic halogen (TOX) formation after chloramination. These isolates were obtained from various water sources by using XAD-8/4 resins. Chloramination was achieved by adding 20mg/L monochloramine to a solution containing one OM isolate at 5mg/L DOC and buffered at pH 7.5 for 7 days. The fluorescence regional integration (FRI) method was used to analyze the fluorescence intensity data obtained from excitation-emission matrix (EEM) fluorescence spectroscopy, in which the EEM figure was divided into five regions and a normalized fluorescence volume was calculated. The cumulative normalized EEM volumes at regions II and IV (Phi(II+IV,)(n)) showed linear relationships with the yields of dichloroacetic acid (DCAA) (R(2)=0.60), chloroform (R(2)=0.42), dichloroacetonitrile (DCAN) (R(2)=0.53), and TOX (R(2)=0.63). The SUVA values were found to have linear relationships with the yields of DCAA (R(2)=0.82), chloroform (R(2)=0.73), DCAN (R(2)=0.88) and TOX (R(2)=0.80), but not with the yields of cyanogen chloride (CNCl) and chloropicrin (CP). A modified model is proposed to simplify the reactions involving chloramination of OM fractions. FTIR spectra of OM before and after chloramination partially confirmed that ketone groups were reactive with monochloramine.     

Investigation of charge-transfer complexes formation between photoluminescent graphene oxide and organic molecules

Charge-transfer complexes have formed between photoluminescent graphene oxide and organic electron-donating molecules. With the increase of electron-donating power of molecules, the colour of solutions containing complexes became darker; UV absorption was red-shifted to longer wavelength and a new charge-transfer complex emission was also enhanced.     

Solar photolysis kinetics of disinfection byproducts

Disinfection byproducts (DBPs) discharged from wastewater treatment plants may impair aquatic ecosystems and downstream drinking-water quality. Sunlight photolysis, as one process by which DBPs may dissipate in the receiving surface water, was investigated. Outdoor natural sunlight experiments were conducted in water for a series of carbonaceous DBPs (trihalomethanes, haloacetic acids, halopropanones, and haloacetaldehydes) and nitrogenous DBPs (nitrosamines, halonitromethanes, and haloacetonitriles). Their pseudo-first-order rate constants for photolytic degradation were then used to calibrate quantitative structure-activity relationship (QSAR) parameters, which, in return, predicted the photolysis potentials of other DBPs or related compounds. Nitrogenous DBPs were found to be more susceptible to solar irradiation than carbonaceous DBPs, with general rankings for the functional groups as follows: N-nitroso (N-NO) > nitro (NO₂) > nitrile (CN) > carbonyl (CO) > carboxyl (COOH). Compounds containing a high degree of halogenation (e.g., three halogens) were usually less stable than less halogenated species (e.g., those with two halogens). Bromine- or iodine-substituted species were more photosensitive than chlorinated analogs. While most bromine- and chlorine-containing trihalomethanes and haloacetic acids persisted over the 6-h test, nearly complete removal (>99%) of nitrosamines occurred within 1 h of sunlight exposure. Indoor laboratory experiments using simulated sunlight demonstrated that the degradation of nitrosamines was ∼50% slower when organic matter was present, and ∼11% slower in non-filtered water than in filtered water.     

Quantification of defects depth in glass fiber reinforced plastic plate by infrared lock-in thermography

The increasing use of composite materials in various industries has evidenced the need for development of more effective nondestructive evaluation methodologies in order to reduce rejected parts and to optimize production cost. Infrared thermography is a noncontact, fast and reliable non-destructive evaluation technique that has received vast and growing attention for diagnostic and monitoring in the recent years. This paper describes the quantitative analysis of artificial defects in Glass fiber reinforced plastic plate by using Lockin infrared thermography. The experimental analysis was performed at several excitation frequencies to investigate the sample ranging from 2.946 Hz down to 0.019 Hz and the effects of each excitation frequency on defect detachability. The four point method was used in post processing of every pixel of thermal images using the MATLAB programming language. The relationship between the phase contrast with defects depth and area was examined. Finally, phase contrast method was used to calculate the defects depth considering the thermal diffusivity of the material being inspected and the excitation frequency for which the defect becomes visible. The obtained results demonstrated the effectiveness of Lock-in infrared thermography as a powerful measurement technique for the inspection of Glass fiber reinforced plastic structures.     

Dissolved organic nitrogen removal during water treatment by aluminum sulfate and cationic polymer coagulation

Coagulation of three surface waters was conducted with aluminum salt and/or cationic polymer to assess dissolved organic nitrogen (DON) removal. Coagulation with aluminum sulfate removed equal or slightly lower amounts of DON as compared to dissolved organic carbon (DOC). At aluminum sulfate dosages up to 5 mg per mg DOC, the cationic polymer improved DON removal by an additional 15% to 20% over aluminum sulfate alone. At very high aluminum sulfate dosages (>8 mg aluminum sulfate per mg DOC), however, the cationic polymer addition negligibly increased DON removal. Molecular weight fractionation before and after coagulation experiments indicated that cationic polymer addition can increase the removal of all molecular weight fractions of DON with the highest molecular weight fraction (>10,000 Da) being preferentially removed. Results indicated that the DON added as part of the cationic polymer was almost completely removed at optimum aluminum sulfate and polymer doses.     

Use of RF electric fields for simultaneous mineral and bio-fouling control in a heat exchanger

The objective of the present study was to investigate the effectiveness of a physical water treatment (PWT) technology using oscillating RF (radio frequency) electric fields in water to mitigate both mineral and bio-fouling in a cooling water application. Heat transfer tests were conducted using a laboratory-scale cooling tower to determine fouling resistance over time, and bio-fouling tests were performed using a heterotrophic plate count method to measure colony forming units (CFU) values per milliliter of cooling water. The results indicated that the present PWT technology could provide an effective mineral fouling prevention by maintaining 90% of the peak heat transfer performance of a heat exchanger, while effectively controlling water-borne microbial organisms.     

Analysis of the impact of flow characteristics on the separation efficiency and pressure drop of a cyclone-type oil separator

The effects of flow structure on the separation efficiency and pressure drop in a cyclone-type oil separator were investigated via Reynolds-averaged Navier-Stokes (RANS) simulations and large eddy simulations (LES), and the results were compared with experiments. Compared with the RANS simulations, the LES results were more similar to the experimental data as they simulated the complex flow structure more realistically. Swirling flow with strong turbulent kinetic energy (TKE) at the top section hindered the flow of particles toward the separator wall. In addition, a decrease in tangential velocity along the wall at the bottom reduced the centrifugal force, resulting in a decreased separation efficiency as particles were able to flow directly toward the outlet. The LES also predicted the pressure drop slightly better than the RANS simulation did, due to increased pressure drop caused by collision of the flow with the helix and outlet tube, which led to the formation of vortical flow structures with strong TKE.

     

Strain tensor effects on SrTiO3 incipient ferroelectric phase transition

Structural distortion of ferroelectric thin films caused by film strain has a strong impact on the microwave dielectric properties. SrTiO₃ thin films epitaxially grown on (110) DyScO₃ substrates using molecular beam epitaxy (MBE) are extremely strained (i.e., ～1% in-plane tensional strain) from 3.905 Å of bulk SrTiO₃. The room temperature dielectric constant and its tuning of the films are observed to be 6000 and 75% with an electric field of 1 V/μm, respectively. The control of strain in SrTiO₃ provides a basis for room temperature tunable microwave applications by elevating its phase transition peak to room temperature. Also, a significant in-plane anisotropy in dielectric constant and tuning was observed in these SrTiO₃ films. The observed in-plane anisotropic dielectric properties have been interpreted based on the phenomenological thermodynamics of film strain.     

Dissolved organic nitrogen measurement using dialysis pretreatment

Dissolved organic nitrogen (DON) is important for ecological and engineering researches. Quantification of low DON concentrations in waters with elevated dissolved inorganic nitrogen (DIN) using existing methods is inaccurate. In this study, a dialysis-based pretreatment technique was optimized and adopted to reduce the interference from DIN to the quantification of DON in natural water. A cellulose ester dialysis tube (nominal molecular weight cutoff = 100 Da) was used in batch and continuous-flow dialysis steps with model compounds, natural organic matter isolates, and bulk waters to develop a dialysis pretreatment approach that selectively reduces DIN from solutions containing DON. By reducing DIN concentrations, propagation of analytical variance in total dissolved nitrogen (TDN) and DIN species concentrations allows more accurate determination of DON (DON = TDN - NO3 - NO2- - NH3/NH4+). Dialysis for 24 h against continuously flowing distilled water reduced DIN species by 70%. With dialysis pretreatment, DON recoveries of more than 95% were obtained for surface water and finished drinking water, but wastewater experienced a slight loss (approximately 10%) of DON possibly due to the adsorption of organics onto the dialysis membrane, permeation of low molecular weight fractions, or biodegradation. Dialysis experiments using surface water spiked with different DIN/TDN ratios concluded that dialysis pretreatment leads to more accurate DON determination than no dialysis when DIN/TDN ratios exceed 0.6 mg of N/mg of N.     

An agent-based self-adaptation architecture for implementing smart devices in Smart Space

Smart Space is a major currently challenging domain that includes ubiquitous, grid, and pervasive computing to provide intelligence, insight, and vision for emerging world of intelligent environment, products, services and human interaction. Smart Space consists of various objects (devices and applications) and, their extremely tight integration of and coordination between information world and physical resources. In Smart Space, people are allowed to acquire useful information and control devices anytime and anywhere with various smart devices. However the physical world where devices are deployed has much uncertainty and uncontrollable conditions, so that it is impossible to make devices suited to all situations. To achieve user satisfaction and overcome the system failure, devices in Smart Space must be dependable, secure, safe, and efficient, and operate in real-time. In addition, they must be scalable, cost-effective and adaptive. Especially, to deal with uncertainty and uncontrollable condition, devices in Smart Space could be more intelligent in the adaptation. In this paper, we propose an agent-based self-adaptation architecture for implementing smart devices in Smart Space. A self-adaptive smart device reasons about its state and environment, and adapts itself at runtime automatically and dynamically in response to changes. Also we present an adaptation mechanism used to implementing a self-adaptive system.