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Bu Q.,CAS Research Center for Eco Environmental Sciences | Wang D.,CAS Research Center for Eco Environmental Sciences | Wang Z.,CAS Research Center for Eco Environmental Sciences | Gu J.,Beijing Waterworks Group Co.
Frontiers of Environmental Science and Technology

The Danjiangkou reservoir was selected to provide the source water for the middle routes of the South to North Water Transfer Project, which has provoked many environmental concerns. To date, investigations of water contamination of the source water of the Danjiangkou reservoir with organic micro-pollutants have been limited. This study was conducted to identify and rank organic contaminants that pose risks in the Danjiangkou reservoir. To this end, the Chemical Hazard Evaluation and Management Strategies (CHEMS-1) approach was adapted to integrate the deconvolution technology of qualitative identifying contaminants for site-specific environmental matrices. The samples were screened for the presence of 1093 contaminants using deconvolution technologies and the hazard values of the identified contaminants were calculated using the adapted CHEMS-1 approach according to their hazardous properties and occurrence in source water. The results showed that 46 contaminants from 1093 targets were present in Danjiangkou water, 23 of which appeared at frequencies higher than 50%, and 15 of which were identified as priorities. Over half (53%) of the highranked contaminants were polycyclic aromatic hydrocarbons (PAHs), with chrysene ranked highest on the list. Health risk assessment of the top-ranked PAHs was conducted and revealed that cancer risks of PAHs detected in the source water of Danjiangkou to different populations ranged from 10-7 to 10-6, indicating a low cancer risk to consumers. The results of this study indicated that the adapted CHEMS-1 approach was feasible for site-specific screening of organic contaminants to identify and rank potential priority pollutants. © 2013 Higher Education Press and Springer-Verlag Berlin Heidelberg. Source

Wang Y.L.,Beijing Forestry University | Yan W.L.,Beijing Forestry University | Qian X.,Beijing Forestry University | Sheng Y.Q.,Beijing Forestry University | Chen Y.J.,Beijing Waterworks Group Co.
Journal of Water Process Engineering

Three types of polyacrylamide (PAM) flocculants of cationic PAM WD4960, non-ionic PAM M351, and anionic PAM WDA110 had different performances on the Ferric hydroxide gel (FHG) dewaterability and that M351 was the best one. The optimum dosages of these PAMs did not completely depend on the FHG total suspended solid (TSS) content of 0.2-1.5. g/L. The amount of PAM absorbed on the FHG surface linearly increased with an increase in its dosage, and saturation adsorption did not occur at the tested PAM dosages. The rise in PAM dosage can increase the size of conditioned FHG flocs/aggregates, while can decrease their compactness. The conditioned FHG aggregates at the optimum M351 dosage exhibited a moderate size, the smoothest surface, and the least compact structure among the three types of PAM. Conditioning the raw FHG with the cationic PAM of WD4960 increased its positive charge and decreased its hydrophilicity and specific surface area (S). However, M351 or WDA110 conditioning only increased the negative surface charge and hydrophilicity and decreased the S value of the conditioned FHG. The osmotic pressure variations indicated that, as a hydrogel, the optimum WD4960-conditioned FHG had stronger potential to absorb water from outside than the M351 or WDA110-conditioned FHG. Compared with that in the raw FHG, the free water content (FWC) reduction in the M351- or WD4960-conditioned FHG contributed entirely to the increase in bound water content (BWC) and the water release outside the hydrogel. © 2015 Elsevier Ltd. Source

Wu J.,Beijing Waterworks Group Co. | Wu J.,Technical University of Denmark | Lind M.,Technical University of Denmark | Zhang X.,Technical University of Denmark | And 2 more authors.
Computer Aided Chemical Engineering

Qualitative modeling paradigm offers process systems engineering a potential for developing effective tools for handling issues related to Process Safety. A qualitative functional modeling environment can accommodate different levels of abstraction for capturing knowledge associated with the process system functionalities as required for the intended safety applications. To provide the scientific rigor and facilitate the acceptance of qualitative modelling, this contribution focuses on developing a scientifically based validation method for functional models. The Multilevel Flow Modeling (MFM) methodology is adopted in the paper as a formalized qualitative functional modeling methodology for dynamic process systems. A functional model validation procedure is proposed to assess whether the intended modeling purpose indeed represents a relevant proposal and whether the model represents the system behavior sufficiently well. With the reasoning capability provided by the MFM syntax and semantics, the validation procedure is illustrated on a three-phase separator system of an MFM model. The MFM model reasoning results successfully compares against analysis results from API RP. 14-C. © 2015 Elsevier B.V. Source

Chen Y.,CAS Research Center for Eco Environmental Sciences | Chen Y.,Beijing Waterworks Group Co. | Xiao F.,CAS Research Center for Eco Environmental Sciences | Liu Y.,Beijing Waterworks Group Co. | And 4 more authors.
Frontiers of Environmental Science and Engineering

The continuous variations of dissolved oxygen (DO), manganese (Mn), pH, and their effect on manganese removal by different water treatment processes are investigated. The results show that the declined DO concentration and pH value in the bottom of reservoir results in the increasing release of Mn from sediment to source water. Manganese concentration increased from 0.1 to 0.4 mg·L-1 under the condition that DO concentration decreased from 12.0 to 2.0 mg·L-1 in raw water. The different water treatment processes exhibited different efficiency on manganese removal. The processes with recycling of the suspended sludge, low elevation velocity in settling tank and slow filter rate, will benefit the manganese removal. During a high release of manganese in raw water, traditional coagulation-sedimentation and filtration could not completely remove Mn, although granular activated carbon filtration (GAC) had been applied. At that case, preoxidation with chlorine or potassium permanganate (KMnO4) was necessary to address the high manganese concentration. © 2014 Higher Education Press and Springer-Verlag Berlin Heidelberg. Source

Zhou Z.,Beijing University of Technology | Yang Y.,Beijing University of Technology | Li X.,Beijing University of Technology | Wang W.,Beijing University of Technology | And 3 more authors.
Separation and Purification Technology

This research innovatively investigated the coagulation performance of recycling pre-sonicated condensate drinking water treatment sludge under different ultrasound (US) conditions (ultrasonic time of 5, 10, 15, 20 and 30 min and US frequencies of 25, 40, 125 and 160 kHz) for low-turbidity surface water treatment. The formation, breakage and re-growth of re-coagulated flocs generated by recycling processes were examined using photometric dispersion analyzer to explore flocs growth properties, flocs strength and re-aggregation potential. The morphological analysis was further conducted to study the structural properties of the broken flocs to elucidate the reversibility/ irreversibility of re-growth process. The results indicated that 25 or 40 kHz within 5 min sonication was more favorable for turbidity removal, while 125 or 160 kHz with 10 or 15 min for organics removal. The recoverability of broken flocs was irreversible for the recycling processes regardless of US frequencies. Additionally, the flocs formed preliminarily exposed to 25 or 40 kHz were stronger and more resistant to breakage, and the recoverability was more irreversible. Furthermore, the flocs formed at 25 or 40 kHz were larger and more irregular with more porous and ramose structure. The average size obtained from morphological analysis could also strongly demonstrate the irreversibility of recovery process. © 2013 Elsevier B.V. All rights reserved. Source

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