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Effects of different sludge disintegration methods on sludge moisture distribution and dewatering performance

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Journal of environmental Sciences 2015年第2期27卷 22-28页

作者： Lingyun Jin Guangming Zhang Xiang Zheng school of environment & resource Renmin University of China

A key step in sludge treatment is sludge dewatering. However, activated sludge is generally very difficult to be dewatered. Sludge dewatering performance is largely affected by the sludge moisture distribution. Sludge disintegration can destroy the sludge structure and cell wall, so as change the sludge floc structure and moisture distribution, thus affecting the dewatering performance of sludge. In this article, the disintegration methods were ultrasound treatment, K2 Fe O4oxidation and KMn O4 oxidation. The degree of disintegration（DDCOD）, sludge moisture distribution and the final water content of sludge cake after centrifuging were measured. Results showed that three disintegration methods were all effective, and K2 Fe O4oxidation was more efficient than KMn O4 oxidation. The content of free water increased obviously with K2 Fe O4and KMn O4 oxidations, while it decreased with ultrasound treatment. The changes of free water and interstitial water were in the opposite trend. The content of bounding water decreased with K2 Fe O4oxidation, and increased slightly with KMn O4 oxidation, while it increased obviously with ultrasound treatment. The water content of sludge cake after centrifuging decreased with K2 Fe O4oxidation, and did not changed with KMn O4 oxidation, but increased obviously with ultrasound treatment. In summary, ultrasound treatment deteriorated the sludge dewaterability, while K2 Fe O4and KMn O4 oxidation improved the sludge dewaterability.

关键词： Ultrasound treatment K2Fe O4oxidation KMn O4oxidation Sludge moisture distribution Dewatering performance

Performance and role of N-acyl-homoserine lactone(AHL)-based quorum sensing(QS) in aerobic granules

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Journal of environmental Sciences 2014年第8期26卷 1615-1621页

作者： Yaochen Li Junping Lv Chen Zhong Wen Hao Yaqin Wang Jianrong Zhu school of environment Beijing Normal University school of Water resource and environment Shijiazhuang University of Economics

The present study investigated the relationship between N-acyl-homoserine lactone（AHL）-based quorum sensing（QS） and the physico-chemical properties of aerobic *** mature granules were observed in SBR2 and SBR3 with average diameters of 0.96,and1.49 mm,respectively. The sludge densities of aerobic granules in SBR2 and SBR3 were1.0246,and 1.0201 g/mL,respectively,which were higher than that of flocculent sludge in SBR1（1.0065 g/mL）. The results showed that the activity of AHL-based QS in SBR2 and SBR3 amounted to 2.4- and 2.1-fold induction,however,that in SBR1 with flocculent sludge was1.6-fold induction. In addition,the results also showed that the activity of AHL-based QS in the three reactors rose in the feast condition,and then dropped with the consumption of substrate. However,the activity of AHL-based QS in these three reactors recovered again in prolonged starvation. Furthermore,the results showed that the enhancement of AHL-based QS favored the extracellular polymeric substance production of microorganisms in activated sludge. Thus,it could be concluded that aerobic granules showed higher AHL-based QS than flocculent sludge,which resulted from the higher sludge density of aerobic granules than flocculent sludge. AHL-based QS was related to the metabolism energy in the feast condition; however,in prolonged starvation,microorganisms would emit more AHL-like molecules to protect themselves to resist starvation. Moreover,the enhancement of AHL-based QS favored the EPS component productivity of the microorganisms in activated sludge,which contributed to maintain the aerobic granular structure.

关键词： Aerobic granules N-acyl-homoserine lactone Quorum sensing Extracellular polymeric substances

Spatial quality evaluation for drinking water based on GIS and ant colony clustering algorithm

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Journal of Central South University 2014年第3期21卷 1051-1057页

作者：侯景伟米文宝李陇堂 school of resource and environment Ningxia University

To develop a better approach for spatial evaluation of drinking water quality, an intelligent evaluation method integrating a geographical information system(GIS) and an ant colony clustering algorithm(ACCA) was used. Drinking water samples from 29 wells in Zhenping County, China, were collected and analyzed. 35 parameters on water quality were selected, such as chloride concentration, sulphate concentration, total hardness, nitrate concentration, fluoride concentration, turbidity, pH, chromium concentration, COD, bacterium amount, total coliforms and color. The best spatial interpolation methods for the 35 parameters were found and selected from all types of interpolation methods in GIS environment according to the minimum cross-validation errors. The ACCA was improved through three strategies, namely mixed distance function, average similitude degree and probability conversion functions. Then, the ACCA was carried out to obtain different water quality grades in the GIS environment. In the end, the result from the ACCA was compared with those from the competitive Hopfield neural network(CHNN) to validate the feasibility and effectiveness of the ACCA according to three evaluation indexes, which are stochastic sampling method, pixel amount and convergence speed. It is shown that the spatial water quality grades obtained from the ACCA were more effective, accurate and intelligent than those obtained from the CHNN.

关键词： geographical information system (GIS) ant colony clustering algorithm (ACCA) quality evaluation drinking water spatial analysis

Rapid degradation of dyes in water by magnetic Fe^0/Fe_3O_4/graphene composites

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Journal of environmental Sciences 2016年第6期28卷 148-157页

作者： Shan Chong Guangming Zhang Huifang Tian He Zhao school of environment & Natural resource Renmin University of China

Magnetic Fe^0/Fe3O4/graphene has been successfully synthesized by a one-step reduction method and investigated in rapid degradation of dyes in this work. The material was characterized by N2 sorption–desorption, scanning electron microscopy（SEM）, Fourier transform infrared spectroscopy（FT-IR）, vibrating-sample magnetometer（VSM） measurements and X-ray photoelectron spectroscopy（XPS）. The results indicated that Fe^0/Fe3O4/graphene had a layered structure with Fe crystals highly dispersed in the interlayers of graphene, which could enhance the mass transfer process between Fe^0/Fe3O4/graphene and pollutants. Fe^0/Fe3O4/graphene exhibited ferromagnetism and could be easily separated and re-dispersed for reuse in water. Typical dyes, such as Methyl Orange, Methylene Blue and Crystal Violet, could be decolorized by Fe^0/Fe3O4/graphene rapidly. After 20 min, the decolorization efficiencies of methyl orange, methylene blue and crystal violet were 94.78%, 91.60% and 89.07%, respectively. The reaction mechanism of Fe^0/Fe3O4/graphene with dyes mainly included adsorption and enhanced reduction by the composite. Thus, Fe^0/Fe3O4/graphene prepared by the one-step reduction method has excellent performance in removal of dyes in water.

关键词： Fe^0/Fe3O4/graphene Magnetic Dyes Removal Reduction

Characteristic of synergistic extraction of oxalic acid with system from rare earth metallurgical wastewater

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Journal of Rare Earths 2010年第6期28卷 858-861页

作者：邱廷省刘庆生方夕辉彭时忠 school of resource and environment Jiangxi University of Science and Technology

Large amount of high concentration acidic wastewater would be produced in the conversion process of chloride rare earth into oxide rare earth. It was a mixed solution of oxalic acid and hydrochloric acid, so the recycling use was very difficult. The method of liquid-liquid extraction was proposed in this paper to achieve wastewater treatment and reclamation. The mechanism of extraction of oxalic acid from the wastewater with the systems of 50% TOB+45% kerosene and 5% 2-ethyl hexanol was investigated. The composition and structure of the extracted species and the establishment of the mathematical model of the oxalic acid extraction were determined by the use of saturation method, equimolar series method. The results showed that extraction of oxalic acid by TOB was a neutral association extraction, oxalic acid existed mainly in a molecular form in the organic phase, and the extraction combination ratio was 2:1. The duality extraction system composed of extractant TOB and TOC had synergistic extraction effect on oxalic acid and chlorhydric acid, and the extraction distribution ratio was improved greatly. The optimum volume fraction of TOB was 0.6-0.8.

关键词： extraction mechanism acid wastewater rare earth extraction

Mg^(2+) improves biomass production from soybean wastewater using purple non-sulfur bacteria

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Journal of environmental Sciences 2015年第2期27卷 43-46页

作者： Pan Wu Guangming Zhang Jianzheng Li State Key Laboratory of Urban Water resource and environment Harbin Institute of Technology school of environment & resource Renmin University of China

Soybean wastewater was used to generate biomass resource by use of purple non-sulfur bacteria（PNSB）. This study investigated the enhancement of PNSB cell accumulation in wastewater by Mg2＋under the light-anaerobic condition. Results showed that with the optimal Mg2＋dosage of 10 mg/L, biomass production was improved by 70% to 3630 mg/L,and biomass yield also was improved by 60%. Chemical Oxygen Demand（COD） removal reached above 86% and hydraulic retention time was shortened from 96 to 72 hr. The mechanism analysis indicated that Mg2＋could promote the content of bacteriochlorophyll in photosynthesis because Mg2＋is the bacteriochlorophyll active center, and thus improved adenosine triphosphate（ATP） production. An increase of ATP production enhanced the conversion of organic matter in wastewater into PNSB cell materials（biomass yield） and COD removal, leading to more biomass production. With 10 mg/L Mg2＋, bacteriochlorophyll content and ATP production were improved by 60% and 33% respectively.

关键词： Purple non-sulfur bacteria Mg2+ Biomass resource Soybean wastewater Photosynthesis

Chemical Behavior of Cadmium in Purple Soil as Affected by Surfactants and EDTA

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Pedosphere 2006年第1期16卷 91-99页

作者： CHEN Yu-Cheng XIONG Zhi-Ting DONG Shan-Yan school of resource and environment Science Wuhan University Wuhan 430072 （China）. school of resource and environment Southwest Agricultural University Chongqing 400716 （China）

A soil batch experiment was conducted to investigate both separate and compound effects of three types of surfactants: anionic dodecylbenzene sulfonic acid sodiumsalt (DBSS), cationic cetyltrimethylammonium bromide (CTAB), and non-ionic nonyl phenol polyethyleneoxy ether (TX-100), as well as ethylenediaminetetraacetic acid (EDTA) on cadmium solubility, sorption kinetics, and sorption-desorption behavior in purple soil. The results indicated that both individual application of the three types of surfactants and surfactants combined with EDTA could stimulate Cd extraction from the soil with a general effectiveness ranking of EDTA/TX-100 > EDTA/DBSS > EDTA/CTAB > EDTA > TX-100 > DBSS > CTAB. Further study showed that the compound application of surfactants and EDTA had stronger (P < 0.05) effects on Cd solubility than those added individually. The application of surfactants and EDTA to purple soil (P < 0.05) decreased the proportion of Cd sorbed, while their effectiveness ranking was similar to that of enhanced solubilization. The sorption kinetics of Cd in purple soil was best described by the double-constant equation, while the Freundlich equation gave an excellent fit to the sorption isotherm curves. Therefore, surfactant-enhanced remediation of Cd contaminated soil is feasible and further research should be conducted.

关键词： cadmium desorption EDTA sorption kinetics surfactant

The Activation of Fluorgypsum with Slag Activator and the Fluorine Solidification Mechanics

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Journal of Wuhan University of Technology(Materials Science) 2011年第5期26卷 1023-1026页

作者：周旻张维昊 school of resource and environment Science Wuhan University

The mechanism of activator to fluorgypsum and the fluorine solidification were investigated by the performances of composite binding *** the setting time testing of fluorgypsum with NaOH,Na2SO4 and NaF,the least activator dosage were all 1%.And the cementitious material over 80% of fluorgypsum was processed to improve its quality with slag,fly ash and *** maximum compressive strength of composite binding material was over 12.90 MPa in 28 days,and the concentration of fluroride reduced 64.7% which compared with the pure fluorgypsum binding *** of X-ray diffraction and scanning electron microscopy images showed that ettringite crystals,dihydrate gypsum crystals and C-S-H gel were filled with each *** unreacted CaF2 crystals were embedded by a great deal of network and filamentous C-S-H *** was the main reason that the composite binding material strength improved,water resistance increased and leaching toxicity reduced.

关键词： fluorgypsum activation slag fluorine solidification

Assessment of Habitat Suitability in the Upper Reaches of the Min River in China

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Journal of Mountain Science 2015年第3期12卷 737-746页

作者： GUO Ya-lin WANG Qing YAN Wei-po ZHOU Qin SHI Min-qiu school of environment and resource Southwest University of Science and Technology

HabRat richness influences and even determines biological diversity. Plant habitat suitability assessment can provide technical guidance and information support for ecological restoration. Thirteen factors in three categories of terrain, meteorology and soil were chosen to build a habitat suitability assessment index framework in the Upper Reaches of the Min River, based on the local natural environment and the actual influencing factors of vegetative growth. Combined with the Analytic Hierarchy Process （AHP） and entropy method, which were used to calculate weights of indexes, habitat suitability was studied by using a multi-objective linear weighting model and geographic information systems （GIS） spatial analysis techniques. The assessment results are as follows： Altitude, soil stability, aspect and slope have more important effects on plant habitat suitability in the Upper Reaches of the Min River, and their weights are o.311, 0.260, o.198 and o.125, respectively. Suitable and sub-suitable habitats cover 4431.8o km2 and 6171.12 km2, respectively; most of which are distributed along both sides of rivers and have higher suitability. Unsuitable habitats cover the largest area （6679.76 km2）, accounting for 29.83% of the whole area; and the worst unsuitable habitats are 5107.23 km2 （22.81%）; they account for more than half of the study area. These results indicate that the plant habitat in the Upper Reaches of the Min River is poor and ecological restoration is both urgent and difficult. Therefore, based on the principle of taking measures suitable to the habitat in ecological restoration projects, ecological and engineering measures should be combined to have better effects, while increasing the strength of ecological protection.

关键词： Habitat suitability Analytic hierarchyprocess (AHP) Entropy method Spatial analysis Min River China