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Zeng G.,CAS Wuhan Institute of Rock and Soil Mechanics | Chen Y.,CAS Wuhan Institute of Rock and Soil Mechanics | Liu L.,CAS Wuhan Institute of Rock and Soil Mechanics | Peng G.,Shenzhen GAD Environmental Technology Co.
Chinese Journal of Environmental Engineering | Year: 2016

In order to study the effect of a magnetic field on the dewaterability of municipal sludge, magnetic treatment tests were conducted on sludge with four different moisture contents (99.15%, 97.41%, 95.52%, 93.73%) through an independently developed magnetic field device. The test results showed that the dewaterability of municipal sludge following magnetic treatment could be significantly improved. The maximum improvement of the capillary suction time of the sludge at different moisture contents were 90.5%, 65.8%, 61.6% and 51.6%, respectively, which indicated that the higher the moisture content, the greater the improvement in dewaterability. The optimal magnetic field intensity and magnetization time of municipal sludge were determined by the experimental data. In addition, the relationship between the best magnetic field intensity, magnetization time, and moisture content of the municipal sludge were quadratic polynomial functions. The centrifugation moisture content of the sludge post-magnetic treatment was reduced by about 0.6% as compared to the sludge without magnetic treatment. It is suggested that magnetic treatment combined with other pretreatment methods can be used to achieve better dewaterability of municipal sludge. © 2016, Science Press. All right reserved. Source


Jin S.,University of Sichuan | Jin S.,Shenzhen GAD Environmental Technology Co. | Liu M.,University of Sichuan | Chen Y.,University of Sichuan | Liu Y.,University of Sichuan
Environmental Engineering Science | Year: 2015

Livestock wastewater is characterized by chlortetracycline (CTC) contamination and alkalinity insufficiency, and ammonia is difficult to remove from this type of wastewater. This study explores the combined effects of alkalinity limitation and CTC addition on the ammonia removal process in sequencing batch reactors. CTC concentrations in the inflow of four bench-scale reactors were 0, 5, 20, and 100mg/L, and the operation phase was divided into five stages by alkalinity/nitrogen (ALK/N) ratios (7.14, 4.76, 3.56, 2.38, and 0). As the ratio of ALK/N decreased from 7.14 to 0, the ammonia removal efficiency dropped from 98.2% to 28% and the ammonia oxidation rate dropped gradually from 3.713 to 1.416mg/g VSS·h. Existence of CTC has an inhibitory effect on ammonia oxidation, ammonia removal efficiency decreased with CTC concentration increases, the same goes for the ammonia oxidation rate. With a decrease in alkalinity, inhibition difference of ammonia removal caused by CTC is narrowed, indicating that alkalinity becomes a limiting factor. CTC had an obvious effect on nitrite accumulation, because nitrite-oxidizing bacteria was more vulnerable to CTC than ammonia-oxidizing bacteria. By considering the use of pH and DO as ammonia removal online detection parameters, only under sufficient alkalinity conditions can pH and DO be used to mark the end of nitrification. CTC does not influence the emergence of the pH and DO inflection points. © Mary Ann Liebert, Inc. Source


Hui X.,Yichang Solid Waste Company | Kai L.,Jiangsu Institute of Zoneco Soil Co. | Guofei W.,Jiangsu Institute of Zoneco Soil Co. | Yan W.,Jiangsu Institute of Zoneco Soil Co. | Guifen P.,Shenzhen GAD Environmental Technology Co.
Electronic Journal of Geotechnical Engineering | Year: 2015

A series of chemical immersion tests were conducted, aiming to reveal the leaching characteristics of metallic ions (iron, calcium, and magnesium) in coal gangue under different pH values and temperatures of the chemical solution. The results indicated that the pH value and temperature of the solution both significantly influence the leaching rate and concentration of metallic ions, except iron, in an acidic environment. The stronger the acidity was, the easier the metallic ions leached from the coal gangue. Under the same conditions, the rate and concentration of the metallic ions leached at 80°C were higher than that at room temperature. The results have important significance in pollution prevention and in the control of the soil-groundwater environment around the coal gangue pile, especially in acid rain-prone areas. The results also provide theoretical basis and technical support for the spontaneous combustion control and resource utilization of coal gangue. © 2015 ejge. Source


Fang G.,Shenzhen GAD Environmental Technology Co. | Li C.,Shenzhen GAD Environmental Technology Co. | Guifen P.,Shenzhen GAD Environmental Technology Co. | Yijun C.,CAS Wuhan Institute of Rock and Soil Mechanics | And 4 more authors.
Electronic Journal of Geotechnical Engineering | Year: 2015

A three-dimensional axisymmetric model has been established for quantitative description of the gas migration in bioreactor landfills. This model is based on the fluid dynamics and solute transport theories in porous media. Variables like the distribution of gas pressure and the amount of gas collection from the landfilled solid waste can thus be theoretically evaluated. The modeling results were compared with the in-situ monitoring data of the gas output in a field test (experimental region No. III) located at Wuhan Second Princess Hill landfill. Numerical simulation results show that landfill gas pressure distribution differs at different depths, which is closely related to both the structural design of landfill and the distinct degrading properties of the solid waste. Gas output shows a declining trend with the landfill life increases. Gas production in summer is higher than those in other seasons. The reliability and viability of the model were satisfyingly verified by the consistence between the numerical simulation results and field monitoring data. The impact of permeability on the influencing radius of gas pumping well (GPW) and gas production was investigated. Results show that the influencing radius of GPW expanded to 17.8 m from 8.5 m when the inherent permeability increased by 15 m2. Gas production and the influencing radius are obviously affected by the change of the inherent permeability when gas production increased by 27 m3/h. It is mainly because that the gas pressure gradient and transmission pore space increase with the increasing inherent permeability at early stage. But the biodegradation of the solid waste leads to the gradual compaction of the waste and the reduction of porosity with the prolonging buried duration, and thus result in the decrease in the gradients of gas production and the influencing radius of the GPW. These findings could provide significant guideline to the parameterization and design of the gas pumping drainage system in landfills as well as the researches and applications in effective prediction, collection and control of landfill gas. © 2015 ejge. Source


Li C.,Shenzhen GAD Environmental Technology Co. | Chen Y.-J.,CAS Wuhan Institute of Rock and Soil Mechanics | Fang G.,Shenzhen GAD Environmental Technology Co. | Xi B.-Q.,CAS Wuhan Institute of Rock and Soil Mechanics | And 3 more authors.
Electronic Journal of Geotechnical Engineering | Year: 2015

A set of remote monitoring system using FPGA data acquisition technology is created and applied successfully in Chen Jiachong landfill. The fact shows that FPGA data acquisition technology in data acquisition of Garbage leachate and gas multi-parameter monitoring system can greatly shorten the hardware development cycle in large scale and improve the sampling frequency and precision. And the supervision scopes of COD/BOD/NH3-N/SS are 25000mg/L/10000mg/L/1500mg/L/10000mg/L respectively, which has important reference value in decreasing the cost of environmental supervision system and increasing the effectiveness data. © 2015 ejge. Source

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