As a key step in waste activated sludge(WAS)treatment and disposal,WAS dewatering can minimize the amount of WAS and decrease the costs of transportation,storage management,treatment,and disposal.Advanced oxidation pr...As a key step in waste activated sludge(WAS)treatment and disposal,WAS dewatering can minimize the amount of WAS and decrease the costs of transportation,storage management,treatment,and disposal.Advanced oxidation processes(AOPs)have been widely explored in WAS dewatering due to the excellent oxidizing properties and efficient decomposition capacity since the 21^(st)century.This review outlined the mechanisms of AOPs to improve WAS dewatering and pointed out the shortcomings of the existing mechanisms.Then,the applications of AOPs-based WAS dewatering processes for enhanced WAS dewatering were reviewed,and the intrinsic limitations of AOPs-based WAS dewatering processes in engineering applications were proposed.In addition,an overall review of AOPs-based WAS dewatering researches was also conducted through bibliometric analysis,and future research hotspots in the field of AOPs-based WAS dewatering were proposed.Finally,the positive effects of the AOPs-based WAS dewatering processes on pollutant removal and resource recovery were investigated,and an integrated plan for the harmless disposal of WAS was constructed to achieve a positive reform of the traditional WAS management plan.This review provided theoretical basis and technical reference for the development of efficient,economical,and environmental AOPs for enhanced WAS dewatering to facilitate the application of AOPs in actual WAS dewatering engineering.展开更多
[Objective] The technological parameter suitable for the dewatering of dredged sediment from Dianchi Lake was studied.[Method] By means of the treatment method of sewage sludge in sewage treatment plant,flocculants in...[Objective] The technological parameter suitable for the dewatering of dredged sediment from Dianchi Lake was studied.[Method] By means of the treatment method of sewage sludge in sewage treatment plant,flocculants including FeCl3,Al2(SO4)3 and PAM were taken as dewatering agents which were added in dredged sediment.[Result] The results showed that Al2(SO4)3 had better dewatering effect than FeCl3 and PAM,and the optimum dosing quantity of Al2(SO4)3 in dredged sediment was 170 mg/L,in addition,the water quality of supernatant met the first class B standard of GB18918-2002 and could be directly discharged to nature water without pollution.[Conclusion] The study could provide a simple and feasible way for the rapid dewatering of dredged sediment from Dianchi Lake,which would be convenient for the disposal and resource utilization of dredged sediment.展开更多
Enhancing sludge dewatering is of importance in reducing environmental burden and disposal costs.In this work, a cationic surfactant, cetyl trimethyl ammonium bromide(CTAB), was combined with Fenton’s reagent for slu...Enhancing sludge dewatering is of importance in reducing environmental burden and disposal costs.In this work, a cationic surfactant, cetyl trimethyl ammonium bromide(CTAB), was combined with Fenton’s reagent for sludge dewatering.Results show that the Fenton-CTAB conditioning significantly promotes the sludge dewatering.Using combined techniques of response surface methodology and uniform design, dosages of Fe2+, H2O2, and CTAB for water content response were optimized to be 89, 276, and 233 mg/g dry solids(DS),respectively.The water content of sludge decreased from 79.0% to 66.8% under the optimal conditions.Compared with cationic polyacrylamide, the Fenton-CTAB system exhibited superior sludge dewatering performance.To gain insights into the mechanisms involved in sludge dewatering, the effects of Fenton-CTAB conditioning on the composition of extracellular polymeric substances(EPS) and the morphology of the sludge flocs were investigated.The decomposition of EPS into some dissolved organics and the release of proteins in tightly bound EPS facilitated the conversion of bound water to free water and further reduced the water content of sludge cake.After conditioning, morphology of sludge showed aggregation.Overall, the enhanced sludge dewatering by Fenton-CTAB treatment provides an efficient way for management of sewage sludge.展开更多
A technology of ultrasonic-electric united desalting and dewatering of crude oil is studied. The ultrasonic setup is designed to form a standing-wave field, which is more efficient for agglomeration of water particles...A technology of ultrasonic-electric united desalting and dewatering of crude oil is studied. The ultrasonic setup is designed to form a standing-wave field, which is more efficient for agglomeration of water particles. The desalting and dewatering results of the ultrasonic-electric united process are compared with those of the electric process. For high salt-contenting crude oil （40-70 mg·L ^-1）, the salt content is still above 10.0 mg·L^-1 after crude oil has been treated by two-stage electric desalting process in refinery, which cannot meet the need of refinery. Ultrasonic-electric united process is a novel technology for treating the high salt-contenting oil. On the optimal operating conditions of the ultrasonic-electric united process, the salt content of crude oil can be reduced from 67 5 mg·L^-1 to 3.97 mg·L ^-1 by one-stage ultrasonic-electric united process, and the water content falls below 0.3% （by volume）. The results show that the ultrasonic-electric united process is more effective than the electric process in high salt-contenting oil desalting. This technology should be useful in the refinery process.展开更多
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...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.展开更多
The filtration and dewatering of fine clean coal not only ensure industrial water recycle in coal washing plant,but also reduce the moisture of coal product in order to meet the requirements of combustion or coking in...The filtration and dewatering of fine clean coal not only ensure industrial water recycle in coal washing plant,but also reduce the moisture of coal product in order to meet the requirements of combustion or coking industry.Fine clean coal is mainly composed by organic matter,and the property difference of different organic matter determines the filtration and dewatering behavior.In this investigation,vitrinite and inertinite were separated from a clean bituminous coal,and the comparative filtration and dewatering behavior of vitrinite and inertinite were conducted.The results showed that inertinite has lower dewatering rate and higher filter cake moisture than vitrinite.The analysis of filter cake structure showed that inertinite particle is easier to be broken into small particles due to the difference of mechanical properties,thus forming more compact filter cake than vitrinite.The analysis of particle surface properties showed that vitrinite is more hydrophobic than inertinite,which makes water easier drained from filter cake.The simulation study showed that the structure of inertinite is more porous than that of vitrinite,and the interaction between inertinite and water is stronger than that between vitrinite and water.This study provides a theoretical basis for improving coal dewatering by selectively improving coal maceral hydrophobicity.展开更多
When pumping is conducted in confined aquifer inside excavation pit(waterproof curtain),the direction of the groundwater seepage outside the excavation changes from horizontal to vertical owing to the existence of the...When pumping is conducted in confined aquifer inside excavation pit(waterproof curtain),the direction of the groundwater seepage outside the excavation changes from horizontal to vertical owing to the existence of the curtain barrier.There is no analytical calculation method for the groundwater head distribution induced by dewatering inside excavation.This paper first analyses the mechanism of the blocking effects from a close barrier in confined aquifer.Then,a simple equation based on analytical solution is proposed to calculate groundwater heads inside and outside of the excavation pit with waterproof curtain(hereafter refer to close barrier)in a confined aquifer.The distribution of groundwater head is derived according to two conditions:(i)pumping with a constant water head,and(ii)pumping with a constant flow rate.The proposed calculation equation is verified by both numerical simulation and experimental results.The comparisons demonstrate that the proposed model can be applied in engineering practice of excavation.展开更多
To further clarify the dewatering performance and torque evolution during the tailings thickening process,a self-made rake was connected to a rheometer to monitor the shear stress and torque.The dewatering performance...To further clarify the dewatering performance and torque evolution during the tailings thickening process,a self-made rake was connected to a rheometer to monitor the shear stress and torque.The dewatering performance of the total tailings was greatly improved to a solid mass fraction of 75.33%in 240 min.The dewatering process could be divided into three stages:the rapid torque growth period,damping torque growth period,and constant torque thickening zone.The machine restart was found to have a significant effect on the rake torque;it could result in rake blockage.Furthermore,the simultaneous evolution of the torque and solid mass fraction of thickened tailings was analyzed.A relationship between the torque and the solid mass fraction was established,which followed a power function.Both the experimental and theoretical results provide a reference for the deep cone thickener design and operation to enhance the dewatering performance.展开更多
The mechanical dewatering of activated sludge is troublesome due to its high compressibility of solids. The dewatering can be enhanced dramatically by the use of electroosmosis,in which an electric field is applied to...The mechanical dewatering of activated sludge is troublesome due to its high compressibility of solids. The dewatering can be enhanced dramatically by the use of electroosmosis,in which an electric field is applied to the sludge cake.In this study,the influence of filter cloth on the cathode on the dewatering of activated sludge was investigated.It was found that thicker filter cloth led to lower water removal from the sludge cake,so a stainless steel cathode net with small pore size instead of filter cloth was applied,which improves the dewatering efficiency and reduces the electric power consumption.Moreover,water absorbent materials were helpful to remove the water from the sludge cake.For the electroosmotic dewatering at 7 kPa and 24 V·cm-1,the water content in the sludge cake decreased to 60%(by mass) with the average 0.075 kW·h·kg-1of water removed by using the cathode net.展开更多
Anaerobic ammonia oxidation（Anammox） process is a novel and promising wastewater nitrogen removal process. The feasibility of transition of Anammox from denitrification and the performance of lab-scale Anammox biofi...Anaerobic ammonia oxidation（Anammox） process is a novel and promising wastewater nitrogen removal process. The feasibility of transition of Anammox from denitrification and the performance of lab-scale Anammox biofilm reactor were investigated with sludge dewatering effluent. The results showed that Anammox process could be successfully started up after cultivation of denitrification biofilm and using it as inoculum. The transition of Anammox from denitrification was accomplished within 85 d. Anammox process was found suitable to remove ammonia from sludge dewatering effluent. The effluent ammonia concentration was detected to be 23.11 mgN/L at HRT of 28 h when influent ammonia concentration was fed 245 mgN/L, which was less than that for the national discharge standard Ⅱ （25 rngN/L） of China. Volumetric total nitrogen loading rate was up to 584.99 mg TN/（L. d） at HRT of 17 h, while influent concentrations were kept 243.25 mg NH4＊ -N/L and 288.31 mg NO2^- -N/L.展开更多
A deep foundation pit constructed for an underground transportation hub was excavated near the Yangtze River.Among the strata,there are two confined aquifers,between which lies an aquiclude that is partially missing.T...A deep foundation pit constructed for an underground transportation hub was excavated near the Yangtze River.Among the strata,there are two confined aquifers,between which lies an aquiclude that is partially missing.To guarantee the safety of pit excavation,the piezometric head of the upper confined aquifer,where the pit bottom is located,should be 1 m below the pit bottom,while that of the lower confined aquifer should be dewatered down to a safe water level to avoid uplift problem.The Yangtze River levee is notably close to the pit,and its deformation caused by dewatering should be controlled.A pumping test was performed to obtain the hydraulic conductivity of the upper confined aquifer.The average value of the hydraulic conductivity obtained from analytical calculation is 20.45 m/d,which is larger than the values from numerical simulation(horizontal hydraulic conductivity K_H=16 m/d and vertical hydraulic conductivity K_V=S m/d).The difference between K_H and K_V indicates the anisotropy of the aquifer.Two dewatering schemes were designed for the construction and simulated by the numerical models for comparison purposes.The results show that though the first scheme could meet the dewatering requirements,the largest accumulated settlement and differential settlement would be94.64 mm and 3.3‰,respectively,greatly exceeding the limited values.Meanwhile,the second scheme,in which the bottoms of the waterproof curtains in ramp B and the river side of ramp A are installed at a deeper elevation of-28 m above sea level,and 27 recharge wells are set along the levee,can control the deformation of the levee significantly.展开更多
Based on analyses of the theories of groundwater unsteady flow in deep well dewatering in the deep foundation pit, Theis equations are chosen to calculate and analyze the relationship between water level drawdown of c...Based on analyses of the theories of groundwater unsteady flow in deep well dewatering in the deep foundation pit, Theis equations are chosen to calculate and analyze the relationship between water level drawdown of confined aquifer and dewatering duration. In order to reduce engineering cost and diminish detrimental effect on ambient surrounding, optimization design target function based on the control of confined water drawdown and four restriction requisitions based on the control of safe water level, resistance to throwing up from the bottom of foundation pit, avoiding excessively great subsidence and unequal surface subsidence are proposed. A deep well dewatering project in the deep foundation pit is optimally designed. The calculated results including confined water level drawdown and surface subsidence are in close agreement with the measured results, and the optimization design can effectively control both surface subsidence outside foundation pit and unequal subsidence as a result of dewatering.展开更多
The dewatering of fine, flotation cleaned coals from Huaibei and Xuzhou (bituminous) and Yongcheng (anthracite) were studied. The supernatant and filter cake were examined to determine the rate and extent of flocculat...The dewatering of fine, flotation cleaned coals from Huaibei and Xuzhou (bituminous) and Yongcheng (anthracite) were studied. The supernatant and filter cake were examined to determine the rate and extent of flocculation and dewatering. A starch-based filter aid was used to increase flocculation and dewatering rates. The filtration constant, K, and compression index, s, of the Yongcheng slurry were measured under various conditions. A designed experiment was performed to determine optimum conditions for dewatering. The results showed that the filter aid enhanced flocculation and coagulation of the fine cleaned coal slurry, enhanced the structure of the filter cake and promoted dewatering of the cake. Moisture content in the cake was reduced to 17% after vacuum filtration.展开更多
Due to large-scale dredging operations, a large amount of sludge is inevitably produced. Large areas of land are occupied when the dredged sludge is discarded in the disposal site as waste material. The sludge dewater...Due to large-scale dredging operations, a large amount of sludge is inevitably produced. Large areas of land are occupied when the dredged sludge is discarded in the disposal site as waste material. The sludge dewatering with aeration-vacuum (SDAV) method is suit for treating the sludge with high water content and high clay content in the disposal site. The water in the sludge can be discharged out. The volume of the sludge can be reduced quickly, and the recycling of the land can be accelerated by this method. Most importantly, this technique is an efficient way to deal with clogging problems when pumping water from high water content, high clay content dredged sludge. Vacuum degree range tests, the aeration rate range tests, and the influencing factors of sludge dewatering behavior tests were conducted with a self-developed SDAV model test device. Sludge samples were taken from the South-to-North Water Diversion East Line Project in Huai’an White-Horse Lake disposal site, Jiangsu Province, China. The optimal range of vacuum degree and aeration rate were obtained through the test results, and the mechanisms for how the two factors work and how they affect the sludge dewatering behavior were analyzed. The suitable vacuum degree range in SDAV is below 50 kPa, and the suitable aeration rate is about 1.0 m3/h. The low-vacuum degree contributes to reduce the ad-sorption effect of micro-channels on soil particles in filter material and to maintain the arch structures. Aeration has the effects of expansion, disturbance, changing Reynolds number, and dynamic sieve separating. The pump quantity of water per meter of filter tube (m) has different change rules as the vacuum degree changes under different aeration rates. The reason is that the formed arch structures’ conformation and permeability differ greatly under different combined-conditions of vacuum degree and aeration rate. The optimal combined-condition for dewatering the sludge is 35 kPa with 1.0 m3/h.展开更多
In this study, a magnetic micro-particle conditioning–pressurized vertical electro-osmotic dewatering（MPEOD） process with magnetic micro-particle conditioning–drainage under gravity–mechanical compression–electr...In this study, a magnetic micro-particle conditioning–pressurized vertical electro-osmotic dewatering（MPEOD） process with magnetic micro-particle conditioning–drainage under gravity–mechanical compression–electrical compression（MMPC–DG–MC–EC） stages was established to study the distribution and migration of water, extracellular polymeric substances（EPS）, and other organic matter in the activated sludge（AS） matrix at each stage.Results showed that the MPEOD process could attain 53.52% water content（WC） in dewatered AS with bound water（BW） and free water（FW） reduction rates of 82.97% and 99.67%,respectively. The coagulation and time-delayed magnetic field effects of magnetic microparticles（MMPs） along the MMPC–DG–MC stages initiated the transformation of partial BW to FW in AS. EC had a coupling driving effect of electro-osmosis and pressure on BW, and the changes in pH and temperature at EC stage induced the aggregation of AS flocs and the release of partial BW. Additionally, MMPs dosing further improved the dewatering performance of AS by acting as skeleton builders to provide water passages. Meanwhile, MMPs could disintegrate sludge cells and EPS fractions, thereby reducing tryptophan-like protein and byproduct-like material concentrations in LB-EPS as well as protein/polysaccharide ratio in AS matrix, which could improve AS filterability. At EC stage, the former four Ex/Em regions of fluorescence regional integration analysis for EPS were obviously reduced, especially the protein-like substances in LB-and TB-EPS, which contributed to improvement of AS dewaterability.展开更多
In this study,a new and facile route was employed for synthesis of polyamidine with abundant cations and attractive five-membered ringlike structural unit.N-vinylformamide and acrylonitrile copolymerized firstly to fo...In this study,a new and facile route was employed for synthesis of polyamidine with abundant cations and attractive five-membered ringlike structural unit.N-vinylformamide and acrylonitrile copolymerized firstly to form intermediates,and the intermediates were processed with hydrochloric acid to produce polyamidine.A series of polymerization conditions（e.g.polymerization time,temperature and dosage of initiator） were optimized through productivity,viscosity and cationic degree as evaluation.SEM analysis illustrated that the amidinization process could reduce the size of spaces between molecular and created compact structure,which would contribute to good flocculation performance and high viscosity.FT-IR,XPS and NMR spectra presented a rather clear structure of polyamidine.34.3%of sludge was sedimentated through the flocculation of polyamidine in the early stages.In contrast,only 6.8%of sludge was sedimentated by polyacrylamide.The moisture content in dehydrated floc could be reduced to 77.7%when 60 mg/L polyamidine was added.These results demonstrated that the polyamidine showed a great potential in the practical application of sludge dewatering.展开更多
The optimized production of a novel bioflocculant M-C11 produced by Klebsiella sp. and its application in sludge dewatering were investigated. The optimal medium carbon source,nitrogen source, metal ion, initial pH an...The optimized production of a novel bioflocculant M-C11 produced by Klebsiella sp. and its application in sludge dewatering were investigated. The optimal medium carbon source,nitrogen source, metal ion, initial pH and culture temperature for the bioflocculant production were glucose, NaNO3, MgSO4, and pH 7.0 and 25°C, respectively. A compositional analysis indicated that the purified M-C11 consisted of 91.2% sugar, 4.6% protein and 3.9% nucleic acids（m/m）. A Fourier transform infrared spectrum confirmed the presence of carboxyl, hydroxyl,methoxyl and amino groups. The microbial flocculant exhibited excellent pH and thermal stability in a kaolin suspension over a pH range of 4.0 to 8.0 and a temperature range of 20 to 60°C.The optimum bioflocculating activity was observed as 92.37% for 2.56 mL M-C11 and 0.37 g/L CaCl2 dosages using response surface methodology. The sludge resistance in filtration（SRF）decreased from 11.6 × 1012 to 4.7 × 1012m/kg, which indicated that the sludge dewaterability was remarkably enhanced by the bioflocculant conditioning. The sludge dewatering performance conditioned by M-C11 was more efficient than that of inorganic flocculating reagents,such as aluminum sulfate and polymeric aluminum chloride. The bioflocculant has advantages over traditional sludge conditioners due to its lower cost, benign biodegradability and negligible secondary pollution. In addition, the bioflocculant was favorably adapted to the specific sludge pH and salinity.展开更多
Realising the importance of pore fluid salinity on the dewatering behaviour of fine-grained porous systems,the present study systematically investigated such impacts on temporal moisture dynamics of kaolin subjected t...Realising the importance of pore fluid salinity on the dewatering behaviour of fine-grained porous systems,the present study systematically investigated such impacts on temporal moisture dynamics of kaolin subjected to evaporative dewatering.A detailed discussion is provided pertaining to the background processes dictating evaporative dewatering response and corresponding alterations in the dielectric behaviour of kaolin.Frequency dependent dielectric spectra of soil,which can be considered as the fingerprint of the transient changes in the condition of water phase within the pore system of the soil and associated densification,are monitored in real time during dewatering using an open-ended coaxial probe with a vector network analyser.The spatial sensitivity of the coaxial probe has been quantified through layered media approach.Combining the results of volume change behaviour of the material along with its moisture loss response,the study characterised the hydro-mechanical response of the material from the windows of frequency dependent dielectric spectroscopy.展开更多
In order to find suitable oily sludge treatment equipment for a produced water treatment station of an oilfield in Iraq,the widely used mechanical dewatering equipments overseas including plate and frame filter,belt p...In order to find suitable oily sludge treatment equipment for a produced water treatment station of an oilfield in Iraq,the widely used mechanical dewatering equipments overseas including plate and frame filter,belt press filter,centrifugal filter and screw press filter were compared and analyzed,and the application situation of screw press filter was investigated at site. The site survey showed that,screw press filter was an integrated equipment combined with functions of concentrating and dewatering,which was characterized by low water content of filter cake,small occupied area,easy to separate,no blocking and can realize self-cleaning,which is suitable to low concentration sludge. Screw press filter can simplify oily sludge treatment process,and save engineering construction and operation cost,which is a better choice for oily sludge dewatering. The design of screw press filter adopted in the produced water treatment station of an oilfield in Iraq was introduced here.展开更多
The mechanical dewatering of activated sludge is difficult due to its high compressibility, which can be improved by electroosmosis. In electroosmosis, direct electric field is applied to sludge cake. Based on the con...The mechanical dewatering of activated sludge is difficult due to its high compressibility, which can be improved by electroosmosis. In electroosmosis, direct electric field is applied to sludge cake. Based on the conductivity modes of different sludge beds, a model is presented in which sludge cake consists of two series parts in the circuit: a dewatered bed and an undewatered one. The dewatered bed called solid conductor is mainly made up of immovable water and sludge particles. The undewatered bed includes movable water and solid conductor, which are connected in parallel in the circuit. The model describes the variation of water content with time and electric power consumption as a function of water content in sludge cake, and interprets the reason for the variation of electroosmotic dewatering rate. Comparison with the experimental data for electroosmotic dewatering under constant voltage supports the validity of the model.展开更多
基金funded under the auspices of the National Key Research and Development Program of China(No.2023YFC3207404-01)the Postdoctoral Fellowship Program of CPSF(No.GZC20233450)the Heilongjiang Province Postdoctoral Science Foundation(No.LBHZ23154)。
文摘As a key step in waste activated sludge(WAS)treatment and disposal,WAS dewatering can minimize the amount of WAS and decrease the costs of transportation,storage management,treatment,and disposal.Advanced oxidation processes(AOPs)have been widely explored in WAS dewatering due to the excellent oxidizing properties and efficient decomposition capacity since the 21^(st)century.This review outlined the mechanisms of AOPs to improve WAS dewatering and pointed out the shortcomings of the existing mechanisms.Then,the applications of AOPs-based WAS dewatering processes for enhanced WAS dewatering were reviewed,and the intrinsic limitations of AOPs-based WAS dewatering processes in engineering applications were proposed.In addition,an overall review of AOPs-based WAS dewatering researches was also conducted through bibliometric analysis,and future research hotspots in the field of AOPs-based WAS dewatering were proposed.Finally,the positive effects of the AOPs-based WAS dewatering processes on pollutant removal and resource recovery were investigated,and an integrated plan for the harmless disposal of WAS was constructed to achieve a positive reform of the traditional WAS management plan.This review provided theoretical basis and technical reference for the development of efficient,economical,and environmental AOPs for enhanced WAS dewatering to facilitate the application of AOPs in actual WAS dewatering engineering.
基金Supported by Scientific Research Foundation of Yunnan Provincial Education Department(09Y0292)~~
文摘[Objective] The technological parameter suitable for the dewatering of dredged sediment from Dianchi Lake was studied.[Method] By means of the treatment method of sewage sludge in sewage treatment plant,flocculants including FeCl3,Al2(SO4)3 and PAM were taken as dewatering agents which were added in dredged sediment.[Result] The results showed that Al2(SO4)3 had better dewatering effect than FeCl3 and PAM,and the optimum dosing quantity of Al2(SO4)3 in dredged sediment was 170 mg/L,in addition,the water quality of supernatant met the first class B standard of GB18918-2002 and could be directly discharged to nature water without pollution.[Conclusion] The study could provide a simple and feasible way for the rapid dewatering of dredged sediment from Dianchi Lake,which would be convenient for the disposal and resource utilization of dredged sediment.
基金supported by the China Postdoctoral Science foundation (No.2018M642479)the National Natural Science Foundation of China (No.51821006)the Postdoctoral Science Foundation of Zhejiang Province (No.zj20180141).
文摘Enhancing sludge dewatering is of importance in reducing environmental burden and disposal costs.In this work, a cationic surfactant, cetyl trimethyl ammonium bromide(CTAB), was combined with Fenton’s reagent for sludge dewatering.Results show that the Fenton-CTAB conditioning significantly promotes the sludge dewatering.Using combined techniques of response surface methodology and uniform design, dosages of Fe2+, H2O2, and CTAB for water content response were optimized to be 89, 276, and 233 mg/g dry solids(DS),respectively.The water content of sludge decreased from 79.0% to 66.8% under the optimal conditions.Compared with cationic polyacrylamide, the Fenton-CTAB system exhibited superior sludge dewatering performance.To gain insights into the mechanisms involved in sludge dewatering, the effects of Fenton-CTAB conditioning on the composition of extracellular polymeric substances(EPS) and the morphology of the sludge flocs were investigated.The decomposition of EPS into some dissolved organics and the release of proteins in tightly bound EPS facilitated the conversion of bound water to free water and further reduced the water content of sludge cake.After conditioning, morphology of sludge showed aggregation.Overall, the enhanced sludge dewatering by Fenton-CTAB treatment provides an efficient way for management of sewage sludge.
文摘A technology of ultrasonic-electric united desalting and dewatering of crude oil is studied. The ultrasonic setup is designed to form a standing-wave field, which is more efficient for agglomeration of water particles. The desalting and dewatering results of the ultrasonic-electric united process are compared with those of the electric process. For high salt-contenting crude oil （40-70 mg·L ^-1）, the salt content is still above 10.0 mg·L^-1 after crude oil has been treated by two-stage electric desalting process in refinery, which cannot meet the need of refinery. Ultrasonic-electric united process is a novel technology for treating the high salt-contenting oil. On the optimal operating conditions of the ultrasonic-electric united process, the salt content of crude oil can be reduced from 67 5 mg·L^-1 to 3.97 mg·L ^-1 by one-stage ultrasonic-electric united process, and the water content falls below 0.3% （by volume）. The results show that the ultrasonic-electric united process is more effective than the electric process in high salt-contenting oil desalting. This technology should be useful in the refinery process.
基金funded by the National Natural Science Foundation of China (No. 51278489)Key Lab for Solid Waste Management and Environmental Safety Open fund (No. 2011-8)
文摘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.
基金supported by the National Natural Science Foundation of China(U2003125)。
文摘The filtration and dewatering of fine clean coal not only ensure industrial water recycle in coal washing plant,but also reduce the moisture of coal product in order to meet the requirements of combustion or coking industry.Fine clean coal is mainly composed by organic matter,and the property difference of different organic matter determines the filtration and dewatering behavior.In this investigation,vitrinite and inertinite were separated from a clean bituminous coal,and the comparative filtration and dewatering behavior of vitrinite and inertinite were conducted.The results showed that inertinite has lower dewatering rate and higher filter cake moisture than vitrinite.The analysis of filter cake structure showed that inertinite particle is easier to be broken into small particles due to the difference of mechanical properties,thus forming more compact filter cake than vitrinite.The analysis of particle surface properties showed that vitrinite is more hydrophobic than inertinite,which makes water easier drained from filter cake.The simulation study showed that the structure of inertinite is more porous than that of vitrinite,and the interaction between inertinite and water is stronger than that between vitrinite and water.This study provides a theoretical basis for improving coal dewatering by selectively improving coal maceral hydrophobicity.
基金“The Pearl River Talent Recruitment Program”in 2019(Grant No.2019CX01G338)Guangdong Province and the Research Funding of Shantou University for New Faculty Member(Grant No.NTF19024-2019)the National Natural Science Foundation of China(NSFC)(Grant No.41807235).
文摘When pumping is conducted in confined aquifer inside excavation pit(waterproof curtain),the direction of the groundwater seepage outside the excavation changes from horizontal to vertical owing to the existence of the curtain barrier.There is no analytical calculation method for the groundwater head distribution induced by dewatering inside excavation.This paper first analyses the mechanism of the blocking effects from a close barrier in confined aquifer.Then,a simple equation based on analytical solution is proposed to calculate groundwater heads inside and outside of the excavation pit with waterproof curtain(hereafter refer to close barrier)in a confined aquifer.The distribution of groundwater head is derived according to two conditions:(i)pumping with a constant water head,and(ii)pumping with a constant flow rate.The proposed calculation equation is verified by both numerical simulation and experimental results.The comparisons demonstrate that the proposed model can be applied in engineering practice of excavation.
基金This work was financially supported by the National Natural Science Foundation of China(Nos.51804015 and 51834001)the Fundamental Research Funds for the Central Universities(No.FRF-TP-17-024A1).
文摘To further clarify the dewatering performance and torque evolution during the tailings thickening process,a self-made rake was connected to a rheometer to monitor the shear stress and torque.The dewatering performance of the total tailings was greatly improved to a solid mass fraction of 75.33%in 240 min.The dewatering process could be divided into three stages:the rapid torque growth period,damping torque growth period,and constant torque thickening zone.The machine restart was found to have a significant effect on the rake torque;it could result in rake blockage.Furthermore,the simultaneous evolution of the torque and solid mass fraction of thickened tailings was analyzed.A relationship between the torque and the solid mass fraction was established,which followed a power function.Both the experimental and theoretical results provide a reference for the deep cone thickener design and operation to enhance the dewatering performance.
基金Supported by Tianjin Application Basis and Advanced Technology Studied Plans(09JCYBJC08200)
文摘The mechanical dewatering of activated sludge is troublesome due to its high compressibility of solids. The dewatering can be enhanced dramatically by the use of electroosmosis,in which an electric field is applied to the sludge cake.In this study,the influence of filter cloth on the cathode on the dewatering of activated sludge was investigated.It was found that thicker filter cloth led to lower water removal from the sludge cake,so a stainless steel cathode net with small pore size instead of filter cloth was applied,which improves the dewatering efficiency and reduces the electric power consumption.Moreover,water absorbent materials were helpful to remove the water from the sludge cake.For the electroosmotic dewatering at 7 kPa and 24 V·cm-1,the water content in the sludge cake decreased to 60%(by mass) with the average 0.075 kW·h·kg-1of water removed by using the cathode net.
文摘Anaerobic ammonia oxidation（Anammox） process is a novel and promising wastewater nitrogen removal process. The feasibility of transition of Anammox from denitrification and the performance of lab-scale Anammox biofilm reactor were investigated with sludge dewatering effluent. The results showed that Anammox process could be successfully started up after cultivation of denitrification biofilm and using it as inoculum. The transition of Anammox from denitrification was accomplished within 85 d. Anammox process was found suitable to remove ammonia from sludge dewatering effluent. The effluent ammonia concentration was detected to be 23.11 mgN/L at HRT of 28 h when influent ammonia concentration was fed 245 mgN/L, which was less than that for the national discharge standard Ⅱ （25 rngN/L） of China. Volumetric total nitrogen loading rate was up to 584.99 mg TN/（L. d） at HRT of 17 h, while influent concentrations were kept 243.25 mg NH4＊ -N/L and 288.31 mg NO2^- -N/L.
基金financially supported by the doctoral fund of the Ministry of Education of Chinathe Nature Science Foundation of Jiangsu Province,China(Grant Nos.20130091110020 and BE2015675)
文摘A deep foundation pit constructed for an underground transportation hub was excavated near the Yangtze River.Among the strata,there are two confined aquifers,between which lies an aquiclude that is partially missing.To guarantee the safety of pit excavation,the piezometric head of the upper confined aquifer,where the pit bottom is located,should be 1 m below the pit bottom,while that of the lower confined aquifer should be dewatered down to a safe water level to avoid uplift problem.The Yangtze River levee is notably close to the pit,and its deformation caused by dewatering should be controlled.A pumping test was performed to obtain the hydraulic conductivity of the upper confined aquifer.The average value of the hydraulic conductivity obtained from analytical calculation is 20.45 m/d,which is larger than the values from numerical simulation(horizontal hydraulic conductivity K_H=16 m/d and vertical hydraulic conductivity K_V=S m/d).The difference between K_H and K_V indicates the anisotropy of the aquifer.Two dewatering schemes were designed for the construction and simulated by the numerical models for comparison purposes.The results show that though the first scheme could meet the dewatering requirements,the largest accumulated settlement and differential settlement would be94.64 mm and 3.3‰,respectively,greatly exceeding the limited values.Meanwhile,the second scheme,in which the bottoms of the waterproof curtains in ramp B and the river side of ramp A are installed at a deeper elevation of-28 m above sea level,and 27 recharge wells are set along the levee,can control the deformation of the levee significantly.
基金This paper is supported by the Hubei Construct Science Foundation of China (G200013).
文摘Based on analyses of the theories of groundwater unsteady flow in deep well dewatering in the deep foundation pit, Theis equations are chosen to calculate and analyze the relationship between water level drawdown of confined aquifer and dewatering duration. In order to reduce engineering cost and diminish detrimental effect on ambient surrounding, optimization design target function based on the control of confined water drawdown and four restriction requisitions based on the control of safe water level, resistance to throwing up from the bottom of foundation pit, avoiding excessively great subsidence and unequal surface subsidence are proposed. A deep well dewatering project in the deep foundation pit is optimally designed. The calculated results including confined water level drawdown and surface subsidence are in close agreement with the measured results, and the optimization design can effectively control both surface subsidence outside foundation pit and unequal subsidence as a result of dewatering.
基金the financial support for this work provided by the Doctoral Fund of Ministry of Education of China (No.200802900503) the Science and Technology Foundation of China University of Mining & Technology (No.2008A027)
文摘The dewatering of fine, flotation cleaned coals from Huaibei and Xuzhou (bituminous) and Yongcheng (anthracite) were studied. The supernatant and filter cake were examined to determine the rate and extent of flocculation and dewatering. A starch-based filter aid was used to increase flocculation and dewatering rates. The filtration constant, K, and compression index, s, of the Yongcheng slurry were measured under various conditions. A designed experiment was performed to determine optimum conditions for dewatering. The results showed that the filter aid enhanced flocculation and coagulation of the fine cleaned coal slurry, enhanced the structure of the filter cake and promoted dewatering of the cake. Moisture content in the cake was reduced to 17% after vacuum filtration.
基金Project supported by the National Natural Science Foundation of China (No. 50879023)the National Hi-Tech Research and Development Program (863) of China (No. 2007AA11Z135)the Min-istry of Water Resources Nonprofit Public Industry Special Foundation of China (No. 200701045)
文摘Due to large-scale dredging operations, a large amount of sludge is inevitably produced. Large areas of land are occupied when the dredged sludge is discarded in the disposal site as waste material. The sludge dewatering with aeration-vacuum (SDAV) method is suit for treating the sludge with high water content and high clay content in the disposal site. The water in the sludge can be discharged out. The volume of the sludge can be reduced quickly, and the recycling of the land can be accelerated by this method. Most importantly, this technique is an efficient way to deal with clogging problems when pumping water from high water content, high clay content dredged sludge. Vacuum degree range tests, the aeration rate range tests, and the influencing factors of sludge dewatering behavior tests were conducted with a self-developed SDAV model test device. Sludge samples were taken from the South-to-North Water Diversion East Line Project in Huai’an White-Horse Lake disposal site, Jiangsu Province, China. The optimal range of vacuum degree and aeration rate were obtained through the test results, and the mechanisms for how the two factors work and how they affect the sludge dewatering behavior were analyzed. The suitable vacuum degree range in SDAV is below 50 kPa, and the suitable aeration rate is about 1.0 m3/h. The low-vacuum degree contributes to reduce the ad-sorption effect of micro-channels on soil particles in filter material and to maintain the arch structures. Aeration has the effects of expansion, disturbance, changing Reynolds number, and dynamic sieve separating. The pump quantity of water per meter of filter tube (m) has different change rules as the vacuum degree changes under different aeration rates. The reason is that the formed arch structures’ conformation and permeability differ greatly under different combined-conditions of vacuum degree and aeration rate. The optimal combined-condition for dewatering the sludge is 35 kPa with 1.0 m3/h.
基金supported by the National Natural Science Foundation of China(Nos.51478041,51678053)Major Projects on Control and Rectification of Water Body Pollution(Nos.2012ZX07105-002-03,2013ZX07202-010)
文摘In this study, a magnetic micro-particle conditioning–pressurized vertical electro-osmotic dewatering（MPEOD） process with magnetic micro-particle conditioning–drainage under gravity–mechanical compression–electrical compression（MMPC–DG–MC–EC） stages was established to study the distribution and migration of water, extracellular polymeric substances（EPS）, and other organic matter in the activated sludge（AS） matrix at each stage.Results showed that the MPEOD process could attain 53.52% water content（WC） in dewatered AS with bound water（BW） and free water（FW） reduction rates of 82.97% and 99.67%,respectively. The coagulation and time-delayed magnetic field effects of magnetic microparticles（MMPs） along the MMPC–DG–MC stages initiated the transformation of partial BW to FW in AS. EC had a coupling driving effect of electro-osmosis and pressure on BW, and the changes in pH and temperature at EC stage induced the aggregation of AS flocs and the release of partial BW. Additionally, MMPs dosing further improved the dewatering performance of AS by acting as skeleton builders to provide water passages. Meanwhile, MMPs could disintegrate sludge cells and EPS fractions, thereby reducing tryptophan-like protein and byproduct-like material concentrations in LB-EPS as well as protein/polysaccharide ratio in AS matrix, which could improve AS filterability. At EC stage, the former four Ex/Em regions of fluorescence regional integration analysis for EPS were obviously reduced, especially the protein-like substances in LB-and TB-EPS, which contributed to improvement of AS dewaterability.
基金supported by the Tai Shan Scholar Foundation(No.ts201511003)
文摘In this study,a new and facile route was employed for synthesis of polyamidine with abundant cations and attractive five-membered ringlike structural unit.N-vinylformamide and acrylonitrile copolymerized firstly to form intermediates,and the intermediates were processed with hydrochloric acid to produce polyamidine.A series of polymerization conditions（e.g.polymerization time,temperature and dosage of initiator） were optimized through productivity,viscosity and cationic degree as evaluation.SEM analysis illustrated that the amidinization process could reduce the size of spaces between molecular and created compact structure,which would contribute to good flocculation performance and high viscosity.FT-IR,XPS and NMR spectra presented a rather clear structure of polyamidine.34.3%of sludge was sedimentated through the flocculation of polyamidine in the early stages.In contrast,only 6.8%of sludge was sedimentated by polyacrylamide.The moisture content in dehydrated floc could be reduced to 77.7%when 60 mg/L polyamidine was added.These results demonstrated that the polyamidine showed a great potential in the practical application of sludge dewatering.
基金supported by the National Water Pollution Control Program (No. 2008ZX07313-002)
文摘The optimized production of a novel bioflocculant M-C11 produced by Klebsiella sp. and its application in sludge dewatering were investigated. The optimal medium carbon source,nitrogen source, metal ion, initial pH and culture temperature for the bioflocculant production were glucose, NaNO3, MgSO4, and pH 7.0 and 25°C, respectively. A compositional analysis indicated that the purified M-C11 consisted of 91.2% sugar, 4.6% protein and 3.9% nucleic acids（m/m）. A Fourier transform infrared spectrum confirmed the presence of carboxyl, hydroxyl,methoxyl and amino groups. The microbial flocculant exhibited excellent pH and thermal stability in a kaolin suspension over a pH range of 4.0 to 8.0 and a temperature range of 20 to 60°C.The optimum bioflocculating activity was observed as 92.37% for 2.56 mL M-C11 and 0.37 g/L CaCl2 dosages using response surface methodology. The sludge resistance in filtration（SRF）decreased from 11.6 × 1012 to 4.7 × 1012m/kg, which indicated that the sludge dewaterability was remarkably enhanced by the bioflocculant conditioning. The sludge dewatering performance conditioned by M-C11 was more efficient than that of inorganic flocculating reagents,such as aluminum sulfate and polymeric aluminum chloride. The bioflocculant has advantages over traditional sludge conditioners due to its lower cost, benign biodegradability and negligible secondary pollution. In addition, the bioflocculant was favorably adapted to the specific sludge pH and salinity.
基金supported through’Australian Government Research Training Program Scholarship’(formerly’International Postgraduate Research Scholarship’)UQ Centennial Scholarship(the University of Queensland)+1 种基金Top-up Scholarship(School of Civil Engineering,the University of Queensland)awarded to Mr.P.N.Mishrathe Port of Brisbane/UQ research venture.
文摘Realising the importance of pore fluid salinity on the dewatering behaviour of fine-grained porous systems,the present study systematically investigated such impacts on temporal moisture dynamics of kaolin subjected to evaporative dewatering.A detailed discussion is provided pertaining to the background processes dictating evaporative dewatering response and corresponding alterations in the dielectric behaviour of kaolin.Frequency dependent dielectric spectra of soil,which can be considered as the fingerprint of the transient changes in the condition of water phase within the pore system of the soil and associated densification,are monitored in real time during dewatering using an open-ended coaxial probe with a vector network analyser.The spatial sensitivity of the coaxial probe has been quantified through layered media approach.Combining the results of volume change behaviour of the material along with its moisture loss response,the study characterised the hydro-mechanical response of the material from the windows of frequency dependent dielectric spectroscopy.
文摘In order to find suitable oily sludge treatment equipment for a produced water treatment station of an oilfield in Iraq,the widely used mechanical dewatering equipments overseas including plate and frame filter,belt press filter,centrifugal filter and screw press filter were compared and analyzed,and the application situation of screw press filter was investigated at site. The site survey showed that,screw press filter was an integrated equipment combined with functions of concentrating and dewatering,which was characterized by low water content of filter cake,small occupied area,easy to separate,no blocking and can realize self-cleaning,which is suitable to low concentration sludge. Screw press filter can simplify oily sludge treatment process,and save engineering construction and operation cost,which is a better choice for oily sludge dewatering. The design of screw press filter adopted in the produced water treatment station of an oilfield in Iraq was introduced here.
基金Supported by Tianjin Research Program of Application Foundation and Advanced Technology(No. 09JCYBJC08200)
文摘The mechanical dewatering of activated sludge is difficult due to its high compressibility, which can be improved by electroosmosis. In electroosmosis, direct electric field is applied to sludge cake. Based on the conductivity modes of different sludge beds, a model is presented in which sludge cake consists of two series parts in the circuit: a dewatered bed and an undewatered one. The dewatered bed called solid conductor is mainly made up of immovable water and sludge particles. The undewatered bed includes movable water and solid conductor, which are connected in parallel in the circuit. The model describes the variation of water content with time and electric power consumption as a function of water content in sludge cake, and interprets the reason for the variation of electroosmotic dewatering rate. Comparison with the experimental data for electroosmotic dewatering under constant voltage supports the validity of the model.
