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
One of the challenges faced by sewage sludge treatment and disposal is its higher water content,and how to efficient dewater those hazardous materials properly is welcome in practice. This study stabilized the sewage ...One of the challenges faced by sewage sludge treatment and disposal is its higher water content,and how to efficient dewater those hazardous materials properly is welcome in practice. This study stabilized the sewage sludge via the using of conventional curing agents and calcined aluminum salts,and the corresponding dewatering mechanisms and structural changes of the stabilized sludge were further comparable analyzed.Experimental results showed that wollastonite and kaolin exhibit a relative higher dewatering efficiency as compared to other conventional curing agents; however the releasing rate of heavy metals of Cu,Cr,Ni for kaolin solidification and Zn,Pb for wollastonite solidification is higher than the sludge samples solidified by other curing agents. For comparison,the sludge samples solidified by calcined aluminum salts (AS),calcium ash,Mg-based curing agent,tricalcium aluminate( C_3A) show a lower heavy metals leaching potential and unconfined compressive strength. In addition,the economic characteristics and local availability of AS,calcium ash,C_3A and CaO makes it have a broad prospect in extension and application. These findings are of great significance for stabilization and dewatering of sewage sludge.展开更多
This work experimentally examined the optimal proportioning of sludge curing agent for dewatered sludge curing on solidified sludge,two components sludge curing agent consisted of cement and slag,and three components ...This work experimentally examined the optimal proportioning of sludge curing agent for dewatered sludge curing on solidified sludge,two components sludge curing agent consisted of cement and slag,and three components consisted of cement,slag and inorganic salt. The results showed that,increasing of curing ages could increase unconfined compressive strength and reduce moisture content for solidified sludge. For the test of two components,the biggest unconfined compressive strength of the solidified sludge achieved to 543. 72 kPa and the minimum moisture content achieved to 3. 56% of 21 d. The optimum proportion of the sludge curing agent of two components is sludge: cement: slag = 1 ∶ 0. 05 ∶ 0. 2 which selected by Design-expert. It could rapidly increasing the unconfined compressive strength of solidified sludge when added three components sludge curing agent( sludge: cement: slag: MgSO4= 1 ∶ 0. 05 ∶ 0. 2 ∶ 0. 03) on sludge curing. The results showed that,curing ages of 7 d,the unconfined compressive strength could achieve to 126. 74 kPa,which was more than 11 times comparison with the solidified sludge curing by two components curing agent. Two or three components sludge curing agent all could stabilize the heavy metals on solidified sludge and the leaching of heavy metals was below the government standard,while the stability of the heavy metals was superior for three components sludge curing agent.展开更多
Ultraviolet(UV)assisted zero-valent iron(ZVI)-activated sodium persulfate(PDS)oxidation(UV-ZVI-PDS)was used to treat waste activated sludge(WAS)in this study.The dewaterability performance and mechanism of WAS dewater...Ultraviolet(UV)assisted zero-valent iron(ZVI)-activated sodium persulfate(PDS)oxidation(UV-ZVI-PDS)was used to treat waste activated sludge(WAS)in this study.The dewaterability performance and mechanism of WAS dewatering were analyzed.The results showed that UV-ZVI-PDS can obtain better sludge dewatering performance in a wide pH range(2.0-8.0).When the molar ratio of ZVI/PDS was 0.6,UV was 254nm,PDS dosage was 200 mg/g TS(total solid),pH was 6.54,reaction time was 20 min,the CST(capillary suction time)and SRF(specific resistance to filtration)were decreased by 64.0%and 78.2%,respectively.The molar ratio of ZVI/PDS used in this paper is much lower than that of literatures,and the contents of total Fe and Fe^(2+) in sludge supernatant remained at a low level,as 3.7 mg/L and 0.0 mg/L.The analysis of extracellular polymeric substances(EPS),scanning electron microscope(SEM)and particle size distribution showed that the EPS could be effectively destroyed by UV-ZVI-PDS,the sludge flocs broken down into smaller particles,cracks and holes appeared,and then the bound water was released.At the same time,the highly hydrophilic tightly bound-EPS(TB-EPS)were converted into loosely bound EPS(LB-EPS)and soluble EPS(S-EPS).During sludge pretreated by UV-ZVI-PDS,positively charged ions,such as Fe^(2+),Fe^(3+) and H^(+),produced in the reaction system could reduce the electronegativity of sludge surface,promote sludge particles aggregation,and then enhanced the sludge dewaterability.展开更多
Organic polymeric flocculants are commonly used in improving dredged sludge dewaterability, but less attention has been paid to residual water quality. In this paper, the effects of cationic etherified starch(CS) and ...Organic polymeric flocculants are commonly used in improving dredged sludge dewaterability, but less attention has been paid to residual water quality. In this paper, the effects of cationic etherified starch(CS) and poly-dimethyl diallyl ammonium chloride(PDDA) on dredged sludge dewatering efficiency and residual water quality of Baiyangdian lake were comprehensively investigated and evaluated by analytic hierarchy process(AHP). The results indicated that PDDA had stronger electrical effect and flocculation performance compared with CS, resulting in more efficient dewatering performance. PDDA can reduce the pollutants of discharged residual water, while CS significantly promoted the increase of NH_(4)^(+)-N and NO_(3)^(–)-N in the residual water. The increase of NH_(4)^(+)-N in the residual water of CS was due to the release of dredged sludge, while the increase of NO_(3)^(-)-N was introduced by CS leaching. AHP showed that PDDA performed better in flocculation treatment of dredged sludge than other organic polymers. This work provides a method for optimization of flocculation treatment for dredged sludge dewaterability.展开更多
This study mainly focused on the occurrence of pharmaceutical and personal care products(PPCPs)in sewage dewatered sludge and their discharges through sludge disposal from wastewater treatment plants(WWTPs).The data w...This study mainly focused on the occurrence of pharmaceutical and personal care products(PPCPs)in sewage dewatered sludge and their discharges through sludge disposal from wastewater treatment plants(WWTPs).The data were obtained and calculated from seven PPCPs in dewatered sludge collected from 12WWTPs in two typical cities,Beijing and Shenzhen in China.Four of seven PPCPs,diclofenac acid,carbamazepine,mefenamic acid and N,N-diethyl-m-toluamide were detectable in dewatered sludge from Beijing and Shenzhen with concentration up to 4240,11,060,92 and 219μg/kg respectively.While,the other three compounds,trimethoprim,chloramphenicol and bezafibrate were not detected in collected samples from these two cities.The highest discharge of diclofenac acid and carbamazepine were 1023 g/d and 494 g/d respectively.In addition,the total discharge of these four detected PPCPs from each plant ranged from 5 to 1092 g/d in Beijing and 4e497 g/d in Shenzhen.Thus,PPCP discharge through sludge disposal cannot be neglected,and further research on transfer of PPCPs during sludge disposal onto agriculture land and influence of sludge application is required and essential.展开更多
Over the past twenty years,various commercial technologies have been deployed to remove ammonia(NH4eN)from anaerobic digestion(AD)liquors.In recent years many anaerobic digesters have been upgraded to include a pre-tr...Over the past twenty years,various commercial technologies have been deployed to remove ammonia(NH4eN)from anaerobic digestion(AD)liquors.In recent years many anaerobic digesters have been upgraded to include a pre-treatment,such as the thermal hydrolysis process(THP),to produce more biogas,increasing NH4eN concentrations in the liquors are costly to treat.This study provides a comparative techno-economic assessment of sidestream technologies to remove NH4eN from conventional AD and THP/AD dewatering liquors:a deammonification continuous stirred tank reactor(PNA),a nitrification/denitrification sequencing batch reactor(SBR)and thermal ammonia stripping process with an ammonia scrubber(STRIP).The SBR and PNA were based on full-scale data,whereas the STRIP was designed using a computational approach to achieve NH4eN removals of 90e95%.The PNA presented the lowest whole-life cost(WLC)over 40 years,with£7.7 M,while the STRIP had a WLC of£43.9 M.This study identified that THP dewatering liquors,and thus a higher ammonia load,can lead to a 1.5e3.0 times increase in operational expenditure with the PNA and the SBR.Furthermore,this study highlighted that deammonification is a capable and cost-effective nitrogen removal technology.Processes like the STRIP respond to current pressures faced by the water industry on ammonia recovery together with targets to reduce nitrous oxide emissions.Nevertheless,ammonia striping-based processes must further be demonstrated in WWTPs and WLC reduced to grant their wide implementation and replace existing technologies.展开更多
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Sponsored by the National Natural Science Foundation of China(Grant No.51408159)the China Postdoctoral Science Foundation of China(Grant No.2013T60375 and 2012M520744)
文摘One of the challenges faced by sewage sludge treatment and disposal is its higher water content,and how to efficient dewater those hazardous materials properly is welcome in practice. This study stabilized the sewage sludge via the using of conventional curing agents and calcined aluminum salts,and the corresponding dewatering mechanisms and structural changes of the stabilized sludge were further comparable analyzed.Experimental results showed that wollastonite and kaolin exhibit a relative higher dewatering efficiency as compared to other conventional curing agents; however the releasing rate of heavy metals of Cu,Cr,Ni for kaolin solidification and Zn,Pb for wollastonite solidification is higher than the sludge samples solidified by other curing agents. For comparison,the sludge samples solidified by calcined aluminum salts (AS),calcium ash,Mg-based curing agent,tricalcium aluminate( C_3A) show a lower heavy metals leaching potential and unconfined compressive strength. In addition,the economic characteristics and local availability of AS,calcium ash,C_3A and CaO makes it have a broad prospect in extension and application. These findings are of great significance for stabilization and dewatering of sewage sludge.
基金Sponsored by the Technology Research Projects of Harbin Science and Technology Bureau(Grant No.2010AA4CS024)the Fundamental Research Funds for the Central Universities(Grant No.HIT.NSRIF.201192)+1 种基金the National Natural Science Key Foundation of China(Grant No.51206036)the State Key Laboratory of Urban Water Resource and Environment,Harbin Institute of Technology(Grant No.2013DX04)
文摘This work experimentally examined the optimal proportioning of sludge curing agent for dewatered sludge curing on solidified sludge,two components sludge curing agent consisted of cement and slag,and three components consisted of cement,slag and inorganic salt. The results showed that,increasing of curing ages could increase unconfined compressive strength and reduce moisture content for solidified sludge. For the test of two components,the biggest unconfined compressive strength of the solidified sludge achieved to 543. 72 kPa and the minimum moisture content achieved to 3. 56% of 21 d. The optimum proportion of the sludge curing agent of two components is sludge: cement: slag = 1 ∶ 0. 05 ∶ 0. 2 which selected by Design-expert. It could rapidly increasing the unconfined compressive strength of solidified sludge when added three components sludge curing agent( sludge: cement: slag: MgSO4= 1 ∶ 0. 05 ∶ 0. 2 ∶ 0. 03) on sludge curing. The results showed that,curing ages of 7 d,the unconfined compressive strength could achieve to 126. 74 kPa,which was more than 11 times comparison with the solidified sludge curing by two components curing agent. Two or three components sludge curing agent all could stabilize the heavy metals on solidified sludge and the leaching of heavy metals was below the government standard,while the stability of the heavy metals was superior for three components sludge curing agent.
基金This work was supported by the National Natural Science Foundation of China(No.51608166)the China Scholarship Council(No.201906705003).
文摘Ultraviolet(UV)assisted zero-valent iron(ZVI)-activated sodium persulfate(PDS)oxidation(UV-ZVI-PDS)was used to treat waste activated sludge(WAS)in this study.The dewaterability performance and mechanism of WAS dewatering were analyzed.The results showed that UV-ZVI-PDS can obtain better sludge dewatering performance in a wide pH range(2.0-8.0).When the molar ratio of ZVI/PDS was 0.6,UV was 254nm,PDS dosage was 200 mg/g TS(total solid),pH was 6.54,reaction time was 20 min,the CST(capillary suction time)and SRF(specific resistance to filtration)were decreased by 64.0%and 78.2%,respectively.The molar ratio of ZVI/PDS used in this paper is much lower than that of literatures,and the contents of total Fe and Fe^(2+) in sludge supernatant remained at a low level,as 3.7 mg/L and 0.0 mg/L.The analysis of extracellular polymeric substances(EPS),scanning electron microscope(SEM)and particle size distribution showed that the EPS could be effectively destroyed by UV-ZVI-PDS,the sludge flocs broken down into smaller particles,cracks and holes appeared,and then the bound water was released.At the same time,the highly hydrophilic tightly bound-EPS(TB-EPS)were converted into loosely bound EPS(LB-EPS)and soluble EPS(S-EPS).During sludge pretreated by UV-ZVI-PDS,positively charged ions,such as Fe^(2+),Fe^(3+) and H^(+),produced in the reaction system could reduce the electronegativity of sludge surface,promote sludge particles aggregation,and then enhanced the sludge dewaterability.
基金supported by the Major Science and Technology Program for Water Pollution Control and Treatment(No.2018ZX07110004)。
文摘Organic polymeric flocculants are commonly used in improving dredged sludge dewaterability, but less attention has been paid to residual water quality. In this paper, the effects of cationic etherified starch(CS) and poly-dimethyl diallyl ammonium chloride(PDDA) on dredged sludge dewatering efficiency and residual water quality of Baiyangdian lake were comprehensively investigated and evaluated by analytic hierarchy process(AHP). The results indicated that PDDA had stronger electrical effect and flocculation performance compared with CS, resulting in more efficient dewatering performance. PDDA can reduce the pollutants of discharged residual water, while CS significantly promoted the increase of NH_(4)^(+)-N and NO_(3)^(–)-N in the residual water. The increase of NH_(4)^(+)-N in the residual water of CS was due to the release of dredged sludge, while the increase of NO_(3)^(-)-N was introduced by CS leaching. AHP showed that PDDA performed better in flocculation treatment of dredged sludge than other organic polymers. This work provides a method for optimization of flocculation treatment for dredged sludge dewaterability.
基金supported by Tsinghua University e Veolia Environment Joint Research Center for Advanced Environment Technology and the Program for Changjiang Scholars and Innovative Research Team in University(IRT1261).
文摘This study mainly focused on the occurrence of pharmaceutical and personal care products(PPCPs)in sewage dewatered sludge and their discharges through sludge disposal from wastewater treatment plants(WWTPs).The data were obtained and calculated from seven PPCPs in dewatered sludge collected from 12WWTPs in two typical cities,Beijing and Shenzhen in China.Four of seven PPCPs,diclofenac acid,carbamazepine,mefenamic acid and N,N-diethyl-m-toluamide were detectable in dewatered sludge from Beijing and Shenzhen with concentration up to 4240,11,060,92 and 219μg/kg respectively.While,the other three compounds,trimethoprim,chloramphenicol and bezafibrate were not detected in collected samples from these two cities.The highest discharge of diclofenac acid and carbamazepine were 1023 g/d and 494 g/d respectively.In addition,the total discharge of these four detected PPCPs from each plant ranged from 5 to 1092 g/d in Beijing and 4e497 g/d in Shenzhen.Thus,PPCP discharge through sludge disposal cannot be neglected,and further research on transfer of PPCPs during sludge disposal onto agriculture land and influence of sludge application is required and essential.
基金funding provided by Thames Water Utilities Ltd.and the Engineering and Physical Sciences Research Council(EPSRC)through their funding of the STREAM Industrial Doctoral Centre(IDC)EP/L015412/1.
文摘Over the past twenty years,various commercial technologies have been deployed to remove ammonia(NH4eN)from anaerobic digestion(AD)liquors.In recent years many anaerobic digesters have been upgraded to include a pre-treatment,such as the thermal hydrolysis process(THP),to produce more biogas,increasing NH4eN concentrations in the liquors are costly to treat.This study provides a comparative techno-economic assessment of sidestream technologies to remove NH4eN from conventional AD and THP/AD dewatering liquors:a deammonification continuous stirred tank reactor(PNA),a nitrification/denitrification sequencing batch reactor(SBR)and thermal ammonia stripping process with an ammonia scrubber(STRIP).The SBR and PNA were based on full-scale data,whereas the STRIP was designed using a computational approach to achieve NH4eN removals of 90e95%.The PNA presented the lowest whole-life cost(WLC)over 40 years,with£7.7 M,while the STRIP had a WLC of£43.9 M.This study identified that THP dewatering liquors,and thus a higher ammonia load,can lead to a 1.5e3.0 times increase in operational expenditure with the PNA and the SBR.Furthermore,this study highlighted that deammonification is a capable and cost-effective nitrogen removal technology.Processes like the STRIP respond to current pressures faced by the water industry on ammonia recovery together with targets to reduce nitrous oxide emissions.Nevertheless,ammonia striping-based processes must further be demonstrated in WWTPs and WLC reduced to grant their wide implementation and replace existing technologies.
