The high concentration of heavy metal (Cu, Cr, Zn, Pb) in tannery sludge causes severe heavy metal emissions in the process of incineration. In the present investigation, the tannery sludge was treated with 85% phosph...The high concentration of heavy metal (Cu, Cr, Zn, Pb) in tannery sludge causes severe heavy metal emissions in the process of incineration. In the present investigation, the tannery sludge was treated with 85% phosphoric acid before the incineration process in the tube furnace to control the heavy metal emissions. The thermal behavior and heavy metal vaporization of pre-treated tannery sludge were investigated, and X-ray diffraction (XRD) and scanning electron microscopy (SEM) analysis were also implemente...展开更多
The purpose of this research is to investigate the potential of pre-treatment with phosphoric acid(PA) and monobasic calcium phosphate(MCP) for the stabilization of heavy metals in sludge and its bottom ash.The tanner...The purpose of this research is to investigate the potential of pre-treatment with phosphoric acid(PA) and monobasic calcium phosphate(MCP) for the stabilization of heavy metals in sludge and its bottom ash.The tannery sludge samples were collected in Wenzhou,China and heavily contaminated with heavy metals,such as Pb,Cr and so on.The samples were pre-treated with PA or MCP.Then XRD and TCLP tests were adopted as the evaluating methods to characterize the Pb,Cr,Cu,Zn and Cd immobilization in the pre-treated sludge and its bottom ash.The results showed that this treatment effectively immobilized Pb and Cd in the sludge,lightly stabilized the metal Cu,and adversely,enhanced the leachability of Zn.After incineration at 900℃,Pb and Cr in the bottom ash of pre-treated sludge were significantly stabilized due to the formation of their highly thermostable phosphates and pyromorphite-like minerals during the incineration process.However,an increase of Cu and Zn solubility was observed which might be attributable to the acidification of sludge due to the addition of PA or MCP.展开更多
Phosphorus(P)recovery from incinerated sewage sludge ash(ISSA)has been extensively investigated,but insufficient research has been conducted to evaluate the effect of different kinds of recovered phosphate fertilizers...Phosphorus(P)recovery from incinerated sewage sludge ash(ISSA)has been extensively investigated,but insufficient research has been conducted to evaluate the effect of different kinds of recovered phosphate fertilizers(RPFs)on plant growth with respect to the P and heavy metal contents of RPFs.In this study,three kinds of RPFs,precipitated calcium phosphate fertilizer(CaP),struvite phosphate fertilizer(SP),and P-loaded biochar(BP),produced from ISSA were characterized,and their agronomic effectiveness was verified by hydroponic and soil cultivation.In addition to the three kinds of RPFs,a control group(mono-phosphate fertilizer in hydroponic group/compound fertilizer in soil cultivation group)and a blank control group(BC,with zero P)were tested on choy sum and ryegrass at the same time.SP has the highest P purity(76.0%of struvite)while the BP has the most complex P species(P was co-exist with Fe,Al,and Mg).Plant growth results showed that the RPFs greatly facilitated plant growth and demonstrated superior/comparable effects to those of control group.In hydroponics testing,SP showed the best effect(shoot length of 17.0 cm,chlorophyll content of 2.05 mg/g)due to the Mg involved and the high P purity of SP,while BP performed the best(shoot length of 13.7 cm,chlorophyll content of 2.42 mg/g)in the soil testing system among all of the groups because of the additional nutritional elements and the high P availability of BP.Additionally,the accumulation of heavy metals in the plants under all conditions did not exceed the limits stipulated in the regulations.These results indicate that recovering P from ISSA is an attractive technology to produce P fertilizers,which can alleviate both the scarcity of phosphate resources and the burden of ISSA management.展开更多
Management of incinerated sewage sludge ash(ISSA)and dredged contaminated marine sediments(CMSs)is a great challenge for Hong Kong and other coastal cities due to limited landfilling capacity.The present study investi...Management of incinerated sewage sludge ash(ISSA)and dredged contaminated marine sediments(CMSs)is a great challenge for Hong Kong and other coastal cities due to limited landfilling capacity.The present study investigates the use of high content(20%of sediment by mass)of ISSA in combination with cement/lime for solidification/stabilization(S/S)treatment of CMSs to provide a way to reuse the wastes as construction materials.The results showed that ISSA being a porous material was able to absorb a large amount of water rendering a more efficient solidification process of the marine sediment which normally had a very high water content(w80%).The S/S treatment improved the engineering properties of the sediment,but reduced the workability,especially for the lime-treated samples.Lime can be used to replace ordinary Portland cement(OPC)for better heavy metal immobilization and carbon emission reduction.The hardened sediment samples prepared with 10%of lime and 20%of ISSA could attain a strength of 1.6 MPa after 28 d of curing.In addition,leaching tests confirmed that there was no environmental risk induced by these stabilized materials.The formation of hydrated cementitious compounds including calcium silicate hydrate(CeSeH)/calcium aluminate silicate hydrate(C-A-S-H)/hydrocalumite/calcite was mainly responsible for the strength development in the ISSA/lime-treated sediments.展开更多
Material conversion from paper sludge ash (PSA) in NaOH solution was attempted to synthesize the adsorbent for removal of inorganic pollutants, such as Pb^2+, NH^4+ and PO4^3- from aqueous solution. PSA of 0.5 g w...Material conversion from paper sludge ash (PSA) in NaOH solution was attempted to synthesize the adsorbent for removal of inorganic pollutants, such as Pb^2+, NH^4+ and PO4^3- from aqueous solution. PSA of 0.5 g was added into 10 mL of 3 mol/L NaOH solution, and then heated at 80, 120, and 160℃ for 6-48 hr to obtain the product. PSA mainly composed of two crystalline phases, gehlenite (Ca2Al2SiO7) and anorthite (CaAl2Si2O8), and amorphous phase. Hydroxysodalite (Na6Al6Si6O24-8H2O) was formed at 80℃, and anorthite dissolved, whereas gehlenite remained unaffected. Katoite (Ca3Al2SiO4(OH)8) was formed over 120℃, and hydroxycancrinite (Nas(OH)2Al6Si6O24·2H2O) was formed at 160℃, due to the dissolution of both gehlenite and anorthite. Specific surface areas of the products were almost same and were higher than that of raw ash. Cation exchange capacities (CECs) of the products were also higher than that of raw ash, and CEC obtained at lower temperature was higher. Removal abilities of products for Pb^2+, NH4+, and PO4^3- were higher than that of raw ash. With increasing reaction temperature, the removal efficiencies of Pb^2+ and NH4+ decreased due to the decrease of CEC of the product, while removal efficiency for PO4^3- was almost same. The concentrations of Si and AI in the solution and the crystalline phases in the solid during the reaction explain the formation of the product phases at each temperature.展开更多
基金the Education Ministryof China (No. 305005)the Department of Sci-ence and Technology of Zhejiang Province, China (No.2007C210054)
文摘The high concentration of heavy metal (Cu, Cr, Zn, Pb) in tannery sludge causes severe heavy metal emissions in the process of incineration. In the present investigation, the tannery sludge was treated with 85% phosphoric acid before the incineration process in the tube furnace to control the heavy metal emissions. The thermal behavior and heavy metal vaporization of pre-treated tannery sludge were investigated, and X-ray diffraction (XRD) and scanning electron microscopy (SEM) analysis were also implemente...
基金Project (No. 50908070) supported by the National Nature Science Foundation of China
文摘The purpose of this research is to investigate the potential of pre-treatment with phosphoric acid(PA) and monobasic calcium phosphate(MCP) for the stabilization of heavy metals in sludge and its bottom ash.The tannery sludge samples were collected in Wenzhou,China and heavily contaminated with heavy metals,such as Pb,Cr and so on.The samples were pre-treated with PA or MCP.Then XRD and TCLP tests were adopted as the evaluating methods to characterize the Pb,Cr,Cu,Zn and Cd immobilization in the pre-treated sludge and its bottom ash.The results showed that this treatment effectively immobilized Pb and Cd in the sludge,lightly stabilized the metal Cu,and adversely,enhanced the leachability of Zn.After incineration at 900℃,Pb and Cr in the bottom ash of pre-treated sludge were significantly stabilized due to the formation of their highly thermostable phosphates and pyromorphite-like minerals during the incineration process.However,an increase of Cu and Zn solubility was observed which might be attributable to the acidification of sludge due to the addition of PA or MCP.
基金support from Major Scientific and Technological Innovation Projects of Shandong Province(No.2021CXGC011201)the start-up funding for the new introduced talents of the Beijing Normal University(No.28707-111032107)Hong Kong Research Grants Council(PolyU No.152132/14E)for financial support.
文摘Phosphorus(P)recovery from incinerated sewage sludge ash(ISSA)has been extensively investigated,but insufficient research has been conducted to evaluate the effect of different kinds of recovered phosphate fertilizers(RPFs)on plant growth with respect to the P and heavy metal contents of RPFs.In this study,three kinds of RPFs,precipitated calcium phosphate fertilizer(CaP),struvite phosphate fertilizer(SP),and P-loaded biochar(BP),produced from ISSA were characterized,and their agronomic effectiveness was verified by hydroponic and soil cultivation.In addition to the three kinds of RPFs,a control group(mono-phosphate fertilizer in hydroponic group/compound fertilizer in soil cultivation group)and a blank control group(BC,with zero P)were tested on choy sum and ryegrass at the same time.SP has the highest P purity(76.0%of struvite)while the BP has the most complex P species(P was co-exist with Fe,Al,and Mg).Plant growth results showed that the RPFs greatly facilitated plant growth and demonstrated superior/comparable effects to those of control group.In hydroponics testing,SP showed the best effect(shoot length of 17.0 cm,chlorophyll content of 2.05 mg/g)due to the Mg involved and the high P purity of SP,while BP performed the best(shoot length of 13.7 cm,chlorophyll content of 2.42 mg/g)in the soil testing system among all of the groups because of the additional nutritional elements and the high P availability of BP.Additionally,the accumulation of heavy metals in the plants under all conditions did not exceed the limits stipulated in the regulations.These results indicate that recovering P from ISSA is an attractive technology to produce P fertilizers,which can alleviate both the scarcity of phosphate resources and the burden of ISSA management.
基金The authors would like to thank the financial support of National Natural Science Foundation of China(Grant Nos.51861165104 and 51625903)National Key Research and Development Project(Grant No.2019YFC1804002).
文摘Management of incinerated sewage sludge ash(ISSA)and dredged contaminated marine sediments(CMSs)is a great challenge for Hong Kong and other coastal cities due to limited landfilling capacity.The present study investigates the use of high content(20%of sediment by mass)of ISSA in combination with cement/lime for solidification/stabilization(S/S)treatment of CMSs to provide a way to reuse the wastes as construction materials.The results showed that ISSA being a porous material was able to absorb a large amount of water rendering a more efficient solidification process of the marine sediment which normally had a very high water content(w80%).The S/S treatment improved the engineering properties of the sediment,but reduced the workability,especially for the lime-treated samples.Lime can be used to replace ordinary Portland cement(OPC)for better heavy metal immobilization and carbon emission reduction.The hardened sediment samples prepared with 10%of lime and 20%of ISSA could attain a strength of 1.6 MPa after 28 d of curing.In addition,leaching tests confirmed that there was no environmental risk induced by these stabilized materials.The formation of hydrated cementitious compounds including calcium silicate hydrate(CeSeH)/calcium aluminate silicate hydrate(C-A-S-H)/hydrocalumite/calcite was mainly responsible for the strength development in the ISSA/lime-treated sediments.
基金supported by the Mukai Science and Technology Foundation and the Intelligent Cosmos Academic Foundation
文摘Material conversion from paper sludge ash (PSA) in NaOH solution was attempted to synthesize the adsorbent for removal of inorganic pollutants, such as Pb^2+, NH^4+ and PO4^3- from aqueous solution. PSA of 0.5 g was added into 10 mL of 3 mol/L NaOH solution, and then heated at 80, 120, and 160℃ for 6-48 hr to obtain the product. PSA mainly composed of two crystalline phases, gehlenite (Ca2Al2SiO7) and anorthite (CaAl2Si2O8), and amorphous phase. Hydroxysodalite (Na6Al6Si6O24-8H2O) was formed at 80℃, and anorthite dissolved, whereas gehlenite remained unaffected. Katoite (Ca3Al2SiO4(OH)8) was formed over 120℃, and hydroxycancrinite (Nas(OH)2Al6Si6O24·2H2O) was formed at 160℃, due to the dissolution of both gehlenite and anorthite. Specific surface areas of the products were almost same and were higher than that of raw ash. Cation exchange capacities (CECs) of the products were also higher than that of raw ash, and CEC obtained at lower temperature was higher. Removal abilities of products for Pb^2+, NH4+, and PO4^3- were higher than that of raw ash. With increasing reaction temperature, the removal efficiencies of Pb^2+ and NH4+ decreased due to the decrease of CEC of the product, while removal efficiency for PO4^3- was almost same. The concentrations of Si and AI in the solution and the crystalline phases in the solid during the reaction explain the formation of the product phases at each temperature.