Kiln phosphoric acid(KPA)technology could produce P2O5 with high purity and has been applied in thermal phosphoric acid industry;however the formation of fouling in the high-temperature rotary kiln restricts the stabl...Kiln phosphoric acid(KPA)technology could produce P2O5 with high purity and has been applied in thermal phosphoric acid industry;however the formation of fouling in the high-temperature rotary kiln restricts the stable and long-term operation.In this paper,the reaction of phosphate ores with gaseous P2O5 was investigated in a high-temperature reactor,and the Ca O-SiO2-P2O5 ternary phase diagram was analyzed to understand the fouling formation mechanism.The results showed that the low-melting-point products,such as Ca(PO3)2and Ca2P2O7,are responsible for the fouling in the KPA process.In addition,a small amount of impurities,e.g.,aluminum and iron,could facilitate the generation of the low-melting-point products and cause serious fouling.Based on the high-temperature SiO2-P2O5 and CaO-SiO2-P2O5 phase diagram analysis,the control of Si/Ca molar ratio(e.g.,Si/Ca=2.0)was found to avoid fouling formation in the kiln.These results could provide the operation parameters of reaction temperature and feeds composition to suppress the fouling in the kiln reactor for the phosphoric acid production in industry.展开更多
Chlorine is usually applied in the urban water treatment process to deactivate pathogens and prevent waterborne diseases.As a pre-treatment,it remains unclear whether chlorinated water can effectively alleviate membra...Chlorine is usually applied in the urban water treatment process to deactivate pathogens and prevent waterborne diseases.As a pre-treatment,it remains unclear whether chlorinated water can effectively alleviate membrane fouling during ultrafiltration(UF).In this study,tap water was investigated for its effect on biofilm formation and biofouling in a gravity-driven membrane(GDM)filtration system.For comparison,biofilm/biofouling with untreated surface(lake)water was studied in parallel.It was found that more severe membrane fouling occurred with the filtration of tap water than lake water,and larger quantities of polysaccharide and extracellular DNA(eDNA)were present in the tap-water biofilm than in the lake-water biofilm.The tap-water biofilm had a densely compact morphology.In contrast,a porous,spider-like structure was observed for the lake-water biofilm,which was assumed to be associated with the bacteria in the biofilm.This hypothesis was verified by 16S ribosomal RNA(rRNA)sequencing,which demonstrated that Xanthobacter was the dominant taxon in the tap-water biofilm.Additionally,membrane hydrophobicity/hydrophilicity played a minor role in affecting the membrane fouling properties and microbial community.This study revealed the significant role of chlorine-resistant bacteria in biofouling formation and provides a deeper understanding of membrane fouling,which can potentially aid in searching for effective ways of controlling membrane fouling.展开更多
In this review paper, Anaerobic Membrane Bioreactor (AnMBR) is considering as highly efficient and reliable technology for organic material removal from wastewater with no additional energy requirement for aeration. A...In this review paper, Anaerobic Membrane Bioreactor (AnMBR) is considering as highly efficient and reliable technology for organic material removal from wastewater with no additional energy requirement for aeration. AnMBR is a combination of conventional anaerobic technology and modern membrane system. AnMBR is cost effective alternative technology with pros of anaerobic microbial activity because Methogenic microorganism can convert organic pollutant load of wastewater into renewable energy in the form of methane rich biogas, this conversion is mainly done by transformation of organic matter into energy by high chemical oxygen demand (COD), total suspended solid (TSS) and pathogens removal. Methane rich biogas can be used as a storable source of supplemental energy for the production of heat or power thus AnMBR technology provides improved effluent quality, reliability, and efficiency over the other traditional technologies. This review paper is included the overview of AnMBR, the advantages over other wastewater treatment technology, operational constraints and the concerned factors that has affected the performances of implemented systems, applications of AnMBR for various types of wastewaters, research and development summary and future perspective for further research.展开更多
基金support from the National Key R&D Program of China(2018YFC1900201)the Provincial Key R&D Program of Shanxi(201603D31212003)。
文摘Kiln phosphoric acid(KPA)technology could produce P2O5 with high purity and has been applied in thermal phosphoric acid industry;however the formation of fouling in the high-temperature rotary kiln restricts the stable and long-term operation.In this paper,the reaction of phosphate ores with gaseous P2O5 was investigated in a high-temperature reactor,and the Ca O-SiO2-P2O5 ternary phase diagram was analyzed to understand the fouling formation mechanism.The results showed that the low-melting-point products,such as Ca(PO3)2and Ca2P2O7,are responsible for the fouling in the KPA process.In addition,a small amount of impurities,e.g.,aluminum and iron,could facilitate the generation of the low-melting-point products and cause serious fouling.Based on the high-temperature SiO2-P2O5 and CaO-SiO2-P2O5 phase diagram analysis,the control of Si/Ca molar ratio(e.g.,Si/Ca=2.0)was found to avoid fouling formation in the kiln.These results could provide the operation parameters of reaction temperature and feeds composition to suppress the fouling in the kiln reactor for the phosphoric acid production in industry.
基金financially supported by the Key Research and Development Plan of the Ministry of Science and Technology,China(2019YFD1100104 and 2019YFC1906501)。
文摘Chlorine is usually applied in the urban water treatment process to deactivate pathogens and prevent waterborne diseases.As a pre-treatment,it remains unclear whether chlorinated water can effectively alleviate membrane fouling during ultrafiltration(UF).In this study,tap water was investigated for its effect on biofilm formation and biofouling in a gravity-driven membrane(GDM)filtration system.For comparison,biofilm/biofouling with untreated surface(lake)water was studied in parallel.It was found that more severe membrane fouling occurred with the filtration of tap water than lake water,and larger quantities of polysaccharide and extracellular DNA(eDNA)were present in the tap-water biofilm than in the lake-water biofilm.The tap-water biofilm had a densely compact morphology.In contrast,a porous,spider-like structure was observed for the lake-water biofilm,which was assumed to be associated with the bacteria in the biofilm.This hypothesis was verified by 16S ribosomal RNA(rRNA)sequencing,which demonstrated that Xanthobacter was the dominant taxon in the tap-water biofilm.Additionally,membrane hydrophobicity/hydrophilicity played a minor role in affecting the membrane fouling properties and microbial community.This study revealed the significant role of chlorine-resistant bacteria in biofouling formation and provides a deeper understanding of membrane fouling,which can potentially aid in searching for effective ways of controlling membrane fouling.
文摘In this review paper, Anaerobic Membrane Bioreactor (AnMBR) is considering as highly efficient and reliable technology for organic material removal from wastewater with no additional energy requirement for aeration. AnMBR is a combination of conventional anaerobic technology and modern membrane system. AnMBR is cost effective alternative technology with pros of anaerobic microbial activity because Methogenic microorganism can convert organic pollutant load of wastewater into renewable energy in the form of methane rich biogas, this conversion is mainly done by transformation of organic matter into energy by high chemical oxygen demand (COD), total suspended solid (TSS) and pathogens removal. Methane rich biogas can be used as a storable source of supplemental energy for the production of heat or power thus AnMBR technology provides improved effluent quality, reliability, and efficiency over the other traditional technologies. This review paper is included the overview of AnMBR, the advantages over other wastewater treatment technology, operational constraints and the concerned factors that has affected the performances of implemented systems, applications of AnMBR for various types of wastewaters, research and development summary and future perspective for further research.
