In order to enhance the efficiency of aerobic digestion, the excess sludge was irradiated by low intensity ultrasound at a frequency of 28 kHz and acoustic intensity of 0.53 W/cm^2. The results show that the sludge st...In order to enhance the efficiency of aerobic digestion, the excess sludge was irradiated by low intensity ultrasound at a frequency of 28 kHz and acoustic intensity of 0.53 W/cm^2. The results show that the sludge stabilization without ultrasonic treatment can be achieved after 17 d of digestion, whereas the digestion time of ultrasonic groups can be cut by 3-7 d. During the same digestion elapsing, in ultrasonic groups the total volatile suspended solid removal rate is higher than that in the control group. The kinetics of aerobic digestion of excess sludge with ultrasound can also be described with first-order reaction.展开更多
Ultrasound (US)-induced cavitation is an effective way in oxidizing organic contaminants in wastewater either as the independent operation unit or in combination with other oxidation methods. In this paper, black liqu...Ultrasound (US)-induced cavitation is an effective way in oxidizing organic contaminants in wastewater either as the independent operation unit or in combination with other oxidation methods. In this paper, black liquor and filtrate after acidifying and settling were sonicated. The effect of working parameters on ultrasonic degradation of black liquor, such as different combination methods, frequency, power supply, initial concentration, pH, duration time, ionic strength and catalyst were studied. The results were as follows: (1) At the conditions of 40kHz, 100W, 4h, pH at 6 and temperature 30?℃, utilizing US/US-H2O2/US-Fenton, weak-orange filtrate turned to colloid with the increase of time and little sediment produced after settling. Especially filtrate came to be milk white collides and upper water approached to nearly achromatic by US-Fenton. Compared with the US, US-H2O2/US-Fenton COD (Chemical oxidation demand) removal ratio can increase 15%, 30% respectively. Because of more hydroxyl radicals produced in the reaction process; (2) At the condition of 100W and 4h, the degradation efficiency of black liquor was better at 40kHz over at 20kHz. Moreover black liquor can be biodegraded easily. Those based on that the big molecule of contaminants in aqueous solution can be changed into the little molecule with ultrasound (3) At the condition of 40kHz and 4h, the COD removal ratio of black liquor was more higher at 60W than at 80W, while the removal ratio of COD at 60W was nearly close to the ratio at 100W; (4) The initial concentration of black liquor influenced the effect of sonochemical degradation; (5) The variation of pH had no effect on degradation; (6) The longer the duration time, the greater the removal ratio of COD. But this ratio increased slowly after 4h; (7) Adding 0.2g/L NaCl to change the ionic strength of the black liquor, the COD removal ratio can increase 10%; (8) The degradation rates increased by the coexistent catalysts of TiO2, Co2+ and Ag+.展开更多
An advanced sludge reduction process, i.e. sludge reduction and phosphorous removal process, was developed. The results show that excellent sludge reduction and biological phosphorous removal can be achieved perfectly...An advanced sludge reduction process, i.e. sludge reduction and phosphorous removal process, was developed. The results show that excellent sludge reduction and biological phosphorous removal can be achieved perfectly in this system. When chemical oxygen demand ρ（COD） is 332 - 420 mg/L, concentration of ammonia p（NH3-N） is 30 - 40 mg/L and concentration of total phosphorous p（TP） is 6.0 -9.0 mg/L in influent, the system still ensures ρ（COD）〈23 mg/L, ρ（NH3-N）〈3.2 mg/L and ρ（TP）〈0. 72 mg/L in effluent. Besides, when the concentration of dissolved oxygen ρ（DO） is around 1.0 mg/L, sludge production is less than 0. 140 g with the consumption of 1 g COD, and the phosphorous removal exceeds 91 %. Also, 48.4% of total nitrogen is removed by simultaneous nitrification and denitrification.展开更多
The community of Figuig is located in a desert area, east of Morocco. It is characterized by an arid climate. Part of the aquifers of the area has a high salinity which creates even worst conditions for the use of the...The community of Figuig is located in a desert area, east of Morocco. It is characterized by an arid climate. Part of the aquifers of the area has a high salinity which creates even worst conditions for the use of the scarce water available in the area. Therefore, it is essential to develop new water resources, especially for agriculture. For this reason, reclaiming wastewater for agricultural use is an essential strategy to increase water resources. The studied system is a wastewater treatment plant （WWTP） with stabilisation ponds; it treats a part of the wastewater of Figuig. The monitoring of the WWTP will allow to the physico-chemical and biological characterization of the treated water, and then, to verify two principal points： （1） the physico-chemical and pathogen parasites elimination; （2） the possibility of the treated water reuse in agricultural irrigation. The reductions recorded at the WWTP show a relatively preferment operation with an average decrease of 3.17 Ulog for faecal coliforms and 50-60% for organic matter. It was observed that the taxonomic density is slow in the WWTP; observed species are generally Cyanobacteria, Euglénophycea and Chlorophycea characteristic of eutrophic water sources.展开更多
The present study aims to monitor and assess the water quality of the Bezerra River located in the Western Brazilian Parana state. For the monitoring of river waters, six samplings were established per month during on...The present study aims to monitor and assess the water quality of the Bezerra River located in the Western Brazilian Parana state. For the monitoring of river waters, six samplings were established per month during one year. As indicators of the water quality, physico-chemical parameters such as water temperature, pH, turbidity, dissolved oxygen and COD （chemical oxygen demand） were chosen, as well as trace and majority element concentrations. It is noteworthy that the mean annual values of conductivity, turbidity and COD have progressively increased along the river with maximum values after the Cascavel western sewage treatment plant. Only 13 elements were found in the six collection points, but the metallic elements Cr, Mn, Fe, Cu and Zn have shown concentrations above the maximum limits recommended by Brazilian environmental legislation, suggesting the presence of highly polluting anthropogenic sources. Correlation analyses were used to determine the spatio-variability of water quality variables. The six collection sites were grouped into two clusters, with the element composition in the first cluster （sites 1, 2 and 6） being due to strong anthropogenic activities. The study of the Bezerra River water quality could help to develop municipal environmental policies and help with the management of water conservation in the Bezerra River basin.展开更多
Increased attention has been given to the fate of pollutants such as polycyclic aromatic hydrocarbons (PAHs) introduced to the wastewater treatment plants.Dissolved and adsorbed PAHs were detected in the centralized w...Increased attention has been given to the fate of pollutants such as polycyclic aromatic hydrocarbons (PAHs) introduced to the wastewater treatment plants.Dissolved and adsorbed PAHs were detected in the centralized wastewater treatment plant of a chemical industry zone in Zhejiang Province,China.The most abundant PAHs were the low molecular weight PAHs (e.g.,Acy,Ace,Flu and Phe),accounting for more than 80% of the total 16 PAHs in each treatment stage.Phase partitioning suggested that the removal of PAHs in every treatment stage was influenced greater by the sorption of particles or microorganisms.The removal efficiencies of individual PAHs ranged between 4% and 87% in the primary sedimentation stage,between 1% and 42% in anaerobic hydrolysis stage,between <1% and 70% in aerobic bio-process stage,between 1.5% and 80% in high-density clarifier stage,and between 44% and 97% in the whole treatment process.Mass balance calculations in primary stage showed significant losses for low molecular weight PAHs and relatively good agreements for high molecular weight PAHs as well as in anaerobic hydrolysis,high-density clarifier stage and sludge stream for most PAHs.Great gains of 60%-150% were obtained for high molecular weight PAHs in aerobic bio-process stage due to biosorption and bioaccumulation.Our investigations found that PAHs entering the wastewater treatment plant (WWTP) could be derived from the dyeing chemical processes as the byproducts,and the contribution supported by the largest dyeing chemical group was up to 48%.展开更多
文摘In order to enhance the efficiency of aerobic digestion, the excess sludge was irradiated by low intensity ultrasound at a frequency of 28 kHz and acoustic intensity of 0.53 W/cm^2. The results show that the sludge stabilization without ultrasonic treatment can be achieved after 17 d of digestion, whereas the digestion time of ultrasonic groups can be cut by 3-7 d. During the same digestion elapsing, in ultrasonic groups the total volatile suspended solid removal rate is higher than that in the control group. The kinetics of aerobic digestion of excess sludge with ultrasound can also be described with first-order reaction.
文摘Ultrasound (US)-induced cavitation is an effective way in oxidizing organic contaminants in wastewater either as the independent operation unit or in combination with other oxidation methods. In this paper, black liquor and filtrate after acidifying and settling were sonicated. The effect of working parameters on ultrasonic degradation of black liquor, such as different combination methods, frequency, power supply, initial concentration, pH, duration time, ionic strength and catalyst were studied. The results were as follows: (1) At the conditions of 40kHz, 100W, 4h, pH at 6 and temperature 30?℃, utilizing US/US-H2O2/US-Fenton, weak-orange filtrate turned to colloid with the increase of time and little sediment produced after settling. Especially filtrate came to be milk white collides and upper water approached to nearly achromatic by US-Fenton. Compared with the US, US-H2O2/US-Fenton COD (Chemical oxidation demand) removal ratio can increase 15%, 30% respectively. Because of more hydroxyl radicals produced in the reaction process; (2) At the condition of 100W and 4h, the degradation efficiency of black liquor was better at 40kHz over at 20kHz. Moreover black liquor can be biodegraded easily. Those based on that the big molecule of contaminants in aqueous solution can be changed into the little molecule with ultrasound (3) At the condition of 40kHz and 4h, the COD removal ratio of black liquor was more higher at 60W than at 80W, while the removal ratio of COD at 60W was nearly close to the ratio at 100W; (4) The initial concentration of black liquor influenced the effect of sonochemical degradation; (5) The variation of pH had no effect on degradation; (6) The longer the duration time, the greater the removal ratio of COD. But this ratio increased slowly after 4h; (7) Adding 0.2g/L NaCl to change the ionic strength of the black liquor, the COD removal ratio can increase 10%; (8) The degradation rates increased by the coexistent catalysts of TiO2, Co2+ and Ag+.
基金Project (50278101) supported by the National Natural Science Foundation of China Project( CSTC, 2005AB7030)supported by Chongqing Key Technologies Research and Development Program
文摘An advanced sludge reduction process, i.e. sludge reduction and phosphorous removal process, was developed. The results show that excellent sludge reduction and biological phosphorous removal can be achieved perfectly in this system. When chemical oxygen demand ρ（COD） is 332 - 420 mg/L, concentration of ammonia p（NH3-N） is 30 - 40 mg/L and concentration of total phosphorous p（TP） is 6.0 -9.0 mg/L in influent, the system still ensures ρ（COD）〈23 mg/L, ρ（NH3-N）〈3.2 mg/L and ρ（TP）〈0. 72 mg/L in effluent. Besides, when the concentration of dissolved oxygen ρ（DO） is around 1.0 mg/L, sludge production is less than 0. 140 g with the consumption of 1 g COD, and the phosphorous removal exceeds 91 %. Also, 48.4% of total nitrogen is removed by simultaneous nitrification and denitrification.
文摘The community of Figuig is located in a desert area, east of Morocco. It is characterized by an arid climate. Part of the aquifers of the area has a high salinity which creates even worst conditions for the use of the scarce water available in the area. Therefore, it is essential to develop new water resources, especially for agriculture. For this reason, reclaiming wastewater for agricultural use is an essential strategy to increase water resources. The studied system is a wastewater treatment plant （WWTP） with stabilisation ponds; it treats a part of the wastewater of Figuig. The monitoring of the WWTP will allow to the physico-chemical and biological characterization of the treated water, and then, to verify two principal points： （1） the physico-chemical and pathogen parasites elimination; （2） the possibility of the treated water reuse in agricultural irrigation. The reductions recorded at the WWTP show a relatively preferment operation with an average decrease of 3.17 Ulog for faecal coliforms and 50-60% for organic matter. It was observed that the taxonomic density is slow in the WWTP; observed species are generally Cyanobacteria, Euglénophycea and Chlorophycea characteristic of eutrophic water sources.
文摘The present study aims to monitor and assess the water quality of the Bezerra River located in the Western Brazilian Parana state. For the monitoring of river waters, six samplings were established per month during one year. As indicators of the water quality, physico-chemical parameters such as water temperature, pH, turbidity, dissolved oxygen and COD （chemical oxygen demand） were chosen, as well as trace and majority element concentrations. It is noteworthy that the mean annual values of conductivity, turbidity and COD have progressively increased along the river with maximum values after the Cascavel western sewage treatment plant. Only 13 elements were found in the six collection points, but the metallic elements Cr, Mn, Fe, Cu and Zn have shown concentrations above the maximum limits recommended by Brazilian environmental legislation, suggesting the presence of highly polluting anthropogenic sources. Correlation analyses were used to determine the spatio-variability of water quality variables. The six collection sites were grouped into two clusters, with the element composition in the first cluster （sites 1, 2 and 6） being due to strong anthropogenic activities. The study of the Bezerra River water quality could help to develop municipal environmental policies and help with the management of water conservation in the Bezerra River basin.
基金support to this study provided by National Key Technology R&D Program of China (2008BAC32B06)the National Natural Science Foundation of China (21076188,20836008, 20976158,20990221 & 21076189)the Key Innovation Team for Science and Technology of Zhejiang Province of China (2009R50047)
文摘Increased attention has been given to the fate of pollutants such as polycyclic aromatic hydrocarbons (PAHs) introduced to the wastewater treatment plants.Dissolved and adsorbed PAHs were detected in the centralized wastewater treatment plant of a chemical industry zone in Zhejiang Province,China.The most abundant PAHs were the low molecular weight PAHs (e.g.,Acy,Ace,Flu and Phe),accounting for more than 80% of the total 16 PAHs in each treatment stage.Phase partitioning suggested that the removal of PAHs in every treatment stage was influenced greater by the sorption of particles or microorganisms.The removal efficiencies of individual PAHs ranged between 4% and 87% in the primary sedimentation stage,between 1% and 42% in anaerobic hydrolysis stage,between <1% and 70% in aerobic bio-process stage,between 1.5% and 80% in high-density clarifier stage,and between 44% and 97% in the whole treatment process.Mass balance calculations in primary stage showed significant losses for low molecular weight PAHs and relatively good agreements for high molecular weight PAHs as well as in anaerobic hydrolysis,high-density clarifier stage and sludge stream for most PAHs.Great gains of 60%-150% were obtained for high molecular weight PAHs in aerobic bio-process stage due to biosorption and bioaccumulation.Our investigations found that PAHs entering the wastewater treatment plant (WWTP) could be derived from the dyeing chemical processes as the byproducts,and the contribution supported by the largest dyeing chemical group was up to 48%.
