Impacts of Nano-ZnO in Municipal Solid Waste Landfills.

Nano-ZnO enter landfills mostly through disposal of cosmetics, UV protection and catalysts. In this study, the impact of ZnO on municipal solid waste landfills was investigated. Two conventional and two bioreactors were operated using real MSW samples at mesophilic temperature (35 ºC). Results showed that there were no significant differences on biogas and methane production between the reactors with or without nano-ZnO addition. Related with the operation types, there were slight differences observed due to the nano-ZnO concentrations during the first 140 days of this ongoing project

The fate and behaviour of nano ZnO during waste stabilization in landfills

As a result of rapid development in nanotechnology in recent years, the number of commercially available nanotechnology products has exceeded one thousand. The extensive use of NMS in commercial consumer products and their eventual release to the environment through various pathways have recently raised concern about the potential impacts of these materials on the environment and human health. It is estimated that more than 50 % of nanometarials (NMS) used in cosmetics, health, electronic, textile and water treatment sectors, will ultimately be sent to landfills for final disposal after their useful lifes are over. It is reported in the literature that research activities have mostly focused on the ecotoxicity of NMS. However, the fate and behavior of NMs during waste stabilization in landfills, which play a crucial role in integrated waste management systems, is still unknown. In particular, little data is available on how these materials behave in an integrated waste management system under changing environmental conditions. The transport behavior of nanoparticles from the solid waste into leachate is also dependent on the properties of landfill leachate and the environmental factors. Therefore, it is important to investigate the fate of nanoparticles in landfills to understand and control the environmental impacts that may occur in advance. Especially, their potential impacts on waste stabilization, landfill gas production, geomembranes and the risk for the groundwater and surface water contamination are still unknown. Therefore, the main objective of this study is to provide greatly needed fundamental information and insight into the fate and impact of nano ZnO during waste stabilization in landfills. For this purpose, 70 liter lab-scale simulated conventional landfill and bioreactor landfill lysimeters were loaded with fresh municipal solid waste obtained from a real landfill site and the reactors were uniformly mixed with pre-known amounts of nano ZnO. Samples were regularly taken from leachate and gas phases, to assess the impact of nano ZnO on different phases of waste stabilization. Daily and cumulative biogas and methane production values of each reactor were monitored to determine the impact of nano ZnO on gas production

A fuzzy logic based model to predict the effects of ZnO nanoparticles on methane generation in landfills

Nano-ZnO enters landfills mostly through disposal of cosmetics, sunscreens and catalysts. However, its effects on waste degradation are still unclear. In this paper, a fuzzy-based model is proposed to predict biogas and methane production from a bioreactor landfill in the presence of ZnO nano-particles. Eight deterministic inputs (pH, RedOx potential, chemical oxygen demand, volatile fatty acids, alkalinity, Zn concentration, Zn background and recirculation flow rate) were identified as antecedent variables. Two outputs, or consequents, were chosen: methane production rate and methane concentration in biogas. Antecedents and consequents were linked by 30 IF-THEN rules, which stated the effects of the input parameters in a linguistic form. The fuzzy model was tested on the data of a lab-scale study simulating a bioreactor landfill with 0.15 g of added nano-ZnO/kg of waste. The fuzzy model showed good performance in the prediction of methane generation, also compared to the commonly used Gompertz equation. The results confirm the potential use of fuzzy macro-approach for complex processes taking place in landfill environments with unusual operating conditions

Development of Fuzzylogic model to predict the effects of ZnO nanoparticles on methane production from simulated landfill

Nano-ZnO enters landfills mostly through disposal of cosmetics, sunscreens and catalysts. However, its effects on waste degradation are still unclear. In this paper, a fuzzy-based model is proposed to predict biogas and methane production from simulated bioreactor landfill with and without ZnO nanomaterials. Eight deterministic inputs (pH, RedOx potential, chemical oxygen demand, volatile fatty acids, alkalinity, Zn concentration, Zn background and leachate recirculation flow rate) were identified as antecedent variables. Two outputs, or consequents, were chosen: biogas production rate and methane fraction. Antecedents and consequents were linked by 66 IF-THEN rules, which stated the effects of the input parameters in a linguistic form. The fuzzy model was tested on the data of a lab-scale study simulating a bioreactor landfill with 100 mg of added nano-ZnO per kg of dry waste. Experimental results indicated that the addition of nano-ZnO resulted in a reduction of methane generation by about 30%.The fuzzy model showed good performance in the prediction of methane generation; in addition, the comparison with the commonly used Gompertz equation showed that the fuzzy model is more consistent with the data. Fuzzy modelling could easily handle the Zn concentration together with other parameters and it highlighted the importance of including this input in the model. The modelling results confirmed the high potential of fuzzy macro-approach in the modelling of very complex processes taking place in landfill environments under different operating conditions

Bypass during Liver Transplantation: Anachronism or Revival? Liver Transplantation Using a Combined Venovenous/Portal Venous Bypass-Experiences with 163 Liver Transplants in a Newly Established Liver Transplantation Program

Introduction. The venovenous/portal venous (VVP) bypass technique has generally become obsolete in liver transplantation (LT) today. We evaluated our experience with 163 consecutive LTs that used a VVP bypass. Patients and Methods. The liver transplant program was started in our center in 2010. LTs were performed using an extracorporal bypass device. Results. Mean operative time was 269 minutes and warm ischemic time 43 minutes. The median number of transfusion of packed cells and plasma was 7 and 14. There was no intraoperative death, and the 30-day mortality was 3%. Severe bypass-induced complications did not occur. Discussion. The introduction of a new LT program requires maximum safety measures for all of the parties involved. Both surgical and anaesthesiological management (reperfusion) can be controlled very reliably using a VVP bypass device. Particularly when using marginal grafts, this approach helps to minimise both surgical and anaesthesiological complications in terms of less volume overload, less use of vasopressive drugs, less myocardial injury, and better peripheral blood circulation. Conclusion. Based on our experiences while establishing a new liver transplantation program, we advocate the reappraisal of the extracorporeal VVP bypass

Effects of nano- ZnO on biogas generation from simulated landfills.

Extensive use of nanomaterials in commercial consumer products and industrial applications eventually leads to their release to the waste streams and the environment. Nano-ZnO is one of the most widely-used nanomaterials (NMs) due to its unique properties. It is also known to impact biological processes adversely. In this study, the effect of nano-ZnO on biogas generation from sanitary landfills was investigated. Two conventional and two bioreactor landfills were operated using real MSW samples at mesophilic temperature (35 °C) for a period of about 1 year. 100 mg nano-ZnO/kg of dry waste was added to the simulated landfill reactors. Daily gas production, gas composition and leachate Zn concentrations were regularly monitored. A model describing the fate of the nano-ZnO was also developed. The results obtained indicated that as much as 99% of the nano-ZnO was retained within the waste matrix for both reactor operation modes. Waste stabilization was faster in simulated landfill bioreactors with and without the addition of nano-ZnO. Moreover, the presence of the nano-ZnO within the waste led to a decrease in biogas production of about 15%, suggesting that the nano-ZnO might have some inhibitory effects on waste stabilization. This reduction can have potentially significant implications on waste stabilization and the use of biogas from landfills as a renewable energy source

Effects of nano- ZnO on biogas generation from simulated landfills

Extensive use of nanomaterials in commercial consumer products and industrial applications eventually leads to their release to the waste streams and the environment. Nano-ZnO is one of the most widely-used nanomaterials (NMs) due to its unique properties. It is also known to impact biological processes adversely. In this study, the effect of nano-ZnO on biogas generation from sanitary landfills was investigated. Two conventional and two bioreactor landfills were operated using real MSW samples at mesophilic temperature (35 °C) for a period of about 1 year. 100 mg nano-ZnO/kg of dry waste was added to the simulated landfill reactors. Daily gas production, gas composition and leachate Zn concentrations were regularly monitored. A model describing the fate of the nano-ZnO was also developed. The results obtained indicated that as much as 99% of the nano-ZnO was retained within the waste matrix for both reactor operation modes. Waste stabilization was faster in simulated landfill bioreactors with and without the addition of nano-ZnO. Moreover, the presence of the nano-ZnO within the waste led to a decrease in biogas production of about 15%, suggesting that the nano-ZnO might have some inhibitory effects on waste stabilization. This reduction can have potentially significant implications on waste stabilization and the use of biogas from landfills as a renewable energy source

Bypass during Liver Transplantation: Anachronism or Revival? : Liver Transplantation Using a Combined Venovenous/Portal Venous Bypass ; Experiences with 163 Liver Transplants in a Newly Established Liver Transplantation Program

Introduction. The venovenous/portal venous (VVP) bypass technique has generally become obsolete in liver transplantation (LT) today. We evaluated our experience with 163 consecutive LTs that used a VVP bypass. Patients and Methods. The liver transplant program was started in our center in 2010. LTs were performed using an extracorporal bypass device. Results. Mean operative time was 269 minutes and warm ischemic time 43 minutes. The median number of transfusion of packed cells and plasma was 7 and 14. There was no intraoperative death, and the 30-day mortality was 3%. Severe bypass-induced complications did not occur. Discussion. The introduction of a new LT program requires maximum safety measures for all of the parties involved. Both surgical and anaesthesiological management (reperfusion) can be controlled very reliably using a VVP bypass device. Particularly when using marginal grafts, this approach helps to minimise both surgical and anaesthesiological complications in terms of less volume overload, less use of vasopressive drugs, less myocardial injury, and better peripheral blood circulation. Conclusion. Based on our experiences while establishing a new liver transplantation program, we advocate the reappraisal of the extracorporeal VVP bypass