جستجوی مقالات مرتبط با کلیدواژه « anaerobic digestion » در نشریات گروه « پزشکی »

Increasing energy consumption has created an energy crisis in the world. Fossil fuels are limited and depleting. Biogas is considered a fuel that has attracted the attention of researchers. To increase biogas production, different pretreatments have been utilized. The purpose of this study was to investigate the optimal mixing ratio of Municipal Solid Waste (MSW) and Sewage Sludge (SS), as well as the effects of various conditions of alkaline pretreatment on biodegradability of wastes and the amount of biomethane production.

This study was done in a laboratory digester with 1 L volume at 37 °C with different concentrations of NaOH in a completely randomized design. Biogas volume, methane volume, and changes in pH were measured daily. Measurement parameters in the anaerobic digestion including total solids, volatile solids, and carbon and nitrogen content in the feedstock were determined according to the APHA standard methods.

The optimal mixing ratio of MSW to SS was 60:40 with the highest methane yield of 254.87 mL/g VS. Next, the effects of 2, 6, and 10% NaOH concentrations were evaluated on the amount of gas produced, indicating that 6% NaOH concentration significantly improved waste decomposition. Methane production, VS, and TS removal were compared to the control treatment, and there were increases of 30, 27.94, and 27.25%, respectively.

The results showed that the mixing ratio of MSW to SS at 60:40 with 6% NaOH improves the decomposition of organic wastes and increases biomethane production. 

Energy recovery from waste is a proper way to waste management and energy production from foods waste. Anaerobic digestion of the waste is a suitable way to produce clean energy. This study aimed to investigate the anaerobic digestion of food waste and methane production by thermal and thermo-chemical pretreatments at a temperature of thermophilic (55 ˚C) in the Batch Leach Bed Reactor with Down Flow reactor (LBR DF).
In the present study, the food waste collected from Restaurant of Bu-Ali Sina University and autoclaving and microwave pretreatment was performed before feeding LBR DF. In the thermal pretreatments, homogeneous mixture of food waste pretreated using autoclave and microwave. In the thermo-chemical pretreatments, initially, food waste pretreated using NaOH 5N for 60 minutes and then pretreated using autoclave and microwave. LBR DF was launched at thermophilic temperature and SCOD, TCOD, TS and VS values were measured before loading and at the end of tests. By using MATLAB software, the cumulative methane was fitted on modified Gompertz model and B0, Rm and values were determined for all experiments.
According to the results, the best results was in microwave along with NaOH 5N pretreatment that SCOD / TCOD value increased to the amount of 82.25%, methane production to the amount of 39.98 l, TSremoved and VSremoved to the amounts of 6.01% and 7.1% respectively. In addition, lowest of value and highest of Rm value was observed in microwave along with NaOH 5N pretreatment to the amounts of 3.38 (day) and 1.8 (l/day) respectively.
Generally, thermo-chemical pretreatment have the better performance than the thermal pretreatment and without pretreatment. Thermo-chemical pretreatment causes more damage the compounds of food waste and thereby increases the amount of SCOD / TCOD%, TSremoved, VSremoved and methane production.

Waste leachate contains hazardous organic compounds such as nitrogen compounds and high concentrations of poisonous compounds; the remediation of these pollutants from the environment is considered as a global problem. These pollutants make serious environmental problems through their penetration into groundwater and bioaccumulation. Therefore, leachate treatment is essential with suitable and appropriate methods. Anaerobic digestion is considered as one of the most cost-effective methods for this mean. This study aimed to evaluate the efficiency of an anaerobic digester in simultaneous removal of chemical oxygen demand (COD) and TKN from landfill leachate during the process of anaerobic co-digestion for landfill leachate and fresh cow dung.
In this study, landfill leachate of Mashhad and cow dung was mixed in 3/1, 1/1 and 1/3 ratios. These treatments were exposed under anaerobic digestion with same conditions such as environmental temperature. COD and TKN were measured at the beginning and the end of the process.
In the control treatment, COD decreased about 5% and the reduction of TKN was 9.09%. Whilst COD reduction was about 65%, 75%, and 70% in the treatments of 3/1, 1/1 and 1/3 Ratio respectively. Also, TKN decreased 33.26, 82.16 and 84.73% in the 3/1, 1/1 and 1/3 Ratio correspondingly.
The results of this study indicated that the applied method is an efficient and economical approach for elimination of COD and TKN from waste leachate. Because it not only is considered as an environmentally friendly method for this regard, but also it will also make economic benefits from methane production.

Introduction and Energy consumption is on a rapidly growing trend in the world. Accordingly, the non-renewable energy sources are expected to be run out in the future. This issue has resulted in the establishment of efforts targeted toward the development of new energy-generating methods around the world. Biogas energy is one of the new and clean energies that is produced from the anaerobic digestion of biomass wastes. Anaerobic digestion is a cost-effective and environment-friendly method, which facilitates fertilizer and biogas production as well as landfill leachate treatment. Given the high environmental hazards of leachate and its mixture with animal wastes, the present study aimed to estimate the possibility of producing biogas in various mixture ratios.
In this pilot-scale experimental study, the landfill leachate of Mashhad, Iran, were mixed with caw fresh dung in different ratios, but same conditions, under anaerobic digestion. This was conducted to consider the ability to produce methane gas in different proportions and landfill leachate. At the beginning and end of the project, the parameters of EC, pH, VS, TS, COD, TOC, P, K, N, and Na were measured. Additionally, the composition of the gases produced under different operating conditions was analyzed using gas chromatography mass spectrometry.
Gas production began three weeks after uploading and continued for five weeks. The analysis of gas production in three ratios was indicative of the CH4 production in all three proportions. In this regard, 1/1 ratio produced the highest percentage of CH4. No gas production was observed in the two months of study. Other physical and chemical parameters, such as COD, TS, TKN, and TOC were reduced in the given mixtures during the biogas production procedure. For instance, the case with 1/1 ratio, which showed the best results, had almost 80% decrease in the given parameters. However, no gas production or change of parameters were observed in the control sample (leachate), which was examined for two months.
The findings of the study revealed the possibility of producing biogas out of the mixture of waste leachate and animal wastes. Biogas reduces the risk of waste leachate disposal to the environment and facilitates the production of fertilizers containing nutrients (e.g., Na, K, N, and P), which are standard regarding such parameter as pH, EC, C/N, and reduced VS. Moreover, these gases are cost-effective and environment-friendly.

Background and Energy recovery from waste is an appropriate method for waste management and energy production from food waste. Energy production through waste incineration produces significant emission which is a critical threat for environment. Anaerobic digestion of the waste is a suitable way to produce clean energy. This study aimed to investigate the anaerobic digestion from food waste using microwave pretreatments in different levels of power and time that eventually increase anaerobic digestion and produce methane.
The food waste was collected from the restaurant in Bu-Ali Sina University and microwave (MW) treatment was performed before feeding reactor. Pretreatment process of the food waste was done by a domestic MW (P= 450 and 630 W) in different radiation times (100, 200 and 300 s). Reactors at mesophilic temperature (37°C) were launched for 15 days and SCOD and TCOD values were measured before loading and at the end of the tests. Using MATLAB software, the cumulative methane values were fitted on exponential, modified Gompertz and logistic models and the best model was determined in terms of the highest R2 and lowest RMSE and SSE amounts.
Based on the results, the best performance of anaerobic digestion, the maximum percentage of AWT IMAGE and the highest rate of methane production were obtained in 630 W microwave power and 300 s exposure time. Also, cumulative methane production was fitted using exponential, modified Gompertz and logistic models.
Increasing the power and exposure time enhanced solubility and the AWT IMAGE of the food waste. By increase in AWT IMAGE the daily biogas and methane productions also increase. The TSremoved and VSremoved values increase when the microwave power and exposure time increased. Also, the modified Gompertz model is a comprehensive and flexible model that is well fitted the experimental data and modified Gompertz model results in the highest R2 value and the lowest RMSE and SSE.

Disposal of pharmaceutical compounds to environment as an emerging pollutants cause significantly concerns and it is necessary to use the new methods of sewage treatment for removal of these compounds. The aim of this study was to feasibility using of O3/H2O2 process on diclofenac impact on the specific methanogenic activity of anaerobic biomass. Twelve anaerobic digestions at batch mode carried out before and after using an O3/H2O2 process at the 500ml reactors with 30% anaerobic biomass and 70% substrate. The replacement liquid method was used. Duration of each test was range 8-16 days. Cumulative methane production in concentrations of 25, 50, 100, 175, 250 and 350 mg/l of diclofenac were 764.24, 845.42, 82, 102.09, 25.42 and 1.64 ml respectively. These productions were 8.61, 26.65, 4.1 and 4.1 ml in concentrations of 25, 100, 250 and 350 mg/l respectively after 180 min pretreatment with O3/H2O2 process and demonstrate that methane production was reduced in all concentrations after ozonation process. It is concluded that the high concentration of diclofenac has inhibition effects on the anaerobic digesters and after the ozonation process pretreatment on diclofenac, the intermediates compounds can be produced which probably had very diverse effects on the anaerobic bacteria in digesters and also had a lower biodegradability.