Investigation of Biogas Production Process by the Mixture of Landfill Leachate and Animal Waste

Introduction and purpose: 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. Methods: 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. Results: 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. Conclusion: 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

Investigation of anaerobic co- digestion process effects on the removal of COD and TKN from Mashhad’s landfill leachate and cow dung

Introduction: 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. Materials and Methods: 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. Results: 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. Conclusion: 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