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A B S T R A C TIn this study, a new approach was developed for the preparation of magnetic activated carbon (MAC) in which a nanocomposite with the mass ratio of 1:8 (Fe 3 O 4 :AC) was prepared using commercial activated carbon (AC) treated with nitric acid and magnetite nanoparticles synthesized by co-precipitation method. The MAC was characterized by scanning electron microscopy, nitrogen adsorption isotherm at 77 K, vibrating sample magnetometer, X-ray diffraction, and Fourier transform infrared spectroscopy. The results showed that MAC had desirable magnetic properties and pure Fe 3 O 4 nanoparticles were successfully synthesized and added to AC. The nanocomposite was successfully used as a separable adsorbent for removing Pb 2+ and Cd 2+ from aqueous solutions. The adsorption performances were evaluated by Langmuir and Freundlich isotherms, which showed the data were well fitted to the Langmuir model. The adsorbent showed good adsorption capacities of 49.8 and 86.2 mg/g for cadmium and lead at the initial pH levels of 6.0 and 5.0, respectively. Kinetic studies were performed using pseudo-first-order and pseudo-second-order kinetic models and the results demonstrated that the adsorption process followed secondorder model. Thermodynamics of the adsorption of lead and cadmium onto MAC was also studied with results that showed the adsorption process was endothermic and spontaneous. Adsorption performance of MAC was also evaluated using battery manufacture wastewater samples and removal efficiencies of 91.4 and 96.6% were obtained for the removal of Cd 2+ and Pb 2+ , respectively.

Anaerobic digestion (AD) of organic municipal solid waste (OMSW) is considered as a key element in sustainable municipal waste management due to its benefits for energy, environment, and economy. This process reduces emission of greenhouse gases, generates renewable natural gas, and produces fertilizers and soil amendments. Due to its advantages over other treatment methods and waste-to-energy technologies, anaerobic digestion has attracted more attention so that numerous research works in this area are performed. In this chapter, an overview of previous studies on anaerobic digestion using OMSW as the feedstock is presented. First, the principals of anaerobic digestion including chemical and biological pathways and microorganisms responsible for different steps of the process are discussed. Factors influencing the efficiency of the process such as temperature, pH, moisture content, retention time, organic loading rate and C/N ratio are also presented in this chapter. Different methods of pretreatment applied to enhance biogas production from anaerobic digestion of municipal solid waste are also discussed.